Hybrid electrical vehicle control system and method

<u>FIELD</u>

0001Embodiments of the present disclosure generally relate to a vehicle technology filed, and more particularly, to a hybrid electrical vehicle and a control method for the hybrid electrical vehicle.

<u>BACKGROUND</u>

0002A hybrid electrical vehicle (HEV) refers to a vehicle equipped with two types of power sources, i.e., a thermal power source (generating power by a conventional gasoline engine or diesel engine) and an electric power source (generating power by a battery and an electric motor). With disposing the electric motor in the hybrid electrical vehicle, the power system can be adjusted in a flexible manner according to the practical working conditions of the hybrid electrical vehicle and the engine can keep operating in regions with the optimum comprehensive properties, thus reducing the oil wear and the emission.

0003Some of the existing hybrid electrical vehicles adopt a series-parallel hybrid power system, which is characterized by disposing one mechanical gear shifting mechanism in the internal combustion engine system and the electric motor drive system respectively. The two mechanical gear shifting mechanisms are connected via a planetary wheel structure, such that the rotating speed relationship between the internal combustion engine system and the electric motor drive system can be adjusted synthetically.

0004However, the driving mode of the conventional hybrid electrical vehicle is simple and the driver cannot select the driving mode according to individual driving habits, the long term and constant driving condition. For example, considering that Asians often live in concentrated districts and have a relatively constant driving path to and from work which is mostly less than 50km, it is very appropriate to drive in a pure electric driving mode. However, the conventional hybrid electrical vehicle reduces the oil wear by adjusting the engine via the electric motor instead of eliminating the oil wear completely. Therefore, the conventional hybrid electrical vehicle generally does not have the manual electrical vehicle (EV) mode switching function. Even if the conventional electrical vehicle has the manual EV mode switching function, the pure electric driving mileage of the vehicle is short due to the limitation of the electric quantity of the battery.

0005Moreover, since the purpose of the conventional hybrid electrical vehicle is to reduce the oil wear, the electric motor and engine with a high power and a high torque will not be selected, and thus the power performance of the hybrid electrical vehicle is low and the driving fun is greatly reduced. For example, some hybrid electrical vehicles take more than 10s to accelerate from 0 to 100km/h and provide poor high speed performance.

0006Furthermore, some conventional hybrid electrical vehicles adopt the series-parallel structure and the method for controlling the series-parallel structure, and the strategy in which the engine drives the vehicle solely does not exist. In other words, even if in the relatively economical working regions, the engine still charges the battery via a first electric motor MG1 and adjusts the rotating speed thereof via the first electric motor MG1 to implement the gear shift; moreover, in a heavy load acceleration condition, due to the limitation of the battery capacity, only if a part of the power of the engine is used to drive the first electric motor MG1 to generate power, can the engine provide the electric energy to the second electric motor MG2 together with the battery. The above facts reduce the driving efficiency of the engine. In addition, in the engine stop-start strategy, the predetermined demanded power and speed threshold are relatively low, and the speed switching condition is set as a point instead of an interval, thus resulting in premature and frequent start of the engine.

0007In addition, some conventional hybrid electrical vehicles do not adopt the plug-in structure due to the small capacity of the battery, and the electric quantity of the battery is converted from the gasoline totally, thus increasing the cost. Moreover, the series-parallel structure is complex and it is difficult to match with the Electronic Continuously Variable Transmission (ECVT), and the cost is high.

<u>SUMMARY</u>

0008Embodiments of the present disclosure seek to solve at least one of the problems existing in the related art to at least some extent.

0009In the related art, a control strategy of a conventional hybrid electrical vehicle may be: due to the voltage and the electrical quantity of the power battery, the hybrid electrical vehicle cannot operate in the EV mode, thus limiting the driving range of the EV mode; at the same time, due to the limited power of the power battery, the vehicle speed achieved in the EV mode is not very high, and the state of the power battery causes that the maximum vehicle speed in the EV mode to be different, and it is hard to summarize the operation rule, and if the selected power and torque are small related to the electric motor, the operating condition of the EV mode is limited, and the most road driving conditions cannot meet. Based on the above three factors, the proportion of the EV mode in the operation process of the hybrid vehicle is not very large, and it is easily to switch to the HEV mode, which cannot reduce the fuel consumption and the emission in the urban condition. Furthermore, in the related art, the hybrid vehicle can switch between the EV mode and the HEV mode according to the SOC (State Of Charge) of the power battery and the requirement power of the vehicle, which causes the engine to start and to stop frequently, thus reducing the life of the starter motor, increasing the running noise and reducing the driving comfort.

0010An object of the present disclosure is to provide a control system of the hybrid electrical vehicle.

0011Another object of the present disclosure is to provide a control method for a hybrid electrical vehicle.

0012To achieve above objects, embodiments of a first aspect of the present disclosure provide a control system for a hybrid electrical vehicle, including: a transmission device connected with wheels of the hybrid electrical vehicle; an engine power subsystem connected with the transmission device; a motor power subsystem connected with the transmission device; and a control module configured to control the hybrid electrical vehicle to operate in a corresponding work mode by controlling the engine power subsystem and the motor power subsystem, wherein the work mode comprise an electrical mode to a hybrid electrical mode, and to control the hybrid electrical vehicle to switch to the hybrid electrical mode from the electrical mode if a maximum allowable discharge power of the power battery of the motor power subsystem is less than or equal to a first power threshold and a current electric quantity of a power battery of the motor power subsystem is less than or equal to a first electric quantity threshold, or if the current slope detected by the hybrid electrical vehicle is greater than or equal to a maximum slope.

0013With the control system of the hybrid electrical vehicle according to embodiments of the present disclosure, the engine power subsystem and the motor power subsystem are connected in parallel, which can enable the power between the engine power subsystem and the motor power subsystem to match easily, improve the transformation efficiency, and effectively improve an energy utilization factor as compared with a series connection structure adopted in a power system of the conventional hybrid electrical vehicle. Moreover, the parallel connection is simple and can avoid a complex ECVT match in a series-parallel connection, which reduces a risk of driving uncomfortably caused by the match failure, and thus the economy of the hybrid electrical vehicle is greatly improved on the premise of ensuring the power performance of the hybrid electrical vehicle.

0014In order to achieve the above objects, embodiments of a second aspect of the present disclosure provide a control method for a hybrid electrical vehicle, including: controlling the hybrid electrical vehicle to work in a corresponding work mode by controlling the engine power subsystem and the motor power subsystem, when the hybrid electrical vehicle is running, wherein the work mode comprise an electrical mode to a hybrid electrical mode; detecting a current electric quantity of a power battery of the motor power subsystem, a maximum allowable discharge power of the power battery of the motor power subsystem and a current slope of the hybrid electrical vehicle; and controlling the hybrid electrical vehicle to switch to the hybrid electrical mode from the electrical mode if a maximum allowable discharge power of the power battery of the motor power subsystem is less than or equal to a first power threshold and a current electric quantity of a power battery of the motor power subsystem is less than or equal to a first electric quantity threshold, or if the current slope detected by the hybrid electrical vehicle is greater than or equal to a maximum slope.

0015With the method according to embodiments of the present disclosure, by providing a plurality of running modes, a driving requirement of the user in different working conditions can be satisfied, i.e., not only pure electric consumption in a city working condition can be satisfied, but also power performance requirement in a suburban district working condition can be satisfied, and thus the hybrid electrical vehicle can be driven according to subjective operation intentions of the user and the driving fun is improved. Moreover, the method for controlling the hybrid electrical vehicle is simple and reliable and is easy to operate by users. Furthermore, the predetermined starting value is large, which can drop the proportion of the engine-driven participation in the urban condition, reduce the fuel consumption emissions, and avoid the frequent start-stop phenomenon of the engine, thus increasing the starter life, reducing the traffic noise, and improving the driving comfort.

0016Additional aspects and advantages of embodiments of present disclosure will be given in part in the following descriptions, become apparent in part from the following descriptions, or be learned from the practice of the embodiments of the present disclosure.

