JP2019004594A - Power supply unit of vehicle - Google Patents

Abstract

To provide a power supply unit of a vehicle, which can suppress a rise in the voltage of a capacitor when driving of an inverter is stopped during regenerative operation.SOLUTION: A power supply device 1 comprises: an inverter 45; a low-voltage battery BL connected to lines MPL, MNL; a high-voltage battery BH connected to the lines MPL, MNL; a smoothing capacitor C2 connected to the lines MPL, MNL; contactors 11, 12 that are turned on at the normal time to allow a current flow from the smoothing capacitor to the high-voltage battery BH; and an ECU 60 that determines whether or not a current interruption failure occurs between the low-voltage battery BL and the inverter 45. In the case where it is determined that a current interruption failure occurs when regenerative electric power is supplied from the inverter 45 to the batteries BH, BL during regenerative operation, the ECU 60 keeps the contactors 11, 12 in the ON state, stops driving of the inverter 45, and then turns off the contactors 11, 12.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power supply device for a vehicle.

  FIG. 5 is a diagram showing a configuration of a conventional power supply device 100 mounted on a general electric vehicle such as a hybrid vehicle or an electric vehicle. The power supply apparatus 100 includes a battery 101 that outputs direct current, a DC-DC converter 103 that converts voltage, a contactor 102 that intermittently connects the battery 101 and the DC-DC converter 103, a DC-DC converter 103, and a motor 106. And an inverter 105 provided therebetween. Further, a capacitor 104 is provided between the inverter 105 and the DC-DC converter 103 in order to smooth the pulsating flow. In the power supply apparatus 100 as shown in FIG. 5, the back electromotive force generated during the regenerative operation of the motor 106 can be supplied to the battery 101 via the inverter 105 and the DC-DC converter 103 to charge the battery 101. It has become.

  FIG. 6 is a diagram illustrating a change in the voltage of the capacitor 104 when an abnormality occurs during the regenerative operation of the power supply apparatus 100 as described above and the contactor 102 is opened. In particular, in FIG. 6, there occurs an event that the contactor 102 or the DC-DC converter 103 has some trouble at the time t 0, or the contactor 102 has to be opened due to trouble of other parts. The case where the switching element of the inverter 105 is turned off at time t2 after the continuity is cut off is shown. Note that when a switching element provided in the inverter 105 is turned off from on, an instantaneous surge voltage is generated. In FIG. 6, a portion of the voltage of the capacitor 104 that is instantaneously increased by the surge voltage is schematically shown by a broken line. Indicate.

  As shown in FIG. 6, when an abnormality occurs in which conduction is interrupted at time t <b> 0, the voltage of the capacitor 104 starts to rise due to the counter electromotive force from the motor 106. The control device of the power supply device monitors the voltage of the capacitor 104 and can determine that such an abnormality has occurred due to the voltage of the capacitor 104 exceeding the overvoltage threshold at time t1. In addition, since there is a delay due to arithmetic processing, communication processing, or the like in the control device, there is a blocking delay until it is determined that an abnormality has occurred at time t1 and then the inverter 105 is turned off at time t2. For this reason, when the inverter 105 is turned off at the time t2, the voltage of the capacitor 104 is the maximum, the overvoltage threshold, the rising voltage VA corresponding to the length of the cutoff delay, and the surge voltage VB of the switching element. It rises to the combined height.

  On the other hand, a withstand voltage is set for the capacitor 104 and the switching elements used around the capacitor 104. For this reason, the voltage of the capacitor 104 when the inverter 105 is turned off must not exceed this withstand voltage.

  Patent Document 1 discloses a technique for suppressing a surge voltage generated when a gate of a switching element is turned off. In the technique of Patent Document 1, the surge voltage is suppressed by increasing the gate resistance. Therefore, it is conceivable to apply the technique of Patent Document 1 to the power supply apparatus 100 so that the withstand voltage can be reliably protected. That is, for example, when it is determined that an abnormality has occurred at time t1, the inverter 105 may be turned off at time t2 after switching the gate resistance of the switching element of the inverter 105 to a large one.

Japanese Patent Laid-Open No. 2006-116384

  As described above, when the technique of Patent Document 1 is applied, the surge voltage VB generated when the inverter 105 is turned off can be suppressed. Therefore, it is considered that the instantaneous increase in the voltage of the capacitor 104 can be suppressed accordingly.

  However, switching the gate resistance of the switching element of the inverter 105 from a small one to a large one requires time. For this reason, even if the voltage of the capacitor 104 when turning off the inverter 105 can suppress the surge voltage VB, the voltage increase VA corresponding to the length of the cutoff delay becomes large and eventually approaches the breakdown voltage. There is a risk that.

  An object of the present invention is to provide a power supply device for a vehicle that can suppress an increase in voltage of a capacitor when stopping driving of an inverter during regenerative operation of a motor.

