JP2010074885A - Power supply system and control method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To appropriately suppress loss according to the state of a load device, in a power supply system including multiple sets of power accumulating devices and supply voltage converters. <P>SOLUTION: According to the state of load devices including motor generators MG1, MG2, request power to the power supply system and a target voltage for the output voltages of converters 10, 12 are set. When request power is lower than the reference value and step-up operation of the converters 10, 12 is unnecessary in view of the target voltage, upper arm ON mode is selected. When the output voltages of the power accumulating devices B1, B2 are different from each other in upper arm ON mode, the upper arm (switching element Q1 or Q3) and lower arm of the converter, corresponding to the higher output voltage are respectively fixed on and off, and the other converter is stopped. When the output voltages of the power accumulating devices B1, B2 are equal to each other, respective upper arms of the two converters (10, 12) are fixed to "on". <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a power supply system and a control method thereof, and more particularly to a control technique for a power supply system including a plurality of sets of power storage devices and power conversion devices.

  In recent years, in an electric vehicle such as a hybrid vehicle or an electric vehicle equipped with an electric motor as a driving force source, the capacity of the power storage mechanism has been increased in order to improve the driving performance such as acceleration performance and driving distance. As a technique for increasing the capacity of the power storage mechanism, a configuration in which a plurality of power storage devices are arranged in parallel has been proposed.

For example, in Japanese Patent Application Laid-Open No. 2008-17661 (Patent Document 1), in a configuration in which two sets of a power storage device and a converter are connected in parallel, when the required power is smaller than a reference value, one of the converters operates. And controlling the other to stop. According to the above-mentioned document, it is described that such control can suppress power loss in the converter during operation with low required power.
JP 2008-17661 A

  As described above, in a power supply system including a plurality of sets of power storage devices and power conversion devices, the plurality of power conversion devices are controlled so that power according to the required power of the load device is input and output. At this time, when the required power is low, a situation occurs in which the power loss caused by the operation of the power converter for controlling the required power cannot be ignored. That is, in a region where the required power is small, the converter loss tends to be relatively large. According to the technique described in Japanese Patent Application Laid-Open No. 2008-17661 (Patent Document 1), even when the required power is small, at least one of a plurality (specifically, two) converters operates. The loss may be relatively large. Further, when the required power is small but the converter loss becomes large, for example, the power from the load device (for example, the power generated by the regenerative operation of the electric motor included in the electric vehicle) is input to the power storage device when the power storage device accepts it. The power becomes smaller.

  The present invention has been made to solve such problems, and an object of the present invention is to provide a power supply system including a plurality of sets of power storage devices and power supply power conversion devices according to the state of the load device. It is another object of the present invention to provide a power supply system configuration and control capable of appropriately suppressing loss.

  Another object of the present invention is to provide a configuration and control of a power supply system that can input as much power as possible into the power storage device even when the required power is low.

  In summary, the present invention is a power supply system that controls input / output of power to / from a load device connected to a power supply wiring. The power supply system is provided corresponding to each of the plurality of power storage devices and the plurality of power storage devices, and performs bidirectional DC power conversion between the corresponding power storage device of the plurality of power storage devices and the power supply wiring. A plurality of power conversion devices and a control device that controls the operation of each of the plurality of power conversion devices. Each of the plurality of power conversion devices includes a power semiconductor switching element inserted and connected to a current path between the corresponding power storage device and the power supply wiring, and a direction from the corresponding power storage device to the power supply wiring as a forward direction. A semiconductor switching element for use and a diode element connected in parallel. The control device includes a voltage determination unit that determines whether or not at least two power storage devices having the same output voltage are present among the plurality of power storage devices, and a voltage target value of the power supply wiring according to the state of the load device A target value setting unit for setting the mode and a mode determination unit. When the required power from the load device is lower than the reference value and the set voltage target value is a value that does not require the boosting operation by each power conversion device, the mode determination unit includes a plurality of power conversion devices. The first operation mode for fixing the power semiconductor switching element included in at least one power conversion device to the on state is selected. When the voltage determination unit determines that there are at least two power storage devices, the mode determination unit is configured to turn on the power semiconductor switching element included in the power conversion device corresponding to each of the at least two power storage devices. The mode is selected as the first operation mode. When the voltage determination unit determines that at least two power storage devices do not exist, the mode determination unit fixes the power semiconductor switching element included in one power conversion device on and stops the remaining power conversion devices A power supply system that selects an operation mode to be performed as a first operation mode.

  Preferably, the voltage determination unit determines whether there are at least two power storage devices based on output currents of the plurality of power storage devices.

  Preferably, the voltage determination unit determines whether or not there are at least two power storage devices in a state in which the power semiconductor switching element included in one power conversion device is fixed on and the remaining power conversion devices are stopped. judge.

  Preferably, when the required power is equal to or higher than the reference value, the mode determination unit executes voltage control for setting the voltage of the power supply wiring to the target voltage by one of the plurality of power conversion devices, and the remaining power In the conversion device, the second operation mode for executing the current control for controlling the input / output current of the corresponding power storage device is selected.

  Preferably, the mode determination unit includes a plurality of power conversion devices when the required power is lower than the reference value and the voltage target value is a value that requires a boost operation by any one of the plurality of power conversion devices. One of these is used to execute voltage control for setting the voltage of the power supply wiring to the target voltage, and the third operation mode for stopping the operation of the remaining power conversion device is selected.

  Preferably, the power supply system is mounted on a vehicle. The load device is configured to perform bidirectional power conversion so that the AC rotating electric machine operates according to the command value between the AC rotating electric machine that generates the driving force of the vehicle and the AC rotating electric machine and the power supply wiring. Including an inverter. The target value setting unit sets a target voltage according to the rotational speed and torque of the AC rotating electric machine.

  According to another aspect of the present invention, there is provided a control method for a power supply system that controls power input / output to / from a load device connected to a power supply wiring. The power supply system is provided corresponding to each of the plurality of power storage devices and the plurality of power storage devices, and performs bidirectional DC power conversion between the corresponding power storage device of the plurality of power storage devices and the power supply wiring. A plurality of power conversion devices. Each of the plurality of power conversion devices includes a power semiconductor switching element inserted and connected to a current path between the corresponding power storage device and the power supply wiring, and a direction from the corresponding power storage device to the power supply wiring as a forward direction. A semiconductor switching element for use and a diode element connected in parallel. In the control method, a step of determining whether or not there are at least two power storage devices having the same output voltage among the plurality of power storage devices, and setting a voltage target value of the power supply wiring according to the state of the load device And when the required power from the load device is lower than the reference value and the set voltage target value is a value that does not require the boost operation by each power converter, at least of the plurality of power converters Selecting an operation mode for fixing a power semiconductor switching element included in one power converter to an ON state. In the step of selecting the operation mode, when it is determined that there are at least two power storage devices, a mode in which the power semiconductor switching element included in the power conversion device corresponding to each of the at least two power storage devices is fixed on is set. When the operation mode is selected and when it is determined that at least two power storage devices do not exist, the power semiconductor switching element included in one power conversion device is fixed on and the remaining power conversion devices are stopped. Selecting a mode to be performed as an operation mode.

