Power control unit for electric vehicles

Abstract

To reduce the number of components of the whole of a power control unit including a water pump by combining and integrating components of the water pump and components of the power control unit to downsize the power control unit.SOLUTION: A power control unit for an electric vehicle includes: an inverter which controls a supply voltage to a vehicle driving motor from a high-voltage battery 41; a DC / DC converter 10 which steps down the voltage of the high-voltage battery 41 to a voltage capable charging a low-voltage battery 42 serving as a power source for an in-vehicle auxiliary machine; a circuit board 102 which is mounted with a first electrical circuit element constituting the inverter or the DC / DC converter 10; a heat sink which cools the first electrical circuit element; a water pump which circulates a refrigerant in a refrigerant passage of the heat sink; a water pump control circuit which controls the operation of the water pump. A coolant to flow to a refrigerant passage of the heat sink; and a water pump control circuit controlling operation of the water pump. A second electrical circuit element constituting the water pump control circuit is mounted on the circuit board 102 together with the first electrical circuit element.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to a power control unit for an electric vehicle. [Background technology]

[0002] Electric vehicles, hybrid vehicles, plug-in hybrid vehicles, fuel cell vehicles, and other electrically powered vehicles are equipped with a high-voltage battery that powers the vehicle drive motor and a low-voltage battery that powers the vehicle's auxiliary machinery. Electric vehicles also have a power control unit that appropriately controls the vehicle drive motor, generator, etc. The power control unit includes an inverter, a DC-DC converter, etc. The inverter controls the voltage supplied to the vehicle drive motor according to the vehicle's load state, and the DC-DC converter reduces the voltage of the high-voltage battery to a level that can charge the low-voltage battery.

[0003] In electric vehicles, high-voltage batteries are large and have a large capacity, so there is a high need to miniaturize the components installed. In the invention of Patent Document 1, the water pump used to cool the power control unit can be fixed to the power control unit case, eliminating the need for mounting brackets, etc., that are required when attaching the water pump to the vehicle body, thereby miniaturizing the entire system. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-304935 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the invention of Patent Document 1, although brackets and the like can be eliminated by fixing the water pump to the case of the power control unit, the individual parts themselves remain unchanged, and there is room for further improvement.

[0006] The objective of the technology disclosed in this specification is to reduce the number of parts in the entire power control unit, including the water pump, and thereby make the power control unit smaller by combining and integrating the components of the water pump with the components of the power control unit. [Means for solving the problem]

[0007] In order to solve the above problems, the power control unit for an electric vehicle disclosed in this specification takes the following measures.

[0008] The first means is an electric vehicle equipped with a vehicle drive motor, a high-voltage battery that serves as the power source for the vehicle drive motor, and a low-voltage battery that serves as the power source for auxiliary machinery within the vehicle, and includes an inverter that controls the voltage supplied from the high-voltage battery to the vehicle drive motor, a DC-DC converter that reduces the voltage of the high-voltage battery to a voltage that can charge the low-voltage battery, a circuit board that mounts first electrical circuit elements that constitute the inverter or the DC-DC converter, a heat sink that cools the first electrical circuit elements, a water pump that circulates refrigerant through a refrigerant passage of the heat sink, and a water pump control circuit that controls the operation of the water pump, and a second electrical circuit element that constitutes the water pump control circuit is mounted on the circuit board together with the first electrical circuit element.

[0009] According to the first aspect, the second electric circuit element constituting the water pump control circuit is mounted together with the first electric circuit element on the circuit board that mounts the first electric circuit element constituting the inverter or DC-DC converter. This reduces the number of components in the power control unit including the water pump, thereby miniaturizing the power control unit and reducing costs. Furthermore, the second electric circuit element constituting the water pump control circuit can be cooled by the heat sink of the power control unit. This allows the second electric circuit element constituting the water pump control circuit to be one with low heat resistance, thereby increasing design flexibility.

