Method and apparatus for charging multiple energy storage devices

Method and equipment for charging multiple energy storage devices Technical field

[0001] Embodiments of the present invention generally relate to electric drive systems including hybrid electric vehicles and electric vehicles, and more specifically, to use a multi-port energy management system to charge energy storage devices of electric vehicles.

Background technique

[0002] Hybrid electric vehicles may combine an internal combustion engine with an electric motor powered by an energy storage device (such as a traction battery) to propel the vehicle. Such a combination can improve overall fuel efficiency by enabling the internal combustion engine and the electric motor to each operate in a correspondingly improved efficiency range. For example, an electric motor may be efficient when accelerating from a standstill, while an internal combustion engine (ICE) may be efficient for the duration of constant engine operation (such as highway driving). Having the electric motor boost the initial acceleration allows the internal combustion engine in a hybrid vehicle to be smaller and more fuel efficient.

[0003] Pure electric vehicles use stored electrical energy to power the electric motor, which propels the vehicle and can also operate auxiliary drives. Pure electric vehicles can use one or more stored electrical energy sources. For example, the first stored electrical energy source can be used to provide longer-lasting energy, such as a low-voltage battery (commonly referred to as "energy battery"), and the second stored electrical energy source can be used to use a high-voltage battery (commonly referred to as "power battery"). ) Provide higher power energy, for example for vehicle acceleration. Known energy storage devices may also include supercapacitors, which often have faster charging and discharging capabilities and provide long-term operation.

[0004] Plug-in electric vehicles, whether hybrid electric or pure electric, are typically configured to use electrical energy from an external source to recharge the energy storage device. Such vehicles may include, for example, on- and off-road vehicles, golf carts, community electric vehicles, forklifts, and general-purpose trucks. The well-known charging device includes a multi-port energy storage management system (ESMS) for charging both a low-voltage energy storage system and a high-voltage energy storage system of an electric vehicle. Typically, ESMS includes down-boost converters, and these down-boost converters can be used in combination with each other to flexibly apply charging voltages to a variety of devices with different charging voltage requirements. ESMS also typically includes a high voltage side and a low voltage side. In a known ESMS device with four ports, two of the ports are located on the high voltage side of the device and two of the ports are located on the low voltage side of the device. The high voltage side is typically used for charging from the utility grid or renewable energy (one port on the high voltage side) and providing charging power to the power battery (the other port on the high voltage side). The low-voltage side is typically used to charge low-voltage devices (such as energy batteries and supercapacitors) of electric vehicles (ports on the low-voltage side), and in some embodiments may also include one of the low-voltage ports for charging the low-voltage Adaptability of charging source.

[0005] Incidentally, the power battery is typically included in order to provide high-power bursts for vehicle acceleration, and therefore it is desired to operate as a high-voltage device. Compared to the energy battery, the energy battery is typically included to provide a Provide long-distance cruising energy. Therefore, due to the high power requirements of power batteries, high-voltage energy storage devices (eg, power batteries) typically operate at a high voltage of 400 V or more; while low-voltage energy storage devices (eg, energy batteries) typically Provides high energy storage and operates at a much lower nominal voltage (for example, 120 V or lower). Supercapacitors can be used in high or low voltage applications, and therefore can be included on the high or low side of the ESMS charging device, depending on the type of use (high burst of power versus energy storage for cruise) .

[0006] Because of the down-boost converter in ESMS, multiple arrangements of energy storage devices and power sources can be utilized

To charge the energy storage device. That is, the known ESMS can be flexibly configured because the charging voltage can be first reduced on the high voltage side and then raised to the desired charging voltage. And, due to the lowering operation and the subsequent raising operation, the charging on the high voltage side may be higher or lower than the charging voltage provided externally. Similarly, the charging voltage can also be reduced to a lower voltage on the low voltage side. Moreover, due to the multiple down-boost converters in the EMS, the charging voltage can be provided at the same time to charge the high-voltage device on the high-side and one or more low-voltage devices on the low-side. That is, a single high-voltage supply can be split to simultaneously supply energy to, for example, a high-side device and a low-side device or to two low-sides.

[0007] Known devices that split power for charging multiple energy storage devices are typically optimized based only on the condition of the device being charged. That is, known charging or ESMS devices typically have their power separated based on factors such as the charging state of the device and/or the voltage at each corresponding charging port. Although such optimization is often sufficient to provide the maximum overall charging rate for the combination of devices being charged, such charging planning does not take into account additional factors such as the overall impact on the lifetime of the device being charged, temperature limits, etc. That is, although the energy storage device may be physically capable of receiving a high charging rate to reduce the charging time of all devices, this would not be expected if the long-term cost for one or more devices is a decrease in lifespan.

[0008] In other words, the cost of service life and the eventual need to replace energy storage devices such as power batteries, energy batteries, and supercapacitors may not be worth charging based solely on the marginal reduction in charging time in the state of charge. In fact, because the known charging devices determine the power separation and charging rate without taking into account the specific conditions of the device itself (but based only on the state of charge or voltage at the charging end), these devices not only have a long service life Risks, and there is a risk of catastrophic failure if the device is charged at a rate beyond the devices ability to handle it.

[0009] Therefore, it is desirable to provide an equipment and control scheme to optimize the overall recharging time of multiple energy storage devices of an EV, while taking into account the life impact of the charging plan.

Summary of the invention

[0010] The present invention is an apparatus and method for optimizing the overall recharging time of multiple energy storage devices of an EV in consideration of the impact on the life of the energy storage device itself.

[0011] According to one aspect of the present invention, an electric vehicle includes a controller configured to receive sensor feedback from a high-voltage storage device and from a low-voltage storage device, and connect the sensor feedback to the corresponding high-voltage storage device and low-voltage storage device. The operation limit of the device is compared, the total charging current to the high-voltage storage device and the low-voltage storage device and the power separation factor of the total charging current to the high-voltage device and the low-voltage device are determined based on the comparison, and the adjustment to the low voltage based on the determination The total power of the storage device and the high-voltage storage device.

[0012] According to another aspect of the present invention, a method of managing an energy storage system of an electric vehicle includes receiving sensor feedback from a high-voltage energy storage device of the electric vehicle, and combining the sensor feedback from the high-voltage energy storage device with a specific In comparison with the operating limit of the high-voltage energy storage device, sensor feedback is received from the low-voltage energy storage device of the electric vehicle, and the sensor feedback from the low-voltage energy storage device is compared with the operating limit specific to the low-voltage energy storage device. The comparison between the voltage device and the low-voltage device determines the total charging current to the high-voltage storage device and the low-voltage storage device and the power separation factor of the total charging current to the high-voltage device and the low-voltage device, and adjusts to low based on the determination The total power of the voltage storage device and the high voltage storage device.

