Power supply control device

Abstract

The present application provides a power supply control device capable of precharging a capacitor while suppressing an increase in size. The power supply control device is mounted in an electric vehicle without an auxiliary battery, supplies power of a high-voltage battery to an electric motor and an auxiliary load, and is provided with: an inverter that converts power from the high-voltage battery into AC power and outputs the AC power to the electric motor; a first DCDC converter whose high voltage terminal is connected to the high voltage battery without via the relay and whose low voltage terminal is connected to the auxiliary load; a second DCDC converter having a high voltage terminal connected to the high voltage battery via the relay and a low voltage terminal connected to the auxiliary load and connected in parallel to the first DCDC converter; the smoothing capacitor is arranged between the system main relay and the inverter; an auxiliary relay disposed between the high-voltage battery and the second DCDC converter; and a precharge relay disposed between the high voltage terminal of the second DCDC converter and the smoothing capacitor.

Description

Technical Field

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

[0002] In Patent Document 1, regarding a power control device mounted on an electric vehicle, it is disclosed that power from a high-voltage battery is pre-charged to a capacitor of a PCU via a DCDC converter in a state where a system main relay provided between the high-voltage battery and the PCU is disconnected.

[0003] [Prior Art Documents]

[0004] [Patent Documents]

[0005] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2021-145460 Summary of the Invention

[0006] [Problems to be Solved by the Invention]

[0007] In the structure 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. If the structure described in Patent Document 1 includes two relays of the system main relay, a total of seven relays are required, so there is a concern about an increase in size.

[0008] 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 volume.

[0009] [Means for Solving the Problems]

[0010] The present invention relates to 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 is characterized in that it includes: an inverter that converts the power from the high-voltage battery into alternating current power and outputs it to the motor; a first DCDC 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 that steps down the power from the high-voltage battery and outputs it to the auxiliary load; a second DCDC converter, whose high-voltage terminal is connected to the high-voltage battery via a relay, and whose low-voltage terminal is connected to the auxiliary load, and that is connected in parallel with the first DCDC converter and can output bidirectionally to the high-voltage terminal side and the low-voltage terminal side; a first power line that connects the positive terminal of the high-voltage battery and the inverter; a second power line that connects the negative terminal of the high-voltage battery and the inverter; a system main relay that includes 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 that includes a third relay provided between the positive terminal of the high-voltage battery and the second DCDC converter and a fourth relay provided between the negative terminal of the high-voltage battery and the second DCDC converter; and a pre-charge relay that is a fifth relay provided between the high-voltage terminal of the second DCDC converter and the smoothing capacitor.

[0011] [Advantages of the Invention]

[0012] In the present invention, it is possible to pre-charge the capacitor while suppressing the increase in size. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram showing the power control device in the embodiment.

[0014] Figure 2 It is a diagram for explaining the case where the ignition device of the electric vehicle is in the off state.

[0015] Figure 3 It is a diagram for explaining the pre-charge.

[0016] Figure 4 It is a diagram for explaining the running of the electric vehicle. DETAILED DESCRIPTION OF THE EMBODIMENT

[0017] Hereinafter, the power control device in the embodiment of the present invention will be specifically described. In addition, the present invention is not limited to the embodiment described below.

[0018] Figure 1It is a schematic diagram showing the power control device in the embodiment. The power control device 1 is mounted on an electric vehicle without an auxiliary battery. The power 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 driving 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 an auxiliary component mounted on the electric vehicle. The power from the high-voltage battery 2 is stepped down and supplied to the auxiliary load 4.

[0019] The power control device 1 includes an inverter 10, a first DCDC converter 11, a second DCDC 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.

[0020] 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.

[0021] The first DCDC converter 11 is a power conversion device provided between the high-voltage battery 2 and the auxiliary load 4. The first DCDC converter 11 is composed of an isolated DCDC converter. The first DCDC 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 DCDC converter 11 is connected to the high-voltage battery 2 without passing through a relay.

