Power supply control device

Abstract

To provide a power supply control device capable of precharging a capacitor while suppressing an increase in the size of the device.SOLUTION: A power supply control device which is mounted on an electric vehicle that does not have an auxiliary battery and supplies electric power from a high-voltage battery to a motor and an auxiliary load, comprises: an inverter which converts electric power from the high-voltage battery into AC power and outputs it to the motor; a first DCDC converter in which a high-voltage end is connected to the high-voltage battery without a relay and a low-voltage end is connected to the auxiliary load; a second DCDC converter in which a high-voltage end is connected to the high-voltage battery via the relay and a low-voltage end is connected to the auxiliary load and which is connected in parallel with the first DCDC converter; a smoothing capacitor which is provided between a system main relay and the inverter; an auxiliary relay which is provided between the high-voltage battery and the second DCDC converter; and a precharge relay which is provided between the high-voltage end of the second DCDC converter and the smoothing capacitor.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a power control device.

Background Art

[0002] Patent Document 1 discloses pre-charging power from a high-voltage battery to a capacitor of a PCU via a DCDC converter with a system main relay provided between the high-voltage battery and the PCU turned off.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the configuration described in Patent Document 1, three relays and one resistor are required between the high-voltage battery and the DCDC converter, and two relays are required between the DCDC converter and the capacitor of the PCU. The configuration described in Patent Document 1 requires a total of seven relays including the two relays of the system main relay, so there is a risk of an increase in size.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a power control device capable of pre-charging a capacitor while suppressing an increase in size.

Means for Solving the Problems

[0006] The present invention is a power control device mounted on an electric vehicle without an auxiliary battery, which supplies the power of a high-voltage battery in the electric vehicle to a motor and an auxiliary load. The power control device includes an inverter that converts the power from the high-voltage battery into AC power and outputs it to the motor, a first DC-DC converter whose high-voltage terminal is connected to the high-voltage battery without passing through a relay and whose low-voltage terminal is connected to the auxiliary load, and which steps down the power from the high-voltage battery and outputs it to the auxiliary load, a second DC-DC converter whose high-voltage terminal is connected to the high-voltage battery through a relay and whose low-voltage terminal is connected to the auxiliary load, and which is connected in parallel with the first DC-DC converter and can output bidirectionally between the high-voltage terminal side and the low-voltage terminal side, a first power line connecting the positive terminal of the high-voltage battery and the inverter, a second power line connecting the negative terminal of the high-voltage battery and the inverter, a system main relay including a first relay provided on the first power line and a second relay provided on the second power line, a smoothing capacitor provided between the system main relay and the inverter and connected to the first power line and the second power line, an auxiliary relay including a third relay provided between the positive terminal of the high-voltage battery and the second DC-DC converter and a fourth relay provided between the negative terminal of the high-voltage battery and the second DC-DC converter, and a precharge relay which is a fifth relay provided between the high-voltage terminal of the second DC-DC converter and the smoothing capacitor.

Effect of the Invention

[0007] In the present invention, the capacitor can be precharged while suppressing an increase in size.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying out the Invention

[0009] Hereinafter, the power supply control device in the embodiments of the present invention will be specifically described. It should be noted that the present invention is not limited to the embodiments described below.

[0010] FIG. 1 is a schematic diagram showing a power supply control device in an embodiment. The power supply control device 1 is mounted on an electric vehicle without an auxiliary battery. The power supply control device 1 supplies the power of the high-voltage battery 2 in the electric vehicle to the motor 3 and the auxiliary load 4. The high-voltage battery 2 is a battery mounted on the electric vehicle. The high-voltage battery 2 is composed of a secondary battery such as a lithium-ion battery. The high-voltage battery 2 supplies power to the motor 3 and the auxiliary load 4. The motor 3 is a running motor that functions as a power source of the electric vehicle. The motor 3 is driven by the power supplied from the high-voltage battery 2. The auxiliary load 4 is auxiliary component parts mounted on the electric vehicle. The power from the high-voltage battery 2 is stepped down and supplied to the auxiliary load 4.

[0011] The power supply control device 1 includes an inverter 10, a first DC-DC converter 11, a second DC-DC converter 12, a system main relay (hereinafter referred to as SMR) 13, a smoothing capacitor 14, an auxiliary relay 15, and a pre-charge relay 16.

