JP7647650B2 - Discharge Device - Google Patents

Description

The present invention relates to a discharge device.

Conventionally, techniques have been proposed for inverter devices for electric motors in electric vehicles to improve safety in the event of a collision of the electric vehicle. For example, Patent Document 1 proposes a technique in which, when a collision of the electric vehicle is detected, the supply of DC power from the high-voltage battery is cut off and the capacitor of the converter provided in the inverter device is discharged by a forced discharge circuit (Patent Document 1).

JP 2010-193691 A

However, the inverter device described in Patent Document 1 is configured to use one forced discharge circuit to discharge the capacitor shared by the two converters, and if the discharge function of the forced discharge circuit is lost for some reason, it may not be possible to discharge the converter's capacitor.

The present invention was made in consideration of these circumstances, and one of its exemplary objectives is to provide a discharge device that can more reliably discharge the capacitor of a PCU (power control unit).

In order to solve the above problem, a discharge device according to one embodiment of the present invention includes a first discharge circuit that discharges a capacitor of a first power control unit provided in a vehicle, a second discharge circuit that discharges a capacitor of a second power control unit provided in the vehicle, and a circuit breaker that cuts off a transmission path that transmits battery power to each of the first power control unit and the second power control unit, and the first power control unit and the second power control unit each supply power to a corresponding electric motor, and the transmission path includes a path on the battery side and a first branch path and a second branch path branched from an end of the path on the battery side, the first branch path is connected to the first power control unit, and the second branch path is connected to the second power control unit, and the circuit breaker cuts off the path on the battery side in response to detection of a collision of the vehicle.

In addition, any combination of the above components, and any transformation of the present invention into a method, device, system, recording medium, computer program, etc., are also valid aspects of the present invention.

The present invention provides a discharge device that can more reliably discharge the PCU capacitor.

1 is a schematic configuration diagram of a vehicle according to a first embodiment. FIG. 2 is a diagram for explaining the configuration of a PCU according to the embodiment. FIG. 11 is a schematic configuration diagram of a vehicle according to a second embodiment.

Below, the embodiment of the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same elements are given the same reference numerals, and duplicated descriptions are omitted as appropriate. In this specification and the drawings, multiple components having substantially the same functional configuration may be distinguished by adding different alphabets after the same reference numerals. However, when there is no need to particularly distinguish between multiple components having substantially the same functional configuration, only the same reference numerals are given to each of the multiple components. For example, when there is no particular distinction between PCU 30a and PCU 30b, they are simply referred to as "PCU 30". In addition, the configuration described below is an example, and does not limit the scope of the present invention in any way.

[First embodiment]
1 is a schematic configuration diagram of a vehicle 1 according to an embodiment of the present invention. The vehicle 1 may be an electric vehicle such as a hybrid electric vehicle, a plug-in hybrid electric vehicle, a fuel cell electric vehicle, or a battery electric vehicle.

As shown in FIG. 1, the vehicle 1 according to this embodiment includes a battery 10, a transmission unit 20, a PCU 30a (first PCU), a PCU 30b (second PCU), electric motors 40a and 40b, and wheels 42a and 42b.

The transmission unit 20 transmits power from the battery 10, which is a DC power source, to the PCU 30. The transmission unit 20 can also cut off the path as necessary to stop the transmission of power to the PCU 30. The transmission unit 20 includes a transmission path 200, a branching box 210, and a circuit breaker 220.

The transmission path 200 is a path for transmitting the power of the battery 10 to the PCU 30, and may be configured with a PN cable. The transmission path 200 according to this embodiment includes battery side paths 202a and 202b, first branch paths 206a and 206b, and second branch paths 208a and 208b.

The battery side path 202 in this embodiment is connected to the battery 10. The battery side path 202a includes path 203a and path 204a, which are connected to each other via the interrupter 224. The battery side path 202b includes path 203b and path 204b, which are connected to each other via the interrupter 224.

