Vehicle power supply

Abstract

To easily suppress deterioration of a relay provided in a power passage different from a power passage to a traveling motor.SOLUTION: A vehicular power supply device 10 includes: a first relay (a first positive electrode side relay 11, for instance); a second relay (a second positive electrode side relay 13, for instance); and a DCDC converter 15. The DCDC converter 15 is provided between a first conductive path (a first positive electrode side conductive wire 61, for instance) to be an electric path between the first relay in a first branch path 42 and a first capacitor 45 and a low-voltage battery 53, steps down a voltage input from the first conductive path (a first positive electrode side conductive wire 61, for instance) side, and outputs the voltage to the low-voltage battery 53 side. The DCDC converter 15 is provided between a second conductive path (a second positive electrode side conductive wire 63, for instance) to be an electric path between a second relay in a second branch path 50 and a second capacitor 52 and the low-voltage battery 53, performs a boosting operation for boosting a voltage input from the low-voltage battery 53 side, and supplies electric power to the second capacitor 52.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a vehicle power supply device.

Background Art

[0002] Patent Document 1 discloses a drive battery composed of battery modules. This drive battery supplies high-voltage DC power to an MCU inverter via a high-voltage line provided with a main contactor. The MCU inverter supplies drive AC power to a motor.

[0003] [[ID=1...]]

[0004] According to the configuration of Patent Document 1, by switching the rapid charging contactor to the on state, charging from an external vehicle charging device becomes possible without switching the main contactor to the on state. Therefore, deterioration of the main contactor can be suppressed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] When a contactor is switched to the on state while a potential difference exists across its two ends, an inrush current occurs and the contactor deteriorates. Therefore, in the configuration of Patent Document 1, when the rapid charging contactor is switched to the on state, an inrush current occurs in the rapid charging contactor, and there is concern that the rapid charging contactor will deteriorate. Such a problem also occurs in other configurations in which a relay is provided in a power path different from the power path to the motor for running. ​

[0007] This disclosure aims to provide a technology that can easily suppress the deterioration of relays installed in a power circuit separate from the power circuit to the motor used for driving. [Means for solving the problem]

[0008] The vehicle power supply device disclosed herein is A vehicle power supply device used in a vehicle power supply system comprising: a high-voltage battery; a common path from which power is supplied from the high-voltage battery; a first branch path branching from the common path; a motor for driving that is supplied with power from the high-voltage battery via the first branch path; a power conversion unit connected to the first branch path for converting power between the high-voltage battery and the motor; a first capacitor connected to the first branch path on the high-voltage battery side of the power conversion unit; a second branch path branching from the common path; a power exchange unit connected to the second branch path for exchanging power with the high-voltage battery; a second capacitor connected to the second branch path on the high-voltage battery side of the power exchange unit; and a low-voltage battery, wherein A first relay is provided in the first branch circuit on the high-voltage battery side of the first capacitor, A second relay is provided in the second branch circuit on the high-voltage battery side of the second capacitor, The system comprises a first conductive path which is the electrical path between the first relay and the first capacitor in the first branch circuit, and a DC-DC converter provided between the first conductive path and the low-voltage battery, which steps down the voltage input from the first conductive path and outputs it to the low-voltage battery side. The DC-DC converter is provided between the second conductive path, which is the electrical path between the second relay and the second capacitor in the second branch circuit, and the low-voltage battery, and supplies power to the second capacitor by performing a boost operation to increase the voltage input from the low-voltage battery side. [Effects of the Invention]

[0009] The technology disclosed herein makes it easier to suppress the deterioration of relays located in a power circuit separate from the power circuit to the motor used for driving. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a schematic circuit diagram showing a vehicle power supply system equipped with a vehicle power supply device according to the first embodiment. [Figure 2] Figure 2 is a conceptual diagram illustrating the state in which power is supplied from the DC-DC converter to the first capacitor and the second capacitor in the first embodiment. [Figure 3] Figure 3 is a schematic circuit diagram showing a vehicle power supply system equipped with a vehicle power supply device according to the second embodiment. [Figure 4] Figure 4 is a conceptual diagram illustrating the state in which power is supplied from the DC-DC converter to the second capacitor in the second embodiment. [Figure 5] Figure 5 is a schematic circuit diagram showing a vehicle power supply system equipped with a vehicle power supply device according to the third embodiment. [Figure 6] Figure 6 is a conceptual diagram illustrating the state in which power is supplied from the DC-DC converter to the first capacitor in the third embodiment. [Figure 7] Figure 7 is a conceptual diagram illustrating the state in which power is supplied from the DC-DC converter to the second capacitor in the third embodiment. [Modes for carrying out the invention]

[0011] The embodiments of this disclosure are listed and illustrated below.

[0012] [1] A vehicle power supply device used in a vehicle power supply system comprising: a high-voltage battery; a common path supplied with power from the high-voltage battery; a first branch path branching from the common path; a motor for driving that is supplied with power from the high-voltage battery via the first branch path; a power conversion unit connected to the first branch path that converts power between the high-voltage battery and the motor; a first capacitor connected to the first branch path on the high-voltage battery side of the power conversion unit; a second branch path branching from the common path; a power exchange unit connected to the second branch path that exchanges power with the high-voltage battery; a second capacitor connected to the second branch path on the high-voltage battery side of the power exchange unit; and a low-voltage battery, wherein A first relay is provided in the first branch circuit on the high-voltage battery side of the first capacitor, A second relay is provided in the second branch circuit on the high-voltage battery side of the second capacitor, The system comprises a first conductive path which is the electrical path between the first relay and the first capacitor in the first branch circuit, and a DC-DC converter provided between the first conductive path and the low-voltage battery, which steps down the voltage input from the first conductive path and outputs it to the low-voltage battery side. The DC-DC converter is provided between the second conductive path, which is the electrical path between the second relay and the second capacitor in the second branch circuit, and the low-voltage battery, and supplies power to the second capacitor by performing a boost operation to increase the voltage input from the low-voltage battery side. Vehicle power supply unit.

