Vehicle power supply device

Abstract

A vehicle power supply device (10) is provided with a first relay (for example, a first positive-electrode-side relay (11)), a second relay (for example, a second positive-electrode-side relay (13)), and a DC-DC converter (15). A DC-DC converter (15) is provided between a first conductive path (for example, a first positive electrode-side conductive line (61)) and a low-voltage battery (53), reduces a voltage input from the first conductive path (for example, the first positive electrode-side conductive line (61)) side, and outputs the voltage to the low-voltage battery (53) side. The first conductive path is an electrical path between a first relay and a first capacitor (45) in a first branch path (42). A DC-DC converter (15) is provided between a second conductive path (for example, a second positive electrode-side conductive line (63)), which is an electrical path between a second relay in a second branch path (50) and a second capacitor (52), and a low-voltage battery (53), and supplies power to the second capacitor (52) by performing a step-up operation for step-up a voltage input from the low-voltage battery (53) side.

Description

Technical Field

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

[0002] In Patent Document 1, a drive battery composed of battery modules is disclosed. The 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 an electric motor.

[0003] In addition, the drive battery is supplied with high-voltage power from an external charging device for the vehicle via a high-voltage line for quick charging. A quick charging contactor is provided in the high-voltage line for quick charging.

[0004] According to the structure of Patent Document 1, by switching the quick charging contactor to the on state, charging from the external charging device for the vehicle can be performed without switching the main contactor to the on state. Therefore, deterioration of the main contactor can be suppressed.

[0005] Prior Art Documents Patent Documents Patent Document 1: International Publication No. 2014 / 103707 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] If a contactor is switched to the on state in a state where there is a potential difference between both ends, an impact current is generated and deterioration occurs. Therefore, in the structure of Patent Document 1, there is a concern that an impact current is generated in the quick charging contactor when the quick charging contactor is switched to the on state, and thus the quick charging contactor deteriorates. Such a problem also occurs in other structures in which a relay is provided in a power path different from the power path to the electric motor for traveling.

[0008] An object of the present disclosure is to provide a technique that easily suppresses deterioration of a relay provided in a power path different from the power path to the electric motor for traveling.

[0009] Means for Solving the Problems

[0010] The vehicle power supply device of the present disclosure is used in a vehicle power supply system, which includes: a high-voltage battery; a common path supplied with power from the high-voltage battery; a first branch path branched from the common path; a motor for driving supplied with power based on the high-voltage battery via the first branch path; a power conversion unit connected to the first branch path and 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 relative to the power conversion unit; a second branch path branched from the common path; an exchange unit connected to the second branch path and exchanging power with the high-voltage battery; a second capacitor connected to the second branch path on the high-voltage battery side relative to the exchange unit; and a low-voltage battery. Among them, The vehicle power supply device includes: a first relay provided in the first branch path on the high-voltage battery side relative to the first capacitor; a second relay provided in the second branch path on the high-voltage battery side relative to the second capacitor; and a DCDC converter, The DCDC converter is provided between a first conduction path and the low-voltage battery, and steps down the voltage input from the first conduction path side and outputs it to the low-voltage battery side. The first conduction path is the electrical path between the first relay and the first capacitor in the first branch path. The DCDC converter is provided between a second conduction path and the low-voltage battery, and performs a boosting operation of stepping up the voltage input from the low-voltage battery side and supplies power to the second capacitor. The second conduction path is the electrical path between the second relay and the second capacitor in the second branch path.

[0011] Advantages of the Invention

[0012] The technology related to the present disclosure can easily suppress the deterioration of the relay provided in a power path different from the power path to the motor for driving. Brief Description of the Drawings

[0013] Figure 1 It is a circuit diagram schematically showing a vehicle power supply system including the vehicle power supply device of the first embodiment. Figure 2 It is an explanatory diagram schematically showing the state of supplying power from the DCDC converter to the first capacitor and the second capacitor in the first embodiment. Figure 3 It is a circuit diagram schematically showing a vehicle power supply system including the vehicle power supply device of the second embodiment. Figure 4 This is an explanatory diagram schematically showing the state of power supply from the DCDC converter to the second capacitor in the second embodiment. Figure 5 This is a circuit diagram of a vehicle power supply system including a vehicle power supply device according to the third embodiment. Figure 6 This is an explanatory diagram schematically showing the state of power supply from the DCDC converter to the first capacitor in the third embodiment. Figure 7 This is an explanatory diagram schematically showing the state of power supply from the DCDC converter to the second capacitor in the third embodiment. Detailed Embodiments

[0014] Hereinafter, embodiments of the present disclosure will be listed and exemplified.

[0015] 〔1〕A vehicle power supply device used in a vehicle power supply system, the vehicle power supply system including: a high-voltage storage battery; a common path supplied with power from the high-voltage storage battery; a first branch path branching from the common path; a motor for traveling supplied with power based on the high-voltage storage battery via the first branch path; a power conversion unit connected to the first branch path and converting power between the high-voltage storage battery and the motor; a first capacitor connected to the first branch path on the high-voltage storage battery side of the power conversion unit; a second branch path branching from the common path; a switching unit connected to the second branch path and exchanging power with the high-voltage storage battery; a second capacitor connected to the second branch path on the high-voltage storage battery side of the switching unit; and a low-voltage storage battery, wherein the vehicle power supply device includes: a first relay provided in the first branch path on the high-voltage storage battery side of the first capacitor; a second relay provided in the second branch path on the high-voltage storage battery side of the second capacitor; and a DCDC converter, the DCDC converter is provided between the first conductive path and the low-voltage storage battery, and steps down the voltage input from the first conductive path side and outputs it to the low-voltage storage battery side. The first conductive path is an electrical path between the first relay and the first capacitor in the first branch path. the DCDC converter is provided between the second conductive path and the low-voltage storage battery, and performs a boosting operation of boosting the voltage input from the low-voltage storage battery side and supplies power to the second capacitor. The second conductive path is an electrical path between the second relay and the second capacitor in the second branch path.