[0013] According to another aspect of the present invention, a computer-readable storage medium is coupled to an energy storage and management system (ESMS) of an electric vehicle (EV) and stored thereon a computer program containing instructions, which are When the computer is executed, the computer is prompted to perform the following operations: from the high-voltage energy storage device of the EV and from the low-voltage energy storage device of the EV

Receive sensor feedback, compare the sensor feedback with the operating limit of the corresponding energy storage device, and determine the total charging current to the energy storage device based on the comparison and the power separation factor of the total charging current between the high-voltage device and the low-voltage device, And based on determining the total power adjusted to the energy storage device.

[0014] According to a first embodiment, there is provided an electric vehicle including: a controller configured to: receive sensor feedback from a high-voltage storage device and from a low-voltage storage device; and combine the sensor feedback with a corresponding high-voltage Comparison of the operating limits of the storage device and the low-voltage storage device; determining based on the comparison: the total charging current to the high-voltage storage device and the low-voltage storage device; and to the high-voltage storage device and the low-voltage storage device The power separation factor of the total charging current; and the total power adjusted to the low-voltage storage device and the high-voltage storage device based on the determination.

[0015] Preferably, the system according to the first embodiment includes an energy storage and management system (ESMS), the energy storage and management system includes: a plurality of energy ports, the ESMS includes a plurality of DC power converters, each DC power The converter is configured to increase and decrease the DC voltage, wherein: the first port of the plurality of energy ports is a high voltage port that can be coupled to the increased voltage side of each of the DC electrical converters; The second port of the two energy ports is a low voltage port that can be coupled to the reduced voltage side of each of the DC power converters; and at least one of the plurality of energy ports can be coupled to a charging system; The high voltage storage device is coupled to the first port; the low voltage storage device is coupled to the second port; and the charging system is coupled to one of the plurality of energy ports.

[0016] Preferably, the charging system is an auxiliary power unit provided on the electric vehicle, and is configured to output electric power to the power electronic conversion system when the vehicle is in motion. Further, the controller is configured to: determine the voltage of each of the plurality of energy ports; and determine the power separation factor based on the determined voltage of each corresponding energy port.

[0017] Preferably, the controller is configured to: continuously receive the sensor feedback from the high-voltage storage device and the low-voltage storage device; and combine the continuously received sensor feedback with the corresponding high-voltage storage device and The operation limit comparison of the low-voltage storage device; correcting the determined total charging current and the power separation factor; and adjusting the power to the low-voltage storage device and the high-voltage storage device based on the corrected determination.

[0018] Preferably, the controller is configured to determine the power separation factor so that when adjusting the power to the high-voltage energy storage device and to the low-voltage energy storage device, the power is directed to the high Only one of the voltage energy storage device and the low voltage energy storage device.

[0019] Preferably, the operating limit of the respective high-voltage storage device and the low-voltage storage device is determined by at least one of the current limit and the maximum temperature corresponding to each of the respective high-voltage storage device and the low-voltage storage device One composition.

[0020] Preferably, the controller is configured to adjust a fan configured to blow air on one of the high-voltage device and the low-voltage device based on the sensor feedback.

[0021] Preferably, the system according to the first embodiment includes a power device coupled to the high voltage storage device and the low voltage storage device, wherein the power device includes one of the following: a vehicle transmission system , Uninterrupted power supply, mining vehicle transmission system, mining equipment, ship system and aviation system.

[0022] According to a second embodiment, there is provided a method of managing an energy storage system of an electric vehicle, including: receiving sensor feedback from a high-voltage energy storage device of the electric vehicle; The sensor feedback is compared with the operating limit specific to the high-voltage energy storage device; the sensor feedback is received from the low-voltage energy storage device of the electric vehicle; the sensor feedback from the low-voltage energy storage device is compared with the operating limit specific to the low-voltage energy storage device.

Comparison of the operating limit of the voltage energy storage device; based on the comparison from the high-voltage device and from the low-voltage device, determine: the total charging current to the high-voltage storage device and the low-voltage storage device; and to the high The power separation factor of the total charging current of the voltage device and the low voltage device; and the total power adjusted to the low voltage storage device and the high voltage storage device based on the determination.

[0023] Preferably, the method according to the second embodiment includes obtaining energy storage device parameter information and determining the total charging current and the power separation factor based on the energy storage device parameter information, wherein the energy storage parameter information includes The state of charge and current operating voltage corresponding to each of the corresponding high-voltage energy storage device and the low-voltage energy storage device.

[0024] Preferably, the operating limits of the high-voltage device and the low-voltage device include at least one of a current limit and a maximum temperature corresponding to each of the corresponding high-voltage energy storage device and the low-voltage energy storage device .

[0025] Preferably, the method according to the second embodiment includes adjusting the total power of the low-voltage energy storage device and the high-voltage energy storage device by an auxiliary power unit provided on the electric vehicle.

[0026] Preferably, the high-voltage energy storage device is a power battery with an operating voltage of 400 V or more, and the low-voltage energy storage device is an energy battery and a super battery with an operating voltage of 120 V or less. One of capacitors.

[0027] According to a third embodiment, a computer-readable storage medium is provided, which is coupled to an energy storage and management system (ESMS) of an electric vehicle (EV) and stores thereon a computer program containing instructions that are When the computer is executed, the computer is prompted to perform the following operations: receive sensor feedback from the high-voltage energy storage device of the EV and from the low-voltage energy storage device of the EV; connect the sensor feedback to the operation of the corresponding energy storage device Limit comparison; determining based on the comparison: the total charging current to the energy storage device; and the power separation factor of the total charging current between the high-voltage device and the low-voltage device; and based on the determination Adjust to the total power of the energy storage device.

[0028] Preferably, the computer is also prompted to adjust the total power to the energy storage device according to an auxiliary unit, which is provided on the EV and coupled to a port of the ESMS.

[0029] Preferably, the computer is also prompted to determine the voltage of each of the multiple energy ports of the ESMS, and the power separation factor is determined based on the determined voltage of each corresponding energy port.

[0030] Preferably, the computer is also prompted to perform the following operations: continuously receive the sensor feedback from the high-voltage energy storage device and the low-voltage energy storage device; Comparing the operating limits of the voltage storage device and the low voltage storage device; correcting the determined total charging current and the power separation factor; and adjusting the total power to the energy storage device based on the correction.

