JP2019165579A - Power system of vehicle - Google Patents

Abstract

To provide a power system capable of promptly terminating discharge of a capacitor which is provided in a high voltage circuit.SOLUTION: A power system 1 comprises: first power lines 26p, 26n provided with a high voltage battery 21; second power lines 27p, 27n provided with a first inverter 23 and a second smooth capacitor C2 which transfer power with a drive motor M; a high voltage DC-DC converter 22 having a high arm element 225H and a lower arm element 225L, and converts voltage between the first power lines 26p, 26n and the second power lines 27p, 27n; a controller 8 which controls the first inverter 23 and the high voltage DC-DC converter 22; and a backup power supply 5 which supplies the power to the controller 8. The backup power supply 5 is connected with the first power lines 26p, 26n, and the controller 8 maintains the high arm element 225H in an ON state when a predetermined discharge start condition is established.SELECTED DRAWING: Figure 4

Description

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

  An electric vehicle such as a hybrid vehicle or an electric vehicle is equipped with a power supply system, and travels by driving a motor using electric power supplied from the power supply system. The power supply system includes a high-voltage battery, a DCDC converter that converts an output voltage of the high-voltage battery, and an inverter that converts a DC output of the DCDC converter into an AC and supplies the AC to a motor. Further, a plurality of large-capacity smoothing capacitors are provided in a high voltage circuit constituted by these DCDC converters, inverters and the like.

  Incidentally, while the vehicle is running, in order to stabilize the DC power of the power supply system, it is necessary to store electric charges in the plurality of smoothing capacitors. For example, when the vehicle collides, the electric charges are stored in these smoothing capacitors. The charged electric charge is required to be discharged quickly. Therefore, in many vehicles, discharge control is performed to discharge the electric charge accumulated in the smoothing capacitor to some load during a collision and quickly reduce the voltage of the high voltage circuit (for example, refer to Patent Document 1).

  In Patent Document 1, in a high-voltage circuit in which capacitors are connected to a low-voltage side and a high-voltage side of a DCDC converter, when discharging charges accumulated in these high-voltage side capacitor and low-voltage side capacitor, A first step of turning on the switching element of the lower arm of the converter and turning off the switching element of the upper arm; a second step of turning off the switching element of the lower arm of the converter and turning on the switching element of the upper arm; , Are repeated alternately. In the first step, the electric charge accumulated in the low voltage side capacitor is discharged and consumed by the switching element of the lower arm. In the second step, the charge accumulated in the high voltage side capacitor is charged to the low voltage side capacitor via the switching element of the upper arm. Therefore, by alternately repeating the first step and the second step, the charges accumulated in the low voltage side capacitor and the high voltage side capacitor are discharged.

JP 2008-306795 A

  However, in the power supply system of Patent Document 1, since the first step and the second step are repeatedly performed, it may take time until the electric charge stored in the high voltage side capacitor is sufficiently discharged.

  An object of the present invention is to provide a power supply system that can quickly finish discharging a capacitor provided in a high voltage system.

  (1) A power supply system (for example, power supply system 1 to be described later) of a vehicle (for example, vehicle V to be described later) of the present invention has a first circuit (for example, a high voltage battery 21 to be described later) provided. The first power lines 26p and 26n described later, a motor generator (for example, a drive motor M described later), a power converter (for example, a first inverter 23 described later) and a second power storage element (for example, a later-described first inverter 23). A second circuit (for example, second power lines 27p and 27n to be described later) provided with a second smoothing capacitor C2 to be described later, and an upper arm (for example, a high arm element 225H to be described later) and a lower arm (for example, a low arm element to be described later). 225L), and converts a voltage between the first circuit and the second circuit (for example, a high-voltage DCDC converter 22 described later), the power converter, and the voltage A control device (for example, a control device 8 to be described later) that controls the converter, and a control power supply device (for example, a backup power source 5 to be described later) that supplies power to the control device. The power supply device is connected to the first circuit, and the control device maintains the upper arm in an ON state when a predetermined discharge start condition is satisfied.

  (2) In this case, when the discharge start condition is satisfied, the control device uses the power supplied from the second power storage element via the upper arm and the control power supply device, thereby It is preferable to execute discharge control for driving the power converter so that the rotation of the motor generator is decelerated and the voltage of the second circuit is decreased.