[0022] The second DCDC converter 12 is a power conversion device connected in parallel with the first DCDC converter 11 between the high-voltage battery 2 and the auxiliary load 4. The second DCDC converter 12 is a bidirectional DCDC converter capable of outputting in both the high-voltage terminal and the low-voltage terminal directions. The second DCDC converter 12 is composed of an isolated DCDC converter. The second DCDC converter 12 has a capacitor 17 provided on the high-voltage terminal side and a capacitor provided on the low-voltage terminal side. The second DCDC converter 12 is connected to the high-voltage battery 2 via a relay.

[0023] The power control device 1 includes: a first power line 21 that connects the positive terminal of the high-voltage battery 2 to the inverter 10; and a second power line 22 that connects the negative terminal of the high-voltage battery 2 to 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.

[0024] SMR13 is a relay provided between the high-voltage battery 2 and the inverter 10. SMR13 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 high-voltage battery 2 and the inverter 10 are connected in a manner that allows power to flow. 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 flow. SMR13 switches between the on state and the off state according to a command signal from the electronic control device. In addition, SMR13 is described without particularly distinguishing between the first relay 13A and the second relay 13B.

[0025] The smoothing capacitor 14 is a capacitor provided between SMR13 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.

[0026] The power supply control device 1 includes: a third power line 23 that connects the positive terminal of the high-voltage battery 2 to the first DCDC converter 11; and a fourth power line 24 that connects the negative terminal of the high-voltage battery 2 to the first DCDC converter 11. The third power line 23 is a power line of the high-voltage system that connects the first power line 21 and the first DCDC 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 DCDC converter 11. The fourth power line 24 is a power line of the high-voltage system that connects the second power line 22 and the first DCDC 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 DCDC converter 11.

[0027] The power supply control device 1 includes: a fifth power line 25 that connects the positive terminal of the high-voltage battery 2 to the second DCDC converter 12; and a sixth power line 26 that connects the negative terminal of the high-voltage battery 2 to the second DCDC converter 12. The fifth power line 25 is a power line of the high-voltage system that connects the third power line 23 to the second DCDC 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 DCDC converter 12. The sixth power line 26 is a power line of the high-voltage system that connects the fourth power line 24 to the second DCDC 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 DCDC converter 12.

[0028] The auxiliary machine relay 15 is a relay provided between the high-voltage battery 2 and the second DCDC converter 12. The auxiliary machine 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 cuts off or connects the power line between the positive terminal of the high-voltage battery 2 and the high-voltage terminal of the second DCDC converter 12. The fourth relay 15B is a relay that cuts off or connects the power line between the negative terminal of the high-voltage battery 2 and the high-voltage terminal of the second DCDC converter 12.

[0029] When the third relay 15A and the fourth relay 15B are in the on state, the high-voltage battery 2 and the high-voltage terminal of the second DCDC converter 12 are connected in an energizable manner via the auxiliary machine relay 15. When the auxiliary machine relay 15 is in the on state, the second DCDC converter 12 functions as a step-down converter, steps down the power from the high-voltage battery 2, and outputs it to the auxiliary machine load 4. When the third relay 15A and the fourth relay 15B are in the off state, the connection between the high-voltage battery 2 and the high-voltage terminal of the second DCDC converter 12 is cut off and cannot be energized. The auxiliary machine relay 15 is switched between the on state and the off state according to a command signal from the electronic control device. In addition, the auxiliary machine relay 15 is described without particularly distinguishing between the third relay 15A and the fourth relay 15B.

[0030] The power supply control device 1 includes a seventh power line 27 that connects the second DCDC converter 12 to the smoothing capacitor 14. The seventh power line 27 is a power line that connects the first power line 21 to 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 in the first power line 21, and the other end is connected to the portion between the third relay 15A and the second DCDC converter 12 in the fifth power line 25.

[0031] The pre-charge relay 16 is a relay provided between the second DCDC converter 12 and the smoothing capacitor 14. The pre-charge relay 16 is the fifth relay provided on the seventh power line 27. The pre-charge relay 16 consists of only one relay. The pre-charge relay 16 only includes the fifth relay provided between one of the high-voltage terminals of the second DCDC converter 12 and one end of the smoothing capacitor 14. The pre-charge relay 16 is a relay that cuts off or connects the power line between the high-voltage terminal of the second DCDC converter 12 and the smoothing capacitor 14.