<u>BRIEF DESCRIPTION OF THE DRAWINGS</u>

0017These and other aspects and advantages of embodiments of the present disclosure will become apparent and more readily appreciated from the following descriptions made with reference to the accompanying drawings, in which: <ul id="ul0001" list-style="none" compact="compact"><li><figref idref="f0001">Fig. 1A</figref> is a schematic diagram of a control system for a hybrid electrical vehicle according to a first embodiment of the present disclosure;</li><li><figref idref="f0001">Fig. 1B</figref> is a schematic diagram of a control system for a hybrid electrical vehicle according to a second embodiment of the present disclosure;</li><li><figref idref="f0001">Fig. 2</figref> is a schematic diagram showing a signal flow of a hybrid electrical vehicle according to an embodiment of the present disclosure;</li><li><figref idref="f0002">Fig. 3</figref> is a flow chart of a control method for a hybrid electrical vehicle in an electrical-economical mode according to an embodiment of the present disclosure;</li><li><figref idref="f0003">Fig. 4</figref> is a flow chart of a control method for a hybrid electrical vehicle in an electrical-sport mode according to an embodiment of the present disclosure;</li><li><figref idref="f0004 f0005">Fig. 5</figref> is a flow chart of a control method for a hybrid electrical vehicle in a hybrid electrical-economical mode according to an embodiment of the present disclosure;</li><li><figref idref="f0006">Fig. 6</figref> is a flow chart of a control method for a hybrid electrical vehicle in an economical manner when the hybrid electrical vehicle is in a hybrid electrical-economical mode according to an embodiment of the present disclosure;</li><li><figref idref="f0006">Fig. 7</figref> is a schematic diagram showing a working region of an engine when a hybrid electrical vehicle is in a hybrid electrical-economical mode according to an embodiment of the present disclosure;</li><li><figref idref="f0006">Fig. 8</figref> is a schematic diagram showing a relationship between a generation power of an electric motor and an electric quantity of a power battery according to an embodiment of the present disclosure;</li><li><figref idref="f0007">Fig. 9</figref> is a flow chart of a control method for a hybrid electrical vehicle in a low power manner when the hybrid electrical vehicle is in a hybrid electrical-economical mode according to an embodiment of the present disclosure;</li><li><figref idref="f0008">Fig. 10</figref> is a flow chart of a control method for a hybrid electrical vehicle in a hybrid electrical-sport mode according to an embodiment of the present disclosure; and</li><li><figref idref="f0009">Fig. 11</figref> is a flow chart of a control method for a hybrid electrical vehicle according to an embodiment of the present disclosure.</li></ul>

<u>DETAILED DESCRIPTION</u>

0018Reference will be made in detail to embodiments of the present disclosure. Embodiments of the present disclosure will be shown in drawings, in which the same or similar elements and the elements having same or similar functions are denoted by like reference numerals throughout the descriptions. The embodiments described herein according to drawings are explanatory and illustrative, not construed to limit the present disclosure.

0019The following description provides a plurality of embodiments or examples configured to achieve different structures of the present disclosure. To simplify the publication of the present disclosure, components and dispositions of the particular embodiment are described in the following, which are only explanatory and not construed to limit the present disclosure. In addition, the present disclosure may repeat the reference number and/or letter in different embodiments for the purpose of simplicity and clarity, and the repeat does not indicate the relationship of the plurality of embodiments and/or dispositions. Moreover, in description of the embodiments, the structure of the second characteristic "above" the first characteristic may include an embodiment formed by the first and second characteristic contacted directly, and also may include another embodiment formed between the first and the second characteristic, in which the first characteristic and the second characteristic may not contact directly.

0020In the description of the present disclosure, unless specified or limited otherwise, it should be noted that, terms "mounted," "connected" and "coupled" may be understood broadly, such as electronic connection or mechanical connection, inner communication between two elements, direct connection or indirect connection via intermediary. These having ordinary skills in the art should understand the specific meanings in the present disclosure according to specific situations.

0021With reference to the following descriptions and drawings, these and other aspects of embodiments of the present disclosure will be distinct. In the descriptions and drawings, some particular embodiments are described to show means of the principles of embodiments according to the present disclosure, however, it should be appreciated that the scope of embodiments according to the present disclosure is not limited. On the contrary, embodiments of the present disclosure include all the changes, alternatives, and modifications falling into the scope of the spirit and principles of the attached claims.

0022In the following, a hybrid electrical vehicle and a control method for a hybrid electrical vehicle are described in detail with reference to drawings.

0023<figref idref="f0001">Fig. 1A</figref> is a schematic diagram of a control system for a hybrid electrical vehicle according to a first embodiment of the present disclosure. As shown in <figref idref="f0001">Fig. 1A</figref>, the control system for the hybrid electrical vehicle includes a transmission device 10, an engine power subsystem 20, a motor power subsystem 30 and a control module 40.

0024The transmission device 10 is configured to drive the wheels 2a and 2b of the hybrid electrical vehicle, the engine power subsystem 20 is connected with the transmission device 10, the motor power subsystem 30 is connected with the transmission device 10. The control module 40 controls the hybrid electrical vehicle to operate in a corresponding work mode by controlling the engine power subsystem 20 and the motor power subsystem 30, wherein the work mode comprises an electrical mode and a hybrid electrical mode, and controls the hybrid electrical vehicle to switch to the hybrid electrical mode from the electrical mode if a maximum allowable discharge power of the power battery of the motor power subsystem is less than or equal to a first power threshold and a current electric quantity of a power battery of the motor power subsystem is less than or equal to a first electric quantity threshold, or if the current slope detected by the hybrid electrical vehicle is greater than or equal to a maximum slope.

0025<figref idref="f0001">Fig. 1B</figref> is a schematic diagram of a control system for a hybrid electrical vehicle according to a second embodiment of the present disclosure. As shown in <figref idref="f0001">Fig. 1B</figref>, the engine power subsystem 20 includes an engine 3 and a gearbox 4, and the motor power subsystem 30 includes an electric motor 5, a gear reducer 6, a power battery 7 and an inverter 8. The engine 3 is connected with the transmission device 10 via the gearbox 4, the electric motor 5 is connected with the transmission device 10 via the gear reducer 6, and the power battery 7 is configured to provide power to the electric motor 5.

0026In an embodiment of the present disclosure, the above hybrid electrical vehicle is a plug-in dual-mode hybrid electrical vehicle, in which the engine 3 is an efficient turbocharged direct injection engine capable of outputting power for driving the vehicle, and the gearbox 4 is a double clutch gearbox capable of transmitting the power output from the engine 3, and the power battery 7 is connected with the inverter 8 via a DC (direct current) bus, and the inverter 8 is connected with the electric motor 5 via an AC (alternating current) three-phase wire, and then electric power and fuel power are coupled at the transmission device 10 and transmitted to the wheels 2a and 2b. The user can select the running mode of the hybrid electrical vehicle via an EV mode selecting button, a HEV mode selecting button and an operating mode selecting knob.

0027In an embodiment of the present disclosure, the working modes of the hybrid electrical vehicle include the hybrid electrical mode (HEV mode) and the electrical mode (EV mode), in which the EV mode includes two running modes such as an electrical-economical mode (EV-eco mode) and an electrical-sport mode (EV-s mode), the HEV mode includes two running modes such as the hybrid electrical-economical mode (HEV-eco mode) and the hybrid electrical-sport mode (HEV-s mode). In other words, the hybrid electrical vehicle includes the electrical-economical mode (EV-eco mode), the electrical-sport mode (EV-s mode), the hybrid electrical-economical mode (HEV-eco mode) and the hybrid electrical-sport mode (HEV-s mode). The EV mode selecting button is configured to select an EV mode manually, the HEV mode selecting button is configured to select a HEV mode manually, and the operating mode selecting knob is configured to switch between an economical mode and a sport mode manually.

0028In an embodiment of the present disclosure, one of the EV mode and HEV mode can be selected and one of the economical mode and sport mode can be selected, and thus four running modes can be obtained by switching between each two modes, i.e., the EV-eco mode, the EV-s mode, the HEV-eco mode and the HEV-s mode can be obtained. In the EV mode, the hybrid electrical vehicle is in a pure electric power mode and the engine is kept out of operation. In the HEV mode, the hybrid electrical vehicle is in a hybrid power mode, and the electric motor cooperates with the engine or drives the engine or adjusts the engine so as to make the engine to operate in a working region with an optimal comprehensive property. In the economical mode, maximum outputs of the electric motor, the engine and the power battery are limited to ensure the electric motor, the engine and the power battery to operate in the most economical region. In the Sport mode, a power performance of the hybrid electrical vehicle is satisfied preferentially, maximum outputs of the electric motor, the engine and the power battery are not limited, such that total power of the power system can be obtained.

0029<figref idref="f0001">Fig. 2</figref> is a schematic diagram showing a signal flow of a hybrid electrical vehicle according to an embodiment of the present disclosure. The control module 40 includes a gear controller (SCU), an electric motor controller (ECN), a battery manager (BMS), an engine controller (ECM), and a transmission controller (TCU). As shown in <figref idref="f0001">Fig. 2</figref>, the gear controller (SCU) is configured to sample a gear signal and an EV/HEV/eco/Sport mode signal and to transmit the gear signal and the EV/HEV/eco/Sport mode signal to the electric motor controller (ECN). The electric motor controller (ECN) checks the EV/HEV/eco/Sport mode signal and forwards the gear signal and the EV/HEV/eco/Sport mode signal to the battery manager (BMS), the engine controller (ECM), the transmission controller (TCU) and a combination instrument. At the same time, the electric motor controller (ECN) performs a corresponding power system control scheme according to different mode strategies and sends an engine stop-start instruction and an engine target torque signal to the engine controller (ECM). The battery manager (BMS) checks the EV/HEV/eco/Sport mode signal and performs a power management strategy. The engine controller (ECM) performs an engine system control scheme and sends a current torque of the engine to the transmission controller (TCU). The transmission controller (TCU) samples a throttle signal, a brake signal and a vehicle speed signal and shifts the gear according to a gear shifting strategy of the gearbox. The combined instrument is configured to display the current EV/HEV/eco/Sport mode.

0030In an embodiment of the present disclosure, the control module 40 controls the hybrid electrical vehicle to switch among the electrical-economical mode, the electrical-sport mode, the hybrid electrical-economical and the hybrid electrical-sport mode according to a driving state of the hybrid electrical vehicle and/or a working state of the power battery.

0031In an embodiment of the present disclosure, as shown in <figref idref="f0002">Fig. 3</figref>, when the hybrid electrical vehicle is in the electrical-economical mode, the control module 40 controls the hybrid electrical vehicle to switch to the hybrid electrical-economical mode from the electrical-economical mode if a current electric quantity of the power battery is less than or equal to a first electric quantity threshold such as 20%, or a maximum allowable discharge power of the power battery is less than or equal to a first power threshold such as 12KW, or a slope detected by the hybrid electrical vehicle is greater than or equal to the maximum slope such as 15%.