  (3) In this case, the battery further includes a low-voltage battery (for example, a low-voltage battery 31 described later) whose output voltage is lower than that of the power source, and the control device includes a control storage element (for example, a low-voltage battery) A backup capacitor C3), which will be described later, and a gate drive circuit (for example, a gate drive system 85, which will be described later) that drives the upper arm and the lower arm using electric power supplied from the low-voltage battery in the normal state. The discharge start condition is that the voltage of the first circuit is equal to or lower than a predetermined first voltage (for example, a first determination voltage V1th described later) and the voltage of the low-voltage battery is a predetermined second voltage (for example, described later) The second determination voltage VBth) or less, and the gate drive circuit, when the discharge start condition is satisfied, It is preferably maintained in the ON state the upper arm with the power stored in.

  (4) In this case, it is preferable that the voltage converter boosts the power of the first circuit and supplies it to the second circuit.

  (1) A power supply system according to the present invention includes a first circuit provided with a power supply, a power converter that exchanges power with a motor generator, and a second circuit provided with a second power storage element. A voltage converter that converts a voltage, a control device that controls the power converter and the voltage converter, and a control power supply device that supplies power to the control device are provided. In this power supply system, the control power supply device is connected to the first circuit, and the control device maintains the upper arm in the on state when a predetermined discharge start condition is satisfied. Therefore, in this power supply system, when the discharge start condition is satisfied, the upper arm is maintained in the on state, so that the charge stored in the second power storage element is stored in the upper arm, the first circuit, and the control power supply device. And is consumed by the control device for controlling the power converter and the voltage converter. Therefore, according to the power supply system, when the discharge start condition is satisfied, the charge stored in the second power storage device can be quickly discharged and consumed by the control device.

  (2) In the power supply system of the present invention, when the discharge start condition is satisfied, the control device maintains the upper arm in the ON state as described above, and from the second power storage element to the upper arm and the control power supply device. By using the electric power discharged through the electric motor, the discharge control for driving the electric power converter is executed so that the rotation of the motor generator is decelerated and the voltage of the second circuit is lowered. Thereby, in the power supply system, the electric charge accumulated in the second power storage element can be quickly discharged, and an increase in the voltage of the second circuit due to the induced voltage generated in the motor generator can be suppressed.

  (3) In the power supply system of the present invention, the control device includes a control power storage element connected to the low voltage battery, and a gate drive that drives the upper arm and the lower arm using electric power supplied from the low voltage battery in normal operation. A circuit. Further, the gate drive circuit is connected to the low voltage battery when a discharge start condition including that the voltage of the first circuit is lower than the first voltage and the voltage of the low voltage battery is lower than the second voltage is satisfied. The upper arm is maintained in the ON state using the electric power stored in the control power storage element that is normally charged by the low voltage battery. As a result, even when a situation occurs in which power cannot be supplied from the low-voltage battery to the gate drive circuit, the upper arm can be maintained in the ON state, and the charge stored in the second power storage element is discharged. can do.

  (4) In the power supply system of the present invention, the voltage converter boosts the power of the first circuit and supplies it to the second circuit. Therefore, the voltage of the first circuit is kept lower than the voltage of the second circuit while the voltage converter performs this boosting function. Therefore, in the present invention, the control power supply device is connected to the second circuit maintained at a relatively high voltage by connecting the control power supply device to the first circuit maintained at a relatively low voltage in this way. Since the control power supply device can be designed to have a lower withstand voltage than the control power supply device, the control power supply device can be reduced in size and cost.

It is a figure which shows the structure of the electric vehicle carrying the power supply system which concerns on one Embodiment of this invention. It is a figure which shows the structure of a gate drive system. It is a flowchart which shows the specific procedure of the discharge control process by system ECU. It is a figure which shows typically the flow of the electric power implement | achieved in a power supply system, when a high arm element is maintained in an ON state and a low arm element is maintained in an OFF state. It is a time chart which shows the change of the voltage of each place implement | achieved by the discharge control process of FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram illustrating a configuration of an electric vehicle V (hereinafter simply referred to as “vehicle”) equipped with a power supply system 1 according to the present embodiment. In the present embodiment, a so-called hybrid vehicle including an engine E, a drive motor M, and a generator G will be described as an example of the vehicle V, but the present invention is not limited to this. The power supply system according to the present invention is not limited to a hybrid vehicle, and can be applied to any vehicle, such as an electric vehicle and a fuel cell vehicle, as long as the vehicle travels using electric power stored in a battery.