[0012] The inverter 10 is a power conversion device provided between the high-voltage battery 2 and the motor 3. The inverter 10 is connected to the high-voltage battery 2 via a relay. The inverter 10 converts the DC power from the high-voltage battery 2 into AC power and outputs it to the motor 3. The inverter 10 is connected to the high-voltage battery 2 via the SMR 13.

[0013] The first DC-DC converter 11 is a power conversion device provided between the high-voltage battery 2 and the auxiliary load 4. The first DC-DC converter 11 is composed of an isolated DC-DC converter. The first DC-DC converter 11 steps down the voltage of the DC power from the high-voltage battery 2 and outputs it to the auxiliary load 4. The first DC-DC converter 11 is connected to the high-voltage battery 2 without passing through a relay.

[0014] The second DC-DC converter 12 is a power conversion device connected in parallel with the first DC-DC converter 11 between the high-voltage battery 2 and the auxiliary load 4. The second DC-DC converter 12 is a bidirectional DC-DC converter capable of outputting in both the high-voltage end and the low-voltage end directions. The second DC-DC converter 12 is composed of an isolated DC-DC converter. The second DC-DC converter 12 has a capacitor 17 provided on the high-voltage end side and a capacitor provided on the low-voltage end side. The second DC-DC converter 12 is connected to the high-voltage battery 2 via a relay.

[0015] The power supply control device 1 includes a first power line 21 connecting the positive terminal of the high-voltage battery 2 and the inverter 10, and a second power line 22 connecting the negative terminal of the high-voltage battery 2 and the inverter 10. The first power line 21 is a positive-side power line. The second power line 22 is a negative-side power line.

[0016] The SMR 13 is a relay provided between the high-voltage battery 2 and the inverter 10. The SMR 13 includes a first relay 13A provided on the first power line 21 and a second relay 13B provided on the second power line 22. When the first relay 13A and the second relay 13B are in the on state, the connection between the high-voltage battery 2 and the inverter 10 is connected so that power can be supplied. When the first relay 13A and the second relay 13B are in the off state, the connection between the high-voltage battery 2 and the inverter 10 is cut off so that power cannot be supplied. The SMR 13 switches between the on state and the off state according to a command signal from an electronic control device. When the first relay 13A and the second relay 13B are not particularly distinguished, it is described as the SMR 13.

[0017] The smoothing capacitor 14 is a capacitor provided between the SMR 13 and the inverter 10. The smoothing capacitor 14 is connected to the first power line 21 and the second power line 22. One end of the smoothing capacitor 14 is connected to a portion of the first power line 21 between the first relay 13A and the inverter 10. The other end of the smoothing capacitor 14 is connected to a portion of the second power line 22 between the second relay 13B and the inverter 10.

[0018] The power supply control device 1 includes a third power line 23 that connects the positive terminal of the high-voltage battery 2 and the first DC-DC converter 11, and a fourth power line 24 that connects the negative terminal of the high-voltage battery 2 and the first DC-DC converter 11. The third power line 23 is a high-voltage system power line that connects the first power line 21 and the first DC-DC converter 11. One end of the third power line 23 is connected to a portion of the first power line 21 between the positive terminal of the high-voltage battery 2 and the first relay 13A, and the other end is connected to the high-voltage terminal of the first DC-DC converter 11. The fourth power line 24 is a high-voltage system power line that connects the second power line 22 and the first DC-DC converter 11. One end of the fourth power line 24 is connected to a portion of the second power line 22 between the negative terminal of the high-voltage battery 2 and the second relay 13B, and the other end is connected to the high-voltage terminal of the first DC-DC converter 11.

[0019] The power supply control device 1 includes a fifth power line 25 that connects the positive terminal of the high-voltage battery 2 and the second DC-DC converter 12, and a sixth power line 26 that connects the negative terminal of the high-voltage battery 2 and the second DC-DC converter 12. The fifth power line 25 is a high-voltage system power line that connects the third power line 23 and the second DC-DC converter 12. One end of the fifth power line 25 is connected to the third power line 23, and the other end is connected to the high-voltage terminal of the second DC-DC converter 12. The sixth power line 26 is a high-voltage system power line that connects the fourth power line 24 and the second DC-DC converter 12. One end of the sixth power line 26 is connected to the fourth power line 24, and the other end is connected to the high-voltage terminal of the second DC-DC converter 12.