0032In other words, in the embodiment as shown in <figref idref="f0002">Fig. 3</figref>, when the hybrid electrical vehicle is driving in the EV-eco mode and no mode switching condition is triggered, the power battery provides power to the electric motor 5 to drive the hybrid electrical vehicle and the engine 3 is kept out of operation. When the HEV mode selecting button is pressed manually, the mode of the hybrid electrical vehicle is switched to the HEV-eco mode; when the operating mode selecting knob is rotated to the Sport mode, the mode of the hybrid electrical vehicle is switched to the EV-s mode; when there is no manual input to the mode selecting buttons, the control module 40 controls the hybrid electrical vehicle to switch to the HEV-eco mode automatically if the current electric quantity of the power battery is less than or equal to a minimum electric quantity threshold such as 20%, or the maximum allowable discharge power of the power battery is less than or equal to a minimum power threshold such as 12KW, or the slope detected by the hybrid electrical vehicle is greater than or equal to the maximum slope such as 15%. In the EV-eco mode, to improve an electric energy consumption efficiency so as to lengthen a driving mileage, a maximum output power of the electric motor is limited, moreover considering an accelerating ability of the hybrid electrical vehicle, and a maximum output torque of the electric motor is not limited. In other words, when the hybrid electrical vehicle is in the EV-eco mode, the control module 40 controls the hybrid electrical vehicle to drive with a limited power.

0033In another embodiment of the present disclosure, as shown in <figref idref="f0003">Fig. 4</figref>, when the hybrid electrical vehicle is in the electrical-sport mode, the control module 40 controls the hybrid electrical vehicle to switch to the hybrid electrical-sport mode from the electrical-sport mode if the current electric quantity of the power battery is less than or equal to the first electric quantity threshold such as 20%, or the maximum allowable discharge power of the power battery is less than or equal to the first power threshold such as 12KW, or the slope detected by the hybrid electrical vehicle is greater than or equal to the maximum slope such as 15%.

0034In other words, in the embodiment as shown in <figref idref="f0003">Fig. 4</figref>, when the hybrid electrical vehicle is driving in the EV-s mode and no mode switching condition is triggered, the power battery provides power to the electric motor to drive the vehicle and the engine is kept out of operation. When the HEV mode selecting button is pressed manually, the hybrid electrical vehicle is switched to the HEV-s mode; when the operating mode selecting knob is rotated to the economical mode, the hybrid electrical vehicle is switched to the EV-eco mode; when there is no manual input to the mode selecting buttons, the control module 40 controls the hybrid electrical vehicle to switch to the HEV-s mode automatically if the current electric quantity of the power battery is less than or equal to the minimum electric quantity threshold such as 20%, or the maximum allowable discharge power of the power battery is less than or equal to the minimum power threshold such as 12KW, or the slope detected by the hybrid electrical vehicle is greater than or equal to the maximum slope such as 15%. In the EV-s mode, the most important task is to obtain better power performance, and thus the output power of the electric motor is not limited.

0035As shown in <figref idref="f0002">Figs. 3</figref> and <figref idref="f0003">4</figref>, when the hybrid electrical vehicle is in the electrical-economical mode or the electrical-sport mode, if a mode switching instruction is input from the user (i.e., the mode switching condition is triggered), the control module 40 controls the hybrid electrical vehicle to switch to the mode corresponding to the mode switching instruction.

0036Therefore, in an embodiment, by selecting the EV mode and the eco/Sport mode, the hybrid electrical vehicle can operate in the EV-eco mode or the EV-s mode. Due to the hybrid electrical vehicle using a plug-in battery charging structure, the capacity of the power battery is increased and larger power and larger torque of the electric motor 5 is selected, the hybrid electrical vehicle in the EV mode can operate in a more powerful manner, thus dealing with all city road conditions, and most suburban road conditions without triggering the automatic mode switch function. Only when the slope detected by the hybrid electrical vehicle is greater than the maximum slope upper limit slope, e.g., 15% (an upper limit slope in EV mode), the hybrid electrical vehicle is automatically switched to the HEV mode, unless the operator manually selects other modes, otherwise the hybrid electrical vehicle can remain in the HEV mode. In the EV-eco mode, the output maximum torque of the electric motor is limited, and the output power of the electric motor is not limited, and thus the climb performance at the low speed and the high efficiency at the high speed can be ensured. In EV-s mode, the maximum torque output of the electric motor and the output power of the electric motor are not limited to ensure the strongest power in the EV mode. The control system of the hybrid electrical vehicle can ensure the dynamic performance and the extend driving range when the hybrid electrical vehicle is in pure electrical driving mode, at the same time meet the driving needs of the hybrid electric cars, which can avoid the high power consumption for a long time so as to improve the electrical efficiency. Furthermore, to ensure that the hybrid electrical vehicle can continue the normal operation when the electric quantity of the power battery is low or the maximum output power of the power battery or the slope is large, thus avoiding the dynamic performance to decrease due to certain factors. At the same time, only once automatic mode is performed, which may avoid frequent start and stop of the engine, thus improving the life of the started engine, reducing the noise and improving the driving comfort.

0037In an embodiment of the present disclosure, as shown in <figref idref="f0004 f0005">Fig. 5</figref>, when the hybrid electrical vehicle is in the hybrid electrical-economical mode and the control module 40 receives the mode switching instruction to switch to the electrical-economical mode, the control module 40 controls the hybrid electrical vehicle to switch to the electric-economical mode if the current electric quantity of the power battery is greater than or equal to a second electric quantity threshold such as 30%, or a current speed of the hybrid electrical vehicle is less than or equal to a first speed threshold such as 150km/h.

0038Further, when the hybrid electrical vehicle is in the hybrid electrical-economical mode, the control module 40 controls the hybrid electrical vehicle to work in a second manner if the slope detected by the hybrid electrical vehicle is less than or equal to a minimum slope such as 5%, and the current electric quantity of the power battery is greater than or equal to the second electric quantity threshold such as 30% and the maximum allowable discharge power of the power battery is greater than or equal to a second power threshold such as 30kw. When the hybrid electrical vehicle is in the hybrid electrical-economical mode, the control module 40 controls the hybrid electrical vehicle to operate in a first manner if the slope detected by the hybrid electrical vehicle is less than or equal to the minimum slope such as 5% and the current electric quantity of the power battery is less than or equal to the first electric quantity threshold 20%, or if the current slope detected by the hybrid electrical vehicle is less than or equal to the minimum slope such as 5% and the maximum allowable discharge power of the power battery is less than or equal to the first power threshold such as 12KW, in which the second electric quantity threshold is greater than the first electric quantity threshold, and the second power threshold is greater than the first power threshold. It should be noted that, in embodiments of the present disclosure, the second manner may be an economical manner, and the first manner may be a low power manner in which the engine 3 drives the electric motor 5 to generate power quickly so as to exit a low power state, such that the electric motor 5 again has the ability of adjusting the working region of the engine, thus ensuring the economy of the hybrid electrical vehicle.

0039In an embodiment of the present disclosure, as shown in <figref idref="f0006">Fig. 6</figref>, when the hybrid electrical vehicle operates in the economical manner and the speed of the hybrid electrical vehicle is less than or equal to a second speed threshold such as 15km/h, the control module 40 controls the engine 3 of the engine power subsystem 20 to stop and to control the electric motor 5 of the motor power subsystem 30 still to operate, in other words, the hybrid electrical vehicle operates in the hybrid electrical-economical mode, the engine 3 is controlled to stop, at this time only the electric motor 5 is operating. Further, when the hybrid electrical vehicle operates in the economical manner and the speed of the hybrid electrical vehicle is greater than or equal to a third speed threshold such as 30km/h, the control module 40 controls the engine to output a torque with a predetermined torque upper limit curve and controls the electric motor to complement the torque if a torque requirement of the hybrid electrical vehicle exceeds the predetermined torque upper limit curve of the engine (i.e., a torque required to keep the hybrid electrical vehicle driving normally in a current state); the control module 40 controls the engine to output a torque with a predetermined torque lower limit curve and controls the electric motor 5 to generate power if the torque requirement of the hybrid electrical vehicle is below the predetermined torque lower limit curve of the engine; and the control module 40 controls the engine to output a torque satisfying the torque requirement of the hybrid electrical vehicle and controls the electric motor to generate power if the torque requirement of the hybrid electrical vehicle exceeds the predetermined torque lower limit curve of the engine and is below the predetermined torque upper limit curve of the engine. In this embodiment of the present disclosure, the predetermined torque upper limit curve and the predetermined torque lower limit curve of the engine are shown in <figref idref="f0006">Fig. 7</figref>. When the torque requirement of the hybrid electrical vehicle exceeds the predetermined torque lower limit curve of the engine and is below the predetermined torque upper limit curve of the engine, a relationship between a generation power of the electric motor and the state of charge (SOC) of the power battery is shown in <figref idref="f0006">Fig. 8</figref>.