  According to the present invention, in a power supply system including a plurality of sets of power storage devices and power supply power conversion devices, it is possible to appropriately suppress loss according to the state of the load device.

  Further, according to the present invention, in the power supply system having the above-described configuration, it is possible to input more power to the power storage device even when the required power is low.

  Embodiments of the present invention will be described below in detail with reference to the drawings. In the following, the same or corresponding parts in the drawings are denoted by the same reference numerals and description thereof will not be repeated.

  FIG. 1 is an overall block diagram of a hybrid vehicle shown as an example of a vehicle equipped with a power supply system according to the present invention. Referring to FIG. 1, hybrid vehicle 1000 includes an engine 2, motor generators MG <b> 1 and MG <b> 2, a power split mechanism 4, and wheels 6. Hybrid vehicle 1000 further includes power storage devices B 1 and B 2, converters 10 and 12, capacitor C, inverters 20 and 22, and ECU (Electronic Control Unit) 100.

  Power storage devices B1 and B2 correspond to “a plurality of power storage devices” in the present invention, and converters 10 and 12 correspond to “a plurality of voltage conversion devices” in the present invention. Inverters 20 and 22 and motor generators MG1 and MG2 constitute a “load device” in the present invention. Further, the “power supply system” of the present invention is configured by the power storage devices B1 and B2, the converters 10 and 12, and the sensors and control elements associated therewith.

  Hybrid vehicle 1000 travels using engine 2 and motor generator MG2 as power sources. Power split device 4 is coupled to engine 2 and motor generators MG1, MG2 to distribute power between them. Power split device 4 is composed of, for example, a planetary gear mechanism having three rotation shafts of a sun gear, a planetary carrier, and a ring gear, and these three rotation shafts are connected to the rotation shafts of engine 2 and motor generators MG1 and MG2, respectively. It should be noted that engine 2 and motor generators MG1, MG2 can be mechanically connected to power split mechanism 4 by hollowing the rotor of motor generator MG1 and passing the crankshaft of engine 2 through the center thereof. Further, the rotating shaft of motor generator MG2 is coupled to wheel 6 by a reduction gear and an operating gear (not shown).

  Motor generator MG1 is incorporated in hybrid vehicle 1000 as operating as a generator driven by engine 2 and operating as an electric motor that can start engine 2. Motor generator MG2 is incorporated in hybrid vehicle 1000 as an electric motor that drives wheels 6.

  The power storage devices B1 and B2 are DC power sources that can be charged and discharged, and include, for example, secondary batteries such as nickel metal hydride and lithium ions. Power storage device B1 supplies power to converter 10 and is charged by converter 10 during power regeneration. Power storage device B2 supplies power to converter 12 and is charged by converter 12 during power regeneration.

  For example, a secondary battery having a maximum outputable power larger than that of power storage device B2 can be used for power storage device B1, and a secondary battery having a larger storage capacity than power storage device B1 can be used for power storage device B2. be able to. Thus, a high-power and large-capacity DC power source can be configured using the two power storage devices B1 and B2. Further, a large-capacity capacitor may be used for at least one of the power storage devices B1 and B2.

  Converter 10 boosts the voltage from power storage device B1 based on signal PWC1 from ECU 100, and outputs the boosted voltage to positive line PLM. Converter 10 steps down the regenerative power supplied from inverters 20 and 22 via positive line PLM to the voltage level of power storage device B1 based on signal PWC1, and charges power storage device B1. Furthermore, converter 10 stops the switching operation when it receives shutdown signal SD1 from ECU 100.

  Converter 12 is connected in parallel to converter 10 to positive line PLM and negative line NL. Converter 12 boosts the voltage from power storage device B2 based on signal PWC2 from ECU 100, and outputs the boosted voltage to positive line PLM. Converter 12 steps down the regenerative power supplied from inverters 20 and 22 via positive line PLM to the voltage level of power storage device B2 based on signal PWC2, and charges power storage device B2. Furthermore, converter 12 stops the switching operation when it receives shutdown signal SD2 from ECU 100.

  The capacitor C is connected between the positive electrode line PLM and the negative electrode line NL, and smoothes voltage fluctuation between the positive electrode line PLM and the negative electrode line NL. DC voltage VH between positive electrode line PLM and negative electrode line NL is changed from “power supply system” constituted by power storage devices B1 and B2 and converters 10 and 12 to “load device” by inverters 20 and 22 and motor generators MG1 and MG2. This corresponds to the output voltage. Hereinafter, the DC voltage VH is also referred to as a system voltage VH. The positive line PLM corresponds to the “power supply wiring” in the present invention.

  Inverter 20 converts a DC voltage from positive line PLM into a three-phase AC voltage based on signal PWI1 from ECU 100, and outputs the converted three-phase AC voltage to motor generator MG1. Further, inverter 20 converts the three-phase AC voltage generated by motor generator MG1 using the power of engine 2 into a DC voltage based on signal PWI1, and outputs the converted DC voltage to positive line PLM.

  Inverter 22 converts the DC voltage from positive line PLM into a three-phase AC voltage based on signal PWI2 from ECU 100, and outputs the converted three-phase AC voltage to motor generator MG2. In addition, inverter 22 converts the three-phase AC voltage generated by motor generator MG2 by receiving the rotational force from wheel 6 during regenerative braking of the vehicle into a DC voltage based on signal PWI2, and the converted DC voltage is positively connected. Output to line PLM.

  Each of motor generators MG1 and MG2 is a three-phase AC rotating electric machine, and is composed of, for example, a three-phase AC synchronous motor generator. Motor generator MG <b> 1 is regeneratively driven by inverter 20, and outputs a three-phase AC voltage generated using the power of engine 2 to inverter 20. Motor generator MG1 is driven by power by inverter 20 when engine 2 is started, and cranks engine 2. Motor generator MG <b> 2 is driven by power by inverter 22, and generates a driving force for driving wheels 6. Motor generator MG <b> 2 is regeneratively driven by inverter 22 during regenerative braking of the vehicle, and outputs a three-phase AC voltage generated using the rotational force received from wheels 6 to inverter 22.

  In the power supply system, the voltage sensor 42, the current sensor 52, and the temperature sensor 62 that are disposed with respect to the power storage device B1, and the voltage sensor 44, the current sensor 54, and the temperature that are disposed with respect to the power storage device B2. A sensor 64 is provided.

  Voltage sensor 42 detects voltage VB1 of power storage device B1 and outputs it to ECU 100. Temperature sensor 62 detects temperature T1 of power storage device B1 and outputs it to ECU 100. Current sensor 52 detects current I1 input / output from power storage device B1 to converter 10 and outputs the detected current to ECU 100.