  (1) A power supply device (for example, a power supply device 1 to be described later) of a vehicle (for example, an electric vehicle V to be described later) of the present invention is a power converter (for example, an inverter 45 to be described later) for converting DC power and AC power. A power line (for example, a main positive line MPL and a main negative line MNL, which will be described later) connected to a DC input / output side (for example, a DC input / output terminal 47p, 47n which will be described later) of the power converter, and a power line connected to the power line. A first battery (for example, a low voltage battery BL or a high voltage battery BH described later) connected via one circuit (for example, a low voltage circuit 20 or a high voltage circuit 10 described later), and a second circuit (for example, A second battery (for example, a high voltage battery BH or a low voltage battery BL described later) connected via a high voltage circuit 10 or a low voltage circuit 20 described later, and a connection point between the first and second circuits of the power line. And a capacitor (for example, smoothing capacitor C2 described later) connected to the DC input / output side, and connected to an AC input / output side (for example, AC input / output terminal 46 described later) of the power converter. During regenerative operation of an electric motor (for example, a travel motor M described later), regenerative power is supplied to the first capacitor via the power converter. The power supply device is provided in the second circuit, and when turned on, allows a current flow from the capacitor to the second capacitor and cuts off the current flow when turned off (for example, a contactor described later) 23, 24 or contactors 11, 12), a control device (e.g., ECU 60 to be described later) that normally turns on the second switch, and the first capacitor and the power converter are interrupted. Failure determination means for determining whether or not a failure has occurred (for example, an ECU 60 described later and a means related to execution of the processing of S1 of FIG. 3 described later), and the control device is configured to perform the regenerative operation during the regenerative operation. When it is determined that a failure has occurred, the driving of the power converter is stopped after maintaining the second switch in an ON state.

  (2) In this case, the first circuit has a first switch (for example, described later) that allows a current flow from the power converter to the first capacitor when turned on and cuts off the current flow when turned off. Contactors 11 and 12 or contactors 23 and 24), and the control device turns on the first switch in the normal state, and the failure is maintained with the first switch turned off and cannot be turned on. Preferably it is an event.

  (3) In this case, the first circuit (for example, a low voltage circuit 20 to be described later) is connected to the power line via a voltage converter (for example, a VCU 30 to be described later) for converting a voltage, and the second circuit (for example, the lower voltage circuit 20 to be described later). The high voltage circuit 10), which will be described later, is connected between the connection point of the voltage converter of the power line and the capacitor, and the control device drives the voltage converter during the regenerative operation, and the voltage conversion Preferably, the regenerative power is supplied to the first capacitor via a capacitor, and the failure is an event in which the current flow from the DC input / output side to the first capacitor is interrupted in the voltage converter. .

  (4) In this case, the power supply device is a resistance element connected to input terminals of a plurality of switching elements (for example, switching elements UH, UL, VH, VL, WH, WL described later) included in the power converter. Resistance changing means (for example, a gate resistance switching circuit 55 to be described later) is further provided, and the control device sets the second switch when it is determined that the failure has occurred during the regenerative operation. It is preferable to stop driving the power converter after increasing the resistance by the resistance changing means while maintaining the ON state.

  (5) In this case, it is preferable that the control device turns off the second switch after stopping the driving of the power converter.

  (1) In this invention, with respect to the power line connected to the power converter, a 1st electrical storage device is connected via a 1st circuit, and a 2nd electrical storage device is connected via a 2nd circuit. Further, a capacitor is connected to the power converter side of the power line from the connection point of the first and second circuits, and the second circuit is normally turned on to allow a current flow from the capacitor to the second capacitor. A second switch is provided. And when it determines with the control apparatus having generate | occur | produced the failure from which an electric current is interrupted | blocked between a 1st electrical storage device and a power converter at the time of the regenerative operation of an electric motor, without stopping a drive of a power converter immediately. After the second switch is kept on, the driving of the power converter is stopped. In the present invention, as described above, the first capacitor and the second capacitor are connected to the DC input / output side of the power converter via the power line. For this reason, even if a failure occurs in which the current is interrupted between the first capacitor and the power converter, the current from the power converter can be controlled by maintaining the second switch in the ON state. Therefore, the rising speed of the capacitor voltage can be made slower than the rising speed in the power supply device 100 described with reference to FIG. Therefore, according to the present invention, even if it is determined that a failure has occurred, the second switch is maintained in the on state, and the current is passed from the power converter to the second capacitor, thereby suppressing the increase in the voltage of the capacitor. However, it is possible to ensure a long time from when it is determined that a failure has occurred until the drive of the power converter is stopped. In addition, by suppressing the increase in the voltage of the capacitor when the drive of the power converter is stopped in this way, the capacitor and its surrounding elements can be protected from overvoltage. In addition, according to the present invention, by securing a long time from the failure determination to the stop of the power converter drive, the surge voltage generated when the drive of the power converter is stopped can be increased using this time. Control for suppression can also be executed.

  (2) The failure determination means of the present invention sets a failure to be determined as an event in which the first switch provided in the first circuit is maintained in an off state and does not switch on. Therefore, according to the power supply device of the present invention, when a failure occurs in which the first switch is kept off, the failure determination means determines that a failure has occurred, and the control device responds accordingly. Then, the second switch is maintained in the ON state, and the driving of the power converter is stopped while the current to the second capacitor is supplied. As a result, even when a failure that occurs while the first switch is off occurs, the driving of the power converter can be stopped at an appropriate timing while suppressing an increase in the voltage of the capacitor.