  The vehicle V includes a power supply system 1, an engine E, a drive motor M that is a motor generator, a generator G, and drive wheels W. The drive motor M mainly generates power for the vehicle V to travel. The output shaft of the drive motor M is connected to the drive wheels W via a power transmission mechanism (not shown). Torque generated by the drive motor M by supplying power to the drive motor M from the power supply system 1 is transmitted to the drive wheels W via a power transmission mechanism (not shown), and the drive wheels W are rotated to travel the vehicle V. Let Further, the drive motor M acts as a generator when the vehicle V is decelerated and regenerated. The electric power generated by the drive motor M is charged in a high-voltage battery 21 described later included in the power supply system 1.

  A crankshaft that is an output shaft of the engine E is connected to the generator G through a power transmission mechanism (not shown). The generator G is driven by the power of the engine E and generates electric power. The electric power generated by the generator G is charged in the high voltage battery 21. The engine E is connected to the drive wheels W via a power transmission mechanism (not shown), and the drive wheels W can be driven using the power of the engine E.

  The power supply system 1 includes a high voltage circuit 2 provided with a high voltage battery 21, a low voltage circuit 3 provided with a low voltage battery 31 having a lower voltage than the high voltage battery 21, a backup power supply 5, and a drive motor M. And a control device 8 for controlling the generator G, the high voltage circuit 2 and the low voltage circuit 3.

  The high voltage circuit 2 includes a high voltage battery 21, a high voltage DCDC converter 22 as a voltage converter, both positive and negative electrodes of the high voltage battery 21, a low voltage positive terminal 221 and a low voltage negative terminal of the high voltage DCDC converter 22. The first power lines 26p and 26n connecting the power supply 222, the first inverter 23 and the second inverter 24 as power converters, the high-voltage-side positive terminal 223 and the high-voltage-side negative terminal 224 of the high-voltage DCDC converter 22, Second power lines 27p and 27n connecting the DC input / output sides of the inverters 23 and 24, a low voltage DCDC converter 25 connected to the first power lines 26p and 26n, and a second power line connected to the second power lines 27p and 27n. The smoothing capacitor C2, the discharge resistor R2 connected to the second power lines 27p and 27n, and the voltages of the first power lines 26p and 26n It includes a primary voltage sensor 29 for detecting a.

  The high voltage battery 21 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 21, a case where a so-called lithium ion storage battery that performs charging / discharging by moving lithium ions between electrodes will be described, but the present invention is not limited thereto.

  The first power lines 26p and 26n are provided with a positive contactor 28p and a negative contactor 28n, respectively. These contactors 28p and 28n are opened in a state where no external command signal is input, and the both electrodes of the high voltage battery 21 are disconnected from the first power lines 26p and 26n, and the command signal is input. In the normal open type, the high voltage battery 21 is connected to the first power lines 26p and 26n. These contactors 28p and 28n open and close using electric power supplied from the low-voltage battery 31 in response to a command signal transmitted from the battery ECU 36. The positive electrode contactor 28p is a precharge contactor having a precharge resistor for reducing inrush current to a plurality of smoothing capacitors provided in the high voltage circuit 2.

  The high voltage DCDC converter 22 is provided between the first power lines 26p and 26n and the second power lines 27p and 27n. The low voltage side positive terminal 221 and the low voltage side negative terminal 222 of the high voltage DCDC converter 22 are connected to the high voltage battery 21 via the first power lines 26p and 26n, respectively, as described above. The high voltage side positive terminal 223 and the high voltage side negative terminal 224 of the high voltage DCDC converter 22 are connected to the first inverter 23 and the second inverter 24 via the second power lines 27p and 27n, respectively, as described above.

  High voltage DCDC converter 22 is a bidirectional DCDC converter configured by combining reactor L, first smoothing capacitor C1, high arm element 225H, low arm element 225L, and negative bus 227.

  The negative bus 227 is a wiring that connects the low voltage side negative terminal 222 and the high voltage side negative terminal 224. The first smoothing capacitor C <b> 1 has one end connected to the low voltage positive terminal 221 and the other end connected to the negative bus 227. Reactor L has one end connected to low voltage side positive terminal 221 and the other end connected to a connection node between high arm element 225H and low arm element 225L.

  The high arm element 225H includes a known power switching element such as an IGBT or a MOSFET, and a diode connected in parallel to the power switching element. The low arm element 225L includes a known power switching element such as an IGBT or a MOSFET, and a diode connected in parallel to the power switching element. The high arm element 225H and the low arm element 225L are connected in series in this order between the high-voltage-side positive terminal 223 and the negative bus 227.

