JP2010093981A - Power supply system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a constitution capable of quickly detecting short circuit between power storage devices in a power supply system in which a plurality of sets of the power storage devices and power conversion devices are provided. <P>SOLUTION: In the power supply system, when a required power PR of a load device (motor generator MG1, MG2) is lower than a reference value and the step-up operation by converters 10, 12 is not required, the upper arm switching element of the converter corresponding to the power storage device of the highest output voltage out of the power storage devices B1, B2 is fixed in an ON state, and an operation mode (upper arm ON-mode) for shutting down the other converter is selected. Furthermore, the power supply system reduces an overcurrent detection level in the upper arm ON mode. As a result, even when the short circuit occurs between the power storage devices B1, B2, the short circuit between the power storage devices B1, B2 can be quickly detected before a short circuit current becomes large. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a power supply system, 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. In this way, it is possible to suppress power loss in the converter during operation with a small required power.

Further, for example, Japanese Patent Application Laid-Open No. 2008-172966 (Patent Document 2) includes a power storage device and a step-up DC / DC converter, and the upper arm of the DC / DC converter is turned on during non-step-up. Has been.
JP 2008-17661 A JP 2008-172966 A

  As described above, in a power supply system including a plurality of sets of power storage devices and converters, a plurality of converters 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. However, according to the technique described in Japanese Patent 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. There is a possibility that the loss of the converter becomes relatively large.

  In order to solve such a problem, as described in Japanese Patent Application Laid-Open No. 2008-172966 (Patent Document 2), when the step-up operation by the converter is unnecessary, the upper arm of the converter is turned on. It is possible. However, in a configuration including a plurality of sets of power storage devices and converters, the output voltage may be different among the plurality of power storage devices. If a current path from a high-voltage power storage device to a low-voltage power storage device is generated by turning on the upper arm of any of the plurality of converters, the two power storage devices are short-circuited. There is a possibility that a large current flows between the power storage devices. However, neither of Patent Documents 1 and 2 specifically describes the possibility of such a problem.

  The present invention has been made to solve such problems, and an object of the present invention is to quickly detect a short circuit between power storage devices in a power supply system including a plurality of sets of power storage devices and power conversion devices. It is to provide a possible configuration.

  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 line, and is provided for each of a plurality of power storage devices and a plurality of power storage devices. A plurality of power conversion devices that perform bidirectional DC power conversion between a corresponding power storage device and a power line, a control device that controls operations of the plurality of power conversion devices, and inputs of the plurality of power storage devices An overcurrent detection unit configured to detect that at least one of the currents and the output current exceeds the overcurrent level when at least one of the currents exceeds the overcurrent level; 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 line, and a power semiconductor with a direction from the corresponding power storage device to the power line as a forward direction. A switching element and a diode element connected in parallel. The control device includes a mode determination unit. The mode determination unit selects a power semiconductor switching element in the power conversion device corresponding to the power storage device selected from the plurality of power storage devices when a predetermined condition that does not require DC power conversion by each power conversion device is satisfied. When the first operation mode for stopping the operation of the remaining power conversion device is selected and the predetermined condition is not satisfied, at least one of the plurality of power conversion devices performs DC power conversion. The second operation mode to be selected is selected. When the first operation mode is selected, the overcurrent detection unit sets the overcurrent level lower than when the second operation mode is selected.

  Preferably, each of the plurality of power conversion devices further includes a drive circuit that drives the power semiconductor switching element. The overcurrent detection unit is disposed inside the drive circuit.

  Preferably, the power supply system further includes a stop processing unit that stops the power semiconductor switching element when an overcurrent is detected by the overcurrent detection unit.

  Preferably, the selected power storage device is a power storage device having the highest output voltage among the plurality of power storage devices. The control device further includes a voltage determination unit that determines a selected power storage device among the plurality of power storage devices based on output voltages of the plurality of power storage devices.

  ADVANTAGE OF THE INVENTION According to this invention, the short circuit between electrical storage apparatuses can be detected rapidly in a power supply system provided with two or more sets of an electrical storage apparatus and a power converter device.