  (3) The failure determination means of the present invention sets an event in which the current flow from the input / output terminal to the first capacitor is interrupted as a failure to be determined in the voltage converter provided between the first capacitor and the capacitor. . Therefore, according to the power supply device of the present invention, when a failure that interrupts the current occurs in the voltage converter, the failure determination means determines that a failure has occurred, and the control device responds accordingly. 2 The switch is kept on, and the drive of the power converter is stopped while the current flows to the second capacitor. Thereby, even if it is a case where a failure arises in a voltage converter, the drive of a power converter can be stopped at a suitable timing, suppressing the raise of the voltage of a capacitor | condenser.

  (4) In the power supply device of the present invention, when it is determined that a failure has occurred during the regenerative operation, the input terminals of the plurality of switching elements included in the power converter are maintained while maintaining the second switch on. After increasing the resistance of the connected resistance element, the drive of the power converter is stopped. Thereby, in the power supply device of the present invention, when the drive of the power converter is stopped while suppressing the increase in the voltage of the capacitor from the time when it is determined that a failure has occurred until the drive of the power converter is stopped. Since the surge voltage can be suppressed, it is possible to further suppress an increase in the voltage of the capacitor when the drive of the power converter is stopped. Therefore, according to the present invention, there may be a case where a capacitor, a switching element, or the like used in the power supply apparatus can be used that has a lower withstand voltage than conventional ones.

  (5) In the power supply device of the present invention, when it is determined that a failure has occurred during the regenerative operation, the second switch is maintained in the ON state, the drive of the power converter is stopped, and then the second switch is Turn off. In many cases, when the above failure occurs, the second switch is turned off immediately to disconnect the second capacitor from the power converter in order to protect the second capacitor from overcurrent. In contrast, in the power supply device of the present invention, when it is determined that a failure has occurred, the second switch is turned off after the power converter is stopped without immediately turning off the second switch. To do. In other words, the second switch is kept on until at least driving of the power converter is stopped. Thereby, in this invention, the raise of the voltage of a capacitor | condenser at the time of stopping the drive of a power converter can be suppressed, and a capacitor | condenser and its surrounding element can be protected from an overvoltage.

It is a figure which shows the structure of the electric vehicle carrying the power supply device which concerns on 1st Embodiment of this invention. It is a circuit diagram which shows the structure of a gate drive circuit. It is a flowchart which shows the specific procedure of a fail safe process. It is a figure which shows an example of the change of the voltage of the smoothing capacitor in a fail safe process. It is a figure which shows the structure of the conventional power supply device. It is a figure which shows the change of the voltage of the capacitor | condenser at the time of the regenerative operation of the conventional power supply device.

Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a configuration of an electric vehicle V (hereinafter simply referred to as “vehicle”) equipped with a power supply device 1 according to the present embodiment.

  The vehicle V includes a travel motor M that is mechanically connected to drive wheels (not shown), and a power supply device 1 that supplies power to the travel motor M. The traveling motor M is, for example, a three-phase AC motor.

  The power supply device 1 is an abbreviation of a high voltage circuit 10 provided with a high voltage battery BH, a low voltage circuit 20 provided with a low voltage battery BL, and a voltage converter 30 (hereinafter referred to as “VCU (Voltage Control Unit) 30”. ), A power drive unit 40 (hereinafter referred to as “PDU (Power Drive Unit) 40”), a main positive line MPL and a main negative line MNL that connect the VCU 30 and the PDU 40, and a VCU 30 and a PDU 40. It includes a gate drive circuit 50 that drives a plurality of switching elements provided, a current sensor CS, and an ECU 60 that is an electronic control module that controls them.

  The high voltage circuit 10 is provided on the positive electrode line PLH connecting the positive electrode of the high voltage battery BH and the main positive electrode line MPL, the negative electrode line NLH connecting the negative electrode of the high voltage battery BH and the main negative electrode line MNL, and the positive electrode line PLH. Positive electrode contactor 11 and negative electrode contactor 12 provided on negative electrode line NLH. The high voltage circuit 10 is provided with an external connection terminal to which an external charger (not shown) is connected when external charging of the high voltage battery BH or the low voltage battery BL is performed.

  The high-voltage battery BH is a secondary battery capable of both discharging for converting chemical energy into electric energy and charging for converting electric energy into chemical energy. Hereinafter, as the high-voltage battery BH, a case where a so-called lithium ion storage battery that performs charging and discharging by moving lithium ions between electrodes will be described, but the present invention is not limited to this. The positive line PLH and the negative line NLH connected to both poles of the high-voltage battery BH are connected between a connection point of a VCU 30 described later and a smoothing capacitor C2 described later, of the main positive line MPL and the main negative line MNL, respectively. .

  The contactors 11 and 12 are turned off when no external command signal is input, the current flow between the high voltage battery BH and the PDU 40 is cut off, and the contactors 11 and 12 are turned on when the command signal is input. The normally open type that allows the flow of current between the high voltage battery BH and the PDU 40. These contactors 11 and 12 open and close in response to a command signal transmitted from the ECU 60. The negative electrode contactor 12 is a precharge contactor having a precharge resistor for relaxing the inrush current to the capacitor. These contactors 11 and 12 are turned on by the ECU 60 at normal times, that is, when the high-voltage battery BH is discharged or charged and a current interruption failure described later occurs.