0040In an embodiment of the present disclosure, as shown in <figref idref="f0007">Fig. 9</figref>, when the hybrid electrical vehicle operates in the low power manner and is in a non-P gear, the control module 40 controls the engine to output a torque with the predetermined torque upper limit curve and controls the electric motor 5 to complement the torque if the torque requirement of the hybrid electrical vehicle exceeds the predetermined torque upper limit curve of the engine; the control module 40 controls the engine to output a torque with the predetermined torque lower limit curve and controls the electric motor 5 to generate power if the torque requirement of the hybrid electrical vehicle is below the predetermined torque lower limit curve of the engine; and the control module 40 controls the engine 3 to output a torque satisfying the torque requirement of the hybrid electrical vehicle and controls the electric motor 5 to generate power if the torque requirement of the hybrid electrical vehicle exceeds the predetermined torque lower limit curve of the engine and is below the predetermined torque upper limit curve of the engine. Moreover, when the hybrid electrical vehicle operates in the low power manner and is in a P gear, the control module 40 controls the hybrid electrical vehicle to enter an idle stop-start mode. When the hybrid electrical vehicle operates in the idle stop-start mode, the control module 40 determines whether idle stop-start conditions are satisfied, and if the idle stop-start conditions are satisfied, the control module 40 controls an engine of the engine power subsystem to be stalled. In an embodiment, the idle stop-start conditions includes: a current speed of the hybrid electrical vehicle is less than a first speed threshold such as 0; the hybrid electrical vehicle is in a P gear; and the current electric quantity of the power battery of the motor power subsystem is greater than or equal to the first electric quantity threshold such as 20%.

0041In other words, in the embodiment of the present disclosure as shown in <figref idref="f0004 f0005">Fig. 5</figref>, when the hybrid electrical vehicle is driving in the HEV-eco mode and the EV mode selecting button is pressed manually, the hybrid electrical vehicle is allowed to switch to the EV-eco mode only if the current electric quantity of the power battery is greater than or equal to the maximum electric quantity threshold such as 30% or the current speed of the hybrid electrical vehicle is less than or equal to the first speed threshold such as 150km/h, otherwise the hybrid electrical vehicle cannot be switched to the EV-eco mode. When the hybrid electrical vehicle is driving in the HEV-eco mode and the operating mode knob is rotated to the sport mode, the hybrid electrical vehicle is switched to the HEV-s mode. When the hybrid electrical vehicle is in the HEV-eco mode and there is no manual input to the mode selecting buttons, the hybrid electrical vehicle is kept in the HEV-eco mode, and the engine 3 and the electric motor 5 perform power distribution in terms of the economic strategy and the low power strategy respectively according to region division of the electric quantity of the power battery and the maximum allowable discharge power of the power battery. As shown in <figref idref="f0006">Fig. 6</figref>, in the economical manner, if the current speed of the hybrid electrical vehicle is less than or equal to the second speed threshold such as 15km/h, the hybrid electrical vehicle is in the pure electric driving mode; if the current speed of the hybrid electrical vehicle is greater than or equal to the third speed threshold such as 30km/h, the engine 3 takes part in driving the vehicle until the speed of the vehicle is reduced to the second speed threshold as 15km/h, and then the hybrid electrical vehicle returns to the pure electric driving mode. In the pure electric mode, if the electric motor sends an alarm indicating the driving capability is not enough, the engine is started. As shown in <figref idref="f0007">Fig. 9</figref>, in the low power manner, the pure electric driving mode at a low speed is cancelled and an engine stop-start function with engaging the P gear is added. For the economic strategy and the low power strategy, control methods after the engine starts are the same, in which the torque upper limit curve of the engine and the torque lower limit curve of the engine are predetermined, as shown in <figref idref="f0006">Fig. 7</figref>. Principle of designing the curves is that a region between the upper limit curve and the lower limit curve includes as many economical regions of the engine as possible. Since the engine has a poor economy outside the upper limit curve and the lower limit curve, in this region, the electric motor assists the engine to drive the vehicle. During a light load operation, under the premise of satisfying the requirement of the whole vehicle, the engine outputs the torque with the predetermined torque lower limit curve and the redundant torque is used to generate power. During a heavy load operation, the engine outputs the torque with the predetermined torque upper limit and the insufficient torque is complemented by the electric motor. If the electric motor 5 has an insufficient generation capability due to the limitation of itself or the power battery, the electric motor generates power with the maximum allowable capability of itself and the power battery, and the upper limit and lower limit of the output of the engine are cancelled and the engine outputs the torque with reference to requirements of the hybrid electrical vehicle. In the region between the upper limit curve and the lower limit curve, the electric motor mainly takes part in generating power, in which the generation power of the electric motor has a certain function relation with the current SOC of the power battery, as shown in <figref idref="f0006">Fig. 8</figref>. However, a total output torque of the engine does not exceed the predetermined torque upper limit curve, and if the electric motor 5 has an insufficient generation capability due to the limitation of itself or the power battery, the electric motor 5 generates power with the maximum allowable capability of itself and the power battery. The above HEV-eco mode driving strategy is performed when the slope detected by the vehicle is less than or equal to the maximum slope such as 15%. When the slope detected by the vehicle is greater than the maximum slope such as 15%, to satisfy the grade ability of the hybrid electrical vehicle, it is ruled that the engine must start at this time, and the torque upper limit of the engine, the torque lower limit curve of the engine and the output power limit of the electric motor are cancelled, and the original driving strategy is not performed until the slope detected by the vehicle is less than the minimum slope such as 5%.

0042In still yet another embodiment of the present disclosure, as shown in <figref idref="f0008">Fig. 10</figref>, when the hybrid electrical vehicle is in the hybrid electrical-sport mode and the control module 40 receives a mode switching instruction to switch to the electrical-sport mode, the control module 40 controls the hybrid electrical vehicle to switch to the electrical-sport mode if the current electric quantity of the power battery is greater than or equal to the second electric quantity threshold such as 30%, or the current speed of the hybrid electrical vehicle is less than the first speed threshold such as 150km/h.

0043Moreover, when the hybrid electrical vehicle operates in the hybrid electrical-sport mode and is in the P gear, the control module 40 controls the hybrid electrical vehicle to enter the idle stop-start mode. When the hybrid electrical vehicle operates in the hybrid electrical-sport mode and is in a non-P gear, the control module 40 controls the engine to output a predetermined peak torque of the engine and controls the electric motor 5 to complement the torque if the torque requirement of the hybrid electrical vehicle exceeds the predetermined peak torque; and the control module 40 controls the engine to output a torque satisfying the torque requirement of the hybrid electrical vehicle and controls the electric motor 5 to generate power if the torque requirement of the hybrid electrical vehicle is less than or equal to the predetermined peak torque of the engine.

0044In other words, in the embodiment of the present disclosure as shown in <figref idref="f0008">Fig. 10</figref>, for the hybrid electrical vehicle driving in the HEV-s mode, when the EV mode selecting button is pressed manually, only if the current electric quantity of the power battery is greater than or equal to the second electric quantity threshold such as 30%, or the current speed of the electrical vehicle is less than or equal to the first speed threshold such as 150km/h, can the hybrid electrical vehicle be switched to the EV-s mode, otherwise no mode switching is performed; when the operating mode knob is rotated to the economical mode, the hybrid electrical vehicle is switched to the HEV-eco mode; when there is no manual input to the mode selecting buttons, the hybrid electrical vehicle is kept in the HEV-s mode. The HEV-s mode is similar to the low power manner in the HEV-eco mode, the pure electric driving mode at a low speed is cancelled and the engine stop-start function with engaging the P gear is added. Furthermore, the output power of the electric motor is not limited, and the torque upper limit and the torque lower limit of the engine are also cancelled, such that the engine and the electric motor can output the peak values, thus obtaining the best power performance in the HEV-s mode.

0045<img file="EP3045366A1_D0001.tif" /> n embodiments of the present disclosure, when the engine starts to operate, the gearbox transmits the power from the engine and performs the gear shift. When the hybrid electrical vehicle is in the HEV-eco mode or in the HEV-s mode, two gear shift strategies are used respectively. The HEV-eco mode focuses on reducing the oil wear, and a principle of the gear shift strategy thereof is to ensure the engine operates in efficient regions as long as possible, and thus a shift point of each gear may be a little earlier and the engine mainly works in a rotating speed region of 1500-2000rpm during driving. The HEV-s mode focuses on the power performance, and a principle of the gear shift strategy thereof is to ensure the torque transmitted to the wheels from the engine is as large as possible so as to obtain better driving performance, and thus the shift point of each gear may be a little later. Furthermore, with respect to the rapid acceleration with a full throttle, the shift point is defined as a maximum torque point of the engine calibrated under each gear, thus extremely improving the acceleration performance.

0046In an embodiment of the present disclosure, when the hybrid electrical vehicle is in the electrical-economical mode, the maximum output power of the power battery is less than a first predetermined power; when the hybrid electrical vehicle operates in the electrical-sport mode, the maximum output power of the power battery is less than a second predetermined power, in which the second predetermined power is greater than the first predetermined power; when the hybrid electrical vehicle operates in the hybrid electrical-economical mode, each of the maximum output power of the power battery and the maximum output power of the engine is less than the first predetermined power, and a maximum output torque of the engine is less than a first torque threshold; when the hybrid electrical vehicle operates in the hybrid electrical-sport mode, the maximum output power of the power battery is less than the second predetermined power, and the control module 40 allows the engine to output the maximum output torque and the maximum output power. In an embodiment of the present disclosure, the first predetermined power is 70KW, the second predetermined power is 110KW and the first torque threshold is 185 N•M.