[0010] The second means is configured such that, in the above-mentioned first means, some of the multiple pump electrical circuit elements that constitute the water pump control circuit are incorporated into the converter electrical circuit elements that constitute the DC-DC converter.

[0011] According to the second aspect, by incorporating some of the pump electric circuit elements of the water pump control circuit into the converter electric circuit elements of the DC-DC converter, both circuit elements can be integrated. This facilitates a reduction in the number of parts and also leads to cost reduction.

[0012] The third means is the second means described above, wherein the water pump control circuit includes an input filter circuit as one of the pump electrical circuit elements that removes noise from the power supply circuit, and the DC-DC converter includes a smoothing circuit as one of the converter electrical circuit elements that smoothes the pulsating current obtained by rectifying the AC current after power conversion, and the water pump control circuit is connected to the DC-DC converter so that the smoothing circuit also functions as the input filter circuit.

[0013] According to the third aspect, the smoothing circuit of the DC-DC converter also functions as an input filter for the water pump control circuit, eliminating the need for a dedicated input filter for the water pump control circuit. This helps reduce the number of components and costs. Furthermore, it is possible to suppress voltage drops in the water pump control circuit due to the input filter. Furthermore, because the smoothing circuit of the DC-DC converter also functions as an input filter for the water pump control circuit, the water pump control circuit is incorporated on the circuit board of the DC-DC converter. This allows the wiring length of the water pump control circuit to be shortened, suppressing noise on the wiring of the water pump control circuit.

[0014] The fourth means is the second or third means described above, wherein the water pump control circuit includes a motor control circuit that controls the rotation of a water pump drive motor as one of the pump electrical circuit elements, the DCDC converter includes a power conversion control circuit that is configured by a digital computer as one of the converter electrical circuit elements and controls power conversion by a transformer, and the motor control circuit is configured by being incorporated into the digital computer of the power conversion control circuit.

[0015] According to the fourth aspect, two digital computers, one for the DC-DC converter and one for the water pump control circuit, are integrated into one. This reduces the number of parts and makes it possible to miniaturize the power control unit, thereby reducing costs.

[0016] A fifth means is any of the second to fourth means described above, wherein the water pump control circuit includes, as electric circuit elements for the pump, a motor control circuit that controls the rotation of a water pump drive motor, and an output circuit that receives an output from the motor control circuit and controls a voltage supplied to the water pump drive motor, and the second electric circuit element that constitutes the output circuit is mounted on the circuit board together with the first electric circuit element that constitutes the DC-DC converter.

[0017] According to the fifth aspect, the output circuit of the water pump control circuit is mounted on the same circuit board as the first electric circuit element that constitutes the DC-DC converter. Therefore, compared to a case where a dedicated circuit board is provided for the output circuit of the water pump control circuit, the number of parts can be reduced, making it possible to make the power control unit smaller and reducing costs. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is an explanatory diagram of a system configuration of a hybrid vehicle equipped with a power control unit. [Figure 2] 1 is an explanatory view showing the appearance of a power control unit portion of a hybrid vehicle according to an embodiment of the present invention; [Figure 3] 1 is a system configuration diagram of a power control unit and its peripherals according to an embodiment; [Figure 4] 1 is an external perspective view of a power control unit according to an embodiment of the present invention; [Figure 5] FIG. 5 is a perspective view of the power control unit of FIG. 4. [Figure 6] FIG. 1 is a block circuit diagram of an embodiment in which a water pump control circuit is integrated into a DC-DC converter. [Figure 7] This is a block circuit diagram of a DC-DC converter similar to that of Figure 6, showing the state before the water pump control circuit is incorporated and integrated. [Figure 8] This is a block circuit diagram of a water pump control circuit similar to that of Figure 6, showing the state before being incorporated into the DC-DC converter and integrated. DETAILED DESCRIPTION OF THE INVENTION