  Voltage sensor 44 detects voltage VB2 of power storage device B2 and outputs it to ECU 100. Temperature sensor 64 detects temperature T2 of power storage device B2 and outputs it to ECU 100. Current sensor 54 detects current I2 input / output from power storage device B2 to converter 12 and outputs the detected current I2 to ECU 100.

  Furthermore, a voltage sensor 46 for detecting a voltage between terminals of the capacitor C, that is, a system voltage VH is arranged. The value detected by the voltage sensor 46 is output to the ECU 100.

  ECU 100 generates signals PWC1, SD1, and UA1 for controlling converter 10, and outputs any signal selected according to the state of the load device to converter 10. In addition, ECU 100 generates signals PWC 2, SD 2, UA 2 for controlling converter 12, and outputs any signal to converter 12.

  Further, ECU 100 receives power (hereinafter referred to as “required power”) PR required for the power supply system for driving the load device. For example, the required power PR is calculated by a vehicle ECU (not shown) that integrally controls the entire hybrid vehicle 1000 based on the accelerator pedal opening, the vehicle speed, and the like.

  Further, ECU 100 generates signals PWI1 and PWI2 for driving inverters 20 and 22, respectively, and outputs the generated signals PWI1 and PWI2 to inverters 20 and 22, respectively.

FIG. 2 is a circuit diagram showing a configuration of converters 10 and 12 shown in FIG.
Referring to FIG. 2, converter 10 includes power semiconductor switching elements Q1, Q2, diodes D1, D2, and a reactor L1.

  In the present embodiment, an IGBT (Insulated Gate Bipolar Transistor) is applied as a power semiconductor switching element (hereinafter also simply referred to as “switching element”), but can be controlled on / off by a control signal. Any switching element can be applied. For example, a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) or a bipolar transistor can be used.

  Switching elements Q1, Q2 are connected in series between positive electrode line PLM and negative electrode line NL. Diodes D1 and D2 are connected in antiparallel to switching elements Q1 and Q2, respectively. Reactor L1 has one end connected to a connection node of switching elements Q1 and Q2, and the other end connected to positive line PL1.

  Converter 12 has the same configuration as converter 10. In the configuration of converter 10, switching elements Q1 and Q2 are replaced with switching elements Q3 and Q4, diodes D1 and D2 are replaced with diodes D3 and D4, respectively, and reactor L1 and positive line PL1 are replaced with reactor L2 and positive line PL2, respectively. The configuration corresponds to the configuration of the converter 12.

  Converters 10 and 12 are formed of a chopper circuit. Based on signal PWC1 (PWC2) from ECU 100 (FIG. 1), converter 10 (12) boosts the voltage of positive line PL1 (PL2) using reactor L1 (L2), and the boosted voltage is increased. Output to the positive line PLM. Specifically, the step-up ratio of the output voltage from power storage devices B1 and B2 can be controlled by controlling the on / off period ratio (duty) of switching element Q1 (Q3) and / or switching element Q2 (Q4). .

  On the other hand, converter 10 (12) steps down the voltage of positive line PLM based on signal PWC1 (PWC2) from ECU 100 (not shown), and outputs the reduced voltage to positive line PL1 (PL2). Specifically, the voltage step-down ratio of the positive line PLM can be controlled by controlling the on / off period ratio (duty) of the switching element Q1 (Q3) and / or the switching element Q2 (Q4).

  FIG. 3 is a functional block diagram of ECU 100 shown in FIG. Referring to FIG. 3, ECU 100 includes a converter control unit 200 and inverter control units 110 and 120.

  Converter control unit 200 turns on switching elements Q1 and Q2 of converter 10 based on voltage VB1 detected by voltage sensor 42, voltage VH detected by voltage sensor 46, and current I1 detected by current sensor 52. Generates a PWM (Pulse Width Modulation) signal PWC1 for turning off. In addition, shutdown signal SD1 for stopping converter 10 and upper arm on signal UA1 for fixing switching elements Q1 and Q2 to on and off, respectively, are generated.

  Converter control unit 200 selectively outputs one of PWM signal PWC1, shutdown signal SD1, and upper arm on signal UA1 to converter 10 in accordance with the operation mode selected according to the state of the load device. The selection of the operation mode will be described in detail later.

  Similarly, converter control unit 200 turns on / off switching elements Q3, Q4 of converter 12 based on voltage VB2, voltage VH detected by voltage sensor 44, and current I2 detected by current sensor 54. PWM signal PWC2 is generated. In addition, shutdown signal SD2 for stopping converter 12 and upper arm on signal UA2 for fixing switching elements Q3 and Q4 to on and off, respectively, are generated.

  Converter control unit 200 selectively outputs one of PWM signal PWC2, shutdown signal SD2, and upper arm on signal UA2 to converter 10 in accordance with an operation mode selected according to the state of the load device.

  Converter control unit 200 further receives remaining capacities SOC1 and SOC2 which are respective remaining capacities (also referred to as SOC (State of Charge)) of power storage devices B1 and B2. For example, this remaining capacity is defined as 100% when the power storage device is fully charged, and is defined as 0% when the power storage device is completely discharged. The remaining capacity SOC1 (SOC2) can be calculated by various known methods using the voltage VB1 (VB2), the current I1 (or I2), the temperature T1 (or T2), and the like.

  Inverter control unit 110 generates a PWM signal for turning on / off a power transistor included in inverter 20 based on torque command value TR1 of motor generator MG1, motor current MCRT1 and rotor rotation angle θ1, and voltage VH. The generated PWM signal is output to the inverter 20 as a signal PWI1.

  Inverter control unit 120 generates a PWM signal for turning on / off a power transistor included in inverter 22 based on torque command value TR2 of motor generator MG2, motor current MCRT2 and rotor rotation angle θ2, and voltage VH. The generated PWM signal is output to the inverter 22 as the signal PWI2.

  Torque command values TR1 and TR2 are calculated by a vehicle ECU (not shown) based on, for example, the accelerator opening, the brake depression amount, the vehicle speed, and the like. Motor currents MCRT1 and MCRT2 and rotor rotation angles θ1 and θ2 are detected by sensors (not shown).

  Next, control of converters 10 and 12 will be described in detail. First, converter control for generating a PWM signal will be described with reference to FIGS. 4 and 5.

  FIG. 4 is a functional block diagram illustrating normal control (voltage / current control) of converters 10 and 12.

  Referring to FIG. 4, converter control unit 200 (FIG. 3) includes a target value setting unit 210, a voltage control unit 215-1 and a current control unit 215-2. In the example of FIG. 4, during normal control, the converter 10 is voltage-controlled to control the system voltage VH to the target voltage VR, while the converter 12 is current-controlled to change the charge / discharge current of the corresponding power storage device B2 to the target current. It shall be controlled to IR.

  Target value setting unit 210 includes torques of motor generators MG1 and MG2 (typically torque command values TR1 and TR2) and rotation speeds MRN1 and MRN2 (command values or detection values based on detection of rotation angles θ1 and θ2). Based on the remaining capacities SOC1 and SOC2 of power storage devices B1 and B2, a target voltage VR of the voltage controlled converter and a target current IR of the current controlled converter are generated.