[0016] The above vehicle power supply device can be switched to the on state by the second relay, and can exchange power between the high-voltage battery and the switching unit without switching the first relay to the on state. Therefore, it is possible to suppress the deterioration of the first relay caused by switching the first relay to the on state. Moreover, the above vehicle power supply device can pre-charge the second capacitor by using the DCDC converter used in the charging of the low-voltage battery. Therefore, the above vehicle power supply device can suppress the inrush current generated when the second relay is switched to the on state and suppress the deterioration of the second relay. That is, the above vehicle power supply device can easily suppress the deterioration of the second relay provided in a power path different from the power path to the driving motor.

[0017] 〔2〕In the vehicle power supply device described in 〔1〕, the DCDC converter has a structure in which the voltage boosted by the boosting operation is applied to the high-voltage side conduction path. The high-voltage side conduction path is connected to the first conduction path via a third conduction path and is connected to the second conduction path via a fourth conduction path. The vehicle power supply device further includes a switch unit provided in the third conduction path.

[0018] When the switch unit is in the on state, the above vehicle power supply device can supply power from the high-voltage battery to the low-voltage battery via the third conduction path and the DCDC converter. In addition, when supplying the power from the DCDC converter to the second capacitor via the fourth conduction path, by previously setting the switch unit to the off state, it is possible to prevent the power from the DCDC converter from being supplied to the first conduction path. Therefore, when pre-charging the second capacitor, the above vehicle power supply device can prevent the power from the DCDC converter from being consumed by the first capacitor and can avoid delaying the charging speed of the second capacitor.

[0019] 〔3〕In the vehicle power supply device described in 〔2〕, the vehicle power supply device includes a second switch unit provided in the fourth conduction path. When the DCDC converter performs the boosting operation in a state where the switch unit is in the on state and the second switch unit is in the off state, power from the DCDC converter is supplied only to the first capacitor among the first capacitor and the second capacitor. When the DCDC converter performs the boosting operation in a state where the switch unit is in the off state and the second switch unit is in the on state, power from the DCDC converter is supplied only to the second capacitor among the first capacitor and the second capacitor.

[0020] The above vehicle power supply device can selectively supply power from the DCDC converter to the first capacitor and the second capacitor.

[0021] 〔4〕In the vehicle power supply device described in 〔3〕, the vehicle power supply device includes a control unit that controls the first relay, the second relay, the switch unit, the second switch unit, and the DCDC converter. When the condition for precharging both the first capacitor and the second capacitor is satisfied, the control unit precharges the first capacitor by causing the DCDC converter to perform the boosting operation while controlling the switch unit to the on state and the second switch unit to the off state. After precharging the first capacitor, the first relay is switched to the on state. Then, the second switch unit is switched to the on state after switching the first relay to the on state, and the DCDC converter performs the boosting operation to precharge the second capacitor. After precharging the second capacitor, the second relay is switched to the on state.

[0022] When the condition for precharging both the first capacitor and the second capacitor is satisfied, the above vehicle power supply device can give priority to the precharging of the first capacitor. Therefore, the above vehicle power supply device can easily advance the start of power supply via the first branch circuit, and further, can easily advance the start of driving of the motor.

[0023] 〔5〕In the vehicle power supply device described in any one of 〔1〕 to 〔3〕, the vehicle power supply device includes a control unit that controls the DCDC converter. When the condition for precharging both the first capacitor and the second capacitor is satisfied, the control unit causes the DCDC converter to perform the boosting operation to precharge both the first capacitor and the second capacitor at the same time.

[0024] When the condition for precharging both the first capacitor and the second capacitor is satisfied, the above vehicle power supply device can use the DCDC converter used for charging the low-voltage battery to precharge both the first capacitor and the second capacitor at the same time.

[0025] 〔6〕In the vehicle power supply device described in any one of 〔1〕 to 〔5〕, the vehicle power supply device includes a precharging circuit that forms a structure in which a precharging relay and a resistor portion are connected in series. The pre-charge circuit is provided only in parallel with the first relay among the first relay and the second relay, and pre-charges the first capacitor based on the power from the high-voltage storage battery when the pre-charge relay is in the on state.

[0026] By switching the pre-charge relay to the on state, the above vehicle power supply device can pre-charge the first capacitor more quickly than pre-charging by a DCDC converter. Moreover, the above vehicle power supply device can pre-charge the second capacitor using the DCDC converter without providing a pre-charge circuit for the second relay.

[0027] <First Embodiment>

[0028] 1. Structure of Vehicle Power Supply System 100

[0029] Figure 1 Fig. shows a vehicle power supply system 100 including a vehicle power supply device 10. The vehicle power supply system 100 is used in a vehicle (not shown). The vehicle can be an electric vehicle, a fuel cell vehicle, or a hybrid vehicle.

[0030] The vehicle power supply system 100 includes a high-voltage storage 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.