  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 the description thereof will not be repeated in principle.

  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 power 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. Furthermore, when converter 10 detects that power storage device B1 is short-circuited with power storage device B2 at the time of its non-boosting, converter 10 transmits a short circuit signal SH1 to 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. Furthermore, when converter 12 detects that power storage device B1 is short-circuited with power storage device B2 at the time of its non-boosting, converter 12 transmits a short circuit signal SH2 to 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 line” in the present invention.

  Inverter 20 converts the 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. 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. Further, 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 positive. Output to line PLM.

  Each of motor generators MG1 and MG2 is a three-phase AC rotating electric machine, for example, a three-phase AC synchronous motor generator. Motor generator MG1 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.

  When ECU 100 receives short circuit signal SH <b> 1 from converter 10, ECU 100 outputs shutdown signal SD <b> 1 to converter 10. Similarly, when ECU 100 receives short circuit signal SH <b> 2 from converter 12, ECU 100 outputs shutdown signal SD <b> 2 to converter 12.

  Further, ECU 100 receives an input of 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, a reactor L1, and drive circuits 31, 32.

  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. Hereinafter, the control electrodes of these semiconductor switching elements will be collectively referred to as “gates”.

  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. Drive circuits 31 and 32 are connected to the gate electrodes of switching elements Q1 and Q2, respectively. Drive circuits 31 and 32 supply a gate signal (drive voltage) to the gate electrode of the corresponding switching element in accordance with signal PWC1 from ECU 100. Thereby, switching elements Q1 and Q2 are driven.

  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 in which the drive circuits 31 and 32 are replaced with the drive circuits 33 and 34 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.

  Converter control unit 200 further receives short-circuit signals SH1 and SH2. Converter control unit 200 outputs shutdown signal SD1 when it receives short circuit signal SH1, while it outputs shutdown signal SD2 when it receives short circuit signal SH2.

  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 SOC1 and SOC2 of power storage devices B1 and B2, voltage-controlled converter target voltage VR and current-controlled converter target current IR 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 by the motor generator MG (MG1, MG2), which is generally shown below, so that the motor current can be controlled. A target 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 the converter 10 and the current control of the converter 12 by the switching (on / off) operation of the upper arm elements Q1 and / or Q3 and the lower arm elements Q2 and / or Q4, the system The charge / discharge balance of voltage VH and 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 to system voltage VH as the input voltage of the load device, and is supplied to the power line (positive line PLM). The power conversion operation is executed so as to output. On the other hand, during the regenerative braking operation, the power conversion operation is performed so as to charge power storage devices B1 and B2 with the charging power on the power line (positive 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.

  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.

  Instruction selection unit 240-2 outputs one of PWM signal PWC1, upper arm on signal UA1, and shutdown signal SD1 to converter 10 in accordance with mode control signal MS1 from mode determination unit 260.

  Voltage determination unit 250 determines which output voltage of power storage devices B1 and B2 is higher based on voltages VB1 and VB2 detected by voltage sensors 42 and 44, and outputs a signal FV indicating the determination result. To do. 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.

  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 operates as “2CNV mode” in which both converters 10 and 12 are operated, “1CNV mode” in which only one of converters 10 and 12 is operated to perform voltage control, and maximum voltage storage. In the converter corresponding to the apparatus, one of the “upper arm ON modes” in which the switching element of the upper arm is fixed on and the operation of the other converter is stopped is selected. In upper arm ON mode, mode determination unit 260 determines which of converters 10 and 12 is the highest voltage power storage device according to signal FV from voltage determination unit 250.

  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.

  In the upper arm ON mode, mode determination unit 260 outputs an upper arm on signal UA (which collectively represents UA1 and UA2) to the converter corresponding to the highest voltage power storage device 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.