The first branch path 206a and the second branch path 208a branch off from the end 212a of the path 204a in the branch box 210. The first branch path 206b and the second branch path 208b branch off from the end 212b of the path 204b in the branch box 210. Furthermore, the first branch paths 206a and 206b are connected to the PCU 30a, and the second branch paths 208a and 208b are connected to the PCU 30b.

The circuit breaker 220 can perform various controls, for example, cutting off the battery side path 202 in response to detection of a collision of the vehicle 1. The circuit breaker 220 may function as a high-speed circuit breaker that can cut off the path at high speed. The circuit breaker 220 includes a control device 222 and a cutoff unit 224.

The control device 222 performs various controls, for example, controlling the cutoff unit 224 and the PCU 30. The control device 222 may include a CPU (Central Processing Unit), a RAM (Random Access Memory), and a ROM (Read Only Memory).

For example, the control device 222 may control the cutoff unit 224 to cut off the battery side path 202 in response to detection of a collision of the vehicle 1 by various known collision detection sensors (not shown). The control device 222 may also control a discharge circuit and an inverter circuit (described later) provided in the PCU 30.

The cutoff unit 224 is provided in the battery side path 202 and can cut off the battery side path 202 as necessary to stop the flow of power in the transmission path 200. The cutoff unit 224 can be configured, for example, with a pyro fuse that can cut off the path by cutting a bus bar using explosives. For example, the cutoff unit 224 can cut off the battery side path 202 based on control by the control device 222 in response to detection of a collision of the vehicle 1.

The PCU 30 is a known device that converts power, and converts the power of the battery 10. The PCU 30a supplies the converted power to the corresponding electric motor 40a via a motor cable 32a (three-phase cable). The PCU 30b supplies the converted power to the corresponding electric motor 40b via a motor cable 32b (three-phase cable).

The electric motors 40 use the supplied power to rotate the corresponding wheels 42. Specifically, the electric motor 40a rotates the wheel 42a, and the electric motor 40b rotates the wheel 42b. The electric motors 40 in this embodiment are in-wheel motors provided inside the wheels 42.

Figure 2 is a diagram for explaining the configuration of the PCU 30 according to this embodiment. Note that the PCU 30a and PCU 30b shown in Figure 1 have substantially the same configuration as the PCU 30 shown in Figure 2. As shown in Figure 2, the PCU 30 according to this embodiment includes a discharge circuit 300, a smoothing circuit 310, and an inverter circuit 320.

The discharge circuit 300 is configured to be able to discharge the capacitor of the PCU 30, specifically, to discharge the capacitor 312 provided in the smoothing circuit 310. The discharge circuit 300 is connected to the smoothing circuit 310 on one side, and to the first branch path 206a, 206b (in the case of PCU 30a) or the second branch path 208a, 208b (in the case of PCU 30b) on the other side. In this embodiment, the discharge circuit 300 provided in each of the PCUs 30a, 30b and the circuit breaker 220 shown in FIG. 1 constitute a discharge device.

The discharge circuit 300 has a switching element 302 and a resistor 304. The switching element 302 may be composed of various known elements that can control the open/closed state. The switching element 302 according to the present embodiment is composed of an IGBT (insulated gate bipolar transistor). The switching element 302 may be controlled to an open state or a closed state by the control device 222. For example, when charge is stored in the capacitor 312, the switching element 302 may change from an open state to a closed state, causing a current to flow through the switching element 302 and the resistor 304, thereby discharging the capacitor 312.

Furthermore, the discharge circuit 300 according to this embodiment can discharge not only the capacitor 312 of the PCU 30 in which it is provided, but also the capacitors 312 of other PCUs 30. For example, the discharge circuit 300 provided in the PCU 30a may discharge the capacitor 312 of the PCU 30b. As a result, even if the discharge circuit 300 of the PCU 30b cannot discharge for some reason, the discharge circuit 300 provided in the PCU 30a can discharge the capacitor 312 of the PCU 30b instead. In this way, the discharge circuit 300 according to this embodiment is configured to have a capacity capable of discharging the capacitors 312 included in the two PCUs 30.