  The low voltage circuit 20 includes a positive line PLL that connects the positive electrode of the low voltage battery BL and the low voltage side positive terminal 31 of the VCU 30, a negative electrode line NLL that connects the negative electrode of the low voltage battery BL and the low voltage side negative terminal 32 of the VCU 30; A positive contactor 23 provided on the positive line PLL, a negative contactor 24 provided on the negative line NLL, and a vehicle auxiliary machine 22 connected to the VCU 30 side of the positive line PLL and the negative line NLL from the contactors 23, 24. And including. The low voltage circuit 20 is provided with an external connection terminal to which an external charger (not shown) is connected when external charging of the high voltage battery BH or the low voltage battery BL is performed.

  The low-voltage battery BL is a secondary battery capable of both discharging for converting chemical energy into electric energy and charging for converting electric energy into chemical energy. Hereinafter, as the high-voltage battery BH, a case where a so-called lithium ion storage battery that performs charging and discharging by moving lithium ions between electrodes will be described, but the present invention is not limited to this. In the following, a case where the low-voltage battery BL has a full-charge voltage lower than the full-charge voltage of the high-voltage battery BH will be described, but the present invention is not limited to this. The positive electrode line PLL and the negative electrode line NLL connected to both electrodes of the low voltage battery BL are connected to the main positive electrode line MPL and the main negative electrode line MNL via the VCU 30 described later.

  The high voltage battery BH and the low voltage battery BL have the following differences in addition to the full charge voltage. The high-voltage battery BH has a lower output weight density than the low-voltage battery BL, but has a higher energy weight density. That is, the high voltage battery BH is superior to the low voltage battery BL in terms of energy weight density, and the low voltage battery BL is superior to the low voltage battery BL in terms of output weight density. The energy weight density is the amount of power per unit weight [Wh / kg], and the output weight density is the power per unit weight [W / kg]. Therefore, the high voltage battery BH having an excellent energy weight density is a capacitor mainly intended for high capacity, and the low voltage battery BL having an excellent output weight density is a capacitor mainly intended for high output.

  The contactors 23 and 24 are turned off when no external command signal is input, the current flow between the low voltage battery BL and the PDU 40 is interrupted, and the contactors 23 and 24 are turned on when the command signal is input. A normally open type that allows a current to flow between the low-voltage battery BL and the PDU 40. These contactors 23 and 24 open and close in response to a command signal transmitted from the ECU 60. The negative electrode contactor 24 is a precharge contactor having a precharge resistor for relaxing the inrush current to the capacitor. Further, these contactors 23 and 24 are turned on by the ECU 60 at the normal time, that is, at the time of discharging or charging the low voltage battery BL and other than the time of occurrence of a current interruption failure described later.

  The vehicle auxiliary machine 22 includes a plurality of auxiliary machines such as a battery heater, an air conditioner inverter, and a DC-DC converter, and an auxiliary battery (for example, a lead battery) serving as a power source for driving these auxiliary machines. Composed of etc.

  The VCU 30 is provided between the high voltage circuit 10 and the low voltage circuit 20. The low-voltage side positive terminal 31 and the low-voltage side negative terminal 32 of the VCU 30 are respectively connected to the positive line PLL and the negative line NLL of the low voltage circuit 20 as described above. The high voltage side positive terminal 33 and the high voltage side negative terminal 34 of the VCU 30 are connected to the positive line PLH and the negative line NLH of the high voltage circuit 10 through the main positive line MPL and the main negative line MNL, respectively.

  VCU 30 is a bidirectional DC-DC converter configured by combining reactor L, smoothing capacitor C1, high arm element 3H, low arm element 3L, and negative bus 35.

  The negative bus 35 is a wiring that connects the low voltage side negative terminal 32 and the high voltage side negative terminal 34. The smoothing capacitor C <b> 1 has one end connected to the low-voltage positive electrode terminal 31 and the other end connected to the negative bus 35. Reactor L has one end connected to low-voltage side positive terminal 31 and the other end connected to a connection node between high arm element 3H and low arm element 3L.

  The high arm element 3 </ b> H includes a high arm switching element 36 and a diode 37 connected in parallel to the high arm switching element 36. The low arm element 3L includes a low arm switching element 38 and a diode 39 connected in parallel to the low arm switching element 38. These switching elements 36 and 38 are connected in series between the high-voltage side positive terminal 33 and the negative bus 35. The collector of the high arm switching element 36 is connected to the high voltage side positive terminal 33. The emitter of the low arm switching element 38 is connected to the negative bus 35. The forward direction of the diode 37 is a direction from the reactor L toward the high-voltage side positive terminal 33. The forward direction of the diode 39 is the direction from the negative bus 35 toward the reactor L. For the switching elements 36 and 38, known power switching elements such as IGBTs and MOSFETs are used.

  The high arm switching element 36 and the low arm switching element 38 are turned on or off by gate drive signals generated by the gate drive circuit 50 based on control signals from the ECU 60, respectively.

  According to the VCU 30 configured as described above, the step-up function and the step-down function are exhibited by controlling on / off of the switching elements 36 and 38 by the gate drive signal generated at a predetermined timing from the gate drive circuit 50. .

  The step-up function refers to a function of stepping up a voltage applied to the low-voltage side terminals 31 and 32 and outputting the voltage to the high-voltage side terminals 33 and 34, whereby the low-voltage circuit 20 to the high-voltage circuit 10 and the PDU 40. Current flows to During the power running operation of the travel motor M, the ECU 60 supplies DC power from the low voltage battery BL to the PDU 40 by causing the VCU 30 to perform a boost operation via the gate drive circuit 50.