[0020] The auxiliary relay 15 is a relay provided between the high-voltage battery 2 and the second DC-DC converter 12. The auxiliary relay 15 includes a third relay 15A provided on the fifth power line 25 and a fourth relay 15B provided on the sixth power line 26. The third relay 15A is a relay that shuts off or connects the power path between the positive terminal of the high-voltage battery 2 and the high-voltage terminal of the second DC-DC converter 12. The fourth relay 15B is a relay that shuts off or connects the power path between the negative terminal of the high-voltage battery 2 and the high-voltage terminal of the second DC-DC converter 12.

[0021] When the third relay 15A and the fourth relay 15B are turned on, the high-voltage battery 2 and the high-voltage terminal of the second DC-DC converter 12 are connected in a conductive manner via the auxiliary relay 15. When the auxiliary relay 15 is in the on state, the second DC-DC converter 12 functions as a step-down converter, stepping down the power from the high-voltage battery 2 and outputting it to the auxiliary load 4. When the third relay 15A and the fourth relay 15B are turned off, the connection between the high-voltage battery 2 and the high-voltage terminal of the second DC-DC converter 12 is interrupted and non-conductive. The auxiliary relay 15 switches between the on state and the off state according to a command signal from the electronic control device. When the third relay 15A and the fourth relay 15B are not particularly distinguished, it is described as the auxiliary relay 15.

[0022] The power supply control device 1 includes a seventh power line 27 that connects the second DC-DC converter 12 and the smoothing capacitor 14. The seventh power line 27 is a power line that connects the first power line 21 and the fifth power line 25. One end of the seventh power line 27 is connected to the portion between the first relay 13A and the smoothing capacitor 14 on the first power line 21, and the other end is connected to the portion between the third relay 15A and the second DC-DC converter 12 on the fifth power line 25.

[0023] The precharge relay 16 is a relay provided between the second DC-DC converter 12 and the smoothing capacitor 14. The precharge relay 16 is the fifth relay provided on the seventh power line 27. The precharge relay 16 is composed of only one relay. The precharge relay 16 includes only the fifth relay provided between one of the high-voltage terminals of the second DC-DC converter 12 and one end of the smoothing capacitor 14. The precharge relay 16 is a relay that cuts off or connects the power path between the high-voltage terminal of the second DC-DC converter 12 and the smoothing capacitor 14.

[0024] When the precharge relay 16 is in the on state, the capacitor 17 on the high-voltage terminal side of the second DC-DC converter 12 and the smoothing capacitor 14 are connected in an energizable manner. When the precharge relay 16 is in the on state, the second DC-DC converter 12 functions as a boost converter, boosts from low voltage to high voltage, and at the same time, the capacitor 17 on the auxiliary relay 15 side can be precharged and the smoothing capacitor 14 can be precharged.

[0025] The first DC-DC converter 11 is electrically connected between the third power line 23 of the high-voltage system and the low-voltage line 28. The first DC-DC converter 11 steps down the voltage of the third power line 23 and supplies it to the low-voltage line 28. The first DC-DC converter 11 is electrically connected to the auxiliary load 4 and the second DC-DC converter 12 via the low-voltage line 28. The low-voltage terminal of the first DC-DC converter 11 and the low-voltage terminal of the second DC-DC converter 12 are connected via the low-voltage line 28.

[0026] The second DC-DC converter 12 is electrically connected between the fifth power line 25 of the high-voltage system and the low-voltage line 28. The second DC-DC converter 12 is electrically connected to the auxiliary load 4 and the first DC-DC converter 11 via the low-voltage line 28.

[0027] When the auxiliary relay 15 is in the on state, the second DC-DC converter 12 can function as a buck converter. When functioning as a buck converter, the second DC-DC converter 12 steps down the voltage of the fifth power line 25 and supplies it to the low-voltage line 28. When the auxiliary relay 15 is in the off state, the second DC-DC converter 12 functions as a boost converter. When functioning as a boost converter, the second DC-DC converter 12 steps up the voltage of the low-voltage line 28 and supplies it to the fifth power line 25.

