Power generation control device for series hybrid electric vehicle

The present invention relates to a power generation control device for a series hybrid electric vehicle in which a drive motor is driven by electric power from a generator driven by an internal combustion engine and electric power from a battery to travel.

Conventionally, as a technique for controlling charging / discharging of a battery mounted on a hybrid vehicle, for example, the one described in Patent Document 1 is known. The technique described in Patent Document 1 predicts the required state of battery charge / discharge due to future vehicle running, and changes the target SOC of the battery based on the prediction result. Specifically, for example, when a hybrid vehicle is continuously running at a low speed for a predetermined time or longer, the target SOC of the battery is set to a high value by predicting that there will be a large discharge request in the future, and conversely, the hybrid vehicle. When the battery is continuously running at high speed for a predetermined time or longer, it is predicted that a large amount of regenerative power will be generated in the future and charging will be required, and the target SOC of the battery is set to a low value.<patcit num="1"><text>Japanese Unexamined Patent Publication No. 2001-268719</text></patcit>

<p> However, when the conventional technique described in Patent Document 1 is applied to an electric vehicle without a transmission, that is, an electric vehicle in which the rotation speed of a drive motor that generates the drive torque of the vehicle is proportional to the vehicle speed, the following The problem arises. That is, in the conventional technique described in Patent Document 1, the battery voltage is high because the battery SOC is high when the vehicle is running at low speed, and conversely, the battery voltage is low because the battery SOC is low when the vehicle is running at high speed. Will be low. Here, in general, the drive motor of an electric vehicle is more efficient when the voltage is low at low rotation speeds, and is more efficient when the voltage is high at high rotation speeds. There is a problem that the drive motor cannot be operated in an efficient region in both low-speed running and high-speed running.</p><p> The present invention has been devised in view of the above-mentioned problems of the prior art, and provides a power generation control device for a series hybrid electric vehicle capable of efficiently operating a drive motor to improve fuel efficiency. The purpose is to provide.</p>

<p> In the power generation control device of the series hybrid electric vehicle according to the present invention, a target SOC of the battery is set, a target value of power generated by the generator is calculated based on the set target SOC, and internal combustion is performed based on the target value of power generated. In the configuration for controlling the engine and the generator, the vehicle speed of the series hybrid electric vehicle is calculated, and the target SOC of the battery is set to a value lower than that at high speed when the series hybrid electric vehicle is running at low speed. To solve.</p>

<p> According to the power generation control device of the series hybrid electric vehicle according to the present invention, the target SOC of the battery is set to a lower value at low speeds of the series hybrid electric vehicle than at high speeds, so that the drive motor rotates at low speed. The drive motor can be efficiently operated at a low voltage during traveling. In addition, the drive motor can be efficiently operated at a high voltage during high-speed traveling in which the drive motor rotates at a high speed. As a result, it is possible to improve the fuel efficiency of the series hybrid electric vehicle.</p>

Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.

[First Embodiment] FIG. 1 is a configuration diagram showing an example of a drive system of a series hybrid electric vehicle to which the present invention is applied. In this series hybrid electric vehicle, the drive motor 4 is driven by the electric power from the generator 2 driven by the internal combustion engine 1 and the electric power from the high-power battery 3, and the drive motor 4 is mounted on the output shaft of the internal combustion engine 1. The generator 2 is connected so that the driving force is transmitted. The generator 2 is driven by the rotation of the internal combustion engine 1 to generate a three-phase alternating current. An inverter 5 is provided on the output side of the generator 2, and the output generated by the generator 2 is AC / DC converted by the inverter 5. Further, when the internal combustion engine 1 is started, the inverter 5 orthogonally converts the output from the high-power battery 3 and supplies the output to the generator 2, and causes the generator 2 to function as a motor to start the internal combustion engine 1.