0047In other words, in the electrical-economical mode, the hybrid electrical vehicle uses the electric power purely, the maximum output power of the power battery is less than a maximum output power (such as 70KW) in the economical mode and the power battery operates in the most economical regions; in the electrical-sport mode, the hybrid electrical vehicle uses the electric power purely, the maximum output power of the power battery is less than the maximum output power (such as 110KW) in the sport mode; in the hybrid electrical-economical mode, the hybrid electrical vehicle uses both the electric power and the thermal power, the maximum output power of the engine is less than the maximum output power (such as 70KW) in the economical mode, and the maximum output torque of the engine is less than a maximum output torque (such as 185 N•M) in the economical mode, such that the engine and the electric motor operate in the most economical regions; in the hybrid electrical-sport mode, the hybrid electrical vehicle uses both the electric power and the thermal power, the maximum output power of the power battery is less than the maximum output power such as 110KW in the sport mode, and the control module 40 allows the engine to output the maximum output torque and the maximum output power.

0048It should be noted that, in embodiments of the present disclosure, the most economical region in the pure electric driving mode refers to the region in which the power battery operates with a relatively lower discharging power preferentially on the premise of satisfying the power performance (operating performance and acceleration performance) of the vehicle, this is because the working efficiency of the power battery reduces with the increment of the discharging power of the power battery. The most economical region in the hybrid mode refers to the region in which the power battery operates with a relatively lower discharging power preferentially on the premise of satisfying the power performance (operating performance and acceleration performance) of the vehicle, this is because the working efficiency of the power battery reduces with the increment of the discharging power of the power battery. The most economical region of the engine is determined by the torque and rotating speed of engine. As shown in <figref idref="f0006">Fig. 7</figref>, a horizontal ordinate represents the rotating speed of the engine and a longitudinal coordinate represents the torque of the engine, and the most economical region of the engine can be obtained by matching an appropriate rotating speed with a certain torque. In other words, if the torque of the engine is too large, the torque of the engine can be reduced and the rest torque is complemented by the electric motor; if the torque of the engine is too small, the torque of the engine can be increased, but it does not need the increased torque to drive the vehicle, and thus energy generated by the increased torque is recovered to be used for power generation of the electric motor.

0049Further, the maximum output power in the economical mode can be understood as a maximum output power for keeping the power battery or the engine operating in the most economical regions. The maximum output power in the sport mode is a unique property, in which the engine outputs the maximum torque or the maximum power, and the power battery outputs the maximum power, and thus the power system provides the maximum output torque or the maximum output power for the vehicle.

0050In addition, it can be understood that the running mode when the hybrid electrical vehicle starts is still the running mode when the hybrid electrical vehicle is stalled at last time. Moreover, the hybrid electrical vehicle also has a pure fuel mode which is a fault mode.

0051With the control system of the hybrid electrical vehicle according to embodiments of the present disclosure, the engine power subsystem and the motor power subsystem are connected in parallel, which can enable the power between the engine power subsystem and the motor power subsystem to match easily, improve the transformation efficiency, and effectively improve an energy utilization factor as compared with a series connection structure adopted in a power system of the conventional hybrid electrical vehicle. Moreover, the parallel connection is simple in structure and can avoid a complex ECVT match in a series-parallel connection, which reduces a risk of driving uncomfortably caused by the match failure, and thus the economy of the hybrid electrical vehicle is greatly improved on the premise of ensuring the power performance of the hybrid electrical vehicle. In the following, a control method for the hybrid electrical vehicle is described in detail with reference to <figref idref="f0002 f0003 f0004 f0005 f0006 f0007 f0008 f0009">Figs. 3-11</figref>, in which the hybrid electrical vehicle is the hybrid electrical vehicle described in above embodiments of the present disclosure. The hybrid electrical vehicle includes a transmission device, an engine power subsystem, a motor power subsystem and a control module.

0052<figref idref="f0009">Fig. 11</figref> is a flow chart of a control method for a hybrid electrical vehicle according to an embodiment of the present disclosure. As shown in <figref idref="f0009">Fig. 11</figref>, the method for controlling the hybrid electrical vehicle includes following steps. <ul id="ul0002" list-style="none" compact="compact"><li>At step S1, the control module controls the hybrid electrical vehicle to operate in a hybrid electrical-economical mode by controlling the engine power subsystem and the motor power subsystem, when the hybrid electrical vehicle is running. The plurality of running modes include an electrical-economical mode, an electrical-sport mode, a hybrid electrical-economical mode and a hybrid electrical-sport mode.</li><li>At step S2, the control module detects a current electric quantity of a power battery of the motor power subsystem, a maximum allowable discharge power of the power battery of the motor power subsystem and a current slope of the hybrid electrical vehicle.</li><li>At step S3, the control module controls the hybrid electrical vehicle to operate in a first manner if the current slope of the hybrid electrical vehicle is less than or equal to a minimum slope and the current electric quantity of a power battery of the motor power subsystem is less than or equal to a first electric quantity threshold, or if the current slope of the hybrid electrical vehicle is less than or equal to the minimum slope and the maximum allowable discharge power of the power battery of the motor power subsystem is less than or equal to a first power threshold.</li></ul>

0053In embodiments of the present disclosure, the first manner may be a low power manner, and a second manner may be an economical mode.

0054In an embodiment of the present disclosure, as shown in <figref idref="f0002">Fig. 3</figref>, a control method for the hybrid electrical vehicle in an electrical-economical includes following steps. <ul id="ul0003" list-style="none" compact="compact"><li>At step S101, manual switching information is obtained, in which the manual switching information may be about whether a HEV mode selecting button switching operation is performed, whether a Sport mode selecting button switching operation is performed or whether no mode selecting button switching operation is performed. In other words, it is determined whether a manual switch is performed, if yes, execute step S102; and if no, execute step S103.</li><li>At step S102, a running mode switching is performed and a corresponding control strategy of a power system is performed. In other words, when the hybrid electrical vehicle is in the electrical-economical mode and a mode switching instruction is received from a user, the control module controls the hybrid electrical vehicle to switch to a running mode corresponding to the mode switching instruction from the user.</li><li>At step S103, the running mode is not switched, and then a current electric quantity (state of charge, SOC) of the power battery, a maximum allowable discharge power Pb of the power battery and a slope i detected by the hybrid electrical vehicle are compared with predetermined thresholds (i.e., the lower threshold of the electric quantity SOC_down(such as 20%), the lower threshold of the maximum allowable discharge power Pb_down(such as 12KW), and the upper threshold of the slope i_up (such as 15%)) respectively to determine whether SOC≤SOC_down, whether Pb≤Pb_down and whether i_up≤i.</li><li>At step S104, if at least one of the above three conditions is satisfied, the hybrid electrical vehicle is witched to the HEV-eco mode automatically. In other words, if the current electric quantity of the power battery is less than or equal to the first electric quantity threshold such as 20%, or the maximum allowable discharge power of the power battery is less than or equal to the first power threshold such as 12KW, or the slope detected by the hybrid electrical vehicle is greater than or equal to a maximum slope such as 15%, the control module controls the hybrid electrical vehicle to switch to the hybrid electrical-economical mode.</li><li>At step S105, if each of the above three conditions is not satisfied, the hybrid electrical vehicle is not switched to the HEV-eco mode and is kept driving in the EV-eco mode.</li></ul>

0055When the hybrid electrical vehicle is driven in the EV-eco mode and no manual or automatic mode switching is performed, the electric motor drives the hybrid electrical vehicle continuously as a single power source. The EV-eco mode focuses on saving electric power on the premise of satisfying a power performance requirement of the hybrid electrical vehicle, and also focuses on improving the electricity efficiency by avoiding the long term and high power consumption, and thus the maximum output power of the electric motor is limited to a certain value such as 70KW. Furthermore, to satisfy the grade ability of the hybrid electrical vehicle, the maximum output torque of the electric motor is not limited, i.e., when the hybrid electrical vehicle is in the EV-eco mode, the control module controls the hybrid electrical vehicle to drive with a limited power.

0056With the method for controlling the hybrid electrical vehicle in the EV-eco mode, by determining the current electric quantity of the power battery, the maximum allowable discharge power of the power battery and the slope detected by the hybrid electrical vehicle to control the vehicle to switch to the HEV-eco mode automatically, normal driving of the hybrid electrical vehicle can be ensured and risks of reducing the power performance can be avoided. In conclusion, with the method for controlling the hybrid electrical vehicle in the EV-eco mode, on the premise of satisfying the power performance of the whole vehicle, the power battery keeps operating in high efficient regions, thus realizing a longer driving range, a low operation cost and a low emission.