[0013] When the second relay switches to the on state, the vehicle power supply device can transfer power to and from the high-voltage battery through the power transfer unit without switching the first relay to the on state. Therefore, it is possible to suppress deterioration of the first relay caused by switching the first relay to the on state. Furthermore, the vehicle power supply device can pre-charge the second capacitor by using a DC-DC converter used for charging the low-voltage battery. Thus, the vehicle power supply device can suppress the inrush current generated when switching the second relay to the on state and suppress deterioration of the second relay. That is, the vehicle power supply device is likely to suppress deterioration of the second relay provided in a power path different from the power path to the motor for running.

[0014] 〔2〕The DC-DC converter is configured to apply the voltage boosted by the boosting operation to the high-voltage side conductive path. The high-voltage side conductive path is connected to the first conductive path via a third conductive path and is connected to the second conductive path via a fourth conductive path. Furthermore, it includes a switch unit provided in the third conductive path. The vehicle power supply device according to 〔1〕.

[0015] When the switch unit is in the on state, the vehicle power supply device can supply power from the high-voltage battery to the low-voltage battery via the third conductive path and the DC-DC converter. Also, when supplying power from the DC-DC converter to the second capacitor via the fourth conductive path, the vehicle power supply device can prevent the power from the DC-DC converter from being supplied to the first conductive path by keeping the switch unit in the off state. Thus, when pre-charging the second capacitor, the vehicle power supply device can prevent the power from the DC-DC converter from being consumed by the first capacitor and can avoid causing a delay in the charging speed of the second capacitor.

[0016] 〔3〕It includes a second switch unit provided in the fourth conductive path. When the DC-DC converter performs the boost operation while the switch unit is ON and the second switch unit is OFF, power from the DC-DC converter is supplied only to the first capacitor among the first and second capacitors. When the DC-DC converter performs the boost operation while the switch unit is in the OFF state and the second switch unit is in the ON state, power from the DC-DC converter is supplied only to the second capacitor among the first and second capacitors. The vehicle power supply device described in [2].

[0017] The above-mentioned vehicle power supply device can selectively supply power from the DC-DC converter to the first capacitor and the second capacitor.

[0018] [4] The system comprises the first relay, the second relay, the switch section, the second switch section, and a control unit that controls the DC-DC converter, When the conditions for precharging both the first and second capacitors are met, the control unit controls the switch unit to the ON state and the second switch unit to the OFF state, causing the DC-DC converter to perform the boost operation to precharge the first capacitor, after precharging the first capacitor, switches the first relay to the ON state, after switching the first relay to the ON state, switches the second switch unit to the ON state, causing the DC-DC converter to perform the boost operation to precharge the second capacitor, and after precharging the second capacitor, switches the second relay to the ON state. The vehicle power supply device described in [3].

[0019] The above-described vehicle power supply unit can prioritize precharging the first capacitor when the conditions for precharging both the first and second capacitors are met. Therefore, the above-described vehicle power supply unit can easily expedite the start of power supply via the first branch circuit, and consequently, expedite the start of motor operation.

[0020] [5] A control unit for controlling the DC-DC converter, When the conditions for precharging both the first and second capacitors are met, the control unit causes the DC-DC converter to perform the boost operation to precharge both the first and second capacitors simultaneously. A vehicle power supply device as described in any of [1] to [3].

[0021] The above-mentioned vehicle power supply unit can precharge both the first and second capacitors simultaneously by utilizing a DC-DC converter used for charging a low-voltage battery, when the conditions for precharging both the first and second capacitors are met.

[0022] [6] A pre-charge circuit is provided, which has a configuration in which a pre-charge relay and a resistor are connected in series. The pre-charge circuit is provided in parallel with only the first relay among the first and second relays, and pre-charges the first capacitor based on the power from the high-voltage battery when the pre-charge relay is ON. A vehicle power supply device as described in any of [1] to [5].

[0023] The above-described vehicle power supply unit can precharge the first capacitor more rapidly than precharging with a DC-DC converter by switching the precharge relay to the ON state. Furthermore, the above-described vehicle power supply unit can precharge the second capacitor using a DC-DC converter without providing a precharge circuit for the second relay.

[0024] <First Embodiment> 1. Configuration of the vehicle power supply system 100 Figure 1 shows a vehicle power supply system 100 equipped with a vehicle power supply unit 10. The vehicle power supply system 100 is used in a vehicle not shown. The vehicle may be an electric vehicle, a fuel cell vehicle, or a hybrid vehicle.

[0025] The vehicle power supply system 100 includes a high-voltage battery 40, a common path 41, a first branch path 42, a motor 43 for driving, a power conversion unit 44, and a first capacitor 45.

[0026] The high-voltage battery 40 may be a lithium-ion battery, a lead-acid battery, or any other type of battery. The voltage of the high-voltage battery 40 when fully charged may be, for example, 400V, 800V, or any other value.

[0027] The common path 41 is an electrical path supplied with power from the high-voltage battery 40. The common path 41 is connected to the high-voltage battery 40. The common path 41 includes a positive common wire 41A and a negative common wire 41B. The positive common wire 41A is connected to the positive terminal of the high-voltage battery 40. The negative common wire 41B is connected to the negative terminal of the high-voltage battery 40. The negative common wire 41B is connected to a ground (not shown). The output voltage of the high-voltage battery 40 is applied to the common path 41 (more specifically, the positive common wire 41A). In this specification, voltage refers to a voltage relative to the potential of the negative common wire 41B and a voltage relative to the potential of ground.

[0028] The first branch line 42 is an electrical path that branches off from the common path 41. The first branch line 42 includes the first positive-side branch line 42A, which branches off from the positive-side common line 41A, and the first negative-side branch line 42B, which branches off from the negative-side common line 41B.

[0029] The power conversion unit 44 is connected to the first branch circuit 42. The power conversion unit 44 converts power between the high-voltage battery 40 and the motor 43. In this embodiment, the power conversion unit 44 has the function of converting the DC power supplied from the high-voltage battery 40 side into AC power and supplying it to the motor 43. In this embodiment, the power conversion unit 44 is an inverter.

[0030] The first capacitor 45 is connected to the first branch line 42 on the high-voltage battery 40 side of the power conversion unit 44. One end of the first capacitor 45 is connected to the first positive-side branch line 42A, and the other end of the first capacitor 45 is connected to the first negative-side branch line 42B. The first capacitor 45 functions as a smoothing capacitor that smooths the voltage applied to the first branch line 42 between the high-voltage battery 40 and the power conversion unit 44.