[0028] In the power control device 1 configured as described above, a total of five relays including two relays of the SMR 13, two relays of the auxiliary relay 15, and one relay of the precharge relay 16 are provided. The power control device 1 is applied to a system without an auxiliary battery, and the first DC-DC converter 11 always supplies power to low-voltage components instead of the auxiliary battery. The inverter 10 and the second DC-DC converter 12 are each connected to the high-voltage battery 2 via a relay. By providing one precharge relay 16 between the smoothing capacitor 14 and the capacitor 17 of the second DC-DC converter 12, the smoothing capacitor 14 can be precharged with the relays connected to both poles of the high-voltage battery 2.

[0029] Figure 2 is a diagram for explaining the case where the ignition of the electric vehicle is in the off state. When the ignition of the electric vehicle is in the off state, the power control device 1 steps down the voltage of the high-voltage battery 2 to a low voltage with the first DC-DC converter 11 and supplies standby power to the auxiliary load 4. In this case, all of the SMR 13, the auxiliary relay 15, and the precharge relay 16 are in the off state. The SMR 13, the auxiliary relay 15, and the precharge relay 16 are all composed of normally open relays.

[0030] Figure 3 is a diagram for explaining the pre-charge process. When the ignition of the electric vehicle is switched from the off state to the on state, the power control device 1 pre-charges the smoothing capacitor 14. When starting the electric vehicle, as the first operation, the power control device 1 switches the second relay 13B and the pre-charge relay 16 from the off state to the on state. When the second relay 13B and the pre-charge relay 16 are turned on, a power path is formed from the high-voltage battery 2 through the first DC-DC converter 11 and the second DC-DC converter 12 to the smoothing capacitor 14.

[0031] When the first operation is completed during pre-charging, as the second operation, the power control device 1 boosts the second DC-DC converter 12. When the accessory relay 15 is in the off state and the pre-charge relay 16 is in the on state due to the first operation, and the second DC-DC converter 12 is boosted, the voltage is boosted from low voltage on the low-voltage line 28 side to high voltage, and current gradually flows through the capacitor 17 on the accessory relay 15 side to store charge. At the same time, current can gradually flow through the smoothing capacitor 14 to store charge. That is, the power control device 1 performs pre-charging of the smoothing capacitor 14 by boosting the second DC-DC converter 12 (pre-charge operation).

[0032] During the pre-charge operation, the first DC-DC converter 11 steps down the power from the high-voltage battery 2 and outputs it to the low-voltage line 28. The second DC-DC converter 12 functions as a boost converter with the low-voltage terminal as the input terminal and the high-voltage terminal as the output terminal. The second DC-DC converter 12 boosts the low-voltage DC power supplied from the first DC-DC converter 11 to high voltage and outputs it from the high-voltage terminal. The high-voltage DC power output from the high-voltage terminal of the second DC-DC converter 12 is supplied to the smoothing capacitor 14 through the pre-charge relay 16. The power control device 1 increases the voltage of the capacitor 17 of the second DC-DC converter 12 and at the same time increases the voltage of the smoothing capacitor 14 by the pre-charge operation. When the voltage of the smoothing capacitor 14 becomes equal to the voltage of the high-voltage battery 2, the pre-charge is completed.

[0033] FIG. 4 is a diagram for explaining the running of an electric vehicle. When the electric vehicle is running, the power supply control device 1 turns off the pre-charge relay 16. When the pre-charge of the smoothing capacitor 14 is completed and the electric vehicle shifts to the running state, as a first operation, the power supply control device 1 switches the pre-charge relay 16 from the on state to the off state. After the pre-charge relay 16 is switched to the off state, as a second operation, the power supply control device 1 switches the first relay 13A, the third relay 15A, and the fourth relay 15B from the off state to the on state. When this second operation is completed, the high-voltage battery 2 and the inverter 10 are connected via the SMR13, and the motor 3 is driven by the inverter 10. In addition, the high-voltage battery 2 and the second DCDC converter 12 are connected via the accessory relay 15, and the power from the high-voltage battery 2 is stepped down by the second DCDC converter 12 and supplied to the accessory load 4.

[0034] As described above, according to the embodiment, with a simple structure, the smoothing capacitor 14 can be pre-charged simultaneously with the pre-charge of the capacitor 17 of the second DCDC converter 12. By turning on the second relay 13B and the pre-charge relay 16, the smoothing capacitor 14 can be pre-charged simultaneously with the pre-charge of the capacitor 17 on the accessory relay 15 side of the second DCDC converter 12 in a state where the high-voltage battery 2 can be cut off at the diode between the first power line 21 and the second power line 22.