[0019] <Example of hybrid vehicle configuration> FIG. 1 shows an example of the configuration of a general-purpose hybrid vehicle. This hybrid vehicle has four wheels, consisting of drive wheels 71 and driven wheels 72. The left and right drive wheels 71 are driven by an engine 61 and a vehicle drive motor (hereinafter simply referred to as the motor) 51. The hybrid vehicle is equipped with a power control unit 100. The power control unit 100 controls the motor 51 to drive the drive wheels 71 according to the vehicle load, and controls the generator 52 to generate electricity and charge the high-voltage battery 41, which is the power source of the motor 51. To this end, the power control unit 100 controls the supply voltage of the motor 51 and includes an inverter for AC / DC conversion of the output of the generator 52. The power control unit 100 also includes a DC-DC converter that reduces the high voltage of the high-voltage battery 41 to a voltage sufficient to charge the low-voltage battery 42, so that the low-voltage battery 42 can be charged by the high-voltage battery 41. The low-voltage battery 42 is used as a power source for auxiliary equipment within the vehicle. The hybrid vehicle is equipped with a fuel tank 63 that supplies fuel to the engine 61.

[0020] <Configuration Overview of One Embodiment> 2 to 5 show one embodiment of the power control unit 100. In this embodiment, a water pump 31 of a cooling system that cools the power control unit 100 of a hybrid vehicle is integrally provided. As shown in FIGS. 2, 4, and 5, the water pump 31 is coupled and fixed to a housing 101 of the power control unit 100. As shown in FIG. 3, the water pump 31 has its control circuit (not shown) integrated into the DC-DC converter 10 in the power control unit 100. FIG. 5 shows a circuit board 102 of the DC-DC converter 10 that includes a water pump control circuit. A heat sink 103 is disposed below the circuit board 102 to cool the circuit board 102. Therefore, a first electric circuit element (not shown) that constitutes the DC-DC converter 10 and a second electric circuit element (not shown) that constitutes the water pump control circuit are cooled by the heat sink 103.

[0021] As shown in Fig. 3, the power control unit 100 includes an inverter 20 and a DC-DC converter 10. As described above, the inverter 20 is interposed between the high-voltage battery 41 and the motor 51 and generator 52. The DC-DC converter 10 is interposed between the high-voltage battery 41 and the low-voltage battery 42. The water pump 31 is driven and controlled by a water pump control circuit (not shown) that is integrated into the DC-DC converter 10. The water pump control circuit may be integrated into the inverter 20 instead of being integrated into the DC-DC converter 10.

[0022] As shown in FIG. 2, water pump 31 is inserted in a refrigerant passage 34 through which refrigerant (not shown) supplied from reserve tank 33 flows. A radiator 32 is also inserted in the refrigerant passage 34. Therefore, the refrigerant from reserve tank 33 flows from water pump 31 to a heat sink (not shown) in power control unit 100, as shown by the arrows in FIG. 2, and cools each electrical circuit element (not shown) in power control unit 100. In addition, the refrigerant passage 34 downstream of the heat sink is piped so as to cool a generator 52 (not shown in FIG. 2) in a transaxle 62 located below power control unit 100. The refrigerant returning from generator 52 dissipates heat in radiator 32 and is returned to reserve tank 33. Note that the piping of refrigerant passage 34 described above is merely an example, and other piping may be used depending on the situation.

[0023] <Example of a general-purpose DC / DC converter configuration> FIG. 7 shows a general-purpose DC-DC converter 10A that does not incorporate a water pump control circuit like the first embodiment. The DC-DC converter 10A is connected between a high-voltage battery 41 and a low-voltage battery 42 and converts the voltage of the high-voltage battery 41 to a voltage suitable for charging the low-voltage battery 42. The DC-DC converter 10A includes a power converter 16A including a transformer (not shown). In FIG. 7, the left side of the power converter 16A is the primary side (high-voltage side) and the right side is the secondary side (low-voltage side). A half-bridge primary-side switch circuit 15A is connected to the primary side to open and close the primary-side circuit of the transformer. A rectifier circuit 17A and a smoothing circuit 18A are connected to the secondary side to convert the AC current on the secondary side of the transformer to DC current.