[0031] The vehicle power supply system 100 includes a second branch circuit 50, a receiving unit 51, a second capacitor 52, a low-voltage battery 53, and a low-voltage load 54.

[0032] The second branch line 50 is an electrical path that branches off from the common path 41. The second branch line 50 includes a second positive-side branch line 50A that branches off from the positive-side common line 41A, and a second negative-side branch line 50B that branches off from the negative-side common line 41B.

[0033] The power transfer unit 51 is connected to the second branch circuit 50. The power transfer unit 51 exchanges power with the high-voltage battery 40. Here, "exchange" means at least one of supplying power from the high-voltage battery 40 to the power transfer unit 51, and supplying power from the power transfer unit 51 to the high-voltage battery 40. The power transfer unit 51 may be, for example, an electrical device that utilizes V2X (Vehicle to Everything) communication. The power transfer unit 51 may be an in-vehicle device or an external electrical device. More specifically, the power transfer unit 51 may be an in-vehicle charger (e.g., an onboard charger) or an external charger (e.g., an offboard charger). If the power transfer unit 51 is an in-vehicle device, the entire vehicle power supply system 100 is mounted on the vehicle. If the power transfer unit 51 is an external electrical device, the components of the vehicle power supply system 100 other than the power transfer unit 51 are mounted on the vehicle.

[0034] The second capacitor 52 is connected to the second branch line 50 on the high-voltage battery 40 side of the receiving unit 51. One end of the second capacitor 52 is connected to the second positive side branch line 50A, and the other end of the second capacitor 52 is connected to the second negative side branch line 50B. The second capacitor 52 functions as a smoothing capacitor that smooths the voltage applied to the second branch line 50 between the high-voltage battery 40 and the receiving unit 51.

[0035] The low-voltage battery 53 is a battery whose voltage when fully charged is lower than the voltage of the high-voltage battery 40 when fully charged. The low-voltage battery 53 may be a lithium-ion battery, a lead-acid battery, or any other type of battery. The voltage of the low-voltage battery 53 when fully charged may be, for example, 12V, or any other type of battery.

[0036] The low-voltage load 54 is an in-vehicle electrical device. The low-voltage load 54 is driven, for example, by power from a low-voltage battery 53. The low-voltage load 54 may include a starter motor, alternator, electric power steering system, electric parking brake, lighting, wiper drive unit, navigation system, etc.

[0037] 2. Configuration of the vehicle power supply unit 10 The vehicle power supply unit 10 includes a first positive-side relay 11, a first negative-side relay 12, a second positive-side relay 13, a second negative-side relay 14, a DC-DC converter 15, a pre-charge circuit 16, and a control unit 17.

[0038] The first positive-side relay 11 and the first negative-side relay 12 correspond to an example of the first relay. The first positive-side relay 11 is provided on the first positive-side branch line 42A on the high-voltage battery 40 side of the first capacitor 45. The first negative-side relay 12 is provided on the first negative-side branch line 42B on the high-voltage battery 40 side of the first capacitor 45.

[0039] The second positive-side relay 13 and the second negative-side relay 14 are examples of second relays. The second positive-side relay 13 is provided on the second positive-side branch line 50A on the high-voltage battery 40 side of the second capacitor 52. The second negative-side relay 14 is provided on the second negative-side branch line 50B on the high-voltage battery 40 side of the second capacitor 52.

[0040] The first positive relay 11, the first negative relay 12, the second positive relay 13, and the second negative relay 14 are all mechanical relays and have contacts. The contacts of the first positive relay 11, the first negative relay 12, the second positive relay 13, and the second negative relay 14 are closed when they are ON and open when they are OFF.

[0041] The electrical path between the first positive-side relay 11 and the first capacitor 45 in the first branch line 42 (more specifically, the first positive-side branch line 42A) is the first positive-side conductive wire 61. The electrical path between the first negative-side relay 12 and the first capacitor 45 in the first branch line 42 (more specifically, the first negative-side branch line 42B) is the first negative-side conductive wire 62. The first positive-side conductive wire 61 and the first negative-side conductive wire 62 correspond to an example of the first conductive path.

[0042] The electrical path between the second positive-side relay 13 and the second capacitor 52 in the second branch circuit 50 (more specifically, the second positive-side branch line 50A) is the second positive-side conductive wire 63. The electrical path between the second negative-side relay 14 and the second capacitor 52 in the second branch circuit 50 (more specifically, the second negative-side branch line 50B) is the second negative-side conductive wire 64. The second positive-side conductive wire 63 and the second negative-side conductive wire 64 correspond to an example of a second conductive path.

[0043] The DC-DC converter 15 is installed between the first positive electrode conductive wire 61 and the first negative electrode conductive wire 62 and the low-voltage battery 53. The DC-DC converter 15 performs a step-down operation, reducing the voltage input from the first positive electrode conductive wire 61 and the first negative electrode conductive wire 62 and outputting it to the low-voltage battery 53. The DC-DC converter 15 also performs a step-up operation, increasing the voltage input from the low-voltage battery 53 and outputting it to the first positive electrode conductive wire 61 and the first negative electrode conductive wire 62.

[0044] The DC-DC converter 15 is installed between the second positive electrode conductive wire 63 and the second negative electrode conductive wire 64 and the low-voltage battery 53. The DC-DC converter 15 performs a step-down operation, reducing the voltage input from the second positive electrode conductive wire 63 and the second negative electrode conductive wire 64 and outputting it to the low-voltage battery 53. The DC-DC converter 15 also performs a step-up operation, increasing the voltage input from the low-voltage battery 53 and outputting it to the second positive electrode conductive wire 63 and the second negative electrode conductive wire 64.

[0045] In step-down operation, the DC-DC converter 15 steps down the voltage applied to the positive high-voltage side conductive wire 65 (more specifically, between the positive high-voltage side conductive wire 65 and the negative high-voltage side conductive wire 66) and applies it to the positive low-voltage side conductive wire 67 (more specifically, between the positive low-voltage side conductive wire 67 and the negative low-voltage side conductive wire 68).