A high-power battery 3 and a drive inverter 6 are connected in parallel on the DC output side of the inverter 5. The output of the generator 2 converted to AC / DC by the inverter 5 is charged to the high-power battery 3 and supplied to the drive inverter 6. The drive inverter 6 orthogonally converts the output of the generator 2 or the output from the high-power battery 3 orthogonally converted by the inverter 5.

The AC output side of the drive inverter 6 is connected to the drive motor 4, and the drive motor 4 is a series hybrid by supplying power converted to alternating current of a predetermined voltage and a predetermined frequency by the drive inverter 6 to the drive motor 4. It outputs the drive torque that drives the electric motor. The torque output from the drive motor 4 is amplified by the speed reducer 7 and transmitted to the drive wheels 8 via the drive shaft. Further, the regenerative power generated by the drive motor 4 during deceleration of the series hybrid electric vehicle is AC / DC converted by the drive inverter 6 and charged into the high-power battery 3.

The high-power battery 3 is provided with a battery controller 9 that monitors the state of the high-power battery 3. The battery controller 9 acquires the battery voltage, current, etc. of the high-power battery 3, and obtains the state of the high-power battery 3, specifically, the current SOC (State of Charge), temperature, and maximum charge power of the high-power battery 3. , Understand the maximum discharge power, etc.

In addition, the series hybrid electric vehicle is equipped with a control device 10 that comprehensively controls the operation of the drive system. The control device 10 is configured by using, for example, a microcomputer, and information from an input from a series hybrid electric vehicle (for example, accelerator opening, etc.), a battery controller 9, a drive inverter 6, an inverter 5, and an internal combustion engine 1 (for example,). , Battery SOC, drive motor rotation speed, etc.), and controls the operation of the drive motor 4, the generator 2, and the internal combustion engine 1. The present invention is implemented as a function of power generation control by the control device 10. That is, in the control device 10 of the present embodiment, the SOC of the high-power battery 3 is relatively low when the series hybrid electric vehicle is running at low speed, and the SOC of the high-power battery 3 is relatively low when the series hybrid electric vehicle is running at high speed. By controlling the internal combustion engine 1 and the generator 2 so as to be high, the drive motor 4 and the drive inverter 6 can be operated in an efficient region to improve fuel efficiency.

FIG. 2 is a diagram showing the relationship between the battery voltage of the high-power battery 3 and the efficiency η of the drive motor 4 and the drive inverter 6. As shown in FIG. 2, in the region where the motor rotation speed is low, the higher the battery voltage is, the higher the efficiency is, and conversely, in the region where the motor rotation speed is high, the higher the battery voltage is, the higher the efficiency is. .. Therefore, when the series hybrid electric vehicle is running at low speed, the SOC of the high-power battery 3 is set low to lower the battery voltage, and conversely, when running at high speed, the SOC of the high-power battery 3 is set high. By setting the battery voltage to be high, the drive motor 4 and the drive inverter 6 can be efficiently operated both at low speed and at high speed. Although the efficiency of the generator 2 and the inverter 5 changes according to the battery voltage, the efficiency change of the generator 2 and the inverter 5 changes with respect to the efficiency change of the drive motor 4 and the drive inverter 6. Therefore, the efficiency of the entire system is improved by operating at the high efficiency point of the drive motor 4 and the drive inverter 6.

FIG. 3 is a block diagram showing a functional configuration related to power generation control of the control device 10 of the present embodiment. As shown in FIG. 3, the control device 10 of the present embodiment has a vehicle speed low frequency component calculation unit 11, a maximum charge / discharge power calculation unit 12, a target SOC calculation unit 13, and power generation as functional configurations for executing power generation control. It is equipped with a power calculation unit 14, a voltage complementary power generation power calculation unit 15, and a power generation control unit 16.

The vehicle speed low frequency component calculation unit 11 calculates the vehicle speed of the series hybrid electric vehicle at any time based on the drive motor rotation speed from the drive inverter 6, and calculates the low frequency component. Here, the low-frequency component of the vehicle speed calculated by the vehicle speed low-frequency component calculation unit 11 is, for example, the time average of the vehicle speed during traveling during the past 300 seconds.