[0031] The high-voltage storage battery 40 can be a lithium-ion storage battery, a lead storage battery, or other storage batteries. The voltage when the high-voltage storage battery 40 is fully charged can be, for example, 400V, 800V, or other voltages.

[0032] The common path 41 is an electrical path to which power from the high-voltage storage battery 40 is supplied. The common path 41 is connected to the high-voltage storage battery 40. The common path 41 includes a positive-side common line 41A and a negative-side common line 41B. The positive-side common line 41A is connected to the positive electrode of the high-voltage storage battery 40. The negative-side common line 41B is connected to the negative electrode of the high-voltage storage battery 40. The negative-side common line 41B is connected to ground (not shown). The output voltage of the high-voltage storage battery 40 is applied to the common path 41 (more specifically, the positive-side common line 41A). In addition, in this specification, the voltage refers to the voltage with the potential of the negative-side common line 41B as the reference, that is, the voltage with the potential of the ground as the reference.

[0033] The first branch path 42 is an electrical path branched from the common path 41. The first branch path 42 includes a first positive-side branch line 42A branched from the positive-side common line 41A and a first negative-side branch line 42B branched from the negative-side common line 41B.

[0034] The power conversion unit 44 is connected to the first branch circuit 42. The power conversion unit 44 converts electric power between the high-voltage battery 40 and the electric motor 43. In the present embodiment, the power conversion unit 44 has a function of converting DC power supplied from the high-voltage battery 40 side into AC power and supplying it to the electric motor 43. In the present embodiment, the power conversion unit 44 is an inverter.

[0035] The first capacitor 45 is connected to the first branch circuit 42 on the side of the high-voltage battery 40 with respect to 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 circuit 42 between the high-voltage battery 40 and the power conversion unit 44.

[0036] The vehicle power supply system 100 includes a second branch circuit 50, a switching unit 51, a second capacitor 52, a low-voltage battery 53, and a low-voltage load 54.

[0037] The second branch circuit 50 is an electrical path branched from the common path 41. The second branch circuit 50 includes a second positive-side branch line 50A branched from the positive-side common line 41A and a second negative-side branch line 50B branched from the negative-side common line 41B.

[0038] The switching unit 51 is connected to the second branch circuit 50. The switching unit 51 exchanges electric power with the high-voltage battery 40. Here, the so-called "exchange" means supplying at least one of the electric power based on the high-voltage battery 40 to the switching unit 51 and supplying the electric power based on the switching unit 51 to the high-voltage battery 40. The switching unit 51 can be, for example, an electrical device using V2X (Vehicle to Everything: vehicle networking) communication. The switching unit 51 can be an in-vehicle device or an out-of-vehicle electrical device. More specifically, the switching unit 51 can be an on-board charger (e.g., On Board Charger) or an off-board charger (e.g., Off Board Charger). When the switching unit 51 is an in-vehicle device, the entire vehicle power supply system 100 is mounted on the vehicle. When the switching unit 51 is an out-of-vehicle electrical device, the structure of the vehicle power supply system 100 other than the switching unit 51 is mounted on the vehicle.

[0039] The second capacitor 52 is connected to the second branch circuit 50 on the side of the high-voltage battery 40 with respect to the switching 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 circuit 50 between the high-voltage battery 40 and the switching unit 51.

[0040] The low-voltage battery 53 is a battery whose fully charged voltage is lower than that of the high-voltage battery 40. The low-voltage battery 53 can be a lithium-ion battery, a lead battery, or other batteries. The fully charged voltage of the low-voltage battery 53 can be, for example, 12V, or other voltages.

[0041] The low-voltage load 54 is an in-vehicle electrical device. The low-voltage load 54 is driven, for example, based on the power from the low-voltage battery 53. The low-voltage load 54 can also include a starting motor, an alternator, an electric power steering system, an electric parking brake, lighting, a wiper drive unit, a navigation device, etc.

[0042] 2. Structure of the vehicle power supply device 10

[0043] The vehicle power supply device 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 DCDC converter 15, a pre-charge circuit 16, and a control unit 17.

[0044] The first positive-side relay 11 and the first negative-side relay 12 are an example of the first relay. The first positive-side relay 11 is disposed on the first positive-side branch line 42A on the high-voltage battery 40 side relative to the first capacitor 45. The first negative-side relay 12 is disposed on the first negative-side branch line 42B on the high-voltage battery 40 side relative to the first capacitor 45.

[0045] The second positive-side relay 13 and the second negative-side relay 14 are an example of the second relay. The second positive-side relay 13 is disposed on the second positive-side branch line 50A on the high-voltage battery 40 side relative to the second capacitor 52. The second negative-side relay 14 is disposed on the second negative-side branch line 50B on the high-voltage battery 40 side relative to the second capacitor 52.

[0046] 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 are all mechanical relays and have contacts. 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 are all in a state where the contacts are closed in the on state and in a state where the contacts are open in the off state.

[0047] The electrical path between the first positive-side relay 11 and the first capacitor 45 in the first branch path 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 path 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.

[0048] The electrical path between the second positive-side relay 13 and the second capacitor 52 in the second branch path 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 path 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 the second conductive path.

[0049] The DCDC converter 15 is provided between the first positive-side conductive wire 61 and the first negative-side conductive wire 62 and the low-voltage battery 53. The DCDC converter 15 performs the following step-down operation: stepping down the voltage input from the first positive-side conductive wire 61 and the first negative-side conductive wire 62 side and outputting it to the low-voltage battery 53 side. In addition, the DCDC converter 15 performs the following boost operation: stepping up the voltage input from the low-voltage battery 53 side and outputting it to the first positive-side conductive wire 61 and the first negative-side conductive wire 62 side.