  The collector of the power switching element of the high arm element 225H is connected to the high voltage side positive terminal 223, and the emitter thereof is connected to the collector of the low arm element 225L. The emitter of the power switching element of the low arm element 225L is connected to the negative bus 227. The forward direction of the diode provided in the high arm element 225H is a direction from the reactor L toward the high voltage side positive terminal 223. The forward direction of the diode provided in the low arm element 225L is the direction from the negative bus 227 toward the reactor L.

  The high arm element 225H and the low arm element 225L are turned on or off by gate drive signals generated by the gate drive system 85 provided in the control device 8, respectively.

  The high voltage DCDC converter 22 exhibits a step-up function and a step-down function by driving the elements 225H and 225L on / off according to a gate drive signal generated at a predetermined timing from the gate drive system 85. The boosting function refers to a function of boosting the voltage applied to the low-voltage side terminals 221 and 222 and outputting the boosted voltage to the high-voltage side terminals 223 and 224, whereby the first power lines 26p and 26n to the second power line 27p. , 27n. The step-down function refers to a function of stepping down the voltage applied to the terminals 223 and 224 on the high voltage side and outputting it to the terminals 221 and 222 on the low voltage side, whereby the second power lines 27p and 27n to the first power line. Current flows to 26p and 26n. Hereinafter, the potential difference between the first power lines 26p and 26n is referred to as a primary side voltage V1. The potential difference between the second power lines 27p and 27n is referred to as a secondary side voltage V2.

  The primary side voltage sensor 29 detects the primary side voltage V1 and transmits a signal corresponding to the detected value to the system ECU 81 of the control device 8.

  The first inverter 23 and the second inverter 24 are, for example, PWM inverters based on pulse width modulation that include a bridge circuit configured by bridge-connecting a plurality of switching elements (for example, IGBTs). The function to convert between. The first inverter 23 is connected to the second power lines 27p and 27n on the DC input / output side, and is connected to the U-phase, V-phase, and W-phase coils of the drive motor M on the AC input / output side. The second inverter 24 is connected to the second power lines 27p and 27n on the DC input / output side, and is connected to the U-phase, V-phase, and W-phase coils of the generator G on the AC input / output side.

  The first inverter 23 includes a high-side U-phase switching element and a low-side U-phase switching element connected to the U-phase of the drive motor M, and a high-side V-phase switching element and a low-side connected to the V-phase of the drive motor M. A V-phase switching element, a high-side W-phase switching element connected to the W-phase of the drive motor M, and a low-side W-phase switching element are bridge-connected for each phase.

  The first inverter 23 is supplied from the high voltage DCDC converter 22 by driving on / off the switching elements of each phase in accordance with a gate drive signal generated at a predetermined timing from the gate drive system 85 of the control device 8. The DC power is converted to AC power and supplied to the drive motor M, or the AC power supplied from the drive motor M is converted to DC power and supplied to the high voltage DCDC converter 22.

  The second inverter 24 includes a high-side U-phase switching element and a low-side U-phase switching element connected to the U-phase of the generator G, and a high-side V-phase switching element and a low-side connected to the V-phase of the generator G. A V-phase switching element, and a high-side W-phase switching element and a low-side W-phase switching element connected to the W-phase of the generator G are bridge-connected for each phase.

  The second inverter 24 turns on / off the switching elements of each phase in accordance with a gate drive signal generated at a predetermined timing from the gate drive system 85 of the system ECU 81, thereby supplying a direct current supplied from the high voltage DCDC converter 22. The power is converted into AC power and supplied to the generator G, or the AC power supplied from the generator G is converted into DC power and supplied to the high voltage DCDC converter 22.

  The low voltage DCDC converter 25 is connected in parallel with the high voltage DCDC converter 22 with respect to the first power lines 26p and 26n. A drive circuit (not shown) drives the switching element of the low voltage DCDC converter 25 on / off, thereby stepping down the voltage V1 between the first power lines 26p and 26n and supplying it to the low voltage battery 31 via the power line 33. The voltage battery 31 is charged.

  The low voltage circuit 3 includes a low voltage battery 31, a power supply line 34, a collision detection unit 35, a battery ECU 36, and a control voltage sensor 37.