The maximum charge / discharge power calculation unit 12 acquires the battery current, the battery voltage, and the battery temperature from the battery controller 9, and calculates the maximum battery charge power and the maximum battery discharge power for each battery SOC with reference to the maximum charge / discharge power map 21. To do. The maximum battery charge power and the maximum battery discharge power according to the current battery state are grasped by the battery controller 9 as described above, but when the battery SOC or the battery temperature changes, the maximum battery charge power and the maximum battery charge power at that time are obtained. The discharge power also changes. Therefore, in the present embodiment, for example, the maximum charge / discharge power map 21 showing the relationship between the battery temperature, the maximum charge power of the battery, and the maximum discharge power of the battery as shown in FIG. 4 is stored for each battery SOC, and the maximum charge / discharge power calculation is performed. Part 12 makes it possible to calculate the maximum battery charge power and the maximum battery discharge power for each battery SOC in advance with reference to the maximum charge / discharge power map 21.

The target SOC calculation unit 13 acquires the low frequency component of the current vehicle speed calculated by the vehicle speed low frequency component calculation unit 11, and refers to the vehicle speed-target SOC map 22 to obtain the low frequency component of the current vehicle speed (hereinafter referred to as the vehicle speed low frequency component). Set the target SOC of the high-frequency battery 3 corresponding to (simply called vehicle speed). In the vehicle speed-target SOC map 22 used here, the target SOC is set low when the current vehicle speed is in the low-speed driving region, and the target SOC is set high when the current vehicle speed is in the high-speed driving region. The relationship between the vehicle speed and the target SOC is defined so that it can be set. Specifically, when the vehicle speed is 15 km / h or less, the vehicle runs at low speed, when the vehicle speed is 100 km / h or more, the vehicle runs at high speed, and when the vehicle speed is between these, the vehicle speed-target SOC map 22 is shown in FIG. 5, for example. As shown, the relationship between the vehicle speed and the target SOC is defined so that the target SOC of the high-power battery 3 is 30% in the low-speed driving region and the target SOC of the high-power battery 3 is 70% in the high-speed driving region. In the map image of Fig. 5, as an example of the target SOC in the region of medium-speed driving, an example in which the target SOC changes linearly from 30% to 70% between a vehicle speed of 30 km / h and a vehicle speed of 70 km / h is shown. However, the target SOC in the area of medium-speed driving may be set between the target SOC at low speed (for example, 30%) and the target SOC at high speed (for example, 70%), and the pattern of change is It can be set arbitrarily. Further, the target SOC during low-speed driving and the target SOC during high-speed driving need only be lower than the target SOC during high-speed driving, and are illustrated in the map image of FIG. 3030. It can be set to any value, not limited to% and 70%.

In addition, the target SOC calculation unit 13 calculates the target battery voltage corresponding to the target SOC set according to the current vehicle speed of the hybrid electric vehicle with reference to the vehicle speed-target battery voltage map 23. The vehicle speed-target battery voltage map 23 used here is, for example, as shown in FIG. 6, the vehicle speed and the target battery so that the target battery voltage changes in a change pattern (see FIG. 5) corresponding to the vehicle speed-target SOC map 22. It defines the relationship with voltage.

By the way, when the target SOC is set according to the current vehicle speed of the hybrid electric vehicle as described above, the maximum battery charge power of the high-power battery 3 when the target SOC is achieved is smaller than the maximum regenerative power of the drive motor 4. In addition, it may not be possible to charge the high-power battery 3 with all the regenerated power generated by the drive motor 4 during sudden deceleration of the series hybrid electric vehicle, resulting in energy loss and a decrease in efficiency. In addition, if the maximum battery discharge power of the high-power battery 3 when the target SOC is achieved is smaller than the maximum power running power of the drive motor 4, the drive power may be insufficient during sudden acceleration of the series hybrid electric vehicle, resulting in acceleration. There is a risk of performance degradation.