[0032] When the pre-charge relay 16 is in the ON state, the capacitor 17 on the high-voltage terminal side of the second DCDC converter 12 and the smoothing capacitor 14 are connected in a way that allows current to flow. When the pre-charge relay 16 is in the ON state, the second DCDC converter 12 functions as a boost converter. By boosting the voltage from low to high, it can pre-charge the capacitor 17 on the auxiliary relay 15 side and at the same time pre-charge the smoothing capacitor 14.

[0033] The first DCDC converter 11 is electrically connected between the third power line 23 of the high-voltage system and the low-voltage line 28. The first DCDC converter 11 steps down the voltage of the third power line 23 and supplies it to the low-voltage line 28. The first DCDC converter 11 is electrically connected to the auxiliary load 4 and the second DCDC converter 12 via the low-voltage line 28. The low-voltage terminal of the first DCDC converter 11 and the low-voltage terminal of the second DCDC converter 12 are connected via the low-voltage line 28.

[0034] The second DCDC converter 12 is electrically connected between the fifth power line 25 of the high-voltage system and the low-voltage line 28. The second DCDC converter 12 is electrically connected to the auxiliary load 4 and the first DCDC converter 11 via the low-voltage line 28.

[0035] When the auxiliary relay 15 is in the ON state, the second DCDC converter 12 can function as a buck converter. When functioning as a buck converter, the second DCDC 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 DCDC converter 12 functions as a boost converter. When functioning as a boost converter, the second DCDC converter 12 steps up the voltage of the low-voltage line 28 and supplies it to the fifth power line 25.

[0036] In the power control device 1 configured as described above, a total of five relays are provided, including two relays including SMR13, two relays of the auxiliary machine relay 15, and one relay of the precharge relay 16. The power control device 1 is applicable to a system without an auxiliary battery, and the first DCDC converter 11 always supplies power to the low-voltage system components in place of the auxiliary battery. The inverter 10 and the second DCDC converter 12 are each connected to the high-voltage battery 2 via a relay. By providing a precharge relay 16 between the smoothing capacitor 14 and the capacitor 17 of the second DCDC converter 12, the smoothing capacitor 14 can be precharged in a state where the relays at both poles of the high-voltage battery 2 are connected.

[0037] Figure 2 This is a diagram for explaining the case where the ignition device of the electric vehicle is in the off state. When the ignition device 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 low voltage through the first DCDC converter 11 and supplies standby power to the auxiliary load 4. In this case, all of SMR13, the auxiliary machine relay 15, and the precharge relay 16 are in the off state. SMR13, the auxiliary machine relay 15, and the precharge relay 16 are all composed of normally open relays.

[0038] Figure 3 This is a diagram for explaining precharging. When the ignition device of the electric vehicle is switched from the off state to the on state, the power control device 1 performs precharging of the smoothing capacitor 14. When the electric vehicle starts, as a first action, the power control device 1 switches the second relay 13B and the precharge relay 16 from the off state to the on state. When the second relay 13B and the precharge relay 16 are in the on state, a power line is formed from the high-voltage battery 2 through the first DCDC converter 11 and the second DCDC converter 12 to the smoothing capacitor 14.

[0039] If the first action during precharging is completed, then as a second action, the power control device 1 causes the second DCDC converter 12 to perform a boosting operation. When the boosting operation of the second DCDC converter 12 is performed in a state where the auxiliary machine relay 15 is in the off state and the precharge relay 16 is in the on state during the first action, it is possible to boost from low voltage on the low-voltage line 28 side to high voltage, gradually flow current to the capacitor 17 on the auxiliary machine relay 15 side and accumulate charge, and at the same time gradually flow current to the smoothing capacitor 14 and accumulate charge. That is, the power control device 1 performs precharging (precharge operation) of the smoothing capacitor 14 by causing the second DCDC converter 12 to perform a boosting operation.

[0040] During the pre-charge operation, the first DCDC converter 11 steps down the power from the high-voltage battery 2 and outputs it to the low-voltage line 28. The second DCDC 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 DCDC converter 12 boosts the low-voltage DC power supplied from the first DCDC converter 11 to a high voltage and outputs it from the high-voltage terminal. The high-voltage DC power output from the high-voltage terminal of the second DCDC converter 12 is supplied to the smoothing capacitor 14 via the pre-charge relay 16. The power control device 1 raises the voltage of the capacitor 17 of the second DCDC converter 12 and simultaneously raises the voltage of the smoothing capacitor 14 through the pre-charge operation. When the voltage of the smoothing capacitor 14 is equal to the voltage of the high-voltage battery 2, the pre-charge is completed.