[0035] In addition, since the high-voltage battery 2 and the first DCDC converter 11 are directly connected, relays and inrush prevention resistors between the high-voltage battery 2 and the first DCDC converter 11 can be reduced. Furthermore, since there is only one pre-charge relay 16, the number of relays can be reduced compared to the conventional case. As a result, the size of the device can be reduced.

[0036] In addition, when a power control unit (PCU) including the inverter 10 and the smoothing capacitor 14 is configured, the smoothing capacitor 14 can be expressed as the capacitor within the PCU. In this case, the precharge relay 16 can be expressed as the relay provided between the second DC-DC converter 12 and the PCU.

Description of Signs

[0037] 1 Power control device 2 High-voltage battery 3 Motor 4 Auxiliary load 10 Inverter 11 First DC-DC converter 12 Second DC-DC converter 13 System main relay (SMR) 13A First relay 13B Second relay 14 Smoothing capacitor 15 Auxiliary relay 15A Third relay 15B Fourth relay 16 Precharge relay 17 Capacitor 21 First power line 22 Second power line 23 Third power line 24 Fourth power line 25 Fifth power line 26 Sixth power line 27 Seventh power line 28 Low-voltage line

Claims

1. A power control device mounted on an electric vehicle without an auxiliary battery, which supplies power from a high-voltage battery in the electric vehicle to a motor and an auxiliary load, comprising: an inverter that converts the power from the high-voltage battery into AC power and outputs it to the motor; a first DC-DC converter having a high-voltage terminal connected to the high-voltage battery without passing through a relay and a low-voltage terminal connected to the auxiliary load, and stepping down the power from the high-voltage battery and outputting it to the auxiliary load; a second DC-DC converter having a high-voltage terminal connected to the high-voltage battery via a relay and a low-voltage terminal connected to the auxiliary load, and being connected in parallel with the first DC-DC converter, capable of outputting bidirectionally between the high-voltage terminal side and the low-voltage terminal side; a first power line connecting the positive terminal of the high-voltage battery and the inverter; a second power line connecting the negative terminal of the high-voltage battery and the inverter; a system main relay including a first relay provided on the first power line and a second relay provided on the second power line; a smoothing capacitor provided between the system main relay and the inverter and connected to the first power line and the second power line; an auxiliary relay including a third relay provided between the positive terminal of the high-voltage battery and the second DC-DC converter and a fourth relay provided between the negative terminal of the high-voltage battery and the second DC-DC converter; a precharge relay which is a fifth relay provided between the high-voltage terminal of the second DC-DC converter and the smoothing capacitor; A power control device characterized by comprising the above.

2. The second DC-DC converter is an isolated DC-DC converter provided with a capacitor on the high-voltage terminal side, The fifth relay is provided between the capacitor of the second DC-DC converter and the smoothing capacitor. The power control device according to claim 1, characterized by the above.

3. a third power line connecting the first power line and the first DC-DC converter; a fourth power line connecting the second power line and the first DC-DC converter; a fifth power line connecting the third power line and the second DC-DC converter; a sixth power line connecting the fourth power line and the second DC-DC converter; a seventh power line connecting the fifth power line and the first power line; comprising, The third relay is provided on the fifth power line. The fourth relay is provided on the sixth power line, The fifth relay is provided on the seventh power line, One end of the third power line is connected to a portion between the positive terminal of the high-voltage battery and the first relay on the first power line, and the other end is connected to the high-voltage terminal of the first DC-DC converter. One end of the fourth power line is connected to a portion between the negative terminal of the high-voltage battery and the second relay on the second power line, and the other end is connected to the high-voltage terminal of the first DC-DC converter. One end of the fifth power line is connected to the third power line, and the other end is connected to the high-voltage terminal of the second DC-DC converter. One end of the sixth power line is connected to the fourth power line, and the other end is connected to the high-voltage terminal of the second DC-DC converter. One end of the seventh power line is connected to a portion between the first relay and the smoothing capacitor on the first power line, and the other end is connected to a portion between the third relay and the second DC-DC converter on the fifth power line. The power control device according to claim 2, characterized in that.

4. When pre-charging the power from the high-voltage battery to the smoothing capacitor, the second relay and the fifth relay are in the on state, and the first relay, the third relay, and the fourth relay are in the off state. The power control device according to any one of claims 1 to 3, characterized in that.

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