[0046] In boost operation, the DC-DC converter 15 boosts the voltage applied to the positive low-voltage side conductive wire 67 (more specifically, between the positive low-voltage side conductive wire 67 and the negative low-voltage side conductive wire 68) and applies it to the positive high-voltage side conductive wire 65 (more specifically, between the positive high-voltage side conductive wire 65 and the negative high-voltage side conductive wire 66).

[0047] The positive high-voltage side conductive wire 65 and the negative high-voltage side conductive wire 66 represent an example of a high-voltage conductive path. The positive high-voltage side conductive wire 65 is connected to the first positive side conductive wire 61 and the second positive side conductive wire 63. The negative high-voltage side conductive wire 66 is connected to the first negative side conductive wire 62 and the second negative side conductive wire 64. The positive high-voltage side conductive wire 65 is short-circuited to the first capacitor 45 (more specifically, one end of the first capacitor 45) via the first positive side conductive wire 61, and short-circuited to the second capacitor 52 (more specifically, one end of the second capacitor 52) via the second positive side conductive wire 63. The negative high-voltage side conductive wire 66 is short-circuited to the first capacitor 45 (more specifically, the other end of the first capacitor 45) via the first negative side conductive wire 62, and short-circuited to the second capacitor 52 (more specifically, the other end of the second capacitor 52) via the second negative side conductive wire 64. Therefore, when the DC-DC converter 15 performs a boost operation, power is supplied from the DC-DC converter 15 to the first capacitor 45 and the second capacitor 52. In other words, the DC-DC converter 15 can pre-charge the first capacitor 45 and the second capacitor 52.

[0048] The positive low-voltage side conductive wire 67 and the negative low-voltage side conductive wire 68 represent an example of a low-voltage conductive path. The positive terminal of the low-voltage battery 53 is connected to the positive low-voltage side conductive wire 67, and one end of the low-voltage load 54 is connected to it. The negative terminal of the low-voltage battery 53 is connected to the negative low-voltage side conductive wire 68, and the other end of the low-voltage load 54 is connected to it.

[0049] The precharge circuit 16 has a configuration in which the precharge relay 20 and the resistor 21 are connected in series. The precharge circuit 16 is provided in parallel with the first positive side relay 11. Of the first positive side relay 11, the first negative side relay 12, the second positive side relay 13, and the second negative side relay 14, the precharge circuit 16 is provided in parallel only with the first positive side relay 11. One end of the precharge circuit 16 is short-circuited to the positive terminal of the high-voltage battery 40. The other end of the precharge circuit 16 is short-circuited to one end of the first capacitor 45 and one end of the second capacitor 52. When the precharge relay 20 is ON, power from the high-voltage battery 40 is supplied to the first capacitor 45 and the second capacitor 52 via the precharge circuit 16. In other words, when the precharge relay 20 is ON, the precharge circuit 16 precharges the first capacitor 45 and the second capacitor 52 based on the power from the high-voltage battery 40.

[0050] 3. Configuration of the control unit 17 The control unit 17 is composed of an integrated circuit, such as an MCU (Microcontroller Unit). The control unit 17 includes a processing unit such as a CPU and a storage unit such as ROM and RAM. The control unit 17 controls the first positive relay 11, the first negative relay 12, the second positive relay 13, the second negative relay 14, the precharge relay 20, and the DC-DC converter 15.

[0051] The control unit 17 can precharge the first capacitor 45 and the second capacitor 52 using the precharge circuit 16. The control unit 17 switches the first negative side relay 12 and the precharge relay 20 to the ON state, thereby supplying power from the high-voltage battery 40 to the first capacitor 45 and the second capacitor 52 via the precharge circuit 16. This precharges the first capacitor 45 and the second capacitor 52. With this configuration, the voltage of the first capacitor 45 and the second capacitor 52 can be increased more rapidly compared to when precharging is performed using the DC-DC converter 15. However, in this case, the rate at which the voltage of the first capacitor 45 and the second capacitor 52 increases decreases as it approaches the voltage of the high-voltage battery 40. If the first positive side relay 11 is switched to the ON state while a potential difference exists across its terminals, a considerable inrush current will flow through the first positive side relay 11, leading to deterioration of the first positive side relay 11.

[0052] The control unit 17 can precharge the first capacitor 45 and the second capacitor 52 using the DC-DC converter 15. The control unit 17 causes the DC-DC converter 15 to perform a boost operation, thereby supplying power from the low-voltage battery 53 to the first capacitor 45 and the second capacitor 52. This precharges the first capacitor 45 and the second capacitor 52. With this configuration, the voltages of the first capacitor 45 and the second capacitor 52 can be raised to the same voltage as the high-voltage battery 40. Therefore, it is easier to suppress the degradation of the relays when the first positive relay 11, the first negative relay 12, the second positive relay 13, and the second negative relay 14 are switched to the ON state.

[0053] When the conditions for precharging the first capacitor 45 are met, the control unit 17 switches, for example, the precharge relay 20 and the first negative side relay 12 to the ON state to precharge the first capacitor 45. At this time, the second capacitor 52 is also charged. When the voltage of the first capacitor 45 has risen to a certain extent, the control unit 17 switches the first positive side relay 11 to the ON state and switches the precharge relay 20 to the OFF state. As a result, power based on the high-voltage battery 40 is supplied to the power conversion unit 44. Furthermore, the power conversion unit 44 performs a power conversion operation controlled by the control unit 17 or another control device, generating AC power in the power conversion unit 44, and this AC power is supplied to the motor 43. The conditions for precharging the first capacitor 45 may be, for example, the conditions for starting the motor 43 to drive, or the vehicle's start switch may be switched to the ON state. The control unit 17 is configured to receive a signal from an external source that can identify the ON / OFF state of the start switch, and identifies the ON / OFF state of the start switch based on this signal. The start switch is a power switch if the vehicle is an electric vehicle or a fuel cell vehicle, and an ignition switch if the vehicle is a hybrid vehicle. Furthermore, the method for determining that the voltage of the first capacitor 45 has risen to a certain extent may be to determine that the voltage of the first capacitor 45 exceeds a predetermined value, to determine that the potential difference across the first positive side relay 11 falls below a predetermined value, to determine that the value of the current flowing through the precharge circuit 16 falls below a predetermined value, to determine that a predetermined precharge time has elapsed, or by any other method.