Therefore, in the present embodiment, when the target SOC calculation unit 13 sets the target SOC of the high-power battery 3 according to the current vehicle speed of the hybrid electric vehicle, the maximum battery charge power and the maximum battery discharge power for each battery SOC are set. Maximum charge / discharge power Obtained from the calculation unit 12, the maximum charge power of the high-power battery 3 after achieving the target SOC is equal to or higher than the maximum regenerative power of the drive motor 4, and the maximum discharge power of the high-power battery 3 after achieving the target SOC is The target SOC of the high-power battery 3 is set within the range that exceeds the maximum power running power of the drive motor 4. The maximum regenerative power and the maximum power running power are values determined according to vehicle parameters such as the capacity of the drive motor 4 and the drive inverter 6, and may be stored in advance as fixed values for each vehicle type.

The generated power calculation unit 14 acquires the target SOC set by the target SOC calculation unit 13 and also acquires the current SOC (actual SOC) of the high-power battery 3 from the battery controller 9 to obtain the target SOC and the actual SOC. Calculate the difference ΔSOC. Then, the generated power calculation unit 14 refers to the ΔSOC-generated power map 24 as shown in FIG. 7, for example, and calculates the generated power (initial value of the generated power) corresponding to the calculated ΔSOC.

The voltage complementing generated power calculation unit 15 acquires the target battery voltage calculated by the target SOC calculation unit 13 and also acquires the current battery voltage from the battery controller 9, and the difference between the target battery voltage and the current battery voltage. Calculate ΔVbatt. Then, the voltage complementing generated power calculation unit 15 refers to the ΔVbatt-power complement value map 25 as shown in FIG. 8, for example, and calculates the power complement value corresponding to the calculated ΔVbatt. This power complement value is for suppressing a large fluctuation of the battery voltage due to charging / discharging of the high-power battery 3 and suppressing a decrease in efficiency of the drive motor 4 due to the voltage change.

The power generation control unit 16 acquires a value obtained by adding the power complement value calculated by the voltage complementation power generation power calculation unit 15 to the power generation power initial value calculated by the power generation power calculation unit 14 as the power generation power target value, and obtains this power generation power. The internal combustion engine torque command value and the generator rotation speed command value for generating the electric power corresponding to the target value by the generator 2 are calculated. Then, the internal combustion engine 1 is driven and controlled based on the calculated internal combustion engine torque command value, and the calculated generator rotation speed command value is supplied to the inverter 5 to drive and control the generator 2.

FIG. 9 is a flowchart showing a flow of power generation control processing by the control device 10 of the present embodiment. The control device 10 repeatedly executes the process shown in the flowchart of FIG. 9 at a predetermined cycle, so that the SOC of the high-power battery 3 becomes low when the series hybrid electric vehicle is running at low speed, and the control device 10 is running at high speed. At this time, the internal combustion engine 1 and the generator 2 are controlled so that the SOC of the high-power battery 3 becomes high.

When the flow of FIG. 9 is started, the control device 10 first acquires the drive motor rotation speed from the drive inverter 6 in step S101, and calculates the low frequency component of the vehicle speed of the series hybrid electric vehicle.

Next, in step S102, the controller 10 has a relatively low SOC of the high-power battery 3 at low speeds and a high-power battery 3 at high speeds according to the current vehicle speed of the series hybrid electric vehicle calculated in step S101. Set the target SOC of the high-power battery 3 so that the SOC is relatively high. The target SOC setting process in step S102 will be described in detail later with reference to FIG.

Next, in step S103, the control device 10 calculates the target battery voltage corresponding to the target SOC set in step S102, that is, the target battery voltage corresponding to the current vehicle speed of the series hybrid electric vehicle.

Next, in step S104, the control device 10 calculates the generated power target value for achieving the target SOC set in step S102. The details of the power generation target value calculation process in step S104 will be described later with reference to FIG.