0057In another embodiment of the present disclosure, as shown in <figref idref="f0003">Fig. 4</figref>, a control method for the hybrid electrical vehicle in the electrical-sport mode includes following steps. <ul id="ul0004" list-style="none" compact="compact"><li>At step S201, manual switching information is obtained, in which the manual switching information may be about whether a HEV mode selecting button switching operation is performed, whether an economical mode selecting button switching operation is performed or whether no mode selecting button switching operation is performed. In other words, it is determined whether a manual switch is performed, if yes, execute step S202; and if no, execute step S103.</li><li>At step S202, a running mode switching is performed and a corresponding control strategy of the power system is performed. In other words, when the hybrid electrical vehicle is in the electrical-sport mode and a mode switching instruction is received from the user, the control module controls the hybrid electrical vehicle to switch to a running mode corresponding to the mode switching instruction from the user.</li><li>At step S203, the running mode is not switched, and then the current electric quantity (state of charge, SOC) of the power battery, the maximum allowable discharge power Pb of the power battery and a slope i detected by the hybrid electrical vehicle are compared with predetermined thresholds (i.e., the lower threshold of the electric quantity SOC_down (such as 20%), the lower threshold of the maximum allowable discharge power Pb_down (such as 12KW), and the upper threshold of the slope i_up (such as 15%))respectively to determine whether SOC≤SOC_down, whether Pb≤ Pb_down and whether i_up≤i.</li><li>At step S204, if at least one of the above three conditions is satisfied, the hybrid electrical vehicle is switched to the HEV-s mode automatically. In other words, if the current electric quantity of the power battery is less than or equal to the first electric quantity threshold such as 20%, or the maximum allowable discharge power of the power battery is less than or equal to the first power threshold such as 12KW, or the slope detected by the hybrid electrical vehicle is greater than or equal to the maximum slope such as 15%, the control module controls the hybrid electrical vehicle to switch to the hybrid electrical-economical mode.</li><li>At step S205, if each of the above three conditions is not satisfied, the hybrid electrical vehicle is not switched to the HEV-s mode and is kept driving in the EV-s mode.</li></ul>

0058When the hybrid electrical vehicle is driven in the EV-s mode and no manual or automatic mode switching is performed, the electric motor drives the hybrid electrical vehicle continuously as the single power source. In the EV-s mode, the maximum output torque and the maximum output power of the electric motor are not limited, and thus the electric motor drives the vehicle with the maximum capacity, and higher power performance (such as overtaking acceleration and fast climbing) can be achieved in the EV mode.

0059With the method for controlling the hybrid electrical vehicle in the EV-s mode, by determining the current electric quantity of the power battery, the maximum allowable discharge power of the power battery and the slope detected by the hybrid electrical vehicle to control the vehicle to switch to the HEV-s mode automatically, normal driving of the hybrid electrical vehicle can be ensured and risks of reducing the power performance can be avoided. In conclusion, with the method for controlling the hybrid electrical vehicle in the EV-s mode, the vehicle can be driven in the pure electric driving mode and a better power performance can be achieved, and the running mode is flexible and changeable, thus providing the user with more driving fun.

0060In yet another embodiment of the present disclosure, as shown in <figref idref="f0004 f0005">Fig. 5</figref>, a control method for the hybrid electrical vehicle in the hybrid electrical-economical mode includes following steps. <ul id="ul0005" list-style="none" compact="compact"><li>At step S301, switching information about the EV mode selecting button is obtained, and it is determined whether a manual switching to the EV mode is performed, if yes, execute step S302 or step S303; and if no, execute step S306.</li><li>At step S302, the current electric quantity (state of charge, SOC) of the power battery is compared with the predetermined upper electric quantity threshold SOC_up such as 30% to determine whether SOC_up≤SOC, if yes, execute step S304; and if no, execute step S305.</li><li>At step S303, the current speed of the hybrid electrical vehicle is compared with the maximum speed threshold V_max(i.e., a highest speed which allows the hybrid electric vehicle to switch to the EV mode from the HEV mode, such as 150km/h) to determine whether v≤V_max, if yes, execute step 304; and if no, execute step S305.</li><li>At step S304, the hybrid electrical vehicle is controlled to switch to the EV-eco mode and a corresponding control strategy of the power system is performed. In other words, when the hybrid electrical vehicle is in the hybrid electrical-economical mode and the control module receives the mode switching instruction to switch to the electrical-economical mode, the control module controls the hybrid electrical vehicle to switch to the electrical-economical mode if the current electric quantity of the power battery is greater than or equal to the second electric quantity threshold such as 30%, or the current speed of the hybrid electrical vehicle is less than or equal to the first speed threshold such as 150km/h. </li><li>At step S305, the hybrid electrical vehicle keeps driving in the HEV-eco mode.</li><li>At step S306, switching information about the Sport mode selecting button is obtained, and it is determined whether a manual switching to the sport mode is performed, if yes, execute step S307; and if no, execute step S308.</li><li>At step S307, the hybrid electrical vehicle is controlled to switch to the HEV-s mode and a corresponding control strategy of the power system is performed.</li><li>At step S308, the running mode is not switched, and then slope information is obtained, i.e., the slope i is detected.</li><li>At step S309, it is determined whether i≤i_down, if yes, execute step S310, and if no, execute step S317.</li><li>At step S310, the current electric quantity (state of charge, SOC) of the power battery and the maximum allowable discharge power Pb of the power battery are detected, and are compared with the thresholds (i.e., the upper electric quantity threshold SOC_up (such as 30%), the lower electric quantity threshold SOC_down (such as 20%), the upper threshold of the maximum allowable discharge power Pb_up (such as 30KW), the lower threshold of the maximum allowable discharge power Pb_down (such as 12KW)) respectively.</li><li>At step S311, it is determined whether SOC_up≤SOC and whether Pb_up≤Pb, if yes, execute step S312, if no, execute step S313.</li><li>At step S312, the hybrid electrical vehicle is controlled in the economical manner. In other words, when the hybrid electrical vehicle is in the hybrid electrical-economical mode, the control module 40controls the hybrid electrical vehicle to operate in the economical manner if the slope detected by the hybrid electrical vehicle is less than or equal to the minimum slope such as 5%, and the current electric quantity of the power battery is greater than or equal to the second electric quantity threshold such as 30% and the maximum allowable discharge power of the power battery is greater than or equal to the second power threshold such as 30 KW. </li><li>At step S313, it is determined whether SOC_up>SOC>SOC_down and Pb_up≤Pb, or whether SOC_up≤SOC and Pb_up>Pb>Pb_down, if yes, execute step S314, if no, execute step S315.</li><li>At step S314, the hybrid electrical vehicle is controlled in the original manner, i.e., if the original manner is the economical manner, the hybrid electrical vehicle still operates in the economical manner; if the original manner is the low power manner, the hybrid electrical vehicle still operates in the low power manner.</li><li>At step S315, it is determined whether SOC≤SOC_down or whether Pb≤Pb_down, execute step S316.</li><li>At step S316, the hybrid electrical vehicle is controlled in the low power manner. In other words, when the hybrid electrical vehicle is in the hybrid electrical-economical mode, the control module 40controls the hybrid electrical vehicle to operate in the economical manner if the slope detected by the hybrid electrical vehicle is less than or equal to the minimum slope such as 5% and the current electric quantity of the power battery is less than or equal to the first electric quantity threshold such as 20%, or if the current slope detected by the hybrid electrical vehicle is less than or equal to the minimum slope such as 5% and the maximum allowable discharge power of the power battery is less than or equal to the first power threshold such as 12KW, in which the second electric quantity threshold is greater than the first electric quantity threshold, and the second power threshold is greater than the first power threshold. </li><li>At step S317, it is determined whether i_up>i>i_down, and if yes, execute step S318, if no, execute step S319.</li><li>At step S318, the hybrid electrical vehicle is controlled in the original manner.</li><li>At step S319, it is determined that i_up≤i, and execute step S320.</li><li>At step 320, the hybrid electrical vehicle is controlled to operate in the economical manner, moreover, the pure electric driving mode at a low speed, the upper limit of the engine, and the upper limit of the electric motor are cancelled.</li></ul>

0061It should be noted that, in embodiments of the present disclosure, in the low power manner, the engine drives the electric motor to generate power quickly so as to get out of a low power state, such that the electric motor again has the ability of adjusting the working region of the engine, thus ensuring the economy of the hybrid electrical vehicle.