[0054] When the conditions for precharging the second capacitor 52 are met, the control unit 17, for example, causes the DC-DC converter 15 to perform a boost operation to precharge the second capacitor 52 (see Figure 2). At this time, the first capacitor 45 is also charged. When the voltage of the second capacitor 52 has risen to a certain level, the control unit 17 switches the second positive-side relay 13 and the second negative-side relay 14 to the ON state. This causes the high-voltage battery 40 and the power transfer unit 51 to conduct electricity, enabling them to exchange power. With this configuration, it is possible to enable power exchange between the high-voltage battery 40 and the power transfer unit 51 without switching the first positive-side relay 11 to the ON state. Therefore, since it is not necessary to switch the first positive-side relay 11 to the ON state, deterioration of the first positive-side relay 11 caused by switching it to the ON state can be suppressed. The conditions for precharging the second capacitor 52 may be, for example, the conditions for starting the operation of the power transfer unit 51, or other conditions. Furthermore, the conditions for precharging the second capacitor 52 may be the same as or different from the conditions for precharging the first capacitor 45. Also, the method for determining that the voltage of the second capacitor 52 has risen to a certain extent may be to determine that the voltage of the second capacitor 52 exceeds a predetermined value, to determine that the potential difference across the second positive-side relay 13 or the second negative-side relay 14 falls below a predetermined value, to determine that the value of the current flowing through the second positive-side conductive wire 63 falls below a predetermined value, to determine that a predetermined precharging time has elapsed, or by any other method.

[0055] 4. Examples of effects The vehicle power supply unit 10 can exchange power with the high-voltage battery 40 and the power transfer unit 51 without the first positive-side relay 11 being switched on, by switching the second positive-side relay 13 and the second negative-side relay 14 to the ON state. Therefore, deterioration of the first positive-side relay 11 caused by switching the first positive-side relay 11 to the ON state can be suppressed. Furthermore, the vehicle power supply unit 10 can precharge the second capacitor 52 using the DC-DC converter 15 used to charge the low-voltage battery 53. Therefore, the vehicle power supply unit 10 can suppress the inrush current that occurs when the second positive-side relay 13 is switched on, and thus suppress deterioration of the second positive-side relay 13. In other words, the vehicle power supply unit 10 can easily suppress deterioration of the second positive-side relay 13, which is located in a power path separate from the power path to the motor 43 for driving.

[0056] The vehicle power supply unit 10 can precharge both the first capacitor 45 and the second capacitor 52 simultaneously using the DC-DC converter 15 used for charging the low-voltage battery 53 when the conditions for precharging both the first capacitor 45 and the second capacitor 52 are met.

[0057] The vehicle power supply unit 10 can precharge the first capacitor 45 more rapidly than precharging by the DC-DC converter 15 by switching the precharge relay 20 to the ON state. Furthermore, the vehicle power supply unit 10 can precharge the second capacitor 52 using the DC-DC converter 15 without providing a precharge circuit for the second positive side relay 13.

[0058] <Second Embodiment> In the second embodiment, a configuration is described in which the current flow from the DC-DC converter to the first capacitor can be interrupted when the second capacitor is pre-charged using the DC-DC converter. Components identical to those in the first embodiment are denoted by the same reference numerals, and detailed explanations are omitted.

[0059] As shown in Figure 3, the vehicle power supply system 200 of the second embodiment includes a high-voltage battery 40, a common path 41, a first branch path 42, a motor for driving 43, a power conversion unit 44, a first capacitor 45, a second branch path 50, a receiving unit 51, a second capacitor 52, a low-voltage battery 53, a low-voltage load 54, and a vehicle power supply device 210.

[0060] The vehicle power supply unit 210 includes a first positive-side relay 11, a first negative-side relay 12, a second positive-side relay 13, a second negative-side relay 14, a DC-DC converter 15, a pre-charge circuit 16, a control unit 17, a positive-side switch unit 71, and a negative-side switch unit 72.

[0061] In step-down operation, the DC-DC converter 15 steps down the voltage applied to the positive high-voltage side conductive wire 265 (more specifically, between the positive high-voltage side conductive wire 265 and the negative high-voltage side conductive wire 266) and applies it to the positive low-voltage side conductive wire 67 (more specifically, between the positive low-voltage side conductive wire 67 and the negative low-voltage side conductive wire 68).

[0062] In boost operation, the DC-DC converter 15 boosts the voltage applied to the positive low-voltage side conductive wire 67 (more specifically, between the positive low-voltage side conductive wire 67 and the negative low-voltage side conductive wire 68) and applies it to the positive high-voltage side conductive wire 265 (more specifically, between the positive high-voltage side conductive wire 265 and the negative high-voltage side conductive wire 266).

[0063] The positive high-voltage side conductive wire 265 and the negative high-voltage side conductive wire 266 correspond to an example of a high-voltage conductive path. The positive high-voltage side conductive wire 265 is connected to the first positive-side conductive wire 61 via the third positive-side conductive wire 81, which is branched from the positive high-voltage side conductive wire 265. The positive high-voltage side conductive wire 265 is connected to the second positive-side conductive wire 63 via the fourth positive-side conductive wire 83, which is branched from the positive high-voltage side conductive wire 265. The third positive-side conductive wire 81 corresponds to an example of a third conductive path. The fourth positive-side conductive wire 83 corresponds to an example of a fourth conductive path. The positive high-voltage side conductive wire 265 is short-circuited to the first capacitor 45 (more specifically, one end of the first capacitor 45) via the third positive-side conductive wire 81 and the first positive-side conductive wire 61. The positive high-voltage side conductive wire 265 is short-circuited to the second capacitor 52 (more specifically, one end of the second capacitor 52) via the fourth positive side conductive wire 83 and the second positive side conductive wire 63.