  The step-down function refers to a function of stepping down the voltage applied to the high-voltage side terminals 33 and 34 and outputting the voltage to the low-voltage side terminals 31 and 32, whereby the high-voltage circuit 10 and the PDU 40 are connected to the low-voltage circuit 20. Current flows to During the regenerative operation of the travel motor M, the ECU 60 supplies DC power from the PDU 40 to the low voltage battery BL by causing the VCU 30 to perform a step-down operation via the gate drive circuit 50.

  The PDU 40 includes an inverter 45 serving as a power converter, a smoothing capacitor C2, and a voltage sensor 49.

  The inverter 45 includes a U-phase, V-phase, and W-phase AC input / output terminal 46, a positive DC input / output terminal 47p, and a negative DC input / output terminal 47n (hereinafter collectively referred to as “DC input / output terminals 47p, 47n”). DC power and AC power are also converted. The U-phase, V-phase, and W-phase coils of the traveling motor M are connected to the AC input / output terminal 46 to which AC is input or output. Further, the main positive electrode line MPL and the main negative electrode line MNL are connected to the DC input / output terminals 47p and 47n to which DC is input or output, respectively. The inverter 45 is, for example, a PWM inverter using pulse width modulation that includes a bridge circuit configured by bridge-connecting a plurality of switching elements (for example, IGBTs).

  The inverter 45 includes a high-side U-phase switching element UH and a low-side U-phase switching element UL connected to the U-phase of the traveling motor M, and a high-side V-phase switching element VH and a low-side switching element UL connected to the V-phase of the traveling motor M. A bridge circuit configured by bridge-connecting the side V-phase switching element VL and the high-side W-phase switching element WH and the low-side W-phase switching element WL connected to the W phase of the traveling motor M for each phase is provided. . The current sensor CS detects the current of each phase of the traveling motor M and transmits a signal corresponding to the detected value to the ECU 60.

  During the power running operation of the traveling motor M, the ECU 60 controls the on / off of each switching element of the inverter 45 through the gate drive circuit 50, thereby allowing direct current input / output from the high voltage battery BH or from the low voltage battery BL through the VCU 30. The DC power supplied to the terminals 47p and 47n is converted into three-phase AC power, and this AC power is supplied to the traveling motor M connected to the AC input / output terminal 46.

  During the regenerative operation of the traveling motor M, the ECU 60 controls the on / off of each switching element of the inverter 45 via the gate drive circuit 50, whereby the three-phase supplied from the traveling motor M to the AC input / output terminal 46. AC power is converted into DC power, and this DC power is supplied from the DC input / output terminals 47p, 47n to the high voltage battery BH and from the DC input / output terminals 47p, 47n to the low voltage battery BL via the VCU 30, and these batteries BH are supplied. , BL is charged.

  Further, as will be described later with reference to FIG. 3, the ECU 60 executes fail-safe processing during the regenerative operation of the traveling motor M, and the current from the DC input / output terminals 47p and 47n to the high voltage battery BH or the low voltage battery BL. When a failure occurs that interrupts the flow of the inverter 45, the driving of the inverter 45 is stopped at an appropriate timing to protect the smoothing capacitor C2, the switching elements UH, UL, VH, VL, WH, WL and the like from overvoltage.

  The smoothing capacitor C2 is connected between the main positive line MPL and the main negative line MNL. More specifically, the smoothing capacitor C2 is connected to the DC input / output terminals 47p and 47n side of the main positive line MPL and the main negative line MNL from the connection point of the high voltage circuit 10 and the VCU 30.

  The voltage sensor 49 transmits a voltage detection signal V2 corresponding to the voltage between the main positive line MPL and the main negative line MNL, that is, the voltage of the smoothing capacitor C2, to the gate drive circuit 50 and the ECU 60.

  FIG. 2 is a circuit diagram showing a configuration of the gate drive circuit 50. The gate drive circuit 50 generates a gate drive signal for each switching element of the inverter 45 in response to a command signal from the ECU 60, and a plurality of gate wirings 54 that connect the driver circuit 52 and the gate of each switching element. And comprising. FIG. 2 shows only a portion of the gate drive circuit 50 relating to the connection with the high-side U-phase switching element UH.

  The gate wiring 54 is provided with a gate resistance switching circuit 55 that can change the resistance (so-called gate resistance) of a resistance element connected to the gate terminal of the switching element UH. The gate resistance switching circuit 55 includes resistance elements R1 and R2 connected in parallel to each other, and a changeover switch SW. The changeover switch SW is turned on or off in response to a gate resistance switching signal from the ECU 60. Therefore, when the changeover switch SW is turned on, the gate resistance is smaller than when the changeover switch SW is turned off.

  The ECU 60 turns on the change-over switch SW so that the switching loss in the switching element UH is suppressed during normal times, that is, when the high-voltage battery BH is discharged or charged and a current interruption failure described later occurs. Reduce the gate resistance relatively.

  Further, as will be described later with reference to FIG. 3, when the ECU 60 determines that a current interruption failure has occurred, the surge voltage generated when the gate of the switching element UH is turned off is suppressed. Thus, the changeover switch SW is turned off, and the gate resistance is relatively increased.