  Target value setting unit 210 applies system voltage VH according to torque command values TR1, TR2 and rotational speeds MRN1, MRN2 of motor generators MG1, MG2 during power running operation and regenerative braking of motor generators MG1 and / or MG2. Is set to an appropriate level. For example, the target voltage VR is set according to the map MP0 shown in FIG.

  Referring to FIG. 5, map MP0 is a combination of rotational speed MRN (generically indicating MRN1, MRN2, the same applies hereinafter) and torque command value TR (generically indicating TR1, TR2, the same applies hereinafter). For each motor operating point indicated by, the target voltage VR is provided as a map value. By referring to map MP0, an appropriate target voltage VR can be set according to motor generators MG1 and MG2 based on rotational speed MRN and torque (torque command value TR).

  Basically, the system voltage VH is set to a voltage higher than the induced voltage generated by the motor generator MG (generally indicating MG1 and MG2), so that the motor current can be controlled. The voltage VR is set. Further, in accordance with system voltage VH, losses at motor generators MG1, MG2 (copper loss, iron loss), losses at inverters 20, 22 (on loss, switching loss), losses at converters 10, 12 (on loss) Switching loss), loss in reactors L1 and L2 (copper loss, iron loss), and the like change. Considering these loss characteristics, map values (target voltage VR) at each motor operating point It is preferable to set.

  Specifically, map MP0 is separately set for each of motor generators MG1 and MG2, and is obtained by referring to map MP0 based on rotation speeds MRN1 and MRN2 and torque (torque command values TR1 and TR2). In addition, the maximum value of each target voltage of motor generators MG1 and MG2 is set to target voltage VR in the entire power supply system. Target current IR is set in consideration so that the charge level (SOC) between power storage devices B1 and B2 is balanced.

  The calculation of the torque command values TR1 and TR2 is executed based on the required power in the entire hybrid vehicle 1000 reflecting the pedal operation by the user. In particular, in the hybrid vehicle, torque command values TR1 and TR2 are calculated so that the distribution between the output power of the engine and the generated power of motor generators MG1 and MG2 is optimal. In general, torque command values TR1 and TR2 are necessary to reflect the limit value of the input / output power of power storage devices B1 and B2 and the temperature rise of motor generators MG1 and MG2 or inverters 20 and 22 or the like. Limited depending on

  Referring to FIG. 4 again, voltage control unit 215-1 includes subtraction units 222-1 and 226-1, PI control unit 224-1 and modulation unit 228-1. Subtraction unit 222-1 subtracts system voltage VH from target voltage VR and outputs the calculation result to PI control unit 224-1. The PI control unit 224-1 performs a proportional integration calculation with the deviation between the target voltage VR and the system voltage VH as an input, and outputs the calculation result to the subtraction unit 226-1.

  Subtraction unit 226-1 subtracts the output of PI control unit 224-1 from the reciprocal of the theoretical boost ratio of converter 10 indicated by voltage VB1 / target voltage VR, and uses the calculation result as duty command Ton1 to modulation unit 228-1. Output to. Modulator 228-1 generates PWM signal PWC1 based on duty command Ton1 and a carrier wave (carrier wave) generated by an oscillating unit (not shown).

  Current control unit 215-2 includes subtraction units 222-2 and 226-2, PI control unit 224-2, and modulation unit 228-2. Subtraction unit 222-2 subtracts current I2 from target current IR, and outputs the calculation result to PI control unit 224-2. The PI control unit 224-2 performs a proportional integration calculation with the deviation between the target current IR and the current I2 as an input, and outputs the calculation result to the subtraction unit 226-2.

  Subtraction unit 226-2 subtracts the output of PI control unit 224-2 from the inverse of the theoretical boost ratio of converter 12 indicated by VB2 / VR, and outputs the calculation result to modulation unit 228-2 as duty command Ton2. . Modulation section 228-2 generates PWM signal PWC2 based on duty command Ton2 and a carrier wave (carrier wave) generated by an oscillation section (not shown).

  When the system voltage VH is lower than the target voltage VR and when the reciprocal of the theoretical boost ratio (VB1 / VR) is reduced, the voltage control unit 215-1 sets the on-period ratio of the lower arm element (Q2). The PWM signal PWC1 is generated so as to increase (or the OFF period ratio of the upper arm element (Q1) increases).

  On the other hand, when current I2 output from power storage device B2 is lower than target current IR and when the reciprocal of the theoretical boost ratio (VB2 / VR) increases, current control unit 215-2 lowers the lower arm element ( The PWM signal PWC2 is generated so that the on period ratio of Q4) increases.

  Note that the current control unit 215-2 charges the current I2 (I2 <0) more than the target current IR when the power storage device B2 is charged, that is, when the target current IR is set to a negative value (IR <0). When low (| IR | <| I2 |, that is, when the charging current is excessive), the PWM signal PWC2 is generated so that the on-period ratio of the upper arm element (Q3) decreases. On the contrary, when the charging current is insufficient (when IR <I2, that is, when | IR |> | I2 |), the PWM signal PWC2 is generated so that the ON period ratio of the upper arm element (Q3) increases.

  With the control configuration shown in FIG. 4, the voltage control of converter 10 and the current control of converter 12 by the switching (on / off) operation of switching elements Q1 and / or Q2 and switching Q3 and / or Q4, system voltage VH and The charge / discharge balance of power storage devices B1 and B2 can be controlled.

  Thereby, in the power supply system of the present embodiment, during the power running operation, the electric power discharged from power storage devices B1 and B2 is converted into system voltage VH as the input voltage of the load device, and the power supply wiring (positive line PLM) The power conversion operation is executed so as to output to On the other hand, during the regenerative braking operation, the power conversion operation is performed so as to charge the power storage devices B1 and B2 with the charging power on the power supply wiring (positive electrode line PLM).

  FIG. 4 shows a configuration example in which voltage control is executed by the converter 10 while current control is executed by the converter 12. However, in which converter the voltage control and current control are executed is switched. Is possible. For example, it is possible to switch the converter that performs voltage control / current control in accordance with the SOC of power storage devices B1, B2.

(Operation mode control of converter according to this embodiment)
FIG. 6 is a functional block diagram illustrating the configuration of the operation mode control of converters 10 and 12 by converter control unit 200 shown in FIG.

  Referring to FIG. 6, converter control unit 200 (FIG. 3) includes voltage / current control unit 220-1, upper arm ON instruction unit 230-1, shutdown instruction unit 235-1, and the like for controlling converter 10. An instruction selection unit 240-1 is included.

  Further, the converter control unit 200 (FIG. 3) controls the converter 12 with a voltage / current control unit 220-2, an upper arm ON instruction unit 230-2, a shutdown instruction unit 235-2, and an instruction selection unit 240-. 2, a voltage determination unit 250, and a mode determination unit 260.