Next, in step S105, the control device 10 determines whether or not the generated power target value calculated in step S104 is a positive value, that is, whether or not to request the generator 2 to generate power. Then, if the generated power target value calculated in step S104 is a positive value, the internal combustion engine 1 and the generator 2 are driven so that the generator 2 outputs the power corresponding to the generated power target value in step S106. Control. If the generated power target value calculated in step S104 is a negative value, the process ends as it is.

FIG. 10 is a flowchart showing the details of the target SOC setting process (step S102 in FIG. 9) by the control device 10.

When setting the target SOC of the high-power battery 3, the control device 10 first acquires the battery current, the battery voltage, and the battery temperature from the battery controller 9 in step S201, and obtains the maximum battery charge power and the maximum battery discharge power for each battery SOC. Is calculated.

Next, in step S202, the control device 10 acquires the maximum regenerative power of the drive motor 4, and based on the maximum battery charge power for each battery SOC calculated in step S201, the maximum battery charge power of the drive motor 4 is set. Find the battery SOC that is equal to the maximum regenerated power and set this as the upper limit of the target SOC.

Next, in step S203, the control device 10 acquires the maximum power running power of the drive motor 4, and based on the maximum battery discharge power for each battery SOC calculated in step S201, the maximum battery discharge power of the drive motor 4 is set. Find the battery SOC equal to the maximum power running and set this as the lower limit of the target SOC.

Next, in step S204, the control device 10 corresponds to the current vehicle speed of the series hybrid electric vehicle calculated in step S101 of FIG. 9 within the range of the upper limit set in step S202 and the lower limit set in step S203. Set the target SOC of the high-power battery 3. That is, the target SOC according to the vehicle speed is obtained based on the above-mentioned vehicle speed-target SOC map 22, and if the target SOC according to this vehicle speed exceeds the upper limit value set in step S202, the target SOC is limited by the upper limit value. If the target SOC according to the vehicle speed is less than the lower limit set in step S203, the target SOC is limited by the lower limit.

FIG. 11 is a flowchart showing the details of the generated power target value calculation process (step S104 in FIG. 9) by the control device 10.

When calculating the generated power target value for achieving the target SOC, the control device 10 first acquires the current SOC (actual SOC) of the high-power battery 3 from the battery controller 9 in step S301.

Next, in step S302, the control device 10 calculates the difference ΔSOC between the target SOC set in step S102 of FIG. 9 and the actual SOC acquired in step S301.

Next, in step S303, the control device 10 calculates the initial value of generated power corresponding to ΔSOC calculated in step S302 based on the above-mentioned ΔSOC-generated power map 24.

Next, in step S304, the control device 10 acquires the current battery voltage of the high-power battery 3 from the battery controller 9.

Next, in step S305, the control device 10 calculates the difference ΔVbatt between the target battery voltage calculated in step S103 of FIG. 9 and the current battery voltage acquired in step S304.

Next, in step S306, the control device 10 calculates the power complement value corresponding to the ΔVbatt calculated in step S305 based on the ΔVbatt-power complement value map 25 described above.

Next, in step S307, the control device 10 calculates a value obtained by adding the power supplement value calculated in step S306 to the power initial value calculated in step S303 as the generated power target value.

As described in detail above with specific examples, the control device 10 of the present embodiment has a relatively low SOC of the high-power battery 3 at low speeds according to the current vehicle speed of the series hybrid electric vehicle. , The target SOC of the high-power battery 3 is set so that the SOC of the high-power battery 3 becomes relatively high during high-speed driving. Then, the power generation target value by the generator 2 is calculated so that the target SOC according to the vehicle speed is achieved, and the internal combustion engine 1 and the power generation are output so that the power corresponding to the generated power target value is output from the generator 2. The machine 2 is driven and controlled. Therefore, the drive motor 4 should be efficiently operated at a low voltage when the drive motor 4 is running at a low speed at a low speed, and the drive motor 4 should be efficiently operated at a high voltage when the drive motor 4 is running at a high speed at a high speed. As a result, it is possible to improve the fuel efficiency of the series hybrid electric vehicle.