[0050] The DCDC converter 15 is provided between the second positive-side conductive wire 63 and the second negative-side conductive wire 64 and the low-voltage battery 53. The DCDC converter 15 performs the following step-down operation: stepping down the voltage input from the second positive-side conductive wire 63 and the second negative-side conductive wire 64 side and outputting it to the low-voltage battery 53 side. In addition, the DCDC converter 15 performs the following boost operation: stepping up the voltage input from the low-voltage battery 53 side and outputting it to the second positive-side conductive wire 63 and the second negative-side conductive wire 64 side.

[0051] In the step-down operation, the DCDC 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).

[0052] During the boost operation, the DCDC converter 15 boosts the voltage applied to the positive low-voltage side wire 67 (more specifically, between the positive low-voltage side wire 67 and the negative low-voltage side wire 68) and applies it to the positive high-voltage side wire 65 (more specifically, between the positive high-voltage side wire 65 and the negative high-voltage side wire 66).

[0053] The positive high-voltage side wire 65 and the negative high-voltage side wire 66 are examples of a high-voltage side conduction path. The positive high-voltage side wire 65 is connected to the first positive side wire 61 and the second positive side wire 63. The negative high-voltage side wire 66 is connected to the first negative side wire 62 and the second negative side wire 64. The positive high-voltage side wire 65 is short-circuited to the first capacitor 45 (more specifically, one end of the first capacitor 45) via the first positive side wire 61 and short-circuited to the second capacitor 52 (more specifically, one end of the second capacitor 52) via the second positive side wire 63. The negative high-voltage side 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 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 wire 64. Therefore, when the DCDC converter 15 performs a boost operation, power is supplied from the DCDC converter 15 to the first capacitor 45 and the second capacitor 52. That is, the DCDC converter 15 can pre-charge the first capacitor 45 and the second capacitor 52.

[0054] The positive low-voltage side wire 67 and the negative low-voltage side wire 68 are examples of a low-voltage side conduction path. The positive low-voltage side wire 67 is connected to the positive electrode of the low-voltage battery 53 and one end of the low-voltage load 54. The negative low-voltage side wire 68 is connected to the negative electrode of the low-voltage battery 53 and the other end of the low-voltage load 54.

[0055] The pre-charge circuit 16 is configured by connecting the pre-charge relay 20 and the resistor section 21 in series. The pre-charge circuit 16 is provided in parallel with the first positive side relay 11. The pre-charge circuit 16 is provided in parallel only with the first positive side relay 11 among 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. One end of the pre-charge circuit 16 is short-circuited to the positive electrode of the high-voltage battery 40. The other end of the pre-charge circuit 16 is short-circuited to one end of the first capacitor 45 and short-circuited to one end of the second capacitor 52. When the pre-charge relay 20 is in the ON state, power from the high-voltage battery 40 is supplied to the first capacitor 45 and the second capacitor 52 via the pre-charge circuit 16. That is, when the pre-charge relay 20 is in the ON state, the pre-charge circuit 16 pre-charges the first capacitor 45 and the second capacitor 52 based on the power from the high-voltage battery 40.

[0056] 3. Structure of Control Unit 17

[0057] The control unit 17 is configured to include an integrated circuit such as an MCU (Micro Controller Unit). The control unit 17 includes a processing unit such as a CPU, and storage units such as a ROM and a RAM. The control unit 17 controls the first positive-side relay 11, the first negative-side relay 12, the second positive-side relay 13, the second negative-side relay 14, the pre-charge relay 20, and the DCDC converter 15.

[0058] The control unit 17 can pre-charge the first capacitor 45 and the second capacitor 52 using the pre-charge circuit 16. The control unit 17 supplies power from the high-voltage battery 40 to the first capacitor 45 and the second capacitor 52 via the pre-charge circuit 16 by switching the first negative-side relay 12 and the pre-charge relay 20 to the on state. Thereby, the first capacitor 45 and the second capacitor 52 are pre-charged. According to this structure, compared with the case of pre-charging using the DCDC converter 15, the voltages of the first capacitor 45 and the second capacitor 52 can rise rapidly. However, in this case, the rising speed of the voltages of the first capacitor 45 and the second capacitor 52 decreases as they approach the voltage of the high-voltage battery 40. If the first positive-side relay 11 is switched to the on state while there is a potential difference across the first positive-side relay 11, a large inrush current flows through the first positive-side relay 11, leading to deterioration of the first positive-side relay 11.

[0059] The control unit 17 can pre-charge the first capacitor 45 and the second capacitor 52 using the DCDC converter 15. The control unit 17 supplies power based on the low-voltage battery 53 to the first capacitor 45 and the second capacitor 52 by causing the DCDC converter 15 to perform a boosting operation. Thereby, the first capacitor 45 and the second capacitor 52 are pre-charged. According to this structure, the voltages of the first capacitor 45 and the second capacitor 52 can be raised to the same voltage as that of the high-voltage battery 40. Therefore, it is easy to suppress the deterioration of the relays when switching 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 the on state.