The inverter circuit 320 is a known three-phase inverter circuit having six IGBTs 322. The inverter circuit 320 according to this embodiment converts a DC voltage into an AC voltage and supplies the converted AC voltage to the electric motor 40. The operation of the inverter circuit 320 (e.g., the operation of the IGBTs 322) may be controlled by the control device 222.

The configuration of the vehicle 1 according to this embodiment has been described above. According to the discharge device provided in the vehicle 1 according to this embodiment, the circuit breaker 220 cuts off the battery side path 202 in response to detection of a collision of the vehicle 1. This stops the supply of power from the battery 10 to the PCU 30. At this time, the control device 222 controls the switching element 302 of the discharge circuit 300 from an open state to a closed state, so that a current flows through the discharge circuit 300 and the capacitor 312 is discharged. As a result, even if the motor cable 32, the electric motor 40, the branch path 204, etc. are damaged due to a collision of the vehicle 1, the capacitor 312 of the PCU 30 can be discharged, and robust performance can be improved.

In addition, with the discharge device according to this embodiment, even if for some reason one of the two PCUs 30 is unable to discharge using the discharge circuit 300, the capacitor of the other PCU 30 can be discharged using the discharge circuit 300 provided in the other PCU 30. In this way, with the discharge device according to this embodiment, it is possible to more reliably discharge the PCU 30.

When the electric motor is an in-wheel motor as in this embodiment, the electric motor is placed inside the wheel and outside the frame and side members that absorb the collision load. For this reason, measures different from those for vehicles in which a high-voltage unit is placed inside the vehicle frame, as seen in conventional electric vehicles such as general hybrid cars and electric cars, are required. For example, when the electric motor is an in-wheel motor, the vehicle may collide, causing the wheel together with the electric motor to come off the vehicle, and the electric motor or the motor cable to be damaged. In such a case, discharge control using the electric motor may not be possible, and high-voltage contact protection may not be ensured. According to the discharge device of this embodiment, the discharge circuit provided in the PCU 30 allows discharge without using the electric motor, and high-voltage contact protection can be ensured more reliably.

[Second embodiment]
In the first embodiment, an example in which the two electric motors are in-wheel motors is described. In the second embodiment, an example in which the two electric motors are provided on the outside of the wheels and drive the front wheels and the rear wheels, respectively, is described.

Figure 3 is a schematic diagram of a vehicle 2 according to the second embodiment. The vehicle 2 according to the second embodiment includes a battery 11, a transmission unit 26, a PCU 36a (first PCU), a PCU 36b (second PCU), MGs 44a and 44b (motor generators), front wheels 46a and 46b, and rear wheels 46c and 46d.

The power of the battery 11 is transmitted to the PCUs 36a and 36b via the transmission unit 26. The PCU 36a converts the power transmitted from the battery 11 and supplies the converted power to the MG 44a. The PCU 36b converts the power transmitted from the battery 11 and supplies the converted power to the MG 44b. The MG 44a uses the supplied power to rotate the front wheels 46a and 46b, and the MG 44b uses the supplied power to rotate the rear wheels 46c and 46d.

The transmission unit 26 supplies power from the battery 11, which is a DC power source, to the PCU 36. The transmission unit 26 can also cut off the path and stop the transmission of power to the PCU 36 as necessary. The transmission unit 26 includes a transmission path 260, a branching box 270, and a circuit breaker 280.

The transmission path 260 is a path for transmitting the power of the battery 11 to the PCU 36, and includes battery side paths 262a, 262b, first branch paths 266a, 266b, and second branch paths 268a, 268b.

The battery side path 262 in this embodiment is connected to the battery 11. The battery side path 262a includes a path 263a and a path 264a, and these paths are connected to each other via a cutoff unit 284. The battery side path 262b includes a path 263b and a path 264b, and these paths are connected to each other via a cutoff unit 284.