  The low voltage battery 31 is a secondary battery capable of both discharging for converting chemical energy into electrical energy and charging for converting electrical energy into chemical energy. In the present embodiment, a case where a lead battery using lead as an electrode is used as the low voltage battery 31 will be described, but the present invention is not limited to this. In the following, a case where the output voltage of the low voltage battery 31 is lower than the output voltage of the high voltage battery 21 will be described. In the following, the case where the low-voltage battery 31 is provided on the vehicle front side in the engine room (not shown) of the vehicle V in consideration of maintainability by an operator will be described, but the present invention is not limited to this.

  The low voltage battery 31 is connected to the control device 8 via the power supply line 34. The low voltage battery 31 supplies power to the control device 8 through the power supply line 34. The control voltage sensor 37 detects a control voltage VB that is a voltage in the power supply line 34 and transmits a signal corresponding to the detected value to the control device 8.

  The collision detection unit 35 uses a detection signal of an acceleration sensor (not shown) to determine whether or not the vehicle V has collided or overturned. Send a detection signal. The collision detection unit 35 operates using electric power supplied from the low voltage battery 31.

  The battery ECU 36 is a microcomputer that performs control related to ON / OFF of the contactors 28p and 28n, monitoring of the state of the high voltage battery 21 and the low voltage battery 31, and the like. The battery ECU 36 operates using electric power supplied from the low voltage battery 31.

  When the start switch is turned on by the driver, the battery ECU 36 starts under the power supplied from the low voltage battery 31 and precharges the plurality of smoothing capacitors C1 to C2 provided in the high voltage circuit 2. To start. More specifically, the battery ECU 36 precharges the smoothing capacitors C1 and C2 by turning on the contactors 28p and 28n and connecting the high voltage battery 21 to the first power lines 26p and 26n. In addition, when precharging the smoothing capacitors C1 and C2, the battery ECU 36 turns on the negative electrode contactor 28n and turns on the contactor having a precharge resistance in the positive electrode contactor 28p. Further, after the precharge of the smoothing capacitors C1 and C2 is completed, the battery ECU 36 turns on the contactor having no precharge resistor among the positive electrode contactors 28p. Thereby, the inrush current to the smoothing capacitors C1 and C2 at the time of executing the precharge can be reduced.

  Further, the battery ECU 36 turns on the contactors 28p and 28n as described above, and then, when the start switch is turned off to stop the power supply system 1 by the driver, or a collision detection signal is output from the collision detection unit 35. When receiving, the contactors 28p and 28n are turned off, and the high voltage battery 21 is disconnected from the first power lines 26p and 26n.

  The battery ECU 36 can perform CAN communication with a system ECU 81 (described later) of the control device 8 via a CAN bus (not shown). Therefore, when the battery ECU 36 receives a collision detection signal from the collision detection unit 35, the battery ECU 36 turns off the contactors 28p and 28n as described above and transmits a discharge permission signal to the system ECU 81 via CAN communication. The discharge permission signal is a signal that permits execution of discharge control (see S4 in FIG. 3) described later.

  The backup power supply 5 is connected to the first power lines 26 p and 26 n in the high voltage circuit 2, and steps down the power in the first power lines 26 p and 26 n and supplies it to the control device 8. As described above, the control device 8 is basically supplied with power from the low voltage battery 31. The backup power source 5 supplies power to the control device 8 through the first power lines 26p and 26n when sufficient power cannot be supplied from the low voltage battery 31 to the control device 8.

  The control device 8 drives the switching elements of the system ECU 81, which is a microcomputer, and the high-voltage DCDC converter 22, the first inverter 23, and the second inverter 24, in response to a command signal transmitted from the system ECU 81. A gate drive system 85.

  The system ECU 81 operates the high-voltage DCDC converter 22, the first inverter 23, the second inverter 24, the drive motor M, the generator G, and the like so that the vehicle V travels according to the driver's request. The microcomputer is responsible for discharge control for discharging electric charges in the high voltage circuit 2 when a predetermined discharge start condition is satisfied.

  FIG. 2 is a diagram showing a configuration of the gate drive system 85. FIG. 2 shows only a portion of the gate drive system 85 related to driving the high arm element 225H and the low arm element 225L of the high voltage DCDC converter 22.

  The gate drive system 85 includes a high arm side gate drive circuit 86, a low arm side gate drive circuit 87, and a backup capacitor C3. The high arm side gate drive circuit 86 is connected to the input side terminal of the high arm element 225H. The low arm side gate drive circuit 87 is connected to the input terminal side of the low arm element 225L.