[0024] The DC-DC converter 10A includes a microcontroller unit (hereinafter referred to as MCU) 11A that includes a digital computer. The MCU 11A controls the on / off of the primary-side switch circuit 15A and the switching element (not shown) in the rectifier circuit 17A, thereby controlling the appropriate charging of the low-voltage battery 42. Therefore, the MCU 11A forms a power conversion control circuit that controls the power conversion in the DC-DC converter 10A. The DC-DC converter 10A also includes a temperature sensor 13A that detects the temperature of the circuit board in the secondary-side circuit portion, and an input / output circuit 19A that inputs a signal from an inverter (not shown) from outside the DC-DC converter 10A to the MCU 11A.

[0025] <Example of general-purpose water pump configuration> FIG. 8 shows a general-purpose water pump control circuit 10B that is not incorporated into the DC-DC converter 10 as in the first embodiment. The water pump control circuit 10B includes an output inverter 12B, which is an output circuit. The output inverter 12B has six switching elements connected in a three-phase bridge configuration, and operates a brushless water pump drive motor 31A using UV and W output signals. The water pump control circuit 10B also includes an MCU 11B, which includes a digital computer. The MCU 11B receives a pulse-width modulation (PWM) input signal and controls the on / off of each switching element of the output inverter 12B to control the rotation speed of the water pump drive motor 31A. Therefore, the MCU 11B functions as a motor control circuit that controls the rotation speed of the water pump drive motor 31A. The water pump control circuit 10B controls the rotation speed of the water pump drive motor 31A in response to the input pulse-width modulation signal.

[0026] An input filter circuit 18B for noise removal is connected to the power supply side of the output inverter 12B. An overcurrent detection resistor 14B is connected to the earth side of the output inverter 12B. Meanwhile, an input signal processing circuit 19B for converting a pulse width modulated signal into a signal with an amplitude corresponding to the pulse width of the pulse width modulated signal is connected to a circuit that inputs the pulse width modulated signal to the MCU 11B. A detection signal from a temperature sensor 13B for detecting the circuit board temperature is also input to the MCU 11B.

[0027] <Detailed configuration of one embodiment> Figure 6 shows a DC-DC converter 10 according to one embodiment. In this DC-DC converter 10, the water pump control circuit 10B shown in Figure 8 is incorporated into the DC-DC converter 10A shown in Figure 7. Therefore, like the DC-DC converter 10A, the DC-DC converter 10 includes a primary-side switch circuit 15, a power converter 16, a rectifier circuit 17, a smoothing circuit 18, an input / output circuit 19, and a temperature sensor 13.

[0028] The MCU 11 of the DC-DC converter 10 is configured such that the MCU 11A of the DC-DC converter 10A and the MCU 11B of the water pump control circuit 10B are integrated into each other. Therefore, the MCU 11 controls the on / off of the primary-side switch circuit 15 and the switching elements in the rectifier circuit 17. That is, like the MCU 11A, the MCU 11 functions as a power conversion control circuit that controls the power conversion in the DC-DC converter 10. At the same time, the MCU 11 outputs a control signal to the output inverter (also referred to as an output circuit) 12, which is the same as the output inverter 12B of the water pump control circuit 10B. The control of the primary-side switch circuit 15, the rectifier circuit 17, and the output inverter 12 by the MCU 11 is executed by a program pre-stored in a memory (not shown) of the MCU 11. In this way, the MCU 11 can integrate the CPU (Central Processing Unit) of the MCU 11A and the CPU of the MCU 11B into one, which simplifies the configuration compared to when the MCU 11A and the MCU 11B are configured separately. Also, the power control unit 100 can be made smaller and less expensive.