  Although illustration and detailed description are omitted, the gate drive circuit 50 includes the gate resistor between the other switching elements UL, VH, VL, WH, WL constituting the inverter 45 and the driver circuit 52. A gate resistance switching circuit having the same configuration as that of the switching circuit 55 is provided, and the gate resistance of each switching element UL, VH, VL, WH, WL can be changed according to a gate resistance switching signal from the ECU 60. .

Next, details of the fail-safe process during regenerative operation by the ECU 60 will be described.
FIG. 3 is a flowchart showing a specific procedure of fail-safe processing. In the fail-safe process of FIG. 3, the contactor 11 and 12 of the high voltage circuit 10 and the contactor 23 and 24 of the low voltage circuit 20 are both turned on, and the ECU 60 performs a predetermined operation during the regenerative operation of the traveling motor M. It is executed repeatedly in a cycle.

  In S <b> 1, the ECU 60 determines whether or not a failure that interrupts the current (hereinafter referred to as “current interruption failure”) occurs between the inverter 45 and the high-voltage battery BH or the low-voltage battery BL. More specifically, the current interruption failure means that any one of the contactors 11 and 12 of the high-voltage battery BH or the contactors 23 and 24 of the low-voltage battery BL is maintained in the off state and turned on during the regenerative operation. In the event of no switching (hereinafter also referred to as “open failure of the contactor”) or in the regenerative operation, the high arm switching element 36 of the VCU 30 is maintained in the off state and is not switched on, and the VCU 30 switches from the inverter 45 to the low voltage battery BL. This includes events in which current is interrupted (hereinafter also referred to as “VCU open failure”).

  Here, whether or not an open failure of the contactor has occurred can be determined in the ECU 60 by using, for example, a current flowing through the target contactor. Whether or not an open failure of the VCU 30 has occurred is, for example, a fail signal transmitted from a failure detection circuit (not shown) when the high arm switching element 36 of the VCU 30 fails, or communication between the ECU 60 and the VCU 30. Can be determined in the ECU 60.

  If the determination in S1 is NO, the ECU 60 determines that no current interruption failure has occurred, immediately ends this fail-safe process, and starts again from S1 after a predetermined period. If the determination in S1 is YES, the ECU 60 determines that a current interruption failure has occurred, and proceeds to S2.

  In S <b> 2, the ECU 60 switches each switching element UH, UL, VH, VL, WH, WL in the gate drive circuit 50 by switching the switching switch of the gate resistance switching circuit of each switching element UH, UL, The gate resistance of VH, VL, WH, WL is increased.

  After the switching of the gate resistance is completed in S2, the ECU 60 stops driving the inverter 45 in S3. That is, in S3, the ECU 60 turns off all the gates of the plurality of switching elements UH, UL, VH, VL, WH, and WL constituting the inverter 45.

  After stopping the drive of the inverter 45 in S3, in S4, the ECU 60 turns off all of the contactors 11 and 12 on the high voltage battery BH side and the contactors 23 and 24 on the low voltage battery BL side that are currently turned on. Then, the fail safe process of FIG. 3 is terminated.

  FIG. 4 is a time chart showing an example of a change in the voltage of the smoothing capacitor C2 in the fail-safe process as described above. In FIG. 4, while the high voltage battery BH and the low voltage battery BL are being charged by the regenerative electric power from the inverter 45 while all the contactors 11, 12, 23, 24 are turned on during the regenerative operation, A case where a current interruption failure occurs at the time (more specifically, for example, a failure in which the contactor 23 of the low voltage battery BL fails and is turned off and the charging current from the inverter 45 to the low voltage battery BL is interrupted). Show. In FIG. 4, a portion of the capacitor voltage that is instantaneously increased by a surge voltage generated when the switching element of the inverter 45 is turned off is indicated by a broken line.

  As described above, when the charging current from the inverter 45 to the low-voltage battery BL is interrupted during the regenerative operation, surplus charges can be stored in the smoothing capacitor C2. However, in the power supply device 1 according to the present embodiment, the inverter 45 is connected to the high voltage battery BH even when the charging current from the inverter 45 to the low voltage battery BL is interrupted due to such a current interruption failure. Has been. Therefore, as shown in FIG. 4, even after a current interruption failure occurs, the contactor of the battery that has not failed (in the example of FIG. 4, the contactors 11 and 12 of the high-voltage battery BH) are kept on. As long as this is done, the capacitor voltage hardly rises unlike the capacitor voltage in the conventional power supply apparatus 100 shown in FIG.

  At time t11, the ECU 60 determines that a current interruption failure has occurred in response to the occurrence of a fail signal (see S1 in FIG. 3). Further, after time t11, the ECU 60 keeps the contactors that are currently turned on (in the example of FIG. 4, the contactors 11 and 12 of the high voltage battery BH and the contactor 24 of the low voltage battery BL) in the on state. The process of increasing the gate resistance for each switching element UH, HL, VH, VL, WH, WL in the circuit 50 is started (see S2 in FIG. 3). Note that the gate resistance change time, which is the time taken from the start of the process of increasing the gate resistance in the ECU 60 at the time t11 to the actual switching to the gate resistance at the time t12, is specifically, for example, several It is about ten [msec].