[0031] Preferably, the operating limits of the respective high-voltage energy storage devices and low-voltage energy storage devices are determined by the current limit and maximum temperature corresponding to each of the respective high-voltage storage devices and low-voltage storage devices. At least one of them.

[0032] Preferably, the computer is also prompted to adjust a fan set to blow air on one of the high-voltage energy storage device and the low-voltage energy storage device based on the sensor feedback.

[0033] Various other features and advantages will be apparent through the following detailed description and drawings.

Description of the drawings

[0034] These drawings illustrate embodiments currently envisaged for implementing the invention.

[0035] In these drawings: FIG. 1 is a schematic block diagram of an electric vehicle (EV) incorporating an embodiment of the present invention.

[0036] FIG. 2 is a schematic block diagram of a configurable multi-port charger architecture according to an embodiment of the present invention.

[0037] FIG. 3 illustrates an electrical schematic diagram of a multi-port charger according to an embodiment of the present invention.

[0038] FIG. 4 illustrates a control plan specific to the module M2 of FIG. 2 as an example.

[0039] FIGS. 5 and 6 illustrate the flow of charging current in an exemplary operation mode in a multi-port charger.

[0040] FIG. 7 is a table illustrating the configuration of the multi-port charger shown in FIG. 2.

[0041] FIG. 8 is a block diagram illustrating a recharging scenario and the use of a communication interface according to an embodiment of the present invention.

[0042] FIG. 9 illustrates control variables and parameters related to a communication interface according to an embodiment of the present invention.

[0043] FIG. 10 is a schematic block diagram of an electric vehicle (EV) with an auxiliary power unit (APU) incorporating an embodiment of the present invention.

[0044] FIG. 11 is a schematic block diagram of an electric vehicle (EV) with an auxiliary power unit (APU) incorporating an embodiment of the present invention.

Detailed ways

[0045] FIG. 1 illustrates an embodiment of a hybrid electric vehicle (HEV) or electric vehicle (EV) 10, such as a car, a truck, a bus, or an off-highway vehicle, incorporating an embodiment of the present invention. In other embodiments, the vehicle 10 includes one of a vehicle drive system, an uninterruptible power supply, a mining vehicle drive system, mining equipment, a marine system, and an aviation system. The vehicle 10 includes an energy storage and management system (ESMS) 100 controlled by a controller or computer 46, an internal combustion engine or a heat engine 12, a transmission 14 coupled to the engine 12, a differential 16 and a transmission coupled to the The drive shaft assembly 18 between the device 14 and the differential 16. And although the ESMS 100 is shown in the plug-in hybrid electric vehicle (PHEV), it is understood that according to the embodiment of the present invention, the ESMS 100 can be applied to any electric vehicle, such as HEV or EV, or can be applied to operate pulses. Other power electronic drivers for the load.

[0046] According to various embodiments: the engine 12 may be, for example, an internal combustion gasoline engine, an internal combustion diesel engine, an external combustion engine, or a gas turbine engine. The system 10 includes an engine controller 20 provided for controlling the operation of the engine 12. According to one embodiment, the engine controller 20 includes one or more sensors 22 configured to sense the operating conditions of the engine 12. The sensor 22 may include, for example, a rpm sensor, a torque sensor, an oxygen sensor, and a temperature sensor. Therefore, the engine controller 20 is configured to transmit data or receive data from the engine 12. The vehicle 10 also includes an engine speed sensor (not shown) that measures the rotational speed of the crankshaft of the engine 12. According to one embodiment, the speed sensor can measure the engine crankshaft rotation speed in pulses per second by a tachometer (not shown), which can then be converted into a revolutions per minute (rpm) signal.

[0047] The vehicle 10 also includes at least two wheels 24 coupled to respective ends of the differential 16. In one embodiment, the vehicle 10 is configured as a rear-wheel drive vehicle, such that the differential 16 is provided near the rear end of the vehicle 10 and is configured to drive at least one of the wheels 24. Alternatively, the vehicle 10 may be configured as a front-wheel drive vehicle. In one embodiment, the transmission device 14 is a manually operated transmission device that includes a plurality of gears to multiply the input torque received from the engine 12 via a plurality of gear transmission ratios, and is transmitted to the partial speed through the drive shaft assembly 18.Device16. According to such embodiments, the vehicle 10 includes a clutch (not shown) configured to selectively connect and disconnect the engine 12 and the transmission device 14.

[0048] The vehicle 10 also includes an electromechanical device, such as an electric motor or a motor/generator unit 26. The electromechanical device is coupled between the transmission device 14 and the speed divider 16 along the drive shaft assembly 18 to enable the torque generated by the engine 12 It is transmitted to the speed divider 16 through the transmission 14 and through the electric motor or motor/generator unit 26. Can include a speed sensor (not shown) to monitor

The operating speed of the motor 26. According to one embodiment, the electric motor 26 is directly coupled to the transmission 14 and the drive shaft assembly 18 includes an axle or drive shaft coupled to the differential 16.

[0049] A hybrid drive control system or torque controller 28 is provided to control the operation of the electric motor 26, and the torque controller 28 is coupled to the electric motor/generator unit 26. The energy storage system 30 is coupled to the torque controller 28 and can be controlled by the ESMS 100. The energy storage system 30 includes, for example, a low voltage energy storage or energy battery 32, a high voltage energy storage or power battery 34 and a super capacitor 36. However, although the low-voltage energy storage 32, the high-voltage energy storage 34, and the super capacitor 36 are illustrated, it is understood that the energy storage system 30 may include multiple energy storage units as understood in the art, such as sodium metal halide batteries, sodium sickle Chloride battery, sodium sulfur battery, sickle metal hydrogen battery, lithium ion battery, lithium polymer battery, sickle cadmium battery, multiple supercapacitor units, supercapacitor and battery combination or fuel cell. The vehicle 10 also includes an accelerator pedal 38 and a brake pedal 40. The accelerator pedal 38 is configured to send an accelerator command signal or an accelerator pedal signal to the engine controller 20 and the torque control 28.

[0050] According to an embodiment of the present invention, the system 10 includes a charger interface 42 that is coupled to the energy storage units 32-36 of the energy storage system 30 via the ESMS 100. According to an embodiment of the present invention, the charger interface 42 can be coupled to a plurality of energy storage systems 32-36, as shown in the figure, and the charger interface 42 can be coupled to one or more power input lines 44, as shown in the figure Two of the oESMS 100 are configured to selectively engage and disengage the DC electrical device or lower-lift module, as will be discussed. In one embodiment and as will be explained, the charger interface 42 may be connected to the high voltage port of the ESMS 100. Typically, the charger interface 42 includes an interface to one or more input lines 44 so that power from the input lines can be connected to the charging port of the ESMS 100.