  FIG. 7 is a block diagram illustrating the configuration of the drive circuit 31 shown in FIG. Referring to FIG. 7, drive circuit 31 includes a gate drive circuit 71, an upper arm ON determination circuit 72, a gate cutoff command generation circuit 73, an AND circuit 74, an overcurrent detection level switching circuit 75, and a sense resistor. 76 and a comparator 77. The upper arm ON determination circuit 72, the AND circuit 74, the overcurrent detection level switching circuit 75, the sense resistor 76, and the comparator 77 constitute the “overcurrent detection unit” of the present invention.

  The gate drive circuit 71 generates a gate signal G for driving the switching element Q1 (supplied to the gate electrode of the switching element Q1) in response to a signal from the ECU 100. The gate drive circuit 71 generates the gate signal G by amplifying the signal PWC1, for example. Furthermore, when the signal from ECU 100 is shutdown signal SD1 or when command SG is received from gate cutoff command generation circuit 73, gate drive circuit 71 stops the operation of switching element Q1 (blocks the gate). ) Is generated.

  When detecting that the signal from ECU 100 is signal UA1, upper arm ON determination circuit 72 determines that upper arm (switching element Q1) of converter 10 is fixed in the ON state. Upper arm ON determination circuit 72 turns on flag FLG indicating the determination result. In the present embodiment, “the flag FLG is on” means that the potential level of the flag FLG is H (logic high) level, and “the flag FLG is off” means that the potential level of the flag FLG is It means L (logical low) level.

  The gate cutoff command generation circuit 73 generates a command SG and outputs it to the gate drive circuit 71 when an overcurrent flows through the switching element Q1.

  The overcurrent detection level switching circuit 75 sets the value of the voltage VLV corresponding to the overcurrent detection level to a certain initial value when the flag FLG is off, and the voltage VLV when the flag FLG is on. Is set lower than its initial value.

  The sense resistor 76 is for detecting the current Ic output from the switching element Q1. Currents Ic and Is are output from the switching element Q1. The current Ic is a current flowing through the reactor L1 shown in FIG. On the other hand, the current Is is a current having a magnitude proportional to the current Ic. Therefore, the magnitude of the current Ic can be grasped by detecting the current Is.

  The current Is is converted into the voltage Vs by the sense resistor 76. Hereinafter, this voltage Vs is referred to as “sense voltage”.

  The comparator 77 compares the sense voltage Vs with the voltage VLV. When the current Is increases as the current Ic increases, the sense voltage Vs becomes higher than the voltage VLV. In this case, the comparator 77 outputs the detection signal OC. Note that “output of the detection signal OC” means that the potential level of the detection signal OC is H level.

  AND circuit 74 receives flag FLG and detection signal OC. When the potential levels of flag FLG and detection signal OC are both H level, AND circuit 74 outputs short circuit signal SH1. When the potential levels of the flag FLG and the detection signal OC are both H level, the upper arm (switching element Q1) of the converter 10 is in an on state and an overcurrent flows through the switching element Q1. Note that “output of the short circuit signal SH1” means that the potential level of the short circuit signal SH1 is H level.

  Returning to FIG. 2, when the voltage (VB2) of the power storage device B2 is higher than the voltage (VB1) of the power storage device B1, but the switching element Q1 is turned on, the positive line PL2, the reactor L2, The diode D3, the positive electrode line PLM, the switching element Q1, and the reactor L1 form a current path that short-circuits the power storage device B2 and the power storage device B1. Therefore, a large current may flow from power storage device B2 to power storage device B1. That is, if the upper arm of the converter corresponding to the power storage device with the lower output voltage is fixed on, a large current may flow.

  In the present embodiment, the overcurrent detection level is lowered when the upper arm (switching element Q1) of converter 10 is in the on state. Thereby, a short circuit of power storage devices B1 and B2 can be detected quickly. Therefore, an element that may be damaged by a large current, such as a power storage device, a switching element, or a diode, can be quickly protected.