0062In the embodiment of the present disclosure as shown in <figref idref="f0006">Fig. 6</figref>, a control method for the hybrid electrical vehicle in the economical manner includes following steps. <ul id="ul0006" list-style="none" compact="compact"><li>At step S401, the current speed of the hybrid electrical vehicle is obtained and the current speed v of the hybrid electrical vehicle is compared with the second speed threshold such as 15km/h and the third speed threshold such as 30km/h.</li><li>At step S402, it is determined whether v_up≤v, and if yes, execute step S403, if no, execute step S415.</li><li>At step S403, it is determined whether the torque requirement of the hybrid electrical vehicle exceeds the predetermined torque upper limit curve of the engine as shown in <figref idref="f0006">Fig. 7</figref>, and if yes, execute step S404, if no, execute step S407.</li><li>At step S404, it is determined whether a fault occurs in the power system of the hybrid electrical vehicle, if yes, execute step S406; and if no, execute step S405.</li><li>At step S405, the engine is controlled to output a torque with the predetermined torque upper limit curve and the electric motor is controlled to complement the torque. In other words, when the hybrid electrical vehicle operates in the economical manner and the current speed of the hybrid electrical vehicle is greater than or equal to the third speed threshold such as 30km/h, the control module controls the engine to output a torque with the predetermined torque upper limit curve and controls the electric motor to complement the torque if a torque requirement of the hybrid electrical vehicle exceeds the predetermined torque upper limit curve of the engine.</li><li>At step S406, the fault is processed.</li><li>At step S407, it is determined whether the torque requirement of the hybrid electrical vehicle is below the predetermined torque lower limit curve of the engine as shown in <figref idref="f0006">Fig. 7</figref>, and if yes, execute step S408, if no, execute step S411.</li><li>At step S408, it is determined whether a fault occurs in the power system of the hybrid electrical vehicle, if yes, execute step S410; and if no, execute step S409.</li><li>At step S409, the engine is controlled to output a torque with the predetermined torque lower limit curve and the electric motor is controlled to generate power. In other words, when the hybrid electrical vehicle operates in the economical manner and the current speed of the hybrid electrical vehicle is greater than or equal to the third speed threshold such as 30km/h, the control module 40controls the engine to output a torque with the predetermined torque lower limit curve and controls the electric motor to generate power if the torque requirement of the hybrid electrical vehicle is below the predetermined torque lower limit curve of the engine.</li><li>At step S410, the fault is processed.</li><li>At step S411, it is determined that the torque requirement of the hybrid electrical vehicle exceeds the predetermined torque lower limit curve of the engine and is below the predetermined torque upper limit curve of the engine as shown in <figref idref="f0006">Fig. 7</figref>.</li><li>At step S412, it is determined whether a fault occurs in the power system of the hybrid electrical vehicle, if yes, execute step S414; and if no, execute step S413.</li><li>At step S413, the engine is controlled preferentially to satisfy the torque requirement of the hybrid electrical vehicle, and also controlled to output another more torque for generating power. In other words, when the hybrid electrical vehicle operates in the economical manner and the current speed of the hybrid electrical vehicle is greater than or equal to the third speed threshold such as 30km/h, the control module controls the engine to output torque satisfying the torque requirement of the hybrid electrical vehicle and controls the electric motor to generate power if the torque requirement of the hybrid electrical vehicle exceeds the predetermined torque lower limit curve of the engine and is below the predetermined torque upper limit curve of the engine. A principle of generating power follows the functional relationship between the generation power and SOC of the power battery as shown in <figref idref="f0006">Fig. 8</figref>, and following two conditions should be satisfied simultaneously: (1) a generating torque converted to the electric motor is not greater than Tm_max; (2) a total output torque of the engine does not exceed the predetermined torque upper limit curve as shown in <figref idref="f0006">Fig. 7</figref>. If the torque of the engine calculated from a generation power curve does not satisfy any of the above two conditions, the above two conditions are used as upper limits to constrain the torque of the engine configured to generate power.</li><li>At step S414, the fault is processed.</li><li>At step S415, it is determined whether v_up>v>v_down, and if yes, execute step S416, if no, execute step S419.</li><li>At step S416, it is determined whether a fault occurs in the power system of the hybrid electrical vehicle, if yes, execute step S418; and if no, execute step S417.</li><li>At step S417, the hybrid electrical vehicle is controlled to operate in the original manner, i.e., the hybrid electrical vehicle is still driven by the electric motor only, or the electric motor still assists the engine to drive the hybrid electrical vehicle.</li><li>At step S418, the fault is processed.</li><li>At step S419, it is determined that v≤v_down, and execute step S420.</li><li>At step S420, it is determined whether a fault occurs in the power system, if yes, execute step S422; and if no, execute step S421.</li><li>At step S421, the hybrid electrical vehicle is driven by the electric motor only and the engine is stalled. In other words, when the hybrid electrical vehicle operates in the economical manner and the speed of the hybrid electrical vehicle is less than or equal to the second speed threshold such as 15km/h, the control module controls the engine of the engine power subsystem to stop and controls the electric motor of the motor power subsystem still to work, at this time, the hybrid electrical vehicle works in the hybrid electrical-economical mode.</li><li>At step S422, the fault is processed.</li></ul>

0063In the embodiment of the present disclosure as shown in <figref idref="f0007">Fig. 9</figref>, a control method for the hybrid electrical vehicle in the low power manner includes following steps. <ul id="ul0007" list-style="none" compact="compact"><li>At step S501, gear information is obtained.</li><li>At step S502, it is determined whether the hybrid electrical vehicle is in a non-P gear, and execute step S503, if no, execute step S515.</li><li>At step 503, it is determined whether the torque requirement of the hybrid electrical vehicle exceeds the predetermined torque upper limit curve of the engine as shown in <figref idref="f0006">Fig. 7</figref>, and if yes, execute step S504, if no, execute step S507.</li><li>At step S504, it is determined whether a fault occurs in the power system of the hybrid electrical vehicle, if yes, execute step S506; and if no, execute step S505.</li><li>At step S505, the engine is controlled to output a torque with the predetermined torque upper limit curve and the electric motor is controlled to complement the torque. In other words, when the hybrid electrical vehicle operates in the low power manner and is in a non-P gear, the control module 40controls the engine to output a torque with the predetermined torque upper limit curve and controls the electric motor to complement the torque if a torque requirement of the hybrid electrical vehicle exceeds the predetermined torque upper limit curve of the engine.</li><li>At step S506, the fault is processed.</li><li>At step S507, it is determined whether he torque requirement of the hybrid electrical vehicle is below the predetermined torque lower limit curve of the engine as shown in <figref idref="f0006">Fig. 7</figref>, and if yes, execute step S508, if no, execute step S511.</li><li>At step S508, it is determined whether a fault occurs in the power system of the hybrid electrical vehicle, if yes, execute step S510; and if no, execute step S509.</li><li>At step S509, the engine is controlled to output a torque with the predetermined torque lower limit curve and the electric motor is controlled to generate power. In other words, when the hybrid electrical vehicle operates in the low power manner and is in the non-P gear, the control module 40controls the engine to output a torque with the predetermined torque lower limit curve and controls the electric motor to generate power if the torque requirement of the hybrid electrical vehicle is below the predetermined torque lower limit curve of the engine.</li><li>At step S510, the fault is processed.</li><li>At step S511, it is determined that the torque requirement of the hybrid electrical vehicle exceeds the predetermined torque lower limit curve of the engine and is below the predetermined torque upper limit curve of the engine, and execute step S512.</li><li>At step S512, it is determined whether a fault occurs in the power system, if yes, execute step S514; and if no, execute step S513.</li><li>At step S513, the engine is controlled preferentially to satisfy the torque requirement of the hybrid electrical vehicle, and also controlled to output another more torque for generating power. In other words, when the hybrid electrical vehicle operates in the low power manner and is in the non-P gear, the control module 40controls the engine to output the torque satisfying the torque requirement of the hybrid electrical vehicle and controls the electric motor to generate power if the torque requirement of the hybrid electrical vehicle exceeds the predetermined torque lower limit curve of the engine and is below the predetermined torque upper limit curve of the engine. The principle of generating power follows the functional relationship between the generation power and SOC of the power battery as shown in <figref idref="f0006">Fig. 8</figref>, and following two conditions should be satisfied simultaneously: (1) the generating torque converted to the electric motor is not greater than Tm_max; (2) the total output torque of the engine does not exceed the predetermined torque upper limit curve as shown in <figref idref="f0006">Fig. 7</figref>. If the torque of the engine calculated from the generation power curve does not satisfy any of the above two conditions, the above two conditions are used as upper limits to constrain the torque of the engine configured to generate power.</li><li>At step S514, the fault is processed.</li><li>At step S515, it is determined that the hybrid electrical vehicle is in the P gear, and execute step S516.</li><li>At step S516, an idle stop-start strategy is performed. In other words, when the hybrid electrical vehicle operates in the low power manner and is in the P gear, the control module 40controls the hybrid electrical vehicle to enter an idle stop-start mode, and the engine is stalled.</li></ul>

0064When the hybrid electrical vehicle is driven in the HEV-eco mode, the electric motor cooperates with the engine to improve the energy utilization factor, and general procedures are shown as follows. When the hybrid electrical vehicle operates in the non-economical regions of the engine, the electric motor is used more often than the engine; when the hybrid electrical vehicle operates in the economical regions of the engine, the engine can generate some power to charge the power battery, and the less the electric quantity of the power battery is, the higher the generation power of the engine is. Moreover, in this mode, the maximum output power of the electric motor is limited so as to avoid a long term high power consumption, such that the electric quantity of the power battery is kept in a relatively high level and the electric motor always has electric energy to adjust the engine to operate in high efficiency regions, thus reducing the oil wear during the hybrid electrical driving as much as possible and ensuring the economy and emission behavior of the hybrid electrical vehicle. When the hybrid electrical vehicle requires heavy load output, the electric motor can assist the engine to drive the vehicle together, and thus the power performance is greatly improved as compared with that in the EV mode. When the user needs a long distance driving and wants to reduce the oil wear as much as possible, he can choose the above mode.