  The voltage / current control unit 220-1 is configured by, for example, one of the voltage control unit 215-1 and the current control unit 215-2 shown in FIG. 4, and performs voltage control according to the target voltage VR or the target current IR. PWM signal PWC1 for current control is generated. Upper arm ON instructing unit 230-1 generates an upper arm on signal UA1 for fixing converter 10 on the upper arm. According to the upper arm on signal UA1, in the converter 10, the upper arm switching element Q1 is fixed on, while the lower arm switching element Q2 is fixed off.

  Shutdown instruction unit 235-1 outputs a shutdown signal SD1 for stopping the operation of converter 10. According to shutdown signal SD1, in converter 10, switching elements Q1, Q2 are both fixed off.

  In accordance with mode control signal MS1 from mode determination unit 260, instruction selection unit 240-1 outputs one of PWM signal PWC1, upper arm on signal UA1, and shutdown signal SD1 to converter 10.

  Similarly, voltage / current control unit 220-2 is configured by, for example, the other of voltage control unit 215-1 and current control unit 215-2 shown in FIG. 4, and performs current control or target voltage according to target current IR. A PWM signal PWC2 for voltage control according to VR is generated. Upper arm ON instructing unit 230-2 generates upper arm on signal UA2 for fixing converter 12 on the upper arm. According to the upper arm on signal UA2, in the converter 12, the upper arm switching element Q3 is fixed on, while the lower arm switching element Q4 is fixed off.

  Shutdown instruction unit 235-2 outputs a shutdown signal SD2 for stopping the operation of converter 12. According to shutdown signal SD2, in converter 12, switching elements Q3 and Q4 are both fixed off.

  In response to mode control signal MS2 from mode determination unit 260, instruction selection unit 240-2 outputs one of PWM signal PWC2, upper arm on signal UA2, and shutdown signal SD2 to converter 10.

  Based on currents I1 and I2 detected by current sensors 52 and 54, voltage determination unit 250 determines which output voltage of power storage devices B1 and B2 is high, and signal FV indicating the determination result, and Then, determination flag FLG indicating whether the output voltages of power storage devices B1 and B2 are equal to each other is output. That is, signal FV indicates the power storage device having the highest output voltage (hereinafter also referred to as “highest voltage power storage device”) among the plurality of power storage devices B1 and B2. In addition, determination flag FLG indicates whether there are two power storage devices having the same output voltage.

  Voltage determination unit 250 determines that output voltages of power storage devices B1 and B2 are equal to each other when currents I1 and I2 are substantially equal, and turns determination flag FLG on. When current I1 is larger than current I2, voltage determination unit 250 turns off determination flag FLG and outputs signal FV indicating that the highest voltage power storage device is power storage device B1. Further, when current I2 is larger than current I1, voltage determination unit 250 turns off determination flag FLG and outputs signal FV indicating that the highest voltage power storage device is power storage device B2.

  The “determination flag FLG on state” and the “determination flag FLG off state” are, for example, states in which the value of the determination flag FLG is 1 and 0, respectively. However, control of determination flag FLG is not limited to the above control. For example, the states where determination flag FLG is 0 and 1 are “determination flag FLG on state” and “determination flag FLG off state”, respectively. There may be. When currents I1 and I2 are different (that is, when it is determined that the output voltages of power storage devices B1 and B2 are different), determination flag FLG is turned on and currents I1 and I2 are equal (that is, the outputs of power storage devices B1 and B2). The determination flag may be turned off when it is determined that the voltages are equal.

  Mode determination unit 260 includes required power PR required for the power supply system and target voltage set by target value setting unit 210 for driving the load devices (inverters 20 and 22 and motor generators MG1 and MG2). The operation mode of converters 10 and 12 is determined based on VR. Specifically, mode determination unit 260 is a “2CNV mode” in which both converters 10 and 12 are operated, a “1CNV mode” in which only one of converters 10 and 12 is operated to perform voltage control, and converters 10 and 12. One of the “upper arm ON modes” in which the switching elements included in at least one upper arm of both the upper arms is fixed on is selected.

  More specifically, mode determination unit 260 performs mode control so that instruction selection units 240-1 and 240-2 select and output PWM signals PWC 1 and PWC 2 to converters 10 and 12 when the 2CNV mode is selected. Signals MS1 and MS2 are set. In addition, when selecting the 1CNV mode, mode determination unit 260 selects PWM signal PWC (which collectively represents PWC1 and PWC2) in one of converters 10 and 12 that executes voltage control, and in the other converter The mode control signals MS1 and MS2 are set so that the shutdown signal SD (which generally represents SD1 and SD2) is selected. Regarding the converter that executes voltage control in the 1CNV mode, a predetermined one of converters 10 and 12 may be fixedly selected, and voltage control is executed according to the output voltage and SOC at that time. A converter may be selected each time.

  When the upper arm ON mode is selected, mode determination unit 260 fixes a switching element included in one upper arm to be on according to determination flag FLG and signal FV from voltage determination unit 250 (stage 1), and 2 One of the modes (stage 2) in which the switching elements included in each of the upper arms are fixed to ON is selected as the upper arm ON mode. Specifically, mode determination unit 260 selects “stage 1” as the upper arm ON mode when determination flag FLG is OFF. In this case, mode determination unit 260 collectively represents upper arm on signal UA (UA1, UA2) for the converter corresponding to the highest voltage power storage device (any one of power storage devices B1, B2) indicated by signal FV. The mode control signals MS1 and MS2 are set so that the shutdown signal SD is output to the other converter. On the other hand, mode determination unit 260 selects “stage 2” as the upper arm ON mode when determination flag FLG is on. In this case, mode determination unit 260 sets mode control signals MS1 and MS2 such that upper arm ON instruction units 230-1 and 230-2 output upper arm on signals UA1 and UA2, respectively.

  FIG. 7 is a flowchart for explaining the operation mode selection control processing by the mode determination unit 260. The flowchart shown in FIG. 7 is realized by executing a program stored in advance in ECU 100 at a predetermined cycle.

  Referring to FIG. 7, ECU 100 sets target voltage VR of system voltage VH according to the state of the load device, more specifically, according to the torque and rotation speed of motor generators MG1, MG2 (step). S100). In step S110, ECU 100 obtains required power PR required for the power supply system for driving the load devices (inverters 20, 22 and motor generators MG1, MG2). This required power PR is determined based on the vehicle state by a host vehicle ECU (not shown). Alternatively, ECU 100 may execute a calculation based on the product of the torque command value of motor generators MG1 and MG2 and the rotational speed.

  Further, in step S120, ECU 100 determines whether or not required power PR acquired in step S110 is higher than reference value Pth. The reference value Pth is set in accordance with a range in which the required power PR can be supplied even when one converter is stopped, that is, by one of the one power storage devices B1 and B2. Reference value Pth may be a fixed value according to the specifications of power storage devices B1 and B2, or may be a variable value depending on SOC1 and SOC2.