  FIG. 8 is a schematic diagram showing a physical arrangement of the switching element Q1 and the drive circuit 31. As shown in FIG. Referring to FIG. 8, each of switching element Q <b> 1 and drive circuit 31 is formed by one semiconductor chip and mounted on module 80. That is, the drive circuit 31 is disposed in the vicinity of the switching element Q1.

  The switching element Q1 and the drive circuit 31 are electrically connected by a wire 81. Specifically, the switching element Q1 and the drive circuit 31 have pads 82 and 83, respectively. The pads 82 and 83 are electrically connected by a wire 81.

  The switching element Q1 has a plurality of cell transistors CL manufactured by the same process. Part of the plurality of cell transistors CL functions as a sense element SNS for detecting the output current (current Ic in FIG. 7) of the switching element Q1. Since each of the plurality of cell transistors CL has basically the same characteristics, the number of cell transistors CL included in the sense element SNS and the cell transistors CL included in the remaining part of the switching element Q1 other than the sense element SNS. It can be considered that the ratio with the number of is equal to the ratio between the current Is and the current Ic. Therefore, the current Ic can be detected by detecting the current Is.

  The drive circuit 33 is different from the drive circuit 31 in that it drives the switching element Q3 instead of the switching element Q1 and outputs a short circuit signal SH2 instead of the short circuit signal SH1, but its configuration is the drive circuit 31 shown in FIG. It is the same as that of the structure. The physical arrangement of the switching element Q3 and the drive circuit 33 is the same as the physical arrangement of the switching element Q1 and the drive circuit 31 shown in FIG. That is, the drive circuit 33 is disposed in the vicinity of the switching element Q3.

  FIG. 9 is a flowchart for explaining the operation mode selection control processing by the mode determination unit 260. The flowchart shown in FIG. 9 is realized by executing a program stored in advance in ECU 100 at a predetermined control cycle.

  Referring to FIG. 9, ECU 100 sets target voltage VR of system voltage VH in accordance with the state of the load device, more specifically, in accordance with the torque and rotation speed of motor generators MG1 and 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.

  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. 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 in step S200 in order to suppress the loss in the whole as much as possible.

  FIG. 10 is a flowchart illustrating in detail the processing in the upper arm ON mode in step S200. Referring to FIG. 10, when the upper arm ON mode is designated, ECU 100 executes a voltage determination process in step S210. In the voltage determination process, the “highest voltage power storage device” having the highest output voltage is determined from the plurality of power storage devices. That is, the level of output voltages VB1 and VB2 of power storage devices B1 and B2 is determined.

  When ECU 210 determines that VB1 ≧ VB2 (YES in step S220), ECU 210 proceeds to step S230 to fix converter 10 (CNV1) to the upper arm ON while converter 12 ( CNV2) is shut down. Conversely, when it is determined that VB1 <VB2 (NO in step S220), ECU 100 proceeds to step S240 and shuts down converter 10 (CNV1) while converter 12 (CNV2). The upper arm is fixed to ON. 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.

  ECU 100 further executes a transition sequence to the upper arm ON fixed mode in step S250. Specifically, in step S250, each switching element of the converter instructed to be shut down in steps S230 and 240 is turned off, and the system voltage VH is decreased at a constant rate by the converter instructed to fix the upper arm ON. First, voltage control is executed. During this processing, the target voltage VR is gradually decreased from the current value toward the output voltage of the highest voltage power storage device at a constant rate. When system voltage VH decreases to a predetermined level (near the output voltage of the highest voltage power storage device), the upper arm switching element is fixed to the ON state in the converter instructed to fix upper arm ON.

  Although not shown in FIG. 10, step S250 is executed at the time of transition from the other mode to the upper arm ON mode, and is skipped while the upper arm ON mode is continued.

  By performing the control processing in accordance with FIGS. 9 and 10 in this way, 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.

  Furthermore, by designating the converter corresponding to the highest voltage power storage device as the upper arm ON-fixed converter, 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.