  The high arm side gate drive circuit 86 is connected to the power supply line 34 of the low voltage battery 31 via the backup capacitor C3. The backup capacitor C3 is connected to the power supply line 34, and is always fully charged when the low voltage battery 31 or the power supply line 34 is normal. Based on the command signal transmitted from the system ECU 81, the high arm side gate drive circuit 86 generates electric power supplied from the low voltage battery 31 via the power supply line 34 when the low voltage battery 31 or the power supply line 34 is normal. A gate drive signal for consuming and driving the high arm element 225H is generated and input to the high arm element 225H. Further, when power cannot be supplied from the low voltage battery 31 to the high arm side gate drive circuit 86 from the low voltage battery 31 for some reason, the high arm side gate drive circuit 86 consumes the electric power stored in the backup capacitor C3. Thus, the high arm element 225H can be driven.

  Unlike the high arm side gate drive circuit 86, the low arm side gate drive circuit 87 is connected to the power supply line 34 of the low voltage battery 31 without passing through the backup capacitor C3. Based on the command signal transmitted from the system ECU 81, the low arm side gate drive circuit 87 generates electric power supplied from the low voltage battery 31 via the power supply line 34 when the low voltage battery 31 or the power supply line 34 is normal. A gate drive signal for consuming and driving the low arm element 225L is generated and input to the low arm element 225L.

  FIG. 3 is a flowchart showing a specific procedure of the discharge control process by the system ECU 81. The processing in FIG. 3 is performed from when a start switch (not shown) is turned on to start the power supply system 1 by the driver until the start is turned off to stop the power supply system 1 by the driver. In the meantime, it is repeatedly executed by the system ECU 81 at a predetermined control cycle.

  In S1, the system ECU 81 determines whether or not a predetermined first discharge start condition is satisfied. The first discharge start condition is, for example, that the system ECU 81 has received a collision detection signal transmitted from the battery ECU 36. If the determination result in S1 is NO, the system ECU 81 proceeds to S2.

  In S2, the system ECU 81 determines whether or not a predetermined second discharge start condition is satisfied. The second discharge start condition is, for example, that the primary voltage V1 detected by the primary voltage sensor 29 is equal to or lower than a predetermined first determination voltage V1th and the control voltage VB detected by the control voltage sensor 37 is predetermined. The second determination voltage VBth or less.

  If the determination result in S2 is NO, that is, if neither the first discharge start condition nor the second discharge start condition is satisfied, the system ECU 81 ends the process of FIG.

  When the determination result of S1 is YES or when the determination result of S2 is YES, that is, when either the first discharge start condition or the second discharge start condition is satisfied, the system ECU 81 proceeds to S3.

  In S3, the system ECU 81 maintains the high arm element 225H of the high voltage DCDC converter 22 in the on state and maintains the low arm element 225L in the off state in response to the establishment of the first or second discharge start condition. Move on. Here, when the second discharge start condition is satisfied, since the control voltage VB is equal to or lower than the second determination voltage VBth, the high arm side gate drive circuit 86 uses the power supplied from the low voltage battery 31 to drive the high arm element 225H. In some cases, it cannot be maintained in the on state. In this case, the high arm side gate drive circuit 86 maintains the high arm element 225H in the ON state using the electric power stored in the backup capacitor C3.

  FIG. 4 is a diagram schematically showing the flow of power realized in the power supply system 1 when the high arm element 225H is maintained in the on state and the low arm element 225L is maintained in the off state.

  First, as shown in FIG. 4, the charge stored in the first smoothing capacitor C1 is supplied to the backup power source 5 through the first power lines 26p and 26n. Thereby, the primary side voltage V1 falls.

  Further, the charge stored in the second smoothing capacitor C2 is consumed in the discharge resistor R2, as shown in FIG. In addition to this, if the high arm element 225H is maintained in the on state and the low arm element 225L is maintained in the off state as described above, the charge stored in the second smoothing capacitor C2 is maintained in the on state. The electric power flows to the first power lines 26p and 26n having a voltage lower than that of the second power lines 27p and 27n via 225H, and is supplied to the backup power source 5.

  The backup power supply 5 supplies the power supplied from the smoothing capacitors C1 and C2 to the system ECU 81 of the control device 8. As a result, the system ECU 81 is supplied with electric power for executing discharge control to be described later over a predetermined time, and the primary side voltage V1 and the secondary side voltage V2 are reduced.