  When required power PR is higher than reference value Pth (when YES is determined in step S120), ECU 100 sets the operation mode to the 2CNV mode in step S140. In the 2CNV mode, one of converters 10 and 12 is voltage-controlled and the other is current-controlled. That is, the 2CNV mode corresponds to the “second operation mode” in the present invention.

  As described above, the sharing of voltage control and current control may be fixed in advance, and may be appropriately selected according to the state of power storage devices B1 and B2.

  On the other hand, when required power PR is equal to or lower than reference value Pth (NO in S120), ECU 100 proceeds to step S130 and requires boosting operation by converters 10 and 12 in light of target voltage VR. Determine whether or not.

  Then, ECU 100 sets the operation mode to the 1CNV mode in step S150 when the boosting operation is necessary (when YES is determined in S130). In the 1CNV mode, voltage control is performed on one of the converters 10 and 12, and the other converter is controlled to shut down, that is, stop operating. That is, the 1CNV mode corresponds to the “third operation mode” in the present invention. Note that the converter that performs voltage control may specify one of the converters 10 and 12 in a fixed manner, and the state of the power storage devices B1 and B2 (typically, the output voltage or the SOC is high or low). You may make it select each time according to it.

  On the other hand, when step S130 is NO, that is, when required power PR is in a range that can be supplied by one power storage device and boosting by converters 10 and 12 is not required, ECU 100 performs converter 10 , 12, the upper arm ON mode is selected at step S160 in order to suppress the loss as a whole. This upper arm ON mode corresponds to the “first operation mode” in the present invention. When the upper arm ON mode is selected as the operation mode, the control according to either “stage 1” or “stage 2” is executed.

  Note that mode determination unit 260 first selects “stage 1” as the operation mode when selecting the upper arm ON mode (for example, when shifting from the 1CNV mode to the upper arm ON mode). Then, mode determination unit 260 determines whether or not the output voltages of the two power storage devices are equal while the control according to “Stage 1” is being performed. When it is determined that the output voltages of the two power storage devices are equal, the operation mode shifts from “stage 1” to “stage 2”. When the upper arm ON mode is selected, the output voltages of the two power storage devices may be different. Therefore, when the control according to “stage 2” is executed first, a short-circuit current may flow between the two power storage devices. Generation of such a short-circuit current can be prevented by the mode determination unit 260 selecting “stage 1” first.

  When any one of steps S140, S150, and S200 is completed, the entire process is returned to the main routine.

  FIG. 8 is a flowchart illustrating in detail the processing in the upper arm ON mode in step S200.

  Referring to FIG. 8, ECU 100 (mode determination unit 260) determines whether or not determination flag FLG is on in step S210. Thereby, it is determined whether or not output voltages VB1 and VB2 of power storage devices B1 and B2 are equal. In other words, mode determination unit 260 determines whether there are two power storage devices having the same output voltage, and the determination result is output from mode determination unit 260 as determination flag FLG.

  When ECU 100 determines that determination flag FLG is in the off state (NO determination in step S210), ECU 100 executes control of “stage 1” (step S220). That is, ECU 100 specifies the highest voltage power storage device from power storage devices B1 and B2 according to signal FV. Then, ECU 100 sets the converter (one of converters 10 and 12) specified for the highest voltage power storage device to the upper arm ON fixation, and shuts down the other converter. That is, the converter corresponding to the highest voltage power storage device is the target of upper arm ON fixation, and the remaining converters are stopped.

  On the other hand, when ECU 100 determines that determination flag FLG is in the on state (when YES is determined in step S210), ECU 100 executes control of “stage 2” (step S230). In this case, ECU 100 fixes both upper and lower converters 10 and 12 corresponding to power storage devices B1 and B2, respectively. That is, ECU 100 fixes the upper arm ON for converters (10, 12) corresponding to each of two power storage devices (B1, B2) having the same output voltage.

  After control of stage 1 or stage 2 is executed, ECU 100 (voltage determination unit 250) executes flag setting processing (step S240). When the flag setting process ends, the process in the upper arm ON mode in step S200 ends.

  FIG. 9 is a flowchart for explaining in detail the flag setting process in step S240.

  Referring to FIG. 9, in step S241, ECU 100 determines whether or not motor generators MG1 and / or MG2 are currently performing a power running operation, that is, whether or not current is being output from at least one of power storage devices B1 and B2. judge. If neither motor generator MG1 nor MG2 is in power running (NO determination in step S241), the flag setting process ends. Therefore, the state of determination flag FLG is maintained in the state before the processing shown in FIG. 9 is executed.

  When control of converters 10 and 12 is control according to “stage 1”, current is output from the highest voltage power storage device during powering operation of motor generators MG1 and / or MG2, and as a result, the output voltages of the two power storage devices Are almost equal. Since the upper arm of the converter corresponding to the power storage device that was the highest voltage power storage device is fixed ON, a current is output from the power storage device via the switching element of the upper arm. On the other hand, although the switching element of the upper arm of the converter corresponding to the remaining power storage device is off, a current is output from the power storage device via a diode connected in reverse parallel to the switching element. As a result, the currents output from the two power storage devices are substantially equal.

  When hybrid vehicle 1000 is powering (when YES is determined in step S241), ECU 210 (voltage determination unit 250) determines that the absolute value (= | I1-I2 |) of the difference between currents I1 and I2 is greater than predetermined value X. It is determined whether it is smaller (step S242). When the absolute value (= | I1-I2 |) of the difference between currents I1 and I2 is smaller than predetermined value X, voltage determination unit 250 determines that the output voltages of power storage devices B1 and B2 are equal to each other. The predetermined value X is ideally 0, but is set to a value that takes into account, for example, the detection error of the current sensor.

  When the absolute value (= | I1-I2 |) of the difference between currents I1 and I2 is smaller than predetermined value X (when YES is determined in step S242), voltage determination unit 250 sets determination flag FLG to an on state (step S243). On the other hand, when the absolute value (= | I1-I2 |) of the difference between currents I1 and I2 is equal to or greater than a predetermined value X (NO determination in step S242), voltage determination unit 250 sets determination flag FLG to an off state. (Step S244). When the process of step S243 or S244 is finished, the flag setting process is finished.

  The determination process in step S242 corresponds to a process for determining whether or not the transition from stage 1 to stage 2 is possible. If the determination flag FLG is in the on state, it means that a determination result (OK) indicating that the transition from the stage 1 to the stage 2 is permitted is obtained. Therefore, when the determination flag FLG is set to the on state by the process of step S243 and the process shown in FIG. 8 is subsequently executed, the upper arm ON mode shifts from the stage 1 to the stage 2.

  The fact that the judgment flag FLG is in an off state means that a judgment result (NG) indicating that the transition from the stage 1 to the stage 2 is not permitted is obtained. Therefore, when the determination flag FLG is set to the on state by the process of step S244 and the process shown in FIG. 8 is subsequently executed, the upper arm ON mode is maintained in the stage 1 state.