[0051] Although the charger interface 42 is illustrated as being coupled to the energy storage systems 32-36 via the ESMS 100, and the charger interface 42 is illustrated as being coupled to one or more power input lines 44, it is to be understood that the implementation of the present invention Examples should not be limited to this. Rather, it is understood that the charger interface 42 can be coupled to multiple and varying types of energy storage systems and power inputs. Furthermore, each vehicle may have multiple charger interfaces 42 or ESMS units 100, or may have a power system applied to each wheel 24 of the vehicle 10, and each power system has a charger interface 42 coupled to it.

[0052] In operation, it is understood in the art that energy can be supplied from an internal combustion engine or heat engine 12 via the transmission 14 to drive the shaft assembly 18, and energy can be drawn from the energy storage system 30, which can include energy systems 32-36. The drive control system 28 provides energy to the drive shaft assembly 18. Therefore, as understood in the art, the vehicle 10 can be boosted or accelerated to draw energy from, for example, the high voltage energy storage device 34 or from the supercapacitor 36, which can include, for example, a battery. During cruising (ie, generally non-accelerating operation), energy can be drawn for the vehicle 10 via a low-voltage storage device such as the low-voltage energy storage 32.

[0053] And during operation, energy may be drawn from the internal combustion engine or heat engine 12 to provide energy to the energy storage 30, or to provide power to the drive shaft assembly 18, as understood in the art. Furthermore, some systems include regeneration operations, in which energy can be recovered from braking operations and used to recharge the energy storage 30. In addition, some systems may not provide regenerative energy recovery from braking, and some systems may not provide a heat engine such as an internal combustion engine or a heat engine 12. Nonetheless, and although some systems can recharge the energy storage 30, the energy storage 30 needs to be periodically recharged from an external source, such as a 115 V household power supply or a 230 V 3-phase source. The demand for recharging the energy storage 30 is particularly urgent in a plug-in hybrid electric vehicle (PHEV) that does not have a thermal engine to provide power and extends the driving operating range.

[0054] Therefore, embodiments of the present invention are flexible and configurable by having multiple energy ports, and can be coupled to multiple power sources and source types to charge one or more energy storage types. Furthermore, the embodiments of the present invention allow efficient and balanced charging of multiple energy systems 32-36 of the energy storage unit 30, the multiple energy systems having

Varying depletion level.

[0055] In order to meet the needs of modern PHEVs and EVs, the infrastructure should provide typically 7 kW to achieve an 80% state of charge (SOC) (assuming a 25 kWh battery) in a charging time of 2 or 3 hours (home charging). For more aggressive short-stop fast charging schemes (eg, "gas stations"), a significantly higher power level may be required to achieve the desired 80% S0C in 10 minutes. The vehicle interface needs to be designed according to existing standards. Pilot signal (Pot signal) determines the maximum allowable power through its duty cycle. In addition to high integration, the proposed system also provides single-phase and/or three-phase AC input, high efficiency, low harmonics, input power factor close to 1, low cost, low weight, and safety interlocking of equipment. Power factor correction (PFC) requirements can be driven by IEC/ISO/IEEE line harmonic current specifications, as is known in the art.

[0056] The present invention can be applied to conventional electric vehicles (EV) and grid-charged hybrid electric vehicles (PHEV). The grid-charged HEV provides the option of driving the vehicle to a certain range (ie, PHEV20, PHEV40, PHEV60). Traditionally, the goal of PHEV is to provide high electric range (all-electric-range (AER)) capabilities to reduce operating costs and optimize operating strategies. As far as the lower-up stage, charger front end and interface are concerned, if it is designed for EV or PHEV applications, it generally makes a small difference. The role of the DC/DC converter is between two or more energy sources. Efficient energy transfer, reliable for continuous and peak power demand. The integration of the charger unit is the next step in a higher power density design with fewer components and therefore higher reliability. Therefore, the embodiments of the present invention can be applied to multiple electric vehicles, including all-electric and hybrid electric vehicles, generally and broadly referred to as "EV" as an example. Such EVs may include, but are not limited to, road vehicles, golf carts, trains, etc., which can have a power system including electric components for driving the vehicle to move.

[0057] In conventional implementations, many separate units coexist so as to generally include interconnected separate charger, battery management, and control units. In an automotive environment with advanced batteries, the communication between the charger and the battery is an important consideration. In this environment, seamless integration between batteries from different battery vendors is also an important consideration. An energy management system with an integrated charger is advantageous in that there is not much integration required and fewer components improve reliability.

[0058] Referring now to FIG. 2, a general illustration of a configurable multi-port integrated charger architecture-an energy storage and management system (ESMS) 100 has four energy ports 102 and modules 1, 2 and 3 (104, 106). , 108) three DC power conversion devices or down-boost converters. As is well known in the art, the down-boost converters 104-108 can be configured to pass electrical energy in the first direction 110 (described in conjunction with down-boost converter 104, but equally applicable to converters 106 and 108) The upward flow is used to operate in the lowering mode, or the power is passed in the second direction 112 (also described in conjunction with the lower-to-boost converter 104, but is equivalently applicable to the converters 106 and 108) to operate in the boost mode. As shown, the energy port 102 includes a first energy port P1 114, which can be configured to have a first unit 116 attached or electrically coupled thereto. Similarly, the energy port 102 includes fourth, second, and third energy ports P2 118, P3 120, and P4 122, which can be configured to have respective second unit 124, third unit 126 attached or electrically coupled thereto. And the fourth unit 128.

[0059] According to the invention, the charger is part of the vehicle design and is mounted on-board. The integrated on-board charger can continuously adjust the input current to the energy ports 114 and 118-120 due to, for example, the changing SOC of the device connected to it for charging.

[0060] As will be illustrated, the ESMS 100 of FIG. 2 can be configured to charge up to three energy sources (including, for example, low-voltage energy batteries, high-voltage power batteries, and supercapacitors) at the same time or simultaneously. The ESMS 100 can have This article configures a cross-weaving module to reduce ripple current. ESMS can also have multiple charging profiles for different battery technologies and energy storage device types as a function of conditions including SOC and temperature. ESMS 100 includes centralized energy that is centrally controlled by controller 46 of FIG. 1 Flow control, and ESMS 100 can manage a wide range of input and output voltages.