  Returning to FIG. 3, in S4, the system ECU 81 uses the power supplied from the backup power source 5 as described above, whereby the rotation of the drive motor M and the generator G is decelerated and the secondary voltage V2 is decreased. Thus, discharge control for driving the first inverter 23 and the second inverter 24 is executed. For example, when the first discharge start condition or the second discharge start condition is satisfied by the collision of the vehicle V, the drive motor M and the generator G continue to rotate due to inertia, and are generated by the drive motor M and the generator G. The secondary side voltage V2 may increase due to the induced voltage. Therefore, the system ECU 81 executes discharge control for a predetermined time using electric power supplied from the backup power source 5 in order to decelerate the rotation of the drive motor M and the generator G and lower the secondary side voltage V2. In this discharge control, the system ECU 81 performs, for example, three-phase short-circuit control in which all three-phase low arm or high arm switching elements of the first inverter 23 and the second inverter 24 are turned on alternately under a predetermined carrier cycle. . As a result, a short-circuit current flows through each switching element, whereby the rotation of the drive motor M and the generator G is decelerated and the electric charge stored in the smoothing capacitor C2 is consumed.

  FIG. 5 is a time chart showing changes in voltages at various places realized by the discharge control process of FIG. In FIG. 5, the vertical axis represents voltage, and the horizontal axis represents time. FIG. 5 shows the gate drive signal input to the high arm element 225H, the gate drive signal input to the low arm element 225L, the primary side voltage V1, and the secondary side voltage V2 in order from the upper stage to the lower stage.

  FIG. 5 shows a case where the high voltage battery 21 is disconnected from the first power lines 26p and 26n and the power supply line 34 is disconnected due to the collision of the vehicle V at time t0. In this case, the primary side voltage V1 and the control voltage VB are lowered, and the second discharge start condition is satisfied at time t1 (see S2 in FIG. 3).

  When the second discharge start condition is satisfied at time t1, after this time t1, the system ECU 81 maintains the high arm element 225H in the on state and maintains the low arm element 225L in the off state (see S3 in FIG. 3). As a result, as described with reference to FIG. 4, the electric charge stored in the second smoothing capacitor C2 is supplied to the backup power source 5 via the high arm element 225H maintained in the on state, and further to the system ECU 81. Supplied. For this reason, the secondary side voltage gradually decreases after time t2.

  Further, after time t2, the system ECU 81 executes the discharge control by using the electric power supplied from the backup power source 5 (see S4 in FIG. 3), and as shown in FIG. The rise is suppressed.

  The power supply system 1 according to the present embodiment has the following effects.

  (1) The power supply system 1 includes a first power line 26p, 26n provided with a high voltage battery 21, a first inverter 23 that transfers power to and from the drive motor M, and a second power line provided with a second smoothing capacitor C2. 27p, 27n, a high voltage DCDC converter 22 that converts a voltage between them, a control device 8 that controls the first inverter 23 and the high voltage DCDC converter 22, and a backup power source 5 that supplies power to the control device 8 And comprising. In the power supply system 1, the backup power supply 5 is connected to the first power lines 26p and 26n, and the control device 8 maintains the high arm element 225H in the ON state when the first or second discharge start condition is satisfied. . Accordingly, in the power supply system 1, when the first or second discharge start condition is satisfied, the high arm element 225H is maintained in the on state, so that the charge stored in the second smoothing capacitor C2 is the high arm element 225H, The power is supplied to the control device 8 via the first power lines 26p and 26n and the backup power source 5, and is consumed by the control device 8 to control the first inverter 23 and the high voltage DCDC converter 22. Therefore, according to the power supply system 1, when the first or second discharge start condition is satisfied, the power stored in the second smoothing capacitor C2 can be supplied to the control device 8 and consumed by the control device 8. it can.

  (2) In the power supply system 1, when the first or second discharge start condition is satisfied, the control device 8 maintains the high arm 225H in the ON state as described above, and the second smoothing capacitor C2 to the high arm 225H. In addition, by using the power discharged through the backup power source 5, the discharge control for driving the first inverter 23 is executed so that the rotation of the drive motor M is decelerated and the voltage of the second power lines 27p and 27n is decreased. . As a result, the power supply system 1 can quickly discharge the electric charge accumulated in the second smoothing capacitor C2, and also suppresses an increase in the voltage of the second power lines 27p and 27n due to the induced voltage generated in the drive motor M. it can.