  By performing the control processing according to FIGS. 7 to 9 as described above, the required power to the power supply system is in a range that can be supplied by a single power storage device, and the boosting operation by converters 10 and 12 is unnecessary. When the target voltage VR is set, the upper arm ON mode is selected to suppress power loss in the converters 10 and 12, and power can be exchanged between the power supply system and the load device.

  Further, in the upper arm ON mode, when two power storage devices having the same output power do not exist, the converter corresponding to the highest voltage power storage device is designated as the upper arm ON fixed converter (stage 1). Thus, the upper arm ON mode can be started without causing a short-circuit current between the power storage devices. That is, the transition from the other operation mode to the upper arm ON mode can be realized without interrupting the power storage device and the converter each time with a relay or the like.

  Here, as a method for determining the magnitude of the output voltage of the power storage devices B1 and B2, a method of comparing the voltage VB1 of the power storage device B1 and the voltage VB2 of the power storage device B2 detected by the voltage sensors 42 and 44, respectively, can be considered. However, in this method, there is a possibility that the accuracy of the voltage sensors 42 and 44 may affect the comparison result. That is, if the flag setting process shown in FIG. 9 is executed based on the output value of the voltage sensor with low detection accuracy, even if only one upper arm should originally be fixed to ON, If both upper arms are fixed to ON, a short circuit current may be generated between the two power storage devices. On the other hand, if the accuracy of the voltage sensors 42 and 44 is increased, the cost is increased. In the present embodiment, it is determined based on the current of the power storage device detected by the current sensor whether there are two power storage devices having the same output voltage. Thus, the magnitude of the output voltages of the two power storage devices can be determined without considering the detection accuracy of the voltage sensor, and the determination process can be simplified.

  Furthermore, in the present embodiment, in the upper arm ON mode, when there are two power storage devices having the same output power, converters corresponding to each of the two power storage devices are designated as the upper arm ON fixed converter ( Stage 2). In this case, a short-circuit current does not occur between power storage devices having the same output voltage, and each of the two power storage devices can enter and output power. As a result, the amount of power that can be recovered during regeneration can be increased as compared with the case where power is received by only one power storage device.

  In addition, it is conceivable that the wheel slips when the hybrid vehicle 1000 is traveling on a slippery road surface or is over a step, and then the wheel grips the road surface. In this case, there is a possibility that energy from the power storage device taken out at the time of slipping flows back to the power storage device due to a sudden change in the motor rotation speed during gripping. According to the present embodiment, the backflow energy can be received by the two power storage devices.

FIG. 10 is a diagram showing the flow of energy during gripping after the occurrence of slip.
Referring to FIG. 10, when the wheel slips due to slip and the wheel grips the road surface thereafter, currents I1 and I2 flow along the path shown in FIG. The energy of the motor generator is represented by torque × number of rotations, but the number of rotations decreases rapidly during gripping, but the torque cannot be changed suddenly. Therefore, the energy supplied from at least one of the power storage devices B1 and B2 is reduced. It becomes surplus at the time of grip, and the current flows backward to the power storage device B1 or B2.

In the present embodiment, current can be received by both power storage devices B1 and B2 by fixing both of the two upper arms on. Thus, the current flowing back to each of power storage devices B1 and B2 can be reduced as compared with a configuration in which only one of power storage devices B1 and B2 receives current. For example, the calorific value of the battery is governed by the internal resistance of the battery determined by the voltage drop when a direct current is applied, and is expressed by the product (RI ² ) of this internal resistance value and the square of the current value. The amount of heat generated by the battery can be suppressed by reducing the current flowing back to each of the devices B1 and B2. In addition, since current can be received in each of power storage devices B1 and B2, the ability to receive backflow energy to the power storage device during grip after the occurrence of slip can be enhanced. Thereby, the buffering effect with respect to disturbances, such as a grip after slip generation, can be enhanced.

  As described above, according to the power supply system of the present embodiment, depending on the state of load devices (motor generators MG1, MG2), depending on the necessity of boost operation by converters 10, 12, and the level of required power PR. Thus, an operation mode (upper arm ON mode) in which the switching element of the upper arm is fixed to the on state by one or two converters can be selected. Therefore, the upper arm ON mode for suppressing the switching loss can be appropriately selected according to the state of the load device.

  Furthermore, according to the power supply system according to the present embodiment, when there are no two power storage devices having the same output voltage, the switching element of the upper arm is fixed to the on state by the converter corresponding to the highest voltage power storage device, An operation mode (stage 1) for shutting down other converters can be selected. Therefore, it is possible to prevent a short-circuit current from being generated between the power storage devices when the upper arm element is turned on, and to appropriately select the upper arm ON mode for suppressing the switching loss according to the state of the load device.

  Furthermore, according to the power supply system of the present embodiment, when there are two power storage devices having the same output voltage in the upper arm ON mode, the switching element of the upper arm is converted by a converter corresponding to each of the two power storage devices. The operation mode (stage 2) for fixing the signal to the ON state can be selected. Since the output voltages of the two power storage devices are equal, it is possible to prevent a short-circuit current from being generated between the two power storage devices even when each upper arm element is turned on, and an upper arm ON mode for suppressing switching loss. It can be selected appropriately according to the state of the load device. Furthermore, since each of the two power storage devices can input and output power, the amount of power that can be recovered during regeneration can be increased. Further, it is possible to enhance a buffering action against disturbance such as a grip after occurrence of slip.

(Modification)
In the above-described embodiment, the power storage system including the power storage devices B1 and B2 and the converters 10 and 12 corresponding to the power storage devices B1 and B2, respectively, that is, including two sets of the power storage device and the converter has been described. Is not limited to such a configuration.

  That is, as shown in FIG. 11, the operation mode control according to the present embodiment can also be applied to a power supply system having a configuration in which a plurality of pairs of power storage devices and corresponding converters are connected in parallel.

  When there are three or more power storage devices, the number of converters to be operated can be further subdivided and set according to the required power PR from the load device. When power is supplied by two or more power storage devices, voltage control is executed by any one of two or more power conversion devices corresponding to these power storage devices, and the remaining converters What is necessary is just to perform current control.

  When the required power PR can be covered by one power storage device and boosting by each converter is unnecessary, the upper arm ON mode may be selected.

  Even when there are three or more power storage devices, the highest voltage power storage device is determined from the plurality of power storage devices based on the output current of each power storage device, or at least two output voltages having the same output voltage are included in the plurality of power storage devices. It can be determined whether or not there is a power storage device. And, “when there is no at least two power storage devices having the same output voltage”, that is, when the highest voltage power storage device exists due to the output voltages of the power storage devices being different from each other, the converter corresponding to the highest voltage power storage device It is only necessary to fix the upper arm on and to stop the remaining converter.

  For example, when the total number of power storage devices is three, “when there are at least two power storage devices having the same output voltage”, the output voltages of the two power storage devices are equal, or three power storage devices. The device output voltages may all be equal. In these cases, the upper arm of the converter corresponding to the power storage devices having the same output voltage may be fixed on.