[0061] The ESMS 100 of FIGS. 1 and 2 can be configured in a variety of configurations. Each configuration of the ESMS 100 can be selected by a contact. The energy flow is controlled by the ESMS control algorithm implemented in the controller 46 of the hybrid vehicle 10. The controller 46 can simultaneously sense the existence of the energy storage device and the charging device connected to the port 102 and adjust the energy flow direction accordingly. For example, these control algorithms can determine the voltage at each port to which an energy storage device or charging system (such as DC or rectified AC) is coupled, and accordingly and based on the determined voltage, based on the measured frequency, or both ( For example) to operate ESMS 100. And, the advantage of including a rectifier is that even if there is a wrong polarity connection to the DC, the rectifier provides protection even if a single-phase rectifier is used or even for a 3-phase rectifier, the DC input is used for two of the 3-phase inputs.

[0062] The wide input voltage integrated charger allows two or more batteries of any SOC level to be charged independently and simultaneously from any input voltage level within the voltage limit of the ESMS component, respectively. The input voltage can range from a typical single-phase voltage (110V/120V) to 208V/240V and up to 400V or even higher (levels 1...4). The currently specified maximum voltage for fast DC charging is 400V, but by appropriately selecting ESMS components, single-phase or 3-phase AC up to 480V or even 600V DC can be utilized to provide higher charging levels in a shorter duration (i.e. fast Charging). The energy battery is connected to the first energy port 114 or the fourth energy port 118 and has a nominal voltage that is typically lower than the power battery on the second energy port 120. A short-term energy storage device such as a super capacitor may be included on the first energy port 114.

[0063] The ESMS 100 of the general illustration of FIG. 2 can be configured to support multiple charging arrangements by selectively using switches. Fig. 3 illustrates a detailed circuit diagram of a multi-port ESMS according to an embodiment of the present invention. For brevity, the control electronics are omitted. Therefore, ESMS 200 (similar to ESMS 100 of FIGS. 1 and 2) illustrates a first lowering-lifting module 202, a second lowering-lifting module 204, and a third lowering-lifting module 206_oESMS 200 also illustrates that port P1 208 has a lower voltage battery coupled to it, port P2 210 has a higher voltage cell coupled to it, port P3 212 has a rectified AC or DC voltage coupled to it, and port P4 214 Has a lower voltage supercapacitor coupled to it. Thus, in the illustrated example, the energy storage device and the energy charger are coupled to the ESMS 200 in order to illustrate the operation according to one configuration. However, as discussed, ESMS 200 can be configured in multiple arrangements to accommodate multiple charger/energy storage arrangements. Therefore, ESMS 200 includes contacts K3 216, K1 218, K2 220, K4 222, and M 224, which can be selectively engaged or disengaged in order to achieve a charging configuration according to the above description.

[0064] Each of the three lowering-lifting modules M1 202, M2 204, and M3 206 includes an IGBT branch (upper switch and lower switch) and an inductor. The high voltage DC bus can be buffered by multiple power capacitors. The output of each down-boost converter stage is equipped with a current sensor, which measures the inductor current. In the United States and Europe, the voltage limit shown at port P3 212 is derived from the typical single-phase AC outlet voltage. However, in applications requiring a higher charging power level, port P3 can be coupled to 208V. 240V or 480V 3-phase or 400 V DC or up to 600 V DC via the charger interface 42 (Figure 1).

[0065] ESMS 200 uses contacts as the main bus and various module switches. Use two power resistors (for example, 120 ohm, 100 W, RH-50) and contacts or FETs to implement the pre-charge circuit. The additional contact (K4 222 in Figure 3) is used in both cases. One case is under a certain SOC condition of the battery at port P1 208, and the second case is when the interleaving of module 1 202 and module 3 206 is enabled. Figure 3 illustrates the voltage and current sensing points of the ESMS 200 with an integrated charger.

[0066] A single battery or dual batteries can be used for charging. Charging in a dual battery configuration as shown herein allows both batteries to be charged from a wide input voltage range of batteries with any SOC level. Only the internal architecture of the multi-port integrated charger with its software features allows this. When energized, ESMS 200 controls the restoration of the energy storage units of this type in use, their charging current and power energy ratings and limits. From to electric vehicle power supply equipment (EVSE)

Communication interface, ESMS sets the limit of input current, and finally sets the type of power supply (AC or DC).

[0067] Each lowering-lifting module runs an independent state machine. These states are disabled/standby, lowered mode enabled, boosted mode enabled, or enabled permanently on the upper switch (specific to module 2 204, shown as sequence 250 in FIG. 4). At step 252, the module status is selected, and at step 254, the power-on self-check is performed. The input voltage range is determined at step 256, and if Vmin and Vmax are on the high side 258, switch K1 218 is closed and module M2 204 is enabled 260, thereby causing module M2 204 to operate in a reduced mode. If Vmin and Vmax are on the low side 262, the switch K1 218 is opened, and the upper switch of the module M2 is turned on, so that the module M2 204 is permanently turned on 264. At step 266, the module M1 202 is requested, and at step 268, the state of the module M2 204 is returned (ie, the reduced mode at step 202 or the permanent conduction at step 264) for subsequent operations. Part of this sequence will also bring the contacts into the correct state. For charging, the contact K3 216 is generally closed to allow the modules M1 202 and M2 204 to be used for controlled charging of the port P2 210 energy storage device. In this sequence of charging control, the software distinguishes multiple situations that can be applied and selects the appropriate state for each of the three lower-up modules 202-206.

[0068] During the start-up sequence and before any contacts are brought into conduction and before the modules and switches of the IGBT are activated, the ESMS 200 controls the acquisition of the voltage levels of all used energy sources and determines the charger input voltage. This is done in order to avoid any possible uncontrolled current when, for example, the voltage on the low side of the down-boost module is higher than the voltage on the high side. This may be the case, for example, when the power battery on the high side is deeply discharged and the energy storage device of port P1 208 and/or port P4 214± still stores a large amount of energy. This is a situation that the normal operating energy management of the vehicle typically avoids, but if the high-side energy storage device is replaced and it is not charged before the replacement, or the normal operating energy management is not active for a long time for some reason, it may This happens. The integrated charger control can handle even very extreme and unusual voltage levels at all four ports 208-214, and allows controlled energy management to return the system to normal operation.