[0060] When the condition for pre-charging the first capacitor 45 is satisfied, for example, the pre-charging relay 20 and the first negative-side relay 12 are switched to the on state to pre-charge 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 the pre-charging relay 20 to the off state. Thereby, the power from the high-voltage battery 40 is supplied to the power conversion unit 44. In addition, the power conversion unit 44 is controlled by the control unit 17 or other control devices to perform a power conversion operation, whereby AC power is generated in the power conversion unit 44 and this AC power is supplied to the motor 43. Further, the condition for pre-charging the first capacitor 45 can be, for example, the condition for starting the drive of the motor 43 or the condition that the start switch of the vehicle is switched to the on state. The control unit 17 is configured to receive from the outside a signal capable of determining the on / off state of the start switch and determine the on / off state of the start switch based on this signal. The start switch is a power switch in the case of an electric vehicle or a fuel cell vehicle and an ignition switch in the case of a hybrid vehicle. In addition, as a method for determining that the voltage of the first capacitor 45 has risen to a certain extent, it can be determined that the voltage of the first capacitor 45 exceeds a specified value, it can be determined that the potential difference across the first positive-side relay 11 is less than the specified value, it can be determined that the value of the current flowing through the pre-charging circuit 16 is less than the specified value, it can be determined that the pre-charging time has elapsed for a specified time, or it can be other methods.

[0061] When the condition for pre-charging the second capacitor 52 is satisfied, for example, the DCDC converter 15 is made to perform a boosting operation to pre-charge 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 extent, 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 switching unit 51 are electrically connected, and a state where power can be exchanged between them is established. According to this configuration, it is possible to establish a state where power can be exchanged between the high-voltage battery 40 and the switching 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, it is possible to suppress deterioration of the first positive-side relay 11 caused by switching the first positive-side relay 11 to the on state. In addition, the condition for pre-charging the second capacitor 52 can be, for example, the condition for starting the operation of the switching unit 51, or other conditions. Further, the condition for pre-charging the second capacitor 52 can be the same as the condition for pre-charging the first capacitor 45, or different conditions. Additionally, as a method for determining that the voltage of the second capacitor 52 has risen to a certain extent, it can be determined that the voltage of the second capacitor 52 exceeds a specified value, or it can be determined that the potential difference across the second positive-side relay 13 or the second negative-side relay 14 is less than the specified value, or it can be determined that the value of the current flowing through the second positive-side wire 63 is less than the specified value, or it can be determined that the pre-charging time has elapsed for a specified time, or other methods.

[0062] 4. Example of Effect

[0063] By switching the second positive-side relay 13 and the second negative-side relay 14 to the on state, the vehicle power supply device 10 can exchange power between the high-voltage battery 40 and the switching unit 51 without switching the first positive-side relay 11 to the on state. Therefore, it is possible to suppress deterioration of the first positive-side relay 11 caused by switching the first positive-side relay 11 to the on state. Moreover, the vehicle power supply device 10 can pre-charge the second capacitor 52 using the DCDC converter 15 used for charging the low-voltage battery 53. Therefore, the vehicle power supply device 10 can suppress the inrush current generated when the second positive-side relay 13 is switched to the on state and suppress deterioration of the second positive-side relay 13. That is, the vehicle power supply device 10 can easily suppress deterioration of the second positive-side relay 13 provided in a power path different from the power path to the traveling motor 43.

[0064] When the conditions for pre-charging both the first capacitor 45 and the second capacitor 52 are satisfied, the vehicle power supply device 10 can use the DCDC converter 15 used for charging the low-voltage battery 53 to pre-charge both the first capacitor 45 and the second capacitor 52 at the same time.

[0065] By switching the pre-charge relay 20 to the ON state, the vehicle power supply device 10 can pre-charge the first capacitor 45 more quickly than the pre-charge performed by the DCDC converter 15. Moreover, the vehicle power supply device 10 can pre-charge the second capacitor 52 using the DCDC converter 15 without providing a pre-charge circuit for the second positive-side relay 13.

[0066] <Second Embodiment>

[0067] In the second embodiment, a structure that can cut off the flow of current from the DCDC converter to the first capacitor when pre-charging the second capacitor using the DCDC converter will be described. In addition, the same reference numerals are assigned to the same structures as those in the first embodiment, and detailed descriptions thereof are omitted.

[0068] As Figure 3 shown, 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 43 for driving, a power conversion unit 44, a first capacitor 45, a second branch path 50, a switching unit 51, a second capacitor 52, a low-voltage battery 53, a low-voltage load 54, and a vehicle power supply device 210.

[0069] The vehicle power supply device 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 DCDC converter 15, a pre-charge circuit 16, a control unit 17, a positive-side switch unit 71, and a negative-side switch unit 72.

[0070] During the step-down operation, the DCDC converter 15 steps down the voltage applied to the positive high-voltage side wire 265 (more specifically, between the positive high-voltage side wire 265 and the negative high-voltage side wire 266) and applies it to the positive low-voltage side wire 67 (more specifically, between the positive low-voltage side wire 67 and the negative low-voltage side wire 68).

[0071] During the boost operation, the DCDC converter 15 steps up the voltage applied to the positive low-voltage side wire 67 (more specifically, between the positive low-voltage side wire 67 and the negative low-voltage side wire 68) and applies it to the positive high-voltage side wire 265 (more specifically, between the positive high-voltage side wire 265 and the negative high-voltage side wire 266).

[0072] The positive high-voltage side conductive wire 265 and the negative high-voltage side conductive wire 266 are examples of the high-voltage side conductive path. The positive high-voltage side conductive wire 265 is connected to the first positive-side conductive wire 61 via a third positive-side conductive wire 81 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 a fourth positive-side conductive wire 83 branched from the positive high-voltage side conductive wire 265. The third positive-side conductive wire 81 is an example of a third conductive path. The fourth positive-side conductive wire 83 is an example of a fourth conductive path. The positive high-voltage side conductive wire 265 is short-circuited with 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 with 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.