  (3) In the power supply system 1, the control device 8 includes a backup capacitor C3 connected to the low voltage battery 31 and a gate drive that drives the high arm 225H and the low arm 225L using electric power supplied from the low voltage battery 31 in a normal state. And a system 85. Further, the gate drive system 85 satisfies the second discharge start condition including that the primary side voltage V1 is equal to or lower than the first determination voltage V1th and the control voltage VB of the low voltage battery 31 is equal to or lower than the second determination voltage VBth. In this case, the high arm 225H is maintained in the ON state using the power stored in the backup capacitor C3 that is connected to the low voltage battery 31 and is normally charged by the low voltage battery 31 at the normal time. As a result, even when a situation occurs in which power cannot be supplied from the low voltage battery 31 to the gate drive system 85, the high arm 225H can be maintained in the ON state, and thus is stored in the second smoothing capacitor C2. The charge can be discharged.

  (4) In the power supply system 1, the high voltage DCDC converter 22 boosts the power of the first power lines 26p and 26n and supplies the boosted power to the second power lines 27p and 27n. Therefore, while the high voltage DCDC converter 22 performs this boosting function, the voltage of the first power lines 26p and 26n is kept lower than the voltage of the second power lines 27p and 27n. Therefore, in the power supply system 1, the backup power supply 5 is connected to the first power lines 26p and 26n maintained at a relatively low voltage as described above, whereby the backup power supply is connected to the second power lines 27p and 27n maintained at a relatively high voltage. Since the backup power supply 5 can be designed to have a lower withstand voltage than when the power supply 5 is connected, the backup power supply 5 can be reduced in size and cost.

  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, the specific circuit configurations of the high-voltage DCDC converter 22, the first inverter 23, and the second inverter 24 are not limited to those shown in FIG. In particular, as the high-voltage DCDC converter 22, a known circuit such as a multi-level chopper method, an interleave method, or a magnetic coupling may be used in addition to the one shown in FIG. For example, a multi-level chopper circuit includes a capacitor provided in parallel to a series connection body such as a switching element or a diode, in addition to the first smoothing capacitor C1. In the case of a collision of the vehicle V, this capacitor can quickly supply the remaining electric charge to the backup power source 5 via the first power lines 26p and 26n and be consumed by the system ECU 81 in the same manner as the second smoothing capacitor C2. Therefore, the multilevel chopper circuit has many advantages when applied to the present invention.

V ... Vehicle M ... Drive motor (motor generator)
DESCRIPTION OF SYMBOLS 1 ... Power supply system 2 ... High voltage circuit 21 ... High voltage battery (power supply)
22 ... High voltage DCDC converter (voltage converter)
23 ... 1st inverter (power converter)
26p, 26n: first power line (first circuit)
27p, 27n, second power line (second circuit)
C1 ... 1st smoothing capacitor C2 ... 2nd smoothing capacitor (2nd electrical storage element)
R2 ... Discharge resistor 3 ... Low voltage circuit 31 ... Low voltage battery 5 ... Backup power supply (control power supply device)
8 ... Control device 81 ... System ECU
85 ... Gate drive system (gate drive circuit)
C3 ... Backup capacitor (control storage element)

Claims (4)

A first circuit provided with a power source;
A second circuit provided with a power converter and a second power storage element for transferring power to and from the motor generator;
A voltage converter having an upper arm and a lower arm and converting a voltage between the first circuit and the second circuit;
A control device for controlling the power converter and the voltage converter;
A control power supply device for supplying power to the control device, and a vehicle power supply system comprising:
The control power supply device is connected to the first circuit,
The control device maintains the upper arm in an ON state when a predetermined discharge start condition is satisfied.   When the discharge start condition is satisfied, the control device uses electric power supplied from the second power storage element via the upper arm and the control power supply device, thereby rotating the motor generator. 2. The vehicle power supply system according to claim 1, wherein discharge control is performed to drive the power converter so as to decelerate and reduce the voltage of the second circuit. Further comprising a low voltage battery having an output voltage lower than that of the power source;
The control device includes a storage element for control connected to the low voltage battery, and a gate drive circuit that drives the upper arm and the lower arm using electric power supplied from the low voltage battery in a normal state. ,
The discharge start condition includes that the voltage of the first circuit is equal to or lower than a predetermined first voltage and the voltage of the low-voltage battery is equal to or lower than a predetermined second voltage;
The gate drive circuit maintains the upper arm in an ON state using electric power stored in the control power storage element when the discharge start condition is satisfied. The vehicle power system described in 1.   4. The vehicle power supply system according to claim 1, wherein the voltage converter boosts the power of the first circuit and supplies the boosted power to the second circuit. 5.

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