The first branch path 266a and the second branch path 268a branch off from the end 272a of the path 264a in the branch box 270. The first branch path 266b and the second branch path 268b branch off from the end 272b of the path 264b in the branch box 270. Furthermore, the first branch paths 266a and 266b are connected to the PCU 36a, and the second branch paths 268a and 268b are connected to the PCU 36b.

The circuit breaker 280 cuts off the battery side path 262 in response to detection of a collision of the vehicle 2. The circuit breaker 280 includes a control device 282 and a circuit breaker 284. The control device 282 and the circuit breaker 284 included in the circuit breaker 280 have substantially the same configurations as the control device 222 and the circuit breaker 224 described in the first embodiment, respectively, and therefore will not be described here.

PCU36 has substantially the same configuration as PCU30 shown in FIG. 2, specifically, it includes a discharge circuit, a smoothing circuit, and an inverter circuit. The discharge circuits and circuit breakers 280 included in each of PCU36a and 36b constitute the discharge device according to this embodiment.

The discharge circuit provided in the PCU 36 may be controlled by the control device 282 to change from an open state to a closed state in response to, for example, detection of a collision of the vehicle 2. This allows the discharge circuit provided in the PCU 36 to discharge the capacitors of the PCUs 36a and 36b.

[supplement]
The present invention has been described above based on the embodiment. This embodiment is merely an example, and it will be understood by those skilled in the art that various modifications are possible in the combination of each component and each treatment process, and that such modifications are also within the scope of the present invention.

In the above embodiment, an example has been described in which there are two sets of PCUs and electric motors. However, the present invention is not limited to this, and there may be three or more sets of PCUs and electric motors. In this case, the transmission path may have three or more branch paths branching off from the end of the battery side path. Furthermore, each of the three or more PCUs may have a capacitor and a discharge circuit, and the discharge circuit of each PCU may be arranged to discharge the capacitor of the PCU. This allows, for example, the discharge circuit of one PCU to discharge the capacitor of another PCU, thereby more reliably discharging the capacitor of the PCU.

In the above embodiment, the PCU has been described as having an inverter circuit as a converter. However, the PCU may have various converters (e.g., a DC-DC converter, etc.) instead of or in addition to the inverter circuit.

1, 2 vehicle, 10, 11 battery, 20, 26 transmission unit, 30, 36 PCU, 32 motor cable, 40 electric motor, 44 MG, 200, 260 transmission path, 202, 262 battery side path, 204, 264 branch path, 212, 272 branch section, 220, 280 circuit breaker, 222, 282 control device, 224, 284 circuit breaker section, 300 discharge circuit, 302 switching element, 304 resistor, 310 smoothing circuit, 312 capacitor.

Claims (1)

a first discharge circuit for discharging a first capacitor of a first power control unit provided in the vehicle;
a second discharge circuit that discharges a second capacitor of a second power control unit provided in the vehicle;
a circuit breaker that interrupts a transmission path through which battery power is transmitted to each of the first power control unit and the second power control unit,
the first power control unit and the second power control unit each supply power to a corresponding electric motor;
the transmission path includes a path on the battery side, and a first branch path and a second branch path branched from an end of the path on the battery side;
the first branch path is connected to the first power control unit,
the second branch path is connected to the second power control unit,
The circuit breaker cuts off the path on the battery side in response to detection of a collision of the vehicle.
the first discharge circuit has a first switching element and a first resistor connected in series and is configured to discharge the first capacitor by causing a current to flow through the first switching element in a closed state;
the second discharge circuit has a second switching element and a second resistor connected in series, and is configured to discharge the second capacitor by causing a current to flow through the second switching element in a closed state;
the first discharge circuit and the second discharge circuit are provided so as to be able to discharge a capacitor of a power control unit having a discharge circuit of the other of the first power control unit and the second power control unit, instead of the other discharge circuit;
Discharge device.

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