[0073] The negative high-voltage side conductive wire 266 is connected to the first negative-side conductive wire 62 via a third negative-side conductive wire 82 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 a fourth negative-side conductive wire 84 branched from the negative high-voltage side conductive wire 266. The third negative-side conductive wire 82 is an example of a third conductive path. The fourth negative-side conductive wire 84 is an example of a fourth conductive path. The negative high-voltage side conductive wire 266 is short-circuited with 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 with 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.

[0074] The positive-side switch unit 71 and the negative-side switch unit 72 are examples of the switch unit. The positive-side switch unit 71 is provided on the third positive-side conductive wire 81. The negative-side switch unit 72 is provided on the third negative-side conductive wire 82. The positive-side switch unit 71 and the negative-side switch unit 72 can be configured to respectively include a mechanical switch having contacts, or can be configured to include a semiconductor switch. The positive-side switch unit 71 and the negative-side switch unit 72 respectively allow the flow of bidirectional current in the on state and cut off the flow of bidirectional current in the off state.

[0075] When the DCDC converter 15 performs a boosting operation in a state where both the positive-side switch unit 71 and the negative-side switch unit 72 are in the on state, power is supplied from the DCDC converter 15 to the first capacitor 45 and the second capacitor 52. That is, the DCDC converter 15 can pre-charge the first capacitor 45 and the second capacitor 52 at the same time.

[0076] When the DCDC converter 15 performs a boosting operation while the positive-side switch unit 71 and the negative-side switch unit 72 are in the off state, power is supplied from the DCDC converter 15 to the second capacitor 52. That is, the DCDC converter 15 can pre-charge only the second capacitor 52 among the first capacitor 45 and the second capacitor 52.

[0077] The control unit 17 controls the positive-side switch unit 71 and the negative-side switch unit 72. When the condition for charging the low-voltage battery 53 is satisfied, for example, 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 are controlled to the on state, and the DCDC converter 15 performs a bucking operation, thereby charging the low-voltage battery 53 based on the power of the high-voltage battery 40.

[0078] The control unit 17, for example, controls the positive-side switch unit 71 and the negative-side switch unit 72 to the on state and causes the DCDC converter 15 to perform a boosting operation, whereby power can be supplied from the DCDC 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, for example, 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 the on state. Thereby, power is supplied from the high-voltage battery 40 to the power conversion unit 44 via the first branch path 42, and the high-voltage battery 40 and the exchange unit 51 are brought into a state where power can be exchanged 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 is possible to determine that the voltage of the second capacitor 52 exceeds a specified value, or it is possible to determine that the potential difference across the second positive-side relay 13 or the second negative-side relay 14 is less than the specified value, or it is possible to determine that the value of the current flowing through the second positive-side wire 63 is less than the specified value, or it is possible to determine that the pre-charging time has elapsed for a specified time, or it may be other methods.

[0079] When the condition for pre-charging the second capacitor 52 is satisfied, the control unit 17, as Figure 4As shown, for example, the positive-side switch unit 71 and the negative-side switch unit 72 are controlled to be in the off state, and the DCDC converter 15 is caused to perform a boosting operation, whereby power is supplied from the DCDC converter 15 to the second capacitor 52. Thus, only the second capacitor 52 among the first capacitor 45 and the second capacitor 52 is pre-charged. When the voltage of the second capacitor 52 has risen to a certain extent, the control unit 17 switches the second positive-side relay 13 and the second negative-side relay 14 to the on state. Thus, the high-voltage storage battery 40 and the switching unit 51 are electrically connected, and a state where power can be exchanged therebetween is established. According to this configuration, it is possible to establish a state where power can be exchanged between the high-voltage storage battery 40 and the switching unit 51 without switching the first positive-side relay 11 to the on state. Therefore, it is possible to suppress deterioration of the first positive-side relay 11 caused by switching the first positive-side relay 11 to the on state.

[0080] As described above, the vehicle power supply device 210 of the second embodiment can supply power from the high-voltage storage battery 40 to the low-voltage storage battery 53 via the third positive-side wire 81 and the DCDC converter 15 when the positive-side switch unit 71 and the negative-side switch unit 72 are in the on state. In addition, when the vehicle power supply device 210 supplies the power from the DCDC converter 15 to the second capacitor 52 via the fourth positive-side wire 83, by previously setting the positive-side switch unit 71 and the negative-side switch unit 72 to the off state, it is possible to prevent the power from the DCDC converter 15 from being supplied to the first positive-side wire 61. Therefore, when pre-charging the second capacitor 52, the vehicle power supply device 210 can prevent the power from the DCDC converter 15 from being consumed by the first capacitor 45 and can avoid causing a delay in the charging speed of the second capacitor 52.

[0081] <Third Embodiment>

[0082] In the third embodiment, a configuration capable of selectively pre-charging the first capacitor and the second capacitor using a DCDC converter will be described. In addition, the same reference numerals are assigned to the same configurations as those in the second embodiment, and detailed descriptions thereof are omitted.