[0069] In one mode of operation, referring to FIG. 5, a charging current into the high-side energy storage device is established at port P2 210. This is called the single HV battery charging mode. The module M1 202 operates in the lift mode, the contacts K3 216 and M 224 are closed, and the contacts KI 218, K2 220, and K4 222 are open. According to the charger input voltage, the module M2 204 is in a reduced mode (Vp3> Vp2) or the upper switch is permanently turned on (Vp3 <Vp2). The charging current is controlled by the module M1 202. According to the charging strategy, the SOC or voltage level of the device at the port P2 210, the control determines the charging current and the operating time in this mode.

[0070] As an extension of the previously described mode, referring to FIG. 6, the charger control enables charging of the second energy storage device on port P1 208 or port P4 214. This can be called dual battery charging mode. In this mode, the control ensures that there is a controlled current before closing the contacts and enabling the module M3 206. If the voltage level is within the allowable range, the contact K2 220 or K4 222 is brought into a conducting state, the module M3 206 is set to a reduced mode, and the charging current and the operating time in this mode are determined. Apply the initial power separation factor while constantly monitoring the current and voltage to calculate each individual SOC. By using commercial off-the-shelf (C0TS) battery packs, the standardized communication interface of the integrated charger ESMS can also receive voltage and SOC from the system. The integrated charger ESMS implements the desired charging strategy, which depends on battery technology, thermal constraints, etc.

[0071] The SOC of the attached energy storage device is estimated to determine the power separated from the wide voltage input to the energy storage device. The individual device SOC is constantly monitored to determine and optimize the power separation factor. This task is responsible for handling extreme SOC levels appropriately. For example, the fully discharged high-side battery on port P2 210 may operate at a lower voltage than the battery on port P1 208. In this case, the high-side battery on the port P2 210 needs to be charged before the charging power separation can be performed.

[0072] With reference to FIGS. 5 and 6, the energy flow of two charging configurations is illustrated. Referring first to Figure 5, energy flows from a charger (not shown) located at port 3 212 to module 2 210 and then to module 1 208 operating in boost mode. Therefore, the DC source can be boosted to the high voltage output on port 2 210 by ensuring that K1 218 and K2 220 are open.

[0073] In the other example shown in FIG. 6, a DC source (not shown) coupled to port 3 212 can be simultaneously connected to port 1

208 and port 4 214 for charging. For example, two cases can be considered in conjunction with Figure 6.

[0074] Case 1: The input voltage at port 3 212 is higher than the battery voltage at port 1 208. In this case, the module 2 204 operates in a reduced mode and adjusts the current ILB in the LU. Contacts K3 216 and K1 218 are closed, while M 224, K2 220 and K4 222 (OJPOS) are open.

[0075] Case 2: The input voltage at port 3 212 is lower than the battery voltage at port 1 208. In this case, contacts K3 216, M 224, and K4 222 (UP0S) are closed, and K1 218 and K2 220 are open. Module 2 204 is inactive (M2 is permanently on), and module 1 202 operates in boost mode to boost the low input voltage to a certain higher level. Module 3 206 reduces this voltage back to the set voltage of the energy battery at port 1 208. Control the current ILCo in LW in a closed loop

[0076] Thus, FIGS. 5 and 6 illustrate different charging schemes that can be implemented using the ESMS 200 of FIG. 3, and FIG. 3 also illustrates the current flow direction corresponding to the charging arrangement shown. But and as mentioned, ESMS 200 can be used in a variety of configurations. Different energy storage types and chargers can be connected to the ESMS 200 according to an embodiment of the present invention, as shown in FIG. 7 as a table 300. That is, the exemplary charging scheme 1-5 302 includes a function 304 and various chargers and energy storage devices located at ports 1-4. It is conceivable that although five charging schemes 302 are shown, the present invention is not limited to this, and any charger/energy storage arrangement is possible.

[0077] Referring now to FIG. 8, an exemplary charging arrangement is illustrated, which generally corresponds to charging scheme 3 of the table 300 of FIG. 7. In the configuration shown in FIG. 8, the configuration 400 is shown as having an ESMS 200, and the ESMS 200 has ports P1 208, P2 210, P3 212, and P4 214. The configuration 400 is illustrated in order to illustrate the communication interface 402 and its operation. The energy battery or ultracapacitor 404 is coupled to port P1 208, the ultracapacitor or energy battery 406 is coupled to port P4 214, and the power battery 408 is coupled to port P2 210. The AC or DC source 410 is coupled to the port P3 212, and as mentioned above, it can be coupled through the charger interface 42 of FIG. According to the embodiment of the present invention, the communication interface 402 is coupled to the storage devices 404-408, and the source 410. As also shown in FIG. 1, the communication interface 402 communicates with the energy storage 30 (having devices 30-36), the controller 46, and the charger interface 42.

[0078] Still referring to FIG. 8, the communication interface 402 includes a plurality of communication lines 412, 414, 416, and 418 coupled thereto, which enable sensor readings to be carried from the corresponding devices 404-410. That is, the communication lines 412-418 are coupled to their corresponding devices in order to obtain, for example, the temperature limits and current limits of the relevant devices 404-410, and to provide real-time feedback on the temperature, current, and voltage of each corresponding device 404-410. In addition, device parameters such as the current state of charge and voltage measurement can also be obtained from each device 404-410.

[0079] Thus, referring to FIG. 9, according to the present invention, the communication interface 402 is configured to receive multiple inputs from multiple sources in order to optimize the charging operation. According to the present invention, the communication interface 402 is coupled to the controller 46, and the controller 46 is configured to output two parameters 420. The two parameters 420 include total charging current 422 and power separation 424. That is, according to an embodiment of the present invention, based on the information received from the devices 404-410 and about the current status of the devices 404-410, the total charging current 422 and the power separation 424 are determined and fed to the ESMS 100 in order to optimize the devices 404, 406 and 408.

[0080] As seen in FIG. 9, the communication interface 402 receives various types of information about the devices 404-410. For example, the communication interface 402 receives limit information 426, which includes but is not limited to each of N devices (ie, devices 404-410)

The temperature limit is related to the maximum current or the maximum current change rate of each device, for example. The communication interface 402 also receives energy storage device parameters 428 for each of the N devices 404-410. The parameters 428 include, but are not limited to, for example, state of charge (SOC), minimum voltage, and maximum voltage. The communication interface 402 also receives sensor feedback 430 from each of the N devices 404-410. The sensor feedback 430 includes, but is not limited to, the current in each device, the voltage across each device, and the temperature of each device.