[0064] The negative high-voltage side conductive wire 266 is connected to the first negative-side conductive wire 62 via the third negative-side conductive wire 82, which is branched from the negative high-voltage side conductive wire 266. The negative high-voltage side conductive wire 266 is connected to the second negative-side conductive wire 64 via the fourth negative-side conductive wire 84, which is branched from the negative high-voltage side conductive wire 266. The third negative-side conductive wire 82 corresponds to an example of the third conductive path. The fourth negative-side conductive wire 84 corresponds to an example of the fourth conductive path. The negative high-voltage side conductive wire 266 is short-circuited to the first capacitor 45 (more specifically, the other end of the first capacitor 45) via the third negative-side conductive wire 82 and the first negative-side conductive wire 62. The negative high-voltage side conductive wire 266 is short-circuited to the second capacitor 52 (more specifically, the other end of the second capacitor 52) via the fourth negative-side conductive wire 84 and the second negative-side conductive wire 64.

[0065] The positive-side switch section 71 and the negative-side switch section 72 are examples of switch sections. The positive-side switch section 71 is provided on the third positive-side conductive wire 81. The negative-side switch section 72 is provided on the third negative-side conductive wire 82. The positive-side switch section 71 and the negative-side switch section 72 may each be configured to include a mechanical switch having contacts, or they may each be configured to include a semiconductor switch. When the positive-side switch section 71 and the negative-side switch section 72 are in the ON state, they allow bidirectional current flow, and when they are in the OFF state, they block bidirectional current flow.

[0066] When the DC-DC converter 15 performs a boost operation while both the positive-side switch section 71 and the negative-side switch section 72 are in the ON state, power is supplied from the DC-DC converter 15 to the first capacitor 45 and the second capacitor 52. In other words, the DC-DC converter 15 can precharge the first capacitor 45 and the second capacitor 52 at the same time.

[0067] When the DC-DC converter 15 performs a boost operation while the positive-side switch section 71 and the negative-side switch section 72 are in the off state, power is supplied from the DC-DC converter 15 to the second capacitor 52. In other words, the DC-DC converter 15 can precharge only the second capacitor 52 of the two capacitors 52 and the first capacitor 45.

[0068] The control unit 17 controls the positive-side switch unit 71 and the negative-side switch unit 72. When the conditions for charging the low-voltage battery 53 are met, the control unit 17 controls the first positive-side relay 11, the first negative-side relay 12, the positive-side switch unit 71, and the negative-side switch unit 72 to be in the ON state, and causes the DC-DC converter 15 to perform a step-down operation, thereby charging the low-voltage battery 53 based on the power of the high-voltage battery 40.

[0069] The control unit 17 controls the positive-side switch unit 71 and the negative-side switch unit 72 to be ON, for example, and causes the DC-DC converter 15 to perform a boost operation, thereby supplying power from the DC-DC converter 15 to both the first capacitor 45 and the second capacitor 52. As a result, both the first capacitor 45 and the second capacitor 52 are pre-charged at the same time. When the voltages of the first capacitor 45 and the second capacitor 52 have risen to a certain extent, the control unit 17 switches the first positive-side relay 11, the first negative-side relay 12, the second positive-side relay 13, and the second negative-side relay 14 to be ON. As a result, power from the high-voltage battery 40 is supplied to the power conversion unit 44 via the first branch line 42, and the high-voltage battery 40 and the power exchange unit 51 become capable of exchanging power with each other. As a method for determining that the voltages of the first capacitor 45 and the second capacitor 52 have risen to a certain extent, it may be determined that the voltage of the second capacitor 52 exceeds a predetermined value, that the potential difference across the second positive-side relay 13 or the second negative-side relay 14 falls below a predetermined value, that the value of the current flowing through the second positive-side conductive wire 63 falls below a predetermined value, that a predetermined pre-charge time has elapsed, or by any other method.

[0070] When the conditions for precharging the second capacitor 52 are met, the control unit 17 controls the positive-side switch unit 71 and the negative-side switch unit 72 to the OFF state, as shown in Figure 4, and causes the DC-DC converter 15 to perform a boost operation, thereby supplying power from the DC-DC converter 15 to the second capacitor 52. As a result, only the second capacitor 52 of the first capacitor 45 and second capacitor 52 is precharged. When the voltage of the second capacitor 52 rises to a certain level, the control unit 17 switches the second positive-side relay 13 and the second negative-side relay 14 to the ON state. As a result, the high-voltage battery 40 and the power exchange unit 51 become conductive, enabling them to exchange power. With this configuration, it is possible to enable power exchange between the high-voltage battery 40 and the power exchange unit 51 without switching the first positive-side relay 11 to the ON state. Therefore, deterioration of the first positive-side relay 11 caused by switching it to the ON state can be suppressed.

[0071] As described above, the vehicle power supply unit 210 of the second embodiment can supply power from the high-voltage battery 40 to the low-voltage battery 53 via the third positive conductive wire 81 and the DCDC converter 15 when the positive-side switch unit 71 and the negative-side switch unit 72 are ON. Furthermore, when the vehicle power supply unit 210 supplies power from the DCDC converter 15 to the second capacitor 52 via the fourth positive conductive wire 83, it can prevent power from the DCDC converter 15 from being supplied to the first positive conductive wire 61 by keeping the positive-side switch unit 71 and the negative-side switch unit 72 OFF. Therefore, when the vehicle power supply unit 210 precharges the second capacitor 52, it can prevent power from the DCDC converter 15 from being consumed by the first capacitor 45 and avoid delays in the charging speed of the second capacitor 52.

[0072] <Third Embodiment> In the third embodiment, a configuration is described in which precharging using a DC-DC converter can be selectively performed on the first capacitor and the second capacitor. Components identical to those in the second embodiment are denoted by the same reference numerals, and detailed explanations are omitted.

[0073] As shown in Figure 5, the vehicle power supply system 300 of the third embodiment includes a high-voltage battery 40, a common path 41, a first branch path 42, a motor for driving 43, a power conversion unit 44, a first capacitor 45, a second branch path 50, a receiving unit 51, a second capacitor 52, a low-voltage battery 53, a low-voltage load 54, and a vehicle power supply device 310.

[0074] The vehicle power supply unit 310 includes a first positive-side relay 11, a first negative-side relay 12, a second positive-side relay 13, a second negative-side relay 14, a DC-DC converter 15, a pre-charge circuit 16, a control unit 17, a positive-side switch unit 71, a negative-side switch unit 72, a second positive-side switch unit 73, and a second negative-side switch unit 74.