  However, the accuracy of the voltage sensors 42 and 44 becomes a problem when determining the highest voltage power storage device. That is, if the processing of steps S210 and 220 (FIG. 10) is executed based on the output value of the voltage sensor with low detection accuracy, there is a possibility that the converter whose upper arm should be fixed on is erroneously designated. In this case, as described above, a large current may flow between power storage devices B1 and B2.

  Further, when the power storage device is discharged, the voltage decreases. Therefore, for example, when the upper arm ON mode is selected, even if voltage VB1 of power storage device B1 is higher than voltage VB2 of power storage device B2, voltage VB1 becomes lower than voltage VB2 while power storage device B1 is discharged. there is a possibility. However, when the upper arm ON mode is selected, power storage device B1 is set as the highest voltage power storage device, and therefore the upper arm of converter 10 is fixed on. Therefore, when voltage VB1 is lower than voltage VB2 due to discharge of power storage device B1, a large current may flow between power storage devices B1 and B2.

  Therefore, in the present embodiment, as will be described below, overcurrent detection level switching circuit 75 reduces the overcurrent detection level (voltage VLV) when the upper arm of converter 10 (12) is in the on state. . Further, when an overcurrent is detected (when the detection signal OC is output from the comparator 77), the upper arm (switching element Q1 or Q3) in the on state is stopped (turned off).

  FIG. 11 is a flowchart showing the processing of the ECU 100 when an overcurrent is detected by the switching element drive circuit. The flowchart shown in FIG. 11 is realized by executing a program stored in advance in ECU 100 at a predetermined control cycle.

  Referring to FIG. 11, ECU 100 determines whether or not short circuit signal SH1 (or SH2) has been received in step S310. When neither of the signals SH1 and SH2 is received (when NO is determined in step S310), the entire process is returned to the main routine. When ECU 170 receives one of signals SH1 and SH2 (when YES is determined in step S310), ECU 170 stops (turns off) the upper arm of the corresponding converter in step S320. That is, ECU 170 turns off the upper arm of converter 10 when it receives signal SH1. On the other hand, ECU 170 turns off the upper arm of converter 12 when signal SH2 is received.

  FIG. 12 is a timing chart for explaining the operation of the switching element drive circuit. The timing chart of FIG. 12 shows the operation of the drive circuit 31, but the operation of the drive circuit 33 is the same as the timing chart shown in FIG.

  Referring to FIGS. 12 and 7, in the period from time t1 to time t2, ECU 100 controls converter 10 in accordance with 2CNV mode or 1CNV mode. During this period, the signal PWC1 is transmitted from the ECU 100 to the drive circuit 31. The gate drive circuit 71 generates a gate signal G synchronized with the signal PWC1.

  Further, during the period from time t1 to time t2, the signal (signal PWC1) from the ECU 100 changes in the cycle T. Therefore, the upper arm ON determination circuit 72 determines that the upper arm is not fixed on, and turns off the flag FLG. The overcurrent detection level switching circuit 75 sets the value of the voltage VLV indicating the overcurrent detection level to an initial value in accordance with the off-state flag FLG.

  The switching element Q1 is turned on and off in response to the gate signal G. As a result, the currents Ic and Is periodically change. However, the peak value of the current Is is smaller than the overcurrent detection level. That is, the sense voltage Vs is smaller than the voltage VLV. Therefore, the comparator 77 does not output the detection signal OC. That is, the potential of the detection signal OC is L level.

  Since the flag FLG is off and the detection signal OC is not output, the AND circuit 74 does not output the short circuit signal SH1 during the period from time t1 to time t2.

  At time t2, ECU 100 controls converter 10 in accordance with the upper arm ON mode. In this case, the signal (signal UA1) from ECU 100 is kept at the H level for a period longer than the period T of signal PWC1. The upper arm ON determination circuit 72 determines that the upper arm (switching element Q1) is fixed on because the period TA during which the signal from the ECU 100 is at the H level is longer than T, and turns on the flag FLG. When the flag FLG is switched from the off state to the on state, the overcurrent detection level switching circuit 75 reduces the voltage VLV.