[0041] Figure 4 This is a diagram for explaining the operation of the electric vehicle during driving. In the state where the electric vehicle is driving, the power control device 1 makes the pre-charge relay 16 in the off state. When the pre-charge of the smoothing capacitor 14 is completed and the electric vehicle transitions to the driving state, as a first action, the power 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 action, the power 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 action is completed, the high-voltage battery 2 is connected to the inverter 10 via the SMR13, and the motor 3 is driven by the inverter 10. In addition, the high-voltage battery 2 is connected to the second DCDC converter 12 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.

[0042] As described above, according to the embodiment, it is possible to pre-charge the smoothing capacitor 14 simultaneously with the pre-charge of the capacitor 17 of the second DCDC converter 12 with a simple structure. By making the second relay 13B and the pre-charge relay 16 in the on state, it is possible to pre-charge the smoothing capacitor 14 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 two poles of the first power line 21 and the second power line 22 of the high-voltage battery 2 are disconnected.

[0043] In addition, since the high-voltage battery 2 is directly connected to the first DCDC converter 11, it is possible to reduce the relay and the surge protection resistor between the high-voltage battery 2 and the first DCDC converter 11. And since there is only one pre-charge relay 16, the number of relays can be reduced compared to the prior art. Thus, miniaturization of the volume can be achieved.

[0044] In addition, in the case of constituting a power control unit (PCU) including an inverter 10 and a smoothing capacitor 14, the smoothing capacitor 14 can be represented as a capacitor within the PCU. In this case, the pre-charge relay 16 can be represented as a relay provided between the second DCDC converter 12 and the PCU.

[0045] [Description of Reference Numerals]

[0046] 1 Power control device

[0047] 2 High-voltage battery

[0048] 3 Electric motor

[0049] 4 Auxiliary load

[0050] 10 Inverter

[0051] 11 First DCDC converter

[0052] 12 Second DCDC converter

[0053] 13 System main relay (SMR)

[0054] 13A First relay

[0055] 13B Second relay

[0056] 14 Smoothing capacitor

[0057] 15 Auxiliary relay

[0058] 15A Third relay

[0059] 15B Fourth relay

[0060] 16 Pre-charge relay

[0061] 17 Capacitor

[0062] 21 First power line

[0063] 22 Second power line

[0064] 23 Third power line

[0065] 24 Fourth power line

[0066] 25 Fifth power line

[0067] 26 Sixth power line

[0068] 27 Seventh power line

[0069] 28 Low-voltage line

Claims

1. A power control device is mounted on an electric vehicle without an auxiliary battery, and supplies power from a high-voltage battery in the electric vehicle to a motor and an auxiliary load. It is characterized in that the power control device includes: an inverter that converts power from the high-voltage battery into alternating current power and outputs it to the motor; a first DCDC converter, the high-voltage terminal of the first DCDC converter is connected to the high-voltage battery without passing through a relay, and the low-voltage terminal of the first DCDC converter is connected to the auxiliary load. The first DCDC converter steps down the power from the high-voltage battery and outputs it to the auxiliary load; a second DCDC converter, the high-voltage terminal of the second DCDC converter is connected to the high-voltage battery through a relay, and the low-voltage terminal of the second DCDC converter is connected to the auxiliary load. The second DCDC converter is connected in parallel with the first DCDC converter and can output bidirectionally to the high-voltage terminal side and the low-voltage terminal side; a first power line that connects the positive terminal of the high-voltage battery and the inverter; a second power line that connects 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 and a fourth relay. The third relay is provided between the positive terminal of the high-voltage battery and the second DCDC converter, and the fourth relay is provided between the negative terminal of the high-voltage battery and the second DCDC converter; and a pre-charge relay, which is a fifth relay provided between the high-voltage terminal of the second DCDC converter and the smoothing capacitor.

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

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

4. The power supply control device according to any one of claims 1-3, characterized in that When pre-charging the smoothing capacitor with the power from the high-voltage battery, 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.

Images