[0075] The second positive-side switch section 73 and the second negative-side switch section 74 correspond to an example of the second switch section. The second positive-side switch section 73 is provided on the fourth positive-side conductive wire 83. The second negative-side switch section 74 is provided on the fourth negative-side conductive wire 84. The second positive-side switch section 73 and the second negative-side switch section 74 may each be configured to include a mechanical switch having contacts, or to include a semiconductor switch. When the second positive-side switch section 73 and the second negative-side switch section 74 are in the ON state, they allow bidirectional current flow, and when they are in the OFF state, they block bidirectional current flow.

[0076] When the DC-DC converter 15 performs a boost operation while both the positive-side switch section 71 and the negative-side switch section 72 are ON and the second positive-side switch section 73 and the second negative-side switch section 74 are OFF, power is supplied from the DC-DC converter 15 to only the first capacitor 45 of the two capacitors 52, as shown in Figure 6.

[0077] When the DC-DC converter 15 performs a boost operation while the positive-side switch section 71 and the negative-side switch section 72 are in the off state and both the second positive-side switch section 73 and the second negative-side switch section 74 are in the on state, power is supplied from the DC-DC converter 15 to only the second capacitor 52 of the two capacitors 52, as shown in Figure 7.

[0078] The control unit 17 controls the second positive-side switch unit 73 and the second negative-side switch unit 74. When the condition for precharging the first capacitor 45 is met, the control unit 17 performs a first control that turns on the positive-side switch unit 71 and the negative-side switch unit 72, and turns off the second positive-side switch unit 73 and the second negative-side switch unit 74. As a result, power from the DC-DC converter 15 is supplied only to the first capacitor 45 of the two capacitors 52. In other words, only the first capacitor 45 is precharged.

[0079] When the condition for precharging the second capacitor 52 is met, the control unit 17 performs a second control, which controls the positive-side switch unit 71 and the negative-side switch unit 72 to the off state, and controls the second positive-side switch unit 73 and the second negative-side switch unit 74 to the on state. As a result, power from the DC-DC converter 15 is supplied only to the second capacitor 52 of the first capacitor 45 and the second capacitor 52. In other words, only the second capacitor 52 of the first capacitor 45 and the second capacitor 52 is precharged.

[0080] When the conditions for precharging both the first capacitor 45 and the second capacitor 52 are met, the control unit 17 executes the first control to precharge the first capacitor 45. After precharging the first capacitor 45, the control unit 17 switches the first positive relay 11 and the first negative relay 12 to the ON state. For example, the control unit 17 switches the first positive relay 11 and the first negative relay 12 to the ON state when the voltage of the first capacitor 45 has risen to a certain extent. After switching the first positive relay 11 and the first negative relay 12 to the ON state, the control unit 17 executes the second control to precharge the second capacitor 52. After precharging the second capacitor 52, the control unit 17 switches the second positive relay 13 and the second negative relay 14 to the ON state. For example, the control unit 17 switches the second positive relay 13 and the second negative relay 14 to the ON state when the voltage of the second capacitor 52 has risen to a certain extent. The conditions for pre-charging both the first capacitor 45 and the second capacitor 52 may be, for example, when the vehicle's start switch is turned on, or other conditions.

[0081] As described above, the vehicle power supply unit 310 of the third embodiment can selectively supply power from the DC-DC converter to the first capacitor 45 and the second capacitor 52. In other words, the vehicle power supply unit 310 can selectively precharge either the first capacitor 45 or the second capacitor 52 based on the power from the DC-DC converter.

[0082] Furthermore, the vehicle power supply unit 310 can prioritize precharging the first capacitor 45 when the conditions for precharging both the first capacitor 45 and the second capacitor 52 are met. As a result, the vehicle power supply unit 310 can accelerate the start of power supply via the first branch circuit 42, and consequently, accelerate the start of motor 43 operation.

[0083] <Other Embodiments> This disclosure is not limited to the embodiments described above and in the drawings. For example, any combination of the features of the embodiments described above or below is possible as long as it does not contradict each other. Furthermore, any feature of the embodiments described above or below may be omitted unless explicitly stated as essential. In addition, the embodiments described above may be modified as follows.

[0084] In the third embodiment described above, the control unit 17 may cause the DC-DC converter 15 to perform a boost operation to precharge both the first capacitor 45 and the second capacitor 52 simultaneously when the conditions for precharging both the first capacitor 45 and the second capacitor 52 are met. That is, the control unit 17 may control the positive-side switch unit 71, the negative-side switch unit 72, the second positive-side switch unit 73, and the second negative-side switch unit 74 to precharge both the first capacitor 45 and the second capacitor 52 simultaneously based on the power from the DC-DC converter 15.

[0085] In each of the above embodiments, the pre-charge circuit 16 may not be provided. Even in this case, the first capacitor 45 and the second capacitor 52 can be pre-charged using the DC-DC converter 15.

[0086] It should be noted that the embodiments disclosed herein are illustrative and not restrictive in all respects. The scope of the present invention is not limited to the embodiments disclosed herein, and is intended to include all modifications within the scope set forth in the claims or within the scope equivalent to the claims. [Explanation of Symbols]

[0087] 10... Vehicle power supply unit 11…First positive side relay (first relay) 12…First negative side relay (first relay) 13…Second positive side relay (second relay) 14…Second negative electrode relay (second relay) 15…DC-DC converter 16… Pre-charge circuit 17…Control Unit 20… Pre-charge relay 21...Resistance part 40… High-voltage battery 41…Common route 41A... Common wire on the positive side 41B…Negative side common line 42...First fork in the road 42A...First positive pole side branch line 42B...First negative pole side branch line 43…motor 44...Power conversion unit 45…First capacitor 50...Second fork in the road 50A... Second positive pole side branch line 50B...Second negative pole side branch line 51…Give and receive section 52…Second capacitor 53... Low-voltage battery 54... Low-voltage load 61...First positive electrode side conductive wire (first conductive path) 62...First negative electrode conductive wire (first conductive path) 63...Second positive electrode side conductive wire (second conductive path) 64...Second negative electrode conductive wire (second conductive path) 65…Positive electrode high-voltage side conductive wire (high-voltage side conductive path) 66... ​​Negative electrode high-voltage side conductive wire (high-voltage side conductive path) 67…Positive electrode low-voltage side conductive wire (low-voltage side conductive path) 68... Negative electrode low-voltage side conductive wire (low-voltage side conductive path) 71... Positive side switch section (switch section) 72... Negative electrode side switch section (switch section) 73...Second positive electrode side switch section (second switch section) 74...Second negative electrode side switch section (second switch section) 81... Third positive electrode side conductive wire (third conductive path) 82...Third negative electrode conductive wire (third conductive circuit) 83...Fourth positive electrode side conductive wire (fourth conductive path) 84...Fourth negative electrode conductive wire (fourth conductive path) 100... Vehicle power supply system 200... Vehicle power supply system 210... Vehicle power supply unit 265... Positive electrode high-voltage side conductive wire (high-voltage side conductive path) 266... ​​Negative electrode high-voltage side conductive wire (high-voltage side conductive path) 300... Vehicle power supply system 310... Vehicle power supply unit