  Instead of the hybrid vehicle 1000, the present invention can also be applied to an electric vehicle not equipped with an internal combustion engine, and a fuel cell vehicle further equipped with a fuel cell that generates electric energy using fuel. Further, the load device is not limited to an electric motor (motor generator) for generating vehicle driving force, and a power supply system applied to other load devices includes a plurality of sets of power storage devices and converters (power conversion devices). If it is a structure, application of this invention is possible.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 is an overall block diagram of a hybrid vehicle shown as an example of a vehicle equipped with a power supply system according to the present invention. It is a circuit diagram which shows the structure of the converters 10 and 12 shown in FIG. It is a functional block diagram of ECU100 shown in FIG. 3 is a functional block diagram illustrating normal control (voltage / current control) of converters 10 and 12. FIG. It is a conceptual diagram explaining the map structure for setting a target voltage. FIG. 4 is a functional block diagram illustrating a configuration of operation mode control of converters 10 and 12 by converter control unit 200 shown in FIG. 3. 5 is a flowchart for explaining an operation mode selection control process by a mode determination unit 260. It is a flowchart explaining in detail the process in the upper arm ON mode in step S200. It is a flowchart explaining the flag setting process in step S240 in detail. It is the figure which showed the flow of energy at the time of the grip after slip generation. It is a block diagram which shows the modification of a structure of a power supply system.

Explanation of symbols

  2 engine, 4 power split mechanism, 6 wheels, 10, 12 converter, 20, 22 inverter, 42, 44, 46 voltage sensor, 52, 54 current sensor, 62, 64 temperature sensor, 110, 120 inverter control unit, 200 converter Control unit, 210 target value setting unit, 215-1 voltage control unit, 215-2 current control unit, 220-1 voltage / current control unit, 222-1, 222-2, 226-1, 226-2 subtraction unit, 224-1, 244-2 PI control unit, 228-1, 228-2 modulation unit, 230-1, 230-2 Upper arm ON instruction unit, 235-1, 235-1 Shutdown instruction unit, 240-1, 240 -2 instruction selection unit, 250 voltage determination unit, 260 mode determination unit, 1000 hybrid vehicle, B1, B2 power storage device, C condenser , D1 to D4 diodes, L1, L2 reactor, MG1, MG2 motor generator, MP 0 maps, NL negative line, PL1, PL2, PLM positive line, the semiconductor switching element for Q1~Q4 power.

Claims (7)

A power supply system for controlling power input / output to / from a load device connected to a power supply wiring,
A plurality of power storage devices;
A plurality of power conversion devices, each provided corresponding to the plurality of power storage devices, for performing bidirectional DC power conversion between the corresponding power storage device of the plurality of power storage devices and the power supply wiring;
A control device for controlling the operation of each of the plurality of power conversion devices,
Each of the plurality of power conversion devices
A power semiconductor switching element inserted and connected to a current path between the corresponding power storage device and the power supply wiring;
A direction from the corresponding power storage device to the power supply wiring as a forward direction, including a diode element connected in parallel with the power semiconductor switching element,
The control device includes:
A voltage determination unit that determines whether or not there are at least two power storage devices having the same output voltage among the plurality of power storage devices;
A target value setting unit for setting a voltage target value of the power supply wiring according to the state of the load device;
When the required power from the load device is lower than a reference value, and the set voltage target value is a value that does not require the step-up operation by each power converter, at least of the plurality of power converters A mode determination unit that selects a first operation mode for fixing the power semiconductor switching element included in one power conversion device to an on state;
When the voltage determination unit determines that the at least two power storage devices exist, the mode determination unit includes the power semiconductor switching element included in a power conversion device corresponding to each of the at least two power storage devices. Is selected as the first operation mode, and when the voltage determination unit determines that the at least two power storage devices do not exist, the power mode included in one power conversion device A power supply system, wherein an operation mode in which a semiconductor switching element is fixed on and a remaining power converter is stopped is selected as the first operation mode.   The power supply system according to claim 1, wherein the voltage determination unit determines whether or not the at least two power storage devices exist based on output currents of the plurality of power storage devices.   The voltage determination unit determines whether the at least two power storage devices are present in a state where the power semiconductor switching element included in the one power conversion device is fixed on and the remaining power conversion devices are stopped. The power supply system according to claim 1, wherein the power supply system is determined.   The mode determination unit, when the required power is equal to or greater than the reference value, executes voltage control for setting the voltage of the power supply wiring as the target voltage by one of the plurality of power conversion devices, The power supply system according to any one of claims 1 to 3, wherein the remaining power conversion device selects a second operation mode in which current control for controlling input / output current of the corresponding power storage device is executed.   When the required power is lower than the reference value and the voltage target value is a value that requires a boosting operation by any one of the plurality of power converters, the mode determination unit The voltage control for setting the voltage of the power supply wiring to the target voltage is performed by one of the power converters, and the third operation mode for stopping the operation of the remaining power converters is selected. 5. The power supply system according to any one of 1 to 4. The power supply system is mounted on a vehicle,
The load device is:
An AC rotating electric machine that generates the driving force of the vehicle;
An inverter configured to perform bidirectional power conversion so that the AC rotating electrical machine operates in accordance with a command value between the AC rotating electrical machine and the power supply wiring;
The power supply system according to any one of claims 1 to 5, wherein the target value setting unit sets the target voltage in accordance with a rotational speed and torque of the AC rotating electric machine. A control method of a power supply system that controls input / output of power to a load device connected to a power supply wiring,
The power supply system is provided corresponding to each of the plurality of power storage devices and the plurality of power storage devices, and bidirectional DC power conversion is performed between the corresponding power storage device of the plurality of power storage devices and the power supply wiring. A plurality of power conversion devices for performing
Each of the plurality of power conversion devices
A power semiconductor switching element inserted and connected to a current path between the corresponding power storage device and the power supply wiring;
A direction from the corresponding power storage device to the power supply wiring as a forward direction, including a diode element connected in parallel with the power semiconductor switching element,
The control method is:
Determining whether there are at least two power storage devices having the same output voltage among the plurality of power storage devices; and
Setting a voltage target value of the power supply wiring according to the state of the load device;
When the required power from the load device is lower than a reference value, and the set voltage target value is a value that does not require the step-up operation by each power converter, at least of the plurality of power converters Selecting an operation mode for fixing the power semiconductor switching element included in one power conversion device to an on state,
The step of selecting the operation mode includes:
When it is determined that the at least two power storage devices are present, a mode in which the power semiconductor switching element included in a power conversion device corresponding to each of the at least two power storage devices is fixed on is set as the operation mode. A step to choose;
When it is determined that the at least two power storage devices do not exist, a mode in which the power semiconductor switching element included in one power conversion device is fixed on and the remaining power conversion devices are stopped is the operation mode. And a step of selecting as a method for controlling a power supply system.

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