[0081] Thus, the communication interface 402 receives limit information 426, device parameter information 428, and real-time sensor information 430, which are processed and fed to the controller 46 so that the total charging current 422 and power separation can be determined in the controller 46 424 and feed it to ESMS 100_oThe ESMS 100 therefore controls the modules M1-M3 in it accordingly and in turn. According to one embodiment of the present invention, the power split 424 is split between the high voltage side and the low voltage side of the ESMS 100 (the high voltage side includes ports P2 210 and P3 212, and the low voltage side includes ports P1 208 and P4 214). That is, referring to FIG. 8, for example, the power separation 424 includes the percentage of the total power directed to the power battery 408 and the remaining percentage of the total power to the energy storage device 404 and the energy storage device 406 at the same time. Thus, in one embodiment, where only one low-voltage energy storage device is coupled to the low-voltage side of the ESMS 200 and one high-voltage energy storage device is coupled to the high-voltage side of the ESMS 200, a very small proportion of the power Separate into a low-voltage energy storage device and a high-voltage energy storage device, and control the total current to the two devices accordingly.

[0082] According to the present invention, it is possible to continuously adjust the power on the low voltage side and the high voltage side based on continuous monitoring of the sensor. According to one embodiment, if one of the low-voltage or high-voltage storage devices is completely depleted, when starting to charge the low-voltage storage device and the high-voltage storage device, the power separation is 100% to the fully depleted device, and thereafter , Monitoring as described herein indicates continuous correction of total power and power separation, as described herein.

[0083] According to the present invention, the controller 46 can apply thermal balance by controlling the operation of the fan based on feedback, temperature limits, and the like. Therefore, referring to FIG. 1 again, the fan 432 can be set to blow air above one or all of the energy storage devices (32-36) shown therein, and the energy storage devices (32-36) also correspond to those shown in FIG. 8 Energy storage devices 404-408 or energy storage devices 208, 214, and 210 of FIGS. 5 and 6. Temperature information can often be obtained from different energy storage units that can be used to provide coarse thermal balance charging, which is achieved by symmetrically splitting the power flow across all modules. In a solution where there is at least one lithium-ion battery pack in the system, especially if passive balancing is applied, temperature information is often available for charging control. If the sensor distribution is rough or the battery technology allows easy prediction of the temperature distribution within the battery pack, a thermal model can be used. Therefore, for thermal balance, the control goal is to balance the battery pack temperature distribution, and in addition to controlling the total current 422 at port P3 and the power separation 424 between units, fan speed control, thermal modeling, etc. can also be used to control fan operation , In order to optimize the thermal performance of the energy storage device.

[0084] According to the present invention, the power can be maximized for the high voltage side (ie, power battery). The goal of this charging strategy is to quickly increase the DC link voltage and make full use of the available power to charge the power battery. This strategy may be desired in situations where shorter discharge and charge cycles are desired or possible. Therefore, more frequent recharging is performed by the high-performance power battery, keeping the DC link voltage high while avoiding boosting energy from the second battery to improve efficiency. Therefore, in this solution, the control objective is to control the total current 422 at port P3 and the power separation 424 between the cells, and also to control the state of charge at port P2 on the high voltage side and the power battery in the shortest amount of time. maximize.

[0085] According to the present invention, depending on a dual battery configuration (eg, a power battery and an energy battery of similar capacity), it may be desirable to maintain energy balance within the dual battery configuration during charging. The state of charge of the two batteries that can be used for the integrated charger energy management is controlled to an equal level within an acceptable error. Therefore, in this scheme, the control objective is to maintain the state of charge (SOC) at ports P1 and P2 at a similar level, and also to control the total current 422 at port P3 and the power separation 424 between the cells to be similar. The slope makes their corresponding SOC increase.

[0086] According to the present invention, by using lithium ion battery technology in which battery cell groups need to be individually balanced, individual battery cell groups may be significantly unbalanced due to aging temperature effects or discharge rates. The optimal battery pack balancing strategy involves keeping the minimum and maximum cell voltages within limits. Subsequent control uses the available energy to charge less restrictive batteries of different technologies. However, unbalanced lithium-ion battery packs often require a long charging time because the active or passive balancing is time-consuming, and at the same time, the charging current needs to be significantly reduced over a long period of time. Therefore, in this solution, the control target includes controlling the total current 422 at port P3 and the power separation 424 between cells, so as to reduce the difference between the maximum and minimum cell voltages of the two batteries at ports P1 and P2. The voltage gap is minimized.

[0087] According to the present invention, minimizing losses and thereby maximizing the efficiency of the overall system is the goal, and many parameters need to be considered during the design of the DC-DC converter and the boost inductor. Once the multi-port reduction-boost converter design is completed, loss-optimized control can be achieved, for example, by operating the converter dominantly in the high efficiency range. In many cases, at light loads, which is in the vicinity of rated power, the efficiency of which is often often dropped. Also, if a small discharge cycle can be used, such as choosing a daily commute mode of <40 miles, then the use of boosts can be limited to situations that are absolutely necessary during driving operations. The capacity of the battery to provide power is based on the history of charging and discharging cycles. The high C rate operation strategy has an impact on the internal resistance and leads to faster aging. In this regard, the efficiency optimization operation strategy is to some extent related to the service life optimization strategy. Thus, in this scheme, the control target is to operate at the maximum value of the efficiency curve obtained by controlling the total current 422 at the port P3 and the power separation 424 between the cells.

[0088] Thus, a variety of control planning schemes and optimization schemes are included, which can be optimized according to the embodiments of the present invention. Given examples include, but are not limited to, thermal balancing, maximizing the power provided to the high voltage side (power battery), balancing the state of charge level, optimal battery pack balancing, and loss minimization control.

[0089] The source 410 of FIG. 8 includes an AC or DC source 410, and the source 410 may be coupled to the ESMS 200 during parking of the vehicle 10 (eg, at a charging station, a home garage, or during work). However, the present invention is not necessarily limited to charging when the vehicle 10 is stationary. That is, according to the present invention, an auxiliary power unit (APU) may be included, which is provided on the vehicle 10, which enables the energy storage system to be recharged and to provide power for vehicle operation. Referring to FIG. 10, the vehicle 10 in this embodiment includes an APU 500 to replace the energy battery 404 in FIG. 8. Therefore, in accordance with the vehicle 10 of FIG. 1, the vehicle 10 may include an APU in addition to the heat engine 12. The APU provides auxiliary power to the electric motor 26 via the ESMS 200 (also labeled ESMS 100 in FIG. 1). The APU 500 may include, for example, an internal combustion engine (ICE), a permanent magnet generator (PMG), or a fuel cell (FC). That is, instead of the low-voltage/high-energy energy storage system (LV power supply 32 in FIG. 1), the APU can provide electric power to the system 10 via the ESMS 200 in order to provide power for vehicle cruising or provide access to other energy storage units 406, 408. Charging power. For example, in one mode of operation, the thermal engine 12 may provide power to the electric motor 26 to provide power for vehicle operation, while the APU 500 may provide recharging energy to the energy storage units 406,408. In this way, energy usage can be optimized by selectively providing power from the heat engine 12 and recharging other storage units to achieve peak efficiency. APU 500 provides additional flexibility of operation and allows independent or simultaneous charging of batteries 406, 408 and expansion of integrated charging control. Charging is no longer limited to static charging.