[0083] As Figure 5 As shown, the vehicle power supply system 300 of the third embodiment includes a high-voltage storage battery 40, a common path 41, a first branch path 42, a motor 43 for traveling, a power conversion unit 44, a first capacitor 45, a second branch path 50, a switching unit 51, a second capacitor 52, a low-voltage storage battery 53, a low-voltage load 54, and a vehicle power supply device 310.

[0084] The vehicle power supply device 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 DCDC 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.

[0085] The second positive-side switch unit 73 and the second negative-side switch unit 74 are an example of the second switch unit. The second positive-side switch unit 73 is provided on the fourth positive-side wire 83. The second negative-side switch unit 74 is provided on the fourth negative-side wire 84. The second positive-side switch unit 73 and the second negative-side switch unit 74 can be configured to respectively include a mechanical switch having contacts or can be configured to include semiconductor switches. The second positive-side switch unit 73 and the second negative-side switch unit 74 allow the flow of bidirectional current when in the on state and cut off the flow of bidirectional current when in the off state.

[0086] When the DCDC converter 15 performs a boosting operation in a state where both the positive-side switch unit 71 and the negative-side switch unit 72 are in the on state and the second positive-side switch unit 73 and the second negative-side switch unit 74 are in the off state, as Figure 6 shown, power is supplied from the DCDC converter 15 only to the first capacitor 45 among the first capacitor 45 and the second capacitor 52.

[0087] When the DCDC converter 15 performs a boosting operation in a state where the positive-side switch unit 71 and the negative-side switch unit 72 are in the off state and both the second positive-side switch unit 73 and the second negative-side switch unit 74 are in the on state, as Figure 7 shown, power is supplied from the DCDC converter 15 only to the second capacitor 52 among the first capacitor 45 and the second capacitor 52.

[0088] The control unit 17 controls the second positive-side switch unit 73 and the second negative-side switch unit 74. When the condition for pre-charging the first capacitor 45 is satisfied, the control unit 17 performs a first control that controls the positive-side switch unit 71 and the negative-side switch unit 72 to be in the on state and controls the second positive-side switch unit 73 and the second negative-side switch unit 74 to be in the off state. Thereby, power from the DCDC converter 15 is supplied only to the first capacitor 45 among the first capacitor 45 and the second capacitor 52. That is, only the first capacitor 45 among the first capacitor 45 and the second capacitor 52 is pre-charged.

[0089] When the condition for precharging the second capacitor 52 is satisfied, the control unit 17 executes second control that 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. Thereby, the power from the DCDC converter 15 is supplied only to the second capacitor 52 among the first capacitor 45 and the second capacitor 52. That is, only the second capacitor 52 among the first capacitor 45 and the second capacitor 52 is precharged.

[0090] When the condition for precharging both the first capacitor 45 and the second capacitor 52 is satisfied, the control unit 17 executes first control to precharge the first capacitor 45. After precharging the first capacitor 45, the control unit 17 switches the first positive-side relay 11 and the first negative-side relay 12 to the on state. For example, 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 and the first negative-side relay 12 to the on state. After switching the first positive-side relay 11 and the first negative-side relay 12 to the on state, the control unit 17 executes second control to precharge the second capacitor 52. After precharging the second capacitor 52, the control unit 17 switches the second positive-side relay 13 and the second negative-side relay 14 to the on state. For example, when the voltage of the second capacitor 52 has risen to a certain extent, the control unit 17 switches the second positive-side relay 13 and the second negative-side relay 14 to the on state. The condition for precharging both the first capacitor 45 and the second capacitor 52 may be, for example, that the start switch of the vehicle is switched to the on state, or may be other conditions.

[0091] As described above, the vehicle power supply device 310 of the third embodiment can selectively supply the power from the DCDC converter to the first capacitor 45 and the second capacitor 52. That is, the vehicle power supply device 310 can selectively precharge either the first capacitor 45 or the second capacitor 52 based on the power from the DCDC converter.

[0092] In addition, when the condition for precharging both the first capacitor 45 and the second capacitor 52 is satisfied, the vehicle power supply device 310 can give priority to the precharging of the first capacitor 45. Therefore, the vehicle power supply device 310 can easily advance the start of the power supply via the first branch path 42, and further can easily advance the start of driving of the motor 43.

[0093] <Other Embodiments>

[0094] The present disclosure is not limited to the embodiments described above with reference to the accompanying drawings. For example, the features of the above-described or later-described embodiments can be combined in their entirety within a non-contradictory range. In addition, any feature in the above-described or later-described embodiments can also be omitted as long as it is not explicitly stated as an essential feature. Moreover, the above-described embodiments can be modified as follows.

[0095] In the above-described third embodiment, the control unit 17 may also cause the DCDC converter 15 to perform a boosting operation to pre-charge both the first capacitor 45 and the second capacitor 52 at the same time when the condition for pre-charging both the first capacitor 45 and the second capacitor 52 is satisfied. That is, the control unit 17 may also 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 pre-charge both the first capacitor 45 and the second capacitor 52 at the same time based on the power from the DCDC converter 15.

[0096] In each of the above-described embodiments, the pre-charge circuit 16 may not be provided. In this case, the DCDC converter 15 can also be used to pre-charge the first capacitor 45 and the second capacitor 52.

[0097] In addition, it should be considered that the embodiments disclosed herein are illustrative in all respects and not restrictive. The scope of the present invention is not limited to the embodiments disclosed herein, and is intended to include all modifications within the scope shown by the claims or within the scope equivalent to the claims.