Further, in the control device 10 of the present embodiment, when setting the target SOC of the high-power battery 3 according to the current vehicle speed of the series hybrid electric vehicle, the maximum charging power of the high-power battery 3 after achieving the target SOC is the drive motor 4 The target SOC of the high-power battery 3 is set within a range in which the maximum regenerative power of the high-power battery 3 or more and the maximum discharge power of the high-power battery 3 after the target SOC is achieved is equal to or higher than the maximum power running power of the drive motor 4. Therefore, since it is not necessary to limit the regeneration of the drive motor 4 during sudden deceleration of the series hybrid electric vehicle, the kinetic energy can be efficiently converted into electric energy to further improve the fuel efficiency, and the series hybrid electric vehicle can be further improved. Since it is not necessary to limit the power running of the drive motor 4 when the vehicle is suddenly decelerated, it is possible to improve the driving performance.

Further, the control device 10 of the present embodiment obtains a power complement value according to the difference between the target battery voltage and the current battery voltage, and generates a value obtained by adding the power complement value to the initial power generation power corresponding to the target SOC. Since it is calculated as the power target value, it is possible to suppress large fluctuations in the battery voltage due to charging and discharging of the high-power battery 3, suppress a decrease in efficiency of the drive motor 4 due to voltage changes, and further improve fuel efficiency. Can be done.

[Second Embodiment] Next, a second embodiment of the present invention will be described. In this embodiment, the specific method of controlling power generation so that the regeneration and power running of the drive motor 4 are not restricted is different from that of the first embodiment. That is, in the first embodiment, the target SOC is adjusted based on the maximum regenerative power and the maximum power running power of the drive motor 4 so that the regeneration and power running of the drive motor 4 are not restricted. By adjusting the generated power target value based on the maximum regenerative power and the maximum power running power of the drive motor 4, the regeneration and power running of the drive motor 4 are not restricted. The configuration of the drive system of the series hybrid electric vehicle (see FIG. 1) and the basic processing flow of power generation control by the control device 10 (see FIG. 9) are the same as those in the first embodiment described above. , The description overlapping with the first embodiment will be omitted, and only the parts characteristic of the present embodiment will be described.

FIG. 12 is a block diagram showing a functional configuration related to power generation control of the control device 10 of the present embodiment. The control device 10 of the present embodiment does not include the maximum charge / discharge power calculation unit 12 (see FIG. 3) described in the first embodiment, but instead has a generated power limit value calculation unit 17 added. .. Other functional configurations are the same as those in the first embodiment.

In the control device 10 of the present embodiment, the target SOC calculation unit 13 sets the target SOC of the high-power battery 3 based only on the current vehicle speed of the series hybrid electric vehicle calculated by the vehicle speed low-frequency component calculation unit 11. That is, in the first embodiment, when the target SOC calculation unit 13 sets the target SOC of the high-power battery 3, the maximum charging power of the high-power battery 3 after achieving the target SOC becomes equal to or higher than the maximum regenerative power of the drive motor 4. Further, an upper limit and a lower limit are set for the target SOC to be set so that the maximum discharge power of the high-power battery 3 after achieving the target SOC becomes equal to or higher than the maximum power running power of the drive motor 4. However, in the present embodiment, such an upper limit and a lower limit are set. There are no restrictions on the target SOC. Instead, in the control device 10 of the present embodiment, the generated power limit value calculation unit 17 sets the upper limit value and the lower limit value of the generated power target value to limit the generated power target value. ..