0065In an embodiment of the present disclosure as shown in <figref idref="f0008">Fig. 10</figref>, a control method for the hybrid electrical vehicle in the hybrid electrical-sport mode includes following steps. <ul id="ul0008" list-style="none" compact="compact"><li>At step S601, switching information about the EV mode selecting button is obtained and it is determined whether a manual switch to the EV mode is performed, if yes, execute step S602; and if no, execute step S606.</li><li>At step S602, the current electric quantity SOC of the power battery is compared with the second electric quantity threshold such as 30% and it is determined whether SOC_up≤ SOC, if yes, execute step S603, if no, execute step S605.</li><li>At step S603, the current speed of the hybrid electrical vehicle is compared with the first speed threshold V_max(i.e., the highest speed that allows the hybrid electric vehicle to switch to the EV mode from the HEV mode, such as 150km/h), and it is determined whether v≤V_max, if yes, execute step 604; and if no, execute step S605.</li><li>At step S604, the hybrid electrical vehicle is controlled to switch to the EV-s mode and a corresponding control strategy of the power system is performed. In other words, when the hybrid electrical vehicle is in the hybrid electrical-sport mode and the mode switching instruction to switch to the electrical-sport mode is received, the control module 40controls the hybrid electrical vehicle to switch to the electrical-sport mode if the current electric quantity of the power battery is greater than or equal to the second electric quantity threshold such as 30%, or the current speed of the hybrid electrical vehicle is less than or equal to the first speed threshold such as 150km/h. </li><li>At step S605, the hybrid electrical vehicle keeps driving in the HEV-s mode.</li><li>At step S606, the switching information about the economical mode selecting button is obtained, and it is determined whether a manual switch to the economical mode is performed, if yes, execute step S607; and if no, execute step S608.</li><li>At step S607, the hybrid electrical vehicle is controlled to switch to the HEV-eco mode and a corresponding control strategy of the power system is performed.</li><li>At step S608, the running mode is not switched, and the gear information is obtained to determine the current gear of the hybrid electrical vehicle.</li><li>At step S609, it is determined whether the hybrid electrical vehicle is in the P gear, and if yes, execute step S610, and if no, execute step S611.</li><li>At step S610, the idle stop-start strategy is performed. In other words, when the hybrid electrical vehicle operates in the hybrid electrical-sport mode and is in the P gear, the control module 40controls the hybrid electrical vehicle to enter the idle stop-start mode.</li><li>At step S611, it is determined that the hybrid electrical vehicle is in the non-P gear, and if yes, execute step S612.</li><li>At step S612, the torque requirement of the hybrid electrical vehicle is compared with a predetermined peak torque of the engine and it is determined whether the torque requirement of the hybrid electrical vehicle exceeds the predetermined peak torque, if yes, execute step S613; and if no, execute step S614.</li><li>At step S613, the engine is controlled to output the predetermined peak torque and the electric motor is controlled to complement the torque. When the electric motor is limited by the current capability of itself or of the power battery, it drives with the maximum capabilities of itself and the power battery. In other words, when the hybrid electrical vehicle is in the hybrid electrical-sport mode and is in the non-P gear, the control module controls the engine to output the predetermined peak torque of the engine and controls the electric motor to complement the torque if the torque requirement of the hybrid electrical vehicle exceeds the predetermined peak torque of the engine.</li><li>At step S614, the engine is controlled preferentially to satisfy the torque requirement of the hybrid electrical vehicle, and also controlled to output another more torque for generating power. In other words, when the hybrid electrical vehicle is in the hybrid electrical-sport mode and is in the non-P gear, the control module controls the engine to output a torque satisfying the torque requirement of the hybrid electrical vehicle and controls the electric motor to generate power if the torque requirement of the hybrid electrical vehicle is less than or equal to the predetermined peak torque of the engine. The principle of generating power follows the relationship between the generation power and SOC of the power battery as shown in <figref idref="f0006">Fig. 8</figref>, and following two conditions should be satisfied simultaneously: (1) the generating torque converted to the electric motor is not greater than Tm_max; (2) the total output torque of the engine does not exceed the predetermined torque upper limit curve as shown in <figref idref="f0006">Fig. 7</figref>. If the torque of the engine calculated from the generation power curve does not satisfy any of the above two conditions, the above two conditions are used as upper limits to constrain the torque of the engine configured to generate power.</li></ul>

0066When the hybrid electrical vehicle is driven in the HEV-s mode and is in the non-P gear, the engine is kept in a starting state. Only if the hybrid electrical vehicle is in the P gear and the idle stop-start conditions are satisfied, can the engine be stalled. In the HEV-s mode, the maximum output torque and the maximum output power of the engine and the electric motor are not limited any more, and thus a maximum driving capability of the power system can be achieved. Thus, the HEV-s mode realizes the best power performance among the four running modes. However, since the engine keeps operating during the driving process of the hybrid electrical vehicle (either cooperating with the electric motor to drive the vehicle or driving the vehicle and driving the electric motor to generate power synchronously (when the electric quantity of the power battery is less than a certain threshold), the oil wear is relatively high and the economy of the hybrid electrical vehicle cannot be ensured. The HEV-s mode is suitable for users who have a high requirement of the power performance, and has enough power equal to that of the fuel vehicle with a high emission.

0067In embodiments of the present disclosure, by providing the EV, HEV, economical and Sport mode selecting buttons, four different running modes (i.e., the EV-eco mode, the EV-s mode, the HEV-eco mode and the HEV-s mode) can be obtained, each of which has different power performance requirement and economy requirement and thus has different driving strategies. Moreover, the power system of the hybrid electrical vehicle adopts the parallel connection mode instead of the series connection mode or the series-parallel connection mode. In addition, in the driving strategies, a starting point of the engine is optimized, a speed threshold is increased, the slope detection is added and a determination about the demanded power is cancelled. In the economical manner of the HEV-eco mode, the engine is limited to operate in the region between the predetermined torque upper limit curve and the predetermined torque lower limit curve, and the generation power is represented by a dynamic curve taking the SOC value of the power battery as its independent variable.

0068With the method according to embodiments of the present disclosure, by providing a plurality of running modes, a driving requirement of the user in different working conditions can be satisfied, i.e., not only pure electric consumption in a city working condition can be satisfied, but also power performance requirement in a suburban district working condition can be satisfied, and thus the hybrid electrical vehicle can be driven according to subjective operation intentions of the user and the driving fun is improved. The power system of the hybrid electrical vehicle adopts the parallel connection mode which can effectively improve the energy utilization factor as compared with the series connection mode. Moreover, the parallel connection is simple in structure and can avoid a complex ECVT match in the series-parallel connection, which reduces a risk of driving uncomfortably caused by the match failure. Furthermore, in the driving strategy, the starting point of the engine is optimized to avoid premature and frequent start of the engine, such that noise when the engine starts can be reduced effectively, a working life of a starting system can be improved and a risk of pulling down a low voltage frequently caused by frequent start can also be reduced, and thus other low voltage electrical equipment can be ensured to operate normally. The working region of the engine is also optimized so as to ensure that the engine keeps operating in the high efficiency region, and the generation power is also optimized so as to ensure that there are high power equilibrium points during the driving of the vehicle, thus facilitating the hybrid electrical vehicle mostly being in line with an economical strategy and reducing the oil wear efficiently. Moreover, the control method for the hybrid electrical vehicle can ensure the running power performance of the pure electric vehicle and the driving range, avoid the high-power electricity of the vehicle for a long time when meeting the power requirement of the whole vehicle so as to improve the electric efficiency, at the same time, further avoid the frequent start-stop phenomenon of the engine, thus increasing the starter life, reducing the traffic noise, and improve the driving comfort.

0069Any procedure or method described in the flow charts or described in any other way herein may be understood to comprise one or more modules, portions or parts for storing executable codes that realize particular logic functions or procedures. Moreover, advantageous embodiments of the present disclosure comprises other implementations in which the order of execution is different from that which is depicted or discussed, including executing functions in a substantially simultaneous manner or in an opposite order according to the related functions. This should be understood by those skilled in the art which embodiments of the present disclosure belong to.

0070The logic and/or step described in other manners herein or shown in the flow chart, for example, a particular sequence table of executable instructions for realizing the logical function, may be specifically achieved in any computer readable medium to be used by the instruction execution system, device or equipment (such as the system based on computers, the system comprising processors or other systems capable of obtaining the instruction from the instruction execution system, device and equipment and executing the instruction), or to be used in combination with the instruction execution system, device and equipment.

0071It is understood that each part of the present disclosure may be realized by the hardware, software, firmware or their combination. In the above embodiments, a plurality of steps or methods may be realized by the software or firmware stored in the memory and executed by the appropriate instruction execution system. For example, if it is realized by the hardware, likewise in another embodiment, the steps or methods may be realized by one or a combination of the following techniques known in the art: a discrete logic circuit having a logic gate circuit for realizing a logic function of a data signal, an application-specific integrated circuit having an appropriate combination logic gate circuit, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

0072Those skilled in the art shall understand that all or parts of the steps in the above exemplifying method of the present disclosure may be achieved by commanding the related hardware with programs. The programs may be stored in a computer readable storage medium, and the programs comprise one or a combination of the steps in the method embodiments of the present disclosure when run on a computer.

0073In addition, each function cell of the embodiments of the present disclosure may be integrated in a processing module, or these cells may be separate physical existence, or two or more cells are integrated in a processing module. The integrated module may be realized in a form of hardware or in a form of software function modules. When the integrated module is realized in a form of software function module and is sold or used as a standalone product, the integrated module may be stored in a computer readable storage medium.

0074The storage medium mentioned above may be read-only memories, magnetic disks or CD, etc.

0075Reference throughout this specification to "an embodiment," "some embodiments," "one embodiment", "another example," "an example," "a specific example," or "some examples," means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. Thus, the appearances of the phrases such as "in some embodiments," "in one embodiment", "in an embodiment", "in another example," "in an example," "in a specific example," or "in some examples," in various places throughout this specification are not necessarily referring to the same embodiment or example of the present disclosure. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

0076Although explanatory embodiments have been shown and described, it would be appreciated by those skilled in the art that the above embodiments cannot be construed to limit the present disclosure, and changes, alternatives, and modifications can be made in the embodiments without departing from spirit, principles and scope of the present disclosure.