[0029] The output inverter 12 is mounted on a circuit board 102 of the DC-DC converter 10. Six switching elements (corresponding to second electric circuit elements) constituting the output inverter 12 are connected to appropriate gaps on the circuit board 102 of the DC-DC converter 10. The current capacity of the output inverter 12 is significantly smaller than the current capacity handled by the DC-DC converter 10 (e.g., 3 A: 100 A), allowing the output inverter 12 to be inserted into a small gap on the circuit board 102. The power supply circuit of the output inverter 12 is connected to the output side of the smoothing circuit 18 of the DC-DC converter 10. That is, the smoothing circuit 18 of the DC-DC converter 10 functions as the input filter circuit 18B of the water pump control circuit 10B. The smoothing circuit 18 has an internal L (inductance) and C (capacitance) component and smoothes the pulsating current from the rectifier circuit 17. It can function as the input filter circuit 18B in the water pump control circuit 10B. Therefore, the input filter circuit 18B can be omitted from the DC-DC converter 10. An overcurrent detection resistor 14 similar to the overcurrent detection resistor 14B (see FIG. 8) of the general-purpose water pump control circuit 10B is connected to the earth side of the output inverter 12. The configuration shown in FIG. 6, the description of which is omitted here, is a conventionally known configuration.

[0030] Since the second electric circuit element constituting the output inverter 12 is connected to the circuit board 102 of the DC-DC converter 10 in this way, the wiring length of the power supply circuit of the output inverter 12 can be shortened. Moreover, the power supply circuit of the output inverter 12 can be prevented from being exposed to the outside of the housing 101. The housing 101 is made of aluminum and has a noise shielding function. Therefore, it is possible to suppress noise superimposed on the power supply circuit of the output inverter 12 from the outside. Furthermore, the smoothing circuit 18 of the DC-DC converter 10 serves as a substitute for the input filter circuit 18B of the output inverter 12. By omitting the input filter circuit 18B, the decrease in the voltage supplied to the output inverter 12 is suppressed by the voltage drop of the input filter circuit 18B.

[0031] In addition to the signal from the inverter 20, an input signal (corresponding to the PWM signal in FIG. 8) for controlling the water pump is also input to the input terminal CAN for multiplexed communication signals that inputs an input signal to the input / output circuit 19. Therefore, the input / output circuit 19 also serves as the input signal processing circuit 19B of the water pump control circuit 10B. Therefore, in the DC-DC converter 10, the input signal processing circuit 19B can be omitted, simplifying the circuit configuration. Furthermore, the power control unit 100 can be made smaller and less expensive.

[0032] 6 to 8, each of the DC-DC converters 10, 10A and the water pump control circuit 10B is configured by combining multiple electric circuit elements, such as primary-side switch circuits 15, 15A, power converters 16, 16A, and MCUs 11, 11A, and 11B, which are enclosed in square blocks in each figure. Of the electric circuit elements, the electric circuit elements that make up the water pump control circuit 10B are pump electric circuit elements, and the electric circuit elements that make up the DC-DC converters 10, 10A are converter electric circuit elements. Each electric circuit element is configured by assembling electric circuit elements, such as ICs, switching elements, capacitors, diodes, and resistors, selected according to the function of each electric circuit element, onto a circuit board, which is a printed circuit board.

[0033] <Other embodiments> Although the technology disclosed in this specification has been described above as a specific embodiment, it can be implemented in various other forms. For example, in the above embodiment, the water pump is fixed to the housing of the power control unit, but it may also be fixed to a heat sink. Furthermore, the circuit board mounting the first electric circuit element constituting the inverter and the circuit board mounting the first electric circuit element constituting the DC-DC converter may be configured separately or integrally. [Explanation of symbols]