The generated power limit value calculation unit 17 acquires the maximum battery charge power and the maximum battery discharge power according to the current battery SOC from the battery controller 9, and also acquires the maximum regenerative power and the maximum power running power of the drive motor 4. Then, the value obtained by subtracting the maximum battery discharge power according to the current battery SOC from the maximum power running power of the drive motor 4 is set as the lower limit of the generated power target value, and the battery is driven from the maximum battery charge power according to the current battery SOC. The value obtained by subtracting the maximum regenerated power of the motor 4 is set as the upper limit of the generated power target value. Further, the generated power limit value calculation unit 17 acquires a value obtained by adding the power complementary value calculated by the voltage complementary generated power calculation unit 15 to the generated power initial value calculated by the generated power calculation unit 14 as the generated power target value. To do. If the acquired power generation target value is between the lower limit and the upper limit, the generated power target value is set as the final generated power target value, and if the acquired generated power target value exceeds the upper limit, the upper limit is set. If the value and the acquired power generation target value are less than the lower limit, the lower limit is set as the final power generation target value.

In the control device 10 of the present embodiment, the power generation control unit 16 acquires the final power generation power target value calculated by the power generation power limit value calculation unit 17. Then, the power generation control unit 16 calculates the internal combustion engine torque command value and the generator rotation speed command value for generating the electric power corresponding to the final generated power target value by the generator 2, and sets the calculated internal internal engine torque command value. Based on this, the internal combustion engine 1 is driven and controlled, and the calculated generator rotation speed command value is supplied to the inverter 5 to drive and control the generator 2.

FIG. 13 is a flowchart showing the details of the power generation target value calculation process by the control device 10 of the present embodiment. In the present embodiment, when the control device 10 calculates the power generation target value (step S104 in FIG. 9), the process according to the flow of FIG. 13 is replaced with the flow of FIG. 11 described in the first embodiment. I do. In the target SOC setting process in step S102 of FIG. 9, the target SOC is not limited based on the maximum regenerative power and the maximum power running power of the drive motor 4, and the target SOC corresponding to the vehicle speed of the series hybrid electric vehicle is set as it is. ing.

When calculating the generated power target value for achieving the target SOC, the control device 10 of the present embodiment first acquires the current SOC (actual SOC) of the high-power battery 3 from the battery controller 9 in step S401.

Next, in step S402, the control device 10 calculates the difference ΔSOC between the target SOC set according to the vehicle speed of the series hybrid electric vehicle in step S102 of FIG. 9 and the actual SOC acquired in step S401.

Next, in step S403, the control device 10 calculates the initial value of the generated power corresponding to the ΔSOC calculated in step S402.

Next, in step S404, the control device 10 acquires the current battery voltage of the high-power battery 3 from the battery controller 9.

Next, in step S405, the control device 10 calculates the difference ΔVbatt between the target battery voltage calculated in step S103 of FIG. 9 and the current battery voltage acquired in step S404.

Next, in step S406, the control device 10 calculates the power complement value corresponding to the ΔVbatt calculated in step S405.

Next, in step S407, the control device 10 calculates a value obtained by adding the power supplement value calculated in step S406 to the power initial value calculated in step S403 as the generated power target value.

Next, in step S408, the control device 10 acquires the maximum battery charge power and the maximum battery discharge power according to the current battery SOC from the battery controller 9.

Next, in step S409, the control device 10 subtracts the maximum regenerative power of the drive motor 4 from the maximum battery charging power according to the current battery SOC, and sets the value as the generated power upper limit value.

Next, in step S410, the control device 10 subtracts the maximum battery discharge power according to the current battery SOC from the maximum power running power of the drive motor 4, and sets the value as the lower limit value of the generated power.

Next, in step S411, the control device 10 determines whether or not the generated power target value calculated in step S407 exceeds the generated power upper limit value set in step S410. Then, when the generated power target value calculated in step S407 exceeds the generated power upper limit value, the generated power upper limit value is calculated as the final generated power target value in step S412.

On the other hand, if the generated power target value calculated in step S407 is equal to or less than the generated power upper limit value, the control device 10 determines that the generated power target value calculated in step S407 is less than the generated power lower limit set in step S411 in step S413. Judge whether it is. Then, when the generated power target value calculated in step S407 is less than the generated power lower limit value, the generated power lower limit value is calculated as the final generated power target value in step S414. On the other hand, if the generated power target value calculated in step S407 is equal to or higher than the generated power lower limit value, that is, between the generated power lower limit value and the generated power upper limit value, the generated power target value calculated in step S407 in step S415. Is calculated as it is as the final power generation target value.