  After switching to one having a high gate resistance at time t12, at time t13, the ECU 60 turns on the contactors currently turned on (in the example of FIG. 4, the contactors 11 and 12 of the high voltage battery BH and the contactor 24 of the low voltage battery BL). ) Is maintained in the ON state, and the drive of the inverter 45 is stopped (see S3 in FIG. 3). Note that the gate-off time, which is the time taken from the determination that the current interruption failure has occurred at time t11 to the stop of driving of the inverter 45 at time t13, is longer than the gate resistance change time. Specifically, it is about 100 [msec], for example.

  Here, all contactors that are turned on at time t11 are kept on until it is determined that a current interruption failure has occurred at time t11 until the drive of inverter 45 is stopped at time t13. For this reason, according to the power supply device 1, it is possible to suppress an increase in the capacitor voltage (Va in FIG. 4) from when the fail signal is generated at time t11 to when the drive of the inverter 45 is stopped at time t13.

  Further, when the drive of the inverter 45 is stopped at time t13, a surge voltage as shown by a broken line 5a is generated, and the capacitor voltage instantaneously increases. However, in the present embodiment, the gate resistance is already increased at time t12 before the drive of the inverter 45 is stopped at time t13. Therefore, the surge voltage (see the broken line 5a) generated when the drive of the inverter 45 is stopped at time t13 is the surge voltage (see the broken line 5b) generated by the switching control of the inverter 45 before the gate resistance is increased. Smaller than. Therefore, according to the power supply device 1, the rise Vb due to the surge voltage generated when the drive of the inverter 45 is stopped at time t13 can also be suppressed. As described above, according to the power supply device 1, the maximum value of the capacitor voltage when the drive of the inverter 45 is stopped (the sum of the voltage V0 when the fail signal is generated and the Va and Vb) is set to the smoothing capacitor C2 and the inverter 45. It can be made lower than the breakdown voltage of the switching element used in the above.

  After stopping the drive of the inverter 45 at time t13, at time t14, the ECU 60 turns on the contactors that are currently turned on (in the example of FIG. 4, the contactors 11 and 12 of the high-voltage battery BH and the contactor 24 of the low-voltage battery BL). Turn off all. Here, if all the contactors are turned off at time t14, the charging current does not flow from the inverter 45 to the high voltage battery BH and the low voltage battery BL, so the capacitor voltage rises as shown in FIG. Absent.

According to the power supply device 1 of this embodiment, there exist the following effects.
(1) In the power supply device 1, when it is determined that a current interruption failure has occurred during the regenerative operation, the drive of the inverter 45 is not immediately stopped and the contactor that is turned on at that time is turned on. After the maintenance, the drive of the inverter 45 is stopped. In the power supply device 1, even if a current interruption failure occurs in either the high voltage circuit 10 or the low voltage circuit 20, by maintaining the contactor that is turned on at that time, Since the current is supplied to the battery in which no current interruption failure has occurred, the rate of increase in the voltage of the smoothing capacitor C2 can be made slower than the rate of increase in the power supply device 100 described with reference to FIG. Therefore, according to the power supply device 1, the smoothing capacitor C2 is maintained by maintaining the contactor in the on state even after it is determined that a current interruption failure has occurred, and by causing the current to flow from the inverter 45 to the battery that is still connected. A long gate-off time can be ensured while suppressing an increase in voltage. Further, by suppressing the increase in the voltage of the smoothing capacitor C2 when the drive of the inverter 45 is stopped in this way, the smoothing capacitor C2, the surrounding switching elements, and the like can be protected from overvoltage. In addition, according to the power supply device 1, by securing a long gate-off time, it is possible to execute control for suppressing an increase in surge voltage generated when, for example, the drive of the inverter 45 is stopped by using this time. it can.

  (2) The ECU 60 determines an event in which one of the contactors 11 and 12 provided in the high voltage circuit 10 or one of the contactors 23 and 24 provided in the low voltage circuit 20 is maintained in an off state and does not switch on. It is assumed that there is a failure. Therefore, according to the power supply device 1, when a failure occurs in which one of the contactors 11, 12 or any of the contactors 23, 24 is maintained in an off state, the power device 1 is turned on at that time. The contactor is maintained in an ON state, and the drive of the inverter 45 is stopped while a current is supplied to the battery whose connection is maintained. As a result, even when a failure that occurs while the contactor is off occurs, the drive of the inverter 45 can be stopped at an appropriate timing while suppressing an increase in the voltage of the smoothing capacitor C2.

  (3) The ECU 60 determines that an event in which the current flow from the inverter 45 to the low voltage battery BL is interrupted in the VCU 30 is a failure to be determined. Therefore, according to the power supply device 1, when a failure occurs in the VCU 30 where the current is cut off, the contactors 11 and 12 of the high voltage battery BH are maintained in an on state accordingly, and the current flows to the high voltage battery BH. However, the drive of the inverter 45 is stopped. Thereby, even if a failure occurs in the VCU 30, the drive of the inverter 45 can be stopped at an appropriate timing while suppressing an increase in the voltage of the smoothing capacitor C2.

  (4) In the power supply device 1, when it is determined that a current interruption failure has occurred during the regenerative operation, a plurality of switching elements included in the inverter 45 are maintained while maintaining the contactor turned on at that time. After increasing the gate resistance of the element, the drive of the inverter 45 is stopped. Thereby, in the power supply device 1, when the drive of the inverter 45 is stopped while suppressing the increase in the voltage of the smoothing capacitor C <b> 2 from when it is determined that the current interruption failure has occurred until the drive of the inverter 45 is stopped. Since the surge voltage can be suppressed, an increase in the voltage of the smoothing capacitor C2 when the drive of the inverter 45 is stopped can be further suppressed. Therefore, according to the power supply device 1, there are cases where a smoothing capacitor C2 or switching elements UH, UL, VH, VL, WH, WL, etc., having a lower withstand voltage than before can be used.