[0034] 10, 10A DC-DC converter 10B Water pump control circuit 11, 11A microcontroller unit (power conversion control circuit, digital computer) 11B Microcontroller Unit (Motor Control Circuit, Digital Computer) 12, 12B Output inverter (output circuit) 13, 13A, 13B Temperature Sensors 14, 14B Overcurrent detection resistor 15, 15A primary side switch circuit 16, 16A Power Converter 17, 17A rectifier circuit 18, 18A smoothing circuit 18B Input filter circuit 19, 19A input / output circuit 19B Input signal processing circuit 20 Inverter 31 Water pump 31A water pump drive motor 32 Radiator 33 Reserve tank 34 Refrigerant passage 41 High-voltage battery 42 Low voltage battery 51 Vehicle drive motor 52 Generator 61 Engine 62 Transaxle 71 Drive wheels 72 Driven wheels 100 Power Control Unit 101 Case 102 Circuit Board 103 Heatsink

Claims

1. a vehicle drive motor; a high-voltage battery that serves as a power source for the vehicle drive motor; An electric vehicle including a low-voltage battery that serves as a power source for auxiliary machinery within the vehicle, an inverter that controls a supply voltage from the high-voltage battery to the vehicle drive motor; a DC-DC converter that reduces the voltage of the high-voltage battery to a voltage that can charge the low-voltage battery; a circuit board on which a first electric circuit element constituting the inverter or the DC-DC converter is mounted; a heat sink for cooling the first electric circuit element; a water pump for causing a refrigerant to flow through a refrigerant passage of the heat sink; a water pump control circuit that controls the operation of the water pump; a second electric circuit element constituting the water pump control circuit is mounted on the circuit board together with the first electric circuit element; a part of a plurality of pump electric circuit elements constituting the water pump control circuit is incorporated into a converter electric circuit element constituting the DCDC converter; the water pump control circuit includes an input filter circuit as one of the pump electric circuit elements for removing noise from a power supply circuit; The DC-DC converter includes, as one of the converter electric circuit elements, a smoothing circuit that smoothes a pulsating current obtained by rectifying an AC current after power conversion, A power control unit for an electric vehicle, wherein the water pump control circuit is connected to the DCDC converter so that the smoothing circuit also functions as the input filter circuit.

2. A vehicle drive motor; a high-voltage battery that serves as a power source for the vehicle drive motor; An electric vehicle including a low-voltage battery that serves as a power source for auxiliary machinery within the vehicle, an inverter that controls a supply voltage from the high-voltage battery to the vehicle drive motor; a DC-DC converter that reduces the voltage of the high-voltage battery to a voltage that can charge the low-voltage battery; a circuit board on which a first electric circuit element constituting the inverter or the DC-DC converter is mounted; a heat sink for cooling the first electric circuit element; a water pump for causing a refrigerant to flow through a refrigerant passage of the heat sink; a water pump control circuit that controls the operation of the water pump; a second electric circuit element constituting the water pump control circuit is mounted on the circuit board together with the first electric circuit element; a part of a plurality of pump electric circuit elements constituting the water pump control circuit is incorporated into a converter electric circuit element constituting the DCDC converter; the water pump control circuit includes an input signal processing circuit, which is one of the pump electric circuit elements, to which an input signal for controlling the water pump is input; the DC-DC converter includes an input / output circuit for communication as one of the electric circuit elements for the converter; The input / output circuit is a circuit that also serves as the input signal processing circuit, and thus also plays the role of the input signal processing circuit.

3. In claim 1 or 2, the water pump control circuit includes a motor control circuit that controls the rotation of a water pump drive motor as one of the pump electric circuit elements; the DC-DC converter includes a power conversion control circuit configured by a digital computer as one of the electric circuit elements for the converter, and controlling power conversion by a transformer; The motor control circuit is incorporated into the digital computer of the power conversion control circuit.

4. In any one of claims 1 to 3, the water pump control circuit includes, as pump electrical circuit elements, a motor control circuit that controls rotation of a water pump drive motor, and an output circuit that receives an output from the motor control circuit and controls a voltage supplied to the water pump drive motor; The second electric circuit element constituting the output circuit is mounted on the circuit board together with the first electric circuit element constituting the DCDC converter.

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