As described above, also in the present embodiment, as in the first embodiment, the SOC of the high-power battery 3 is relatively low when the series hybrid electric vehicle is running at low speed, and the SOC of the high-power battery 3 is relatively low when running at high speed. Since the target SOC of the high-power battery 3 is set so as to be high and the internal combustion engine 1 and the generator 2 are driven and controlled so that this target SOC is achieved, the drive motor 4 can be operated efficiently and the series. It is possible to improve the fuel efficiency of hybrid electric vehicles. In addition, the power complement value is obtained according to the difference between the target battery voltage and the current battery voltage, and the value obtained by adding the power complement value to the initial power generation power corresponding to the target SOC is calculated as the power generation target value. Therefore, it is possible to suppress a large fluctuation in the battery voltage due to charging / discharging of the high-power battery 3, suppress a decrease in efficiency of the drive motor 4 due to the voltage change, and further improve fuel efficiency.

Further, the control device 10 of the present embodiment sets a value obtained by subtracting the maximum battery discharge power according to the current battery SOC from the maximum power running power of the drive motor 4 as the lower limit value of the generated power target value, and sets the current battery SOC. The value obtained by subtracting the maximum regenerative power of the drive motor 4 from the maximum charge power of the battery according to the above value is set as the upper limit value of the generated power target value, and the generated power target value is calculated between this lower limit value and the upper limit value. ing. Therefore, also in the present embodiment, as in the first embodiment, it is not necessary to limit the regeneration of the drive motor 4 at the time of sudden deceleration of the series hybrid electric vehicle, and the kinetic energy is efficiently converted into the electric energy. In addition to further improving fuel efficiency, it is not necessary to limit the power running of the drive motor 4 during sudden deceleration of a series hybrid electric vehicle, and it is possible to improve driving performance.

It should be noted that each of the above embodiments exemplifies one application example of the present invention, and is not intended to limit the technical scope of the present invention to the contents described as these embodiments. .. That is, the technical scope of the present invention is not limited to the specific technical matters disclosed in each of the above embodiments, but also includes various modifications, modifications, alternative technologies, etc. that can be easily derived from this disclosure.

<figref num="1">It is a block diagram which shows an example of the drive system of the series hybrid electric vehicle to which this invention is applied.</figref><figref num="2">It is a figure which shows the relationship between the battery voltage of a high electric battery and the efficiency of a drive motor and a drive inverter.</figref><figref num="3">It is a block diagram which shows an example of the functional structure related to the power generation control of a control device.</figref><figref num="4">It is a figure which shows the map image of the maximum charge / discharge power map.</figref><figref num="5">Vehicle Speed-A diagram showing a map image of a target SOC map.</figref><figref num="6">It is a figure which shows the map image of the vehicle speed-target battery voltage map.</figref><figref num="7">It is a figure which shows the map image of ΔSOC-generated power map.</figref><figref num="8">It is a figure which shows the map image of ΔVbatt-power complement value map.</figref><figref num="9">It is a flowchart which shows the flow of the process of power generation control by a control device.</figref><figref num="10">It is a flowchart which shows the detail of the target SOC setting process by a control device.</figref><figref num="11">It is a flowchart which shows the detail of the power generation target value calculation process by a control device.</figref><figref num="12">It is a block diagram which shows another example of the functional structure related to the power generation control of a control device.</figref><figref num="13">It is a flowchart which shows another example of the power generation target value calculation processing by a control device.</figref>

Code description

1 Internal combustion engine 2 generator 3 High-power battery 4 drive motor 10 Control unit 11 Vehicle speed low frequency component calculation unit 12 Maximum charge / discharge power calculation unit 13 Target SOC calculation unit 14 Power generation calculation unit 15 Voltage Complementary Power Generation Calculation Unit 16 Power generation control unit 17 Power generation limit value calculation unit