[0090] In another embodiment of the present invention, referring to FIG. 11, the vehicle 10 includes an APU 500 provided thereon and switchably coupled to the port P3 212. That is, the APU 500 is an auxiliary unit provided on the vehicle 10, but is not coupled to the ESMS 200 via the port 1 208 as in FIG. 10, but the APU 500 is coupled to the port P3 212 via the switching device 502. Thus, according to the present invention, the port P1 208 is not dedicated to providing power from the APU 500, but as in the previous illustration, the port P1 208 can be dedicated to coupling the energy battery or the super capacitor 404, and the port P3 212 can be used to Charging is provided from a stationary source 410 and auxiliary power is provided during vehicle operation. That is, by coupling the APU 500 via the charging port P3 212, additional operational flexibility is provided because the thermal engine 12, the energy batteries 404, 406, the power battery 408 and the slave APU

500 draws energy for vehicle operation. When stationary, the switching device 502 can be switched to allow recharging from the stationary source 410.

[0091] As a result, the total charging control can be extended beyond the static situation where AC/DC power is provided from the grid via the static power supply 410. The charging control strategy can be centralized, which allows the interoperability of different battery chemistries on an electric vehicle system. That is, due to sensor feedback, limit information for specific battery types and energy storage types, and due to the ability to obtain and use device parameter information in real time during vehicle operation, system flexibility and efficiency are improved, all through a single centralized energy storage And management system.

[0092] The technical contribution of the disclosed device is that it provides a technology implemented by a controller that uses a multi-port energy management system to charge an energy storage device of an electric vehicle based on system feedback.

[0093] Those skilled in the art will recognize that an interface and control embodiments of the present invention can be implemented through a computer-readable storage medium having a computer program stored thereon. The computer-readable storage medium includes multiple components, such as one or more of electronic components, hardware components, and/or computer software components. These components may include one or more computer-readable storage media, and one or more computer-readable storage media generally store software, firmware, and one or more parts of one or more implementations or embodiments for executing the sequence. / Or assembly language instructions. These computer-readable storage media are generally non-transitory and/or tangible. Examples of such computer-readable storage media include recordable data storage media of computers and/or storage devices. The computer-readable medium may adopt, for example, one or more of magnetic, electrical, optical, biological, and/or atomic data storage media. Moreover, such media may take the form of, for example, floppy disks, magnetic tapes, CD-ROMs, DVD-ROMs, hard drives, and/or electronic storage. Other forms of non-transitory and/or tangible computer-readable storage media not listed may be used in conjunction with the embodiments of the present invention.

[0094] A number of such components can be combined or separated in the implementation of the system. Moreover, such components may include a set and/or series of computer instructions written or implemented using multiple programming languages, as those skilled in the art will recognize. In addition, other forms of computer readable media, such as carrier waves, can be used to implement computer data signals representing a sequence of instructions. When the computer data signals representing a sequence of instructions are executed by one or more computers, one or more computers will execute the sequence. One or more parts of one or more implementations or embodiments.

[0095] According to an embodiment of the present invention, an electric vehicle includes a controller configured to receive sensor feedback from a high-voltage storage device and from a low-voltage storage device, and connect the sensor feedback to a corresponding high-voltage storage device and The operating limit of the low-voltage storage device is compared, and based on the comparison, the total charging current to the high-voltage storage device and the low-voltage storage device and the power separation factor of the total charging current to the high-voltage device and the low-voltage device are determined, and adjusted to The total power of the low-voltage storage device and the high-voltage storage device.

[0096] According to another embodiment of the present invention, a method for managing an energy storage system of an electric vehicle includes receiving sensor feedback from a high-voltage energy storage device of the electric vehicle, and combining the sensor feedback from the high-voltage energy storage device with Comparison of operating limits specific to high-voltage energy storage devices, receiving sensor feedback from low-voltage energy storage devices of electric vehicles, comparing sensor feedback from low-voltage energy storage devices with operating limits specific to low-voltage energy storage devices, based on The high-voltage device and the low-voltage device are compared, and the total charging current to the high-voltage storage device and the low-voltage storage device and the power separation factor of the total charging current to the high-voltage device and the low-voltage device are determined, and adjusted to low based on the determination The total power of the voltage storage device and the high voltage storage device.

[0097] According to yet another embodiment of the present invention, a computer-readable storage medium is coupled to an energy storage and management system (ESMS) of an electric vehicle (EV) and stored thereon a computer program containing instructions, these instructions When executed by the computer, the computer is prompted to perform the following operations: from the high-voltage energy storage device of the EV and from the low-voltage energy storage of the EV

The device receives sensor feedback, compares the sensor feedback with the operating limit of the corresponding energy storage device, and based on the comparison, determines the total charging current to the energy storage device and the power separation factor of the total charging current between the high-voltage device and the low-voltage device, And based on determining the total power adjusted to the energy storage device.

[0098] This written description uses examples to disclose the invention including the best mode, and also enables those skilled in the art to practice the invention, including making and using any device or system and performing any combined method. The patentable scope of the present invention is defined by the claims, and may include other examples that occur to those skilled in the art. If such other examples have structural elements that are not different from the literal language of the claims, or if they include equivalent structural elements that are not substantially different from the literal language of the claims, they are defined as being within the scope of the claims.

[0099] Although the present invention has been described in detail in conjunction with only a limited number of embodiments, it is easy to understand that the present invention is not limited to the disclosed embodiments. More precisely, the present invention can be modified to incorporate any number of changes, alterations, substitutions or equivalent arrangements not described above but commensurate with the spirit and scope of the present invention. In addition, although various embodiments of the present invention have been described, it is to be understood that aspects of the present invention may include only some of the described embodiments. Therefore, the present invention is not limited by the above description, but only by the scope of the appended claims.