Claims

1. A vehicle power supply device used in a vehicle power supply system comprising: a high-voltage battery; a common path from which power is supplied from the high-voltage battery; a first branch path branching from the common path; a motor for driving that is supplied with power from the high-voltage battery via the first branch path; a power conversion unit connected to the first branch path that converts power between the high-voltage battery and the motor; a first capacitor connected to the first branch path on the high-voltage battery side of the power conversion unit; a second branch path branching from the common path; a power exchange unit connected to the second branch path that exchanges power with the high-voltage battery; a second capacitor connected to the second branch path on the high-voltage battery side of the power exchange unit; and a low-voltage battery, wherein The common path includes a positive-side common wire, one end of which is connected to the positive electrode of the high-voltage battery, and a negative-side common wire, one end of which is connected to the negative electrode of the high-voltage battery. The first branch line includes a first positive-side branch line branched from the other end of the positive-side common line and a first negative-side branch line branched from the other end of the negative-side common line. The second branch line includes a second positive-side branch line branched from the other end of the positive-side common line and a second negative-side branch line branched from the other end of the negative-side common line. A first relay is provided on at least one of the first positive electrode branch line and the first negative electrode branch line on the high-voltage battery side of the first capacitor, A second relay is provided on at least one of the second positive electrode branch line and the second negative electrode branch line on the high-voltage battery side of the second capacitor, The system comprises a first conductive path which is the electrical path between the first relay and the first capacitor in the first branch circuit, and a DC-DC converter provided between the first conductive path and the low-voltage battery, which steps down the voltage input from the first conductive path and outputs it to the low-voltage battery side. The DC-DC converter is provided between the second conductive path, which is the electrical path between the second relay and the second capacitor in the second branch circuit, and the low-voltage battery. It performs a boost operation to increase the voltage input from the low-voltage battery side and supplies power to the second capacitor. Vehicle power supply unit.

2. The DC-DC converter is configured to apply the voltage boosted by the boost operation to the high-voltage side conductive path. The high-voltage side conductive path is connected to the first conductive path via the third conductive path and to the second conductive path via the fourth conductive path. Furthermore, it includes a switch section provided in the third conductive path. The vehicle power supply device according to claim 1.

3. A vehicle power supply device used in a vehicle power supply system comprising: a high-voltage battery; a common path to which power is supplied from the high-voltage battery; a first branch path branching off from the common path; a motor for driving to which power is supplied based on the high-voltage battery via the first branch path; a power conversion unit connected to the first branch path for converting power between the high-voltage battery and the motor; a first capacitor connected to the first branch path on the high-voltage battery side of the power conversion unit; a second branch path branching off from the common path; a power exchange unit connected to the second branch path for exchanging power with the high-voltage battery; a second capacitor connected to the second branch path on the high-voltage battery side of the power exchange unit; and a low-voltage battery, wherein A first relay is provided in the first branch circuit on the high-voltage battery side of the first capacitor, A second relay is provided in the second branch circuit on the high-voltage battery side of the second capacitor, The system comprises a first conductive path which is the electrical path between the first relay and the first capacitor in the first branch circuit, and a DC-DC converter provided between the first conductive path and the low-voltage battery, which steps down the voltage input from the first conductive path and outputs it to the low-voltage battery side. The DC-DC converter is provided between the second conductive path, which is the electrical path between the second relay and the second capacitor in the second branch circuit, and the low-voltage battery, and supplies power to the second capacitor by performing a boost operation to increase the voltage input from the low-voltage battery side. Furthermore, the DC-DC converter is configured to apply the voltage boosted by the boost operation to the high-voltage side conductive path. The high-voltage side conductive path is connected to the first conductive path via the third conductive path and to the second conductive path via the fourth conductive path. Furthermore, a switch section is provided in the third conductive path, The device comprises a second switch section provided in the fourth conductive path, When the DC-DC converter performs the boost operation while the switch unit is ON and the second switch unit is OFF, power from the DC-DC converter is supplied only to the first capacitor among the first and second capacitors. When the DC-DC converter performs the boost operation while the switch unit is in the OFF state and the second switch unit is in the ON state, power from the DC-DC converter is supplied only to the second capacitor among the first and second capacitors. Vehicle power supply unit.

4. The system comprises the first relay, the second relay, the switch section, the second switch section, and a control unit for controlling the DC-DC converter, When the conditions for precharging both the first and second capacitors are met, the control unit controls the switch unit to the ON state and the second switch unit to the OFF state, causing the DC-DC converter to perform the boost operation to precharge the first capacitor, after precharging the first capacitor, switches the first relay to the ON state, after switching the first relay to the ON state, switches the second switch unit to the ON state, causing the DC-DC converter to perform the boost operation to precharge the second capacitor, and after precharging the second capacitor, switches the second relay to the ON state. The vehicle power supply device according to claim 3.

5. The DCDC converter is controlled by a control unit, When the condition for precharging both the first and second capacitors is met, the control unit causes the DC-DC converter to perform the boost operation to precharge both the first and second capacitors simultaneously. A vehicle power supply device according to any one of claims 1 to 3.

6. It is equipped with a pre-charge circuit consisting of a pre-charge relay and a resistor connected in series. The pre-charge circuit is provided in parallel with only the first relay among the first and second relays, and pre-charges the first capacitor based on the power from the high-voltage battery when the pre-charge relay is ON. A vehicle power supply device according to any one of claims 1 to 4.

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