  Here, the timing chart of FIG. 12 shows that the upper arm (switching element Q1) is fixed on and the currents Ic and Is rapidly increase after time t2 due to malfunction of the voltage sensor. At time t3, the value of the current Is reaches the overcurrent detection level. Therefore, the sense voltage Vs becomes larger than the voltage VLV.

  The comparator 77 outputs the detection signal OC in response to the sense voltage Vs becoming higher than the voltage VLV. Furthermore, since the flag FLG is on and the detection signal OC is output, the AND circuit 74 outputs the short circuit signal SH1.

  The gate cutoff command generation circuit 73 outputs a command SG for turning off the gate signal G to the gate drive circuit 71 in response to the output of the detection signal OC. In response to this command SG, the gate drive circuit 71 turns off (cuts off) the gate of the switching element Q1. Therefore, the upper arm (switching element Q1) stops.

  In addition, ECU 100 receives short circuit signal SH1 and outputs shutdown signal SD1. However, the ECU 100 repeats the process of outputting the signal UA1 at a predetermined control cycle. Therefore, ECU 100 outputs shutdown signal SD1 in a routine subsequent to the control routine at the time when shutdown signal SD1 is received. For this reason, even if the short circuit signal SH1 is transmitted from the AND circuit 74 at time t3, a certain period TB (for example, approximately one cycle of the control cycle of the ECU 100) is required until the shutdown signal is transmitted from the ECU 100.

  In the present embodiment, in addition to ECU 100, gate cutoff command generation circuit 73 generates a command for shutting off the gate of switching element Q1. As shown in FIG. 8, the drive circuit 31 including the gate cutoff command generation circuit 73 is disposed in the vicinity of the switching element Q1. Therefore, the time required from the detection of the overcurrent by the comparator 77 until the gate of the switching element Q1 is cut off can be shortened. Therefore, it is possible to prevent a large current from flowing through the switching element Q1.

  Further, upper arm ON determination circuit 72 turns off flag FLG in response to shutdown signal SD1 from ECU 100. The overcurrent detection level switching circuit 75 returns the value of the voltage VLV to the initial value when the flag FLG is turned off. Furthermore, when the flag FLG is turned off, the AND circuit 74 ends the output of the short circuit signal SH1. Further, since the switching element Q1 is stopped and the current Is does not flow, the sense voltage Vs becomes zero. Since the flag FLG is turned off, the overcurrent detection level switching circuit 75 returns the value of the voltage VLV to the initial value. Therefore, the output of the detection signal OC from the comparator 77 ends. In response, the gate cutoff command generation circuit 73 ends the output of the command SG.

  After switching element Q1 stops, ECU 100 returns control of the converter to normal control (for example, 1CNV mode) (time t4). Conditions for returning the control of the converter to the normal control are not particularly limited. For example, the converter control may be returned to the normal control after a predetermined time has elapsed since the switching element Q1 was stopped.

  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, it is possible to select the operation mode (upper arm ON mode) in which the switching element of the upper arm is fixed to the ON state in the converter corresponding to the highest voltage power storage device and the other converters are shut down. Therefore, the upper arm ON mode for suppressing the switching loss can be appropriately selected according to the state of the load device while preventing the short-circuit current from being generated between the power storage devices due to the upper arm element being turned on.

  And according to the power supply system by this Embodiment, an overcurrent detection level is reduced in upper arm ON mode. Thus, even when a short circuit current occurs between the power storage devices, it is possible to quickly detect a short circuit between the power storage devices before the short circuit current increases.

  Furthermore, according to the power supply system of the present embodiment, the occurrence of overcurrent is detected by an overcurrent detection unit provided in the switching element drive circuit. Accordingly, a short circuit between the power storage devices can be detected quickly, and elements such as the power storage device and the switching element can be protected quickly.