[0098] Reference Numeral Explanation 10… Vehicle power supply device 11… First positive-side relay (first relay) 12… First negative-side relay (first relay) 13… Second positive-side relay (second relay) 14… Second negative-side relay (second relay) 15… DCDC converter 16… Pre-charge circuit 17… Control unit 20… Pre-charge relay 21… Resistance unit 40… High-voltage storage battery 41… Common path 41A… Positive-side common line 41B… Negative-side common line 42… First branch path 42A… First positive-side branch line 42B… First negative-side branch line 43… Motor 44… Power conversion unit 45… First capacitor 50… Second branch circuit 50A… Second positive-side branch wire 50B… Second negative-side branch wire 51… Switching unit 52… Second capacitor 53… Low-voltage battery 54… Low-voltage load 61… First positive-side conducting wire (first conduction circuit) 62… First negative-side conducting wire (first conduction circuit) 63… Second positive-side conducting wire (second conduction circuit) 64… Second negative-side conducting wire (second conduction circuit) 65… Positive high-voltage side conducting wire (high-voltage side conduction circuit) 66… Negative high-voltage side conducting wire (high-voltage side conduction circuit) 67… Positive low-voltage side conducting wire (low-voltage side conduction circuit) 68… Negative low-voltage side conducting wire (low-voltage side conduction circuit) 71… Positive-side switch unit (switch unit) 72… Negative-side switch unit (switch unit) 73… Second positive-side switch unit (second switch unit) 74… Second negative-side switch unit (second switch unit) 81… Third positive-side conducting wire (third conduction circuit) 82… Third negative-side conducting wire (third conduction circuit) 83… Fourth positive-side conducting wire (fourth conduction circuit) 84… Fourth negative-side conducting wire (fourth conduction circuit) 100… Vehicle power supply system 200… Vehicle power supply device 210… Vehicle power supply device 265… Positive high-voltage side conducting wire (high-voltage side conduction circuit) 266… Negative high-voltage side conducting wire (high-voltage side conduction circuit) 310… Vehicle power supply device.

Claims

1. A power supply device for a vehicle, which is used in a vehicle power supply system. The vehicle power supply system includes: a high-voltage battery; a common path to which power from the high-voltage battery is supplied; a first branch path that branches from the common path ； a traveling motor that is supplied with power based on the high-voltage battery via the first branch path; a power conversion unit that is connected to the first branch path and converts power between the high-voltage battery and the motor; a first capacitor that is connected to the first branch path on the high-voltage battery side of the power conversion unit; a second branch path that branches from the common path; a switching unit that is connected to the second branch path and exchanges power with the high-voltage battery; a second capacitor that is connected to the second branch path on the high-voltage battery side of the switching unit; and a low-voltage battery, where the power supply device for a vehicle includes: a first relay that is provided in the first branch path on the high-voltage battery side of the first capacitor; a second relay that is provided in the second branch path on the high-voltage battery side of the second capacitor; and a DCDC converter, the DCDC converter is provided between a first conductive path and the low-voltage battery, and steps down the voltage input from the first conductive path side and outputs it to the low-voltage battery side. The first conductive path is the electrical path between the first relay and the first capacitor in the first branch path, the DCDC converter is provided between a second conductive path and the low-voltage battery, and performs a boosting operation of boosting the voltage input from the low-voltage battery side and supplies power to the second capacitor. The second conductive path is the electrical path between the second relay and the second capacitor in the second branch path.

2. The power supply device for a vehicle according to claim 1, wherein, the DCDC converter has a structure that applies the voltage boosted by the boosting operation to a 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, the power supply device for a vehicle further includes a switching unit that is provided in the third conductive path.

3. The power supply device for a vehicle according to claim 2, wherein, the power supply device for a vehicle includes a second switching unit that is provided in the fourth conductive path, when the DCDC converter performs the boosting operation in a state where the switching unit is in the on state and the second switching unit is in the off state, power from the DCDC converter is supplied only to the first capacitor among the first capacitor and the second capacitor, when the DCDC converter performs the boosting operation in a state where the switching unit is in the off state and the second switching unit is in the on state, power from the DCDC converter is supplied only to the second capacitor among the first capacitor and the second capacitor.

4. The power supply device for a vehicle according to claim 3, wherein, The vehicle power supply device includes a control unit that controls the first relay, the second relay, the switch unit, the second switch unit, and the DC-DC converter. When the condition for pre-charging both the first capacitor and the second capacitor is satisfied, the control unit pre-charges the first capacitor by causing the DC-DC converter to perform the boosting operation while controlling the switch unit to the on state and the second switch unit to the off state. After pre-charging the first capacitor, the first relay is switched to the on state. Then, after switching the first relay to the on state, the second switch unit is switched to the on state, and the DC-DC converter performs the boosting operation to pre-charge the second capacitor. After pre-charging the second capacitor, the second relay is switched to the on state.

5. The vehicle power supply device according to any one of claims 1 to 3, wherein, the vehicle power supply device includes a control unit that controls the DC-DC converter, when the condition for pre-charging both the first capacitor and the second capacitor is satisfied, the control unit causes the DC-DC converter to perform the boosting operation to pre-charge both the first capacitor and the second capacitor at the same time.

6. The vehicle power supply device according to any one of claims 1 to 4, wherein, the vehicle power supply device includes a pre-charge circuit that is configured by connecting a pre-charge relay and a resistor portion in series, the pre-charge circuit is provided only in parallel with the first relay among the first relay and the second relay, and pre-charges the first capacitor based on the power from the high-voltage battery when the pre-charge relay is in the on state.

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