  (5) In the power supply device 1, when it is determined that a current interruption failure has occurred during the regenerative operation, the contactor that is turned on at that time is kept on and the drive of the inverter 45 is stopped These contactors are turned off. In many cases, when such a current interruption failure occurs, the contactor is immediately turned off to disconnect the battery from the inverter 45 in order to protect the battery that is currently connected from the overcurrent. On the other hand, in the power supply device 1, when it is determined that a current interruption failure has occurred, the contactor that is turned on at that time is not turned off immediately, Turn off the contactor. In other words, each contactor is kept on until at least the drive of the inverter 45 is stopped. Thereby, in the power supply device 1, the rise in the voltage of the smoothing capacitor C2 when the drive of the inverter 45 is stopped can be suppressed, and the smoothing capacitor C2 and the surrounding switching elements can be protected from overvoltage.

  Although one embodiment of the present invention has been described above, the present invention is not limited to this. Within the scope of the gist of the present invention, the detailed configuration may be changed as appropriate.

  For example, in the above embodiment, it is determined whether or not a current interruption failure has occurred using the voltage detection signal V2 of the voltage sensor 49, but means for determining whether or not a current interruption failure has occurred is not limited thereto. . For example, a current sensor may be provided in each of the high voltage circuit 10 and the low voltage circuit 20, and it may be determined whether or not a current interruption failure has occurred using a current detection signal of the current sensor. For example, when the current detection signal of the current sensor provided in the high voltage circuit 10 at the time of regenerative operation shows 0, this is maintained while either of the contactors 11 and 12 of the high voltage battery BH is kept off. It can be determined that a failure has occurred that cannot be switched to. Further, for example, when the current detection signal of the current sensor provided in the low voltage circuit 20 shows 0 during the regenerative operation, this is maintained in a state in which one of the contactors 23 and 24 of the low voltage battery BL is off. It can be determined that a failure has occurred that will not switch on.

V ... Electric vehicle (vehicle)
M ... Travel motor (electric motor)
DESCRIPTION OF SYMBOLS 1 ... Power supply device 10 ... High voltage circuit (2nd circuit)
BH ... High voltage battery (second battery)
11, 12 ... Contactor (second switch)
20 ... Low voltage circuit (first circuit)
BL ... Low voltage battery (first capacitor)
23, 24 ... Contactor (first switch)
30 ... VCU (voltage converter)
40 ... PDU
C2: Smoothing capacitor (capacitor)
MPL ... Main positive line (power line)
MNL ... Main negative line (power line)
45 ... Inverter (power converter)
UH, UL, VH, VL, WH, WL ... Switching element 46 ... AC input / output terminal (AC input / output side)
47p, 47n ... DC input / output terminal (DC input / output side)
49 ... Voltage sensor (failure judging means)
50 ... Gate drive circuit 55 ... Gate resistance switching circuit (resistance changing means)
60 ... ECU (control device, failure determination means)

Claims (5)

A power converter that converts DC power and AC power;
A power line connected to the DC input / output side of the power converter;
A first battery connected to the power line via a first circuit;
A second battery connected to the power line via a second circuit;
A capacitor connected to the DC input / output side of the power line from the connection point of the first and second circuits, and during the regenerative operation of the electric motor connected to the AC input / output side of the power converter, A power supply device for a vehicle in which regenerative power is supplied to the first battery via the power converter,
A second switch that is provided in the second circuit and that allows current flow from the capacitor to the second capacitor when turned on and shuts off the current flow when turned off;
A control device that normally turns on the second switch;
Failure determination means for determining whether or not a failure has occurred that interrupts current between the first capacitor and the power converter;
If it is determined that the failure has occurred during the regenerative operation, the control device stops driving the power converter after maintaining the second switch in an ON state. Power supply. The first circuit is provided with a first switch that allows a current flow from the power converter to the first capacitor when turned on and cuts off the current flow when turned off,
The control device turns on the first switch at the normal time,
2. The vehicle power supply device according to claim 1, wherein the failure is an event in which the first switch is maintained in an off state and is not switched on. 3. The first circuit is connected to the power line via a voltage converter that converts a voltage;
The second circuit is connected between the connection point of the voltage converter and the capacitor in the power line,
The control device drives the voltage converter during the regenerative operation, supplies the regenerative power to the first capacitor via the voltage converter,
2. The vehicle power supply device according to claim 1, wherein the failure is an event in which a current flow from the DC input / output side to the first capacitor is interrupted in the voltage converter. Further comprising resistance changing means for changing the resistance of a resistance element connected to input terminals of a plurality of switching elements included in the power converter,
When it is determined that the failure has occurred during the regenerative operation, the control device increases the resistance by the resistance changing means while maintaining the second switch in an on state, and then converts the power The vehicle power supply device according to any one of claims 1 to 3, wherein the driving of the device is stopped.   5. The vehicle control device according to claim 1, wherein the control device turns off the second switch after the drive of the power converter is stopped. 6.

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