  Furthermore, according to the power supply system of the present embodiment, when the occurrence of overcurrent is detected, the upper arm is stopped by drive circuit 31 and ECU 100. Thereby, elements, such as an electrical storage apparatus and a switching element, can be protected from overcurrent. In particular, when the upper arm is stopped by the drive circuit 31, quick protection can be realized. Further, by stopping the upper arm by the drive circuit 31 and the ECU 100, the above elements can be reliably protected from overcurrent.

(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. 13, the present invention can also be applied to a power supply system having a configuration in which three or more sets 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 detection result of the voltage sensor, and the upper arm of the converter corresponding to the highest voltage power storage device is fixed on. . Also in this case, there is a possibility that the determination of the highest voltage power storage device is erroneous due to the accuracy of the voltage sensor, or the voltage of the power storage device may fluctuate while the upper arm is fixed on. That is, there is a possibility that a short circuit occurs between the power storage devices. Therefore, the present invention can be applied.

  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. FIG. 3 is a block diagram illustrating a configuration of a drive circuit 31 illustrated in FIG. 2. 3 is a schematic diagram showing a physical arrangement of a switching element Q1 and a drive circuit 31. FIG. 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 which shows the process of ECU100 when an overcurrent is detected by the drive circuit of a switching element. 6 is a timing chart for explaining the operation of the switching element drive circuit. 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, 31-34 drive circuit, 42, 44, 46 voltage sensor, 52, 54 current sensor, 62, 64 temperature sensor, 71 gate drive Circuit, 72 upper arm ON determination circuit, 73 gate cutoff command generation circuit, 74 AND circuit, 75 overcurrent detection level switching circuit, 76 sense resistor, 77 comparator, 80 module, 81 wire, 82, 83 pad, 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, 224-2 PI control unit, 228-1, 228-2 modulation 230-1, 230-2 Upper arm ON instruction section, 235-1, 235-1 shutdown instruction section, 240-1, 240-2 instruction selection section, 250 voltage determination section, 260 mode determination section, 1000 hybrid vehicle, B1, B2 power storage device, C capacitor, CL cell transistor, D1-D4 diode, L1, L2 reactor, MG1, MG2 motor generator, MP0 map, NL negative line, PL1, PL2, PLM positive line, Q1-Q4 Power semiconductor Switching element, SNS sense element.

Claims (4)

A power supply system that controls input and output of power to a load device connected to a power line,
A plurality of power storage devices;
A plurality of power conversion devices that are respectively provided corresponding to the plurality of power storage devices and perform bidirectional DC power conversion between the corresponding power storage devices of the plurality of power storage devices and the power line;
A control device for controlling operations of the plurality of power conversion devices;
An overcurrent detection unit that detects that at least one of the currents of the plurality of power storage devices exceeds an overcurrent level when the value of at least one of the input current and the output current exceeds an overcurrent level;
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 line;
A direction from the corresponding power storage device toward the power line as a forward direction, including a diode element connected in parallel with the power semiconductor switching element,
The control device includes:
The power semiconductor switching element is turned on in a power conversion device corresponding to a power storage device selected from the plurality of power storage devices when a predetermined condition that does not require the DC power conversion by each of the power conversion devices is satisfied. When the first operation mode for fixing and stopping the operation of the remaining power converter is selected and the predetermined condition is not satisfied, at least one of the plurality of power converters is the DC power converter Including a mode determination unit for selecting a second operation mode for executing
The overcurrent detection unit sets the overcurrent level lower when the first operation mode is selected than when the second operation mode is selected. Each of the plurality of power conversion devices
A drive circuit for driving the power semiconductor switching element;
The power supply system according to claim 1, wherein the overcurrent detection unit is disposed inside the drive circuit.   The power supply system according to claim 2, further comprising a stop processing unit that stops the power semiconductor switching element when the overcurrent is detected by the overcurrent detection unit. The selected power storage device is a power storage device having the highest output voltage among the plurality of power storage devices,
4. The control device according to claim 1, wherein the control device further includes a voltage determination unit that determines the selected power storage device among the plurality of power storage devices based on output voltages of the plurality of power storage devices. 5. The power supply system according to claim 1.

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