Vehicle-mounted power supply device

Abstract

An in-vehicle power supply device (10) is used in an in-vehicle power supply system (100). A vehicle-mounted power supply system (100) is provided with: a battery (20); a power circuit (21) to which power from the battery (20) is supplied; and a capacitor (22) electrically connected to the power circuit (21). An in-vehicle power supply device (10) is provided with a first circuit (for example, a pre-charge circuit (60)) and a second circuit (for example, a relay circuit (50)). A first circuit (e.g., a pre-charge circuit 60) performs a pre-charge operation that pre-charges a capacitor (22). A second circuit (for example, a relay circuit (50)) has a configuration in which a plurality of relays (for example, a first relay (51)) are connected in parallel, the second circuit being provided in the power circuit (21) further toward the battery (20) side than the capacitor (22).

Description

Technical Field

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

[0002] In the battery system disclosed in Patent Document 1, after pre-charging by a pre-charge circuit, a relay that electrically connects a load device to a battery is closed. According to this configuration, an inrush current flowing into the relay when the relay is closed can be suppressed.

[0003] Prior Art Documents Patent Documents Patent Document 1: Japanese Unexamined Patent Application Publication No. 2020-78196 Summary of the Invention

[0004] Problems to be Solved by the Invention

[0005] However, even if the inrush current is suppressed, deterioration of the relay progresses by repeatedly turning the relay on and off. If the deterioration of the relay progresses, the relay eventually becomes unusable, and it is necessary to replace the device including the relay.

[0006] An object of the present disclosure is to provide a technique that easily enables a long life of a device including a relay.

[0007] Means for Solving the Problems

[0008] The vehicle-mounted power supply device of the present disclosure is used in a vehicle-mounted power supply system including: a storage battery; a power line supplied with power based on the storage battery; and a capacitor electrically connected to the power line. Among them, the vehicle-mounted power supply device includes: a first circuit that performs a pre-charging operation for pre-charging the capacitor; and a second circuit provided on the power line on the storage battery side relative to the capacitor, the second circuit forms a structure in which a plurality of relays are connected in parallel.

[0009] Effects of the Invention

[0010] The technique of the present disclosure easily enables a long life of a device including a relay. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a circuit diagram schematically showing a vehicle-mounted power supply system including the vehicle-mounted power supply device according to the first embodiment. Figure 2 is an explanatory diagram for explaining the operation of the vehicle-mounted power supply device when the first control is executed. Figure 3This is an explanatory diagram for explaining the operation of the in-vehicle power supply device when the second control is executed. Figure 4 This is an explanatory diagram for explaining the operation of the in-vehicle power supply device when the third control is executed. Figure 5 This is a circuit diagram schematically showing an in-vehicle power supply system including the in-vehicle power supply device according to the fourth embodiment. Detailed Embodiments

[0012] Hereinafter, embodiments of the present disclosure will be listed and exemplified.

[0013] 〔1〕An in-vehicle power supply device used in an in-vehicle power supply system, the in-vehicle power supply system including: a storage battery; a power line supplied with power based on the storage battery; and a capacitor electrically connected to the power line, wherein the in-vehicle power supply device includes: a first circuit that performs a pre-charging operation for pre-charging the capacitor; and a second circuit provided in the power line on the storage battery side of the capacitor, the second circuit forms a structure in which a plurality of relays are connected in parallel.

[0014] After pre-charging the capacitor using the first circuit, the above in-vehicle power supply device switches the relay to the on state, thereby being able to suppress the inrush current from flowing into the relay. Moreover, the above in-vehicle power supply device can selectively use any one of the plurality of relays. In addition, the above in-vehicle power supply device can suppress the inrush current flowing into each relay by switching the plurality of relays to the on state at the same time. Therefore, the above in-vehicle power supply device can easily achieve the long life of the device including the relay.

[0015] 〔2〕The in-vehicle power supply device according to 〔1〕, wherein the in-vehicle power supply device includes a control unit that controls the first circuit and the plurality of relays, the control unit executes a first control when a start condition for starting the charge and discharge of the storage battery is satisfied, and the first control causes the first circuit to perform the pre-charging operation, the control unit executes a second control when a first switching condition is satisfied during the execution of the first control, and the second control stops the pre-charging operation and switches a part of the relays to be switched among the plurality of relays to the on state, the control unit executes a third control when a second switching condition is satisfied during the execution of the second control, and the third control switches at least a part of the relays in the off state to the on state.

[0016] By switching only a part of the relays to the ON state in the second control, the in-vehicle power supply device can limit the relays through which inrush current flows to a part, and conduct the battery and the capacitor via the relays. In addition, when the battery and the capacitor are conducted via the relays, the in-vehicle power supply device switches at least a part of the relays in the OFF state to the ON state, thereby increasing the relays in the ON state. As a result, the in-vehicle power supply device can reduce the current flowing through each relay.

[0017] 〔3〕The in-vehicle power supply device according to 〔1〕, wherein the in-vehicle power supply device includes a control unit that controls the first circuit and the plurality of relays, when a start condition for starting charging and discharging of the battery is satisfied, the control unit causes the first circuit to perform the pre-charging operation, and when a switching condition is satisfied during the pre-charging operation, the control unit stops the pre-charging operation and switches two or more of the relays to be switched to the ON state at the same time.

[0018] By switching two or more relays to the ON state at the same time, the in-vehicle power supply device can suppress the inrush current flowing through each relay.

[0019] 〔4〕The in-vehicle power supply device according to 〔2〕 or 〔3〕, wherein when the relay to be switched is a part of the plurality of relays, the control unit selects the relay to be switched in a predetermined order.

[0020] Since the in-vehicle power supply device selects the relays to be switched in a predetermined order, it is easy to deteriorate each relay evenly.

[0021] 〔5〕The in-vehicle power supply device according to 〔2〕 or 〔3〕, wherein when the relay to be switched is a part of the plurality of relays, the control unit determines and compares the deterioration degrees of the respective relays, and selects the relay to be switched based on the comparison result.

[0022] The in-vehicle power supply device can reflect the comparison result of the deterioration degree in the selection of the relay to be switched.

[0023] 〔6〕The in-vehicle power supply device according to 〔5〕, wherein the control unit selects the relay with the smallest deterioration degree as the relay to be switched.

[0024] The above-mentioned in-vehicle power supply device is likely to cause each relay to deteriorate evenly, so that the long life of the device including the relay can be realized more reliably.

[0025] 〔7〕The in-vehicle power supply device according to 〔5〕 or 〔6〕, wherein As the determination of the degree of deterioration, the control unit measures the resistance value in the on-state for each of the relays.

[0026] The above-mentioned in-vehicle power supply device can use the resistance value in the on-state of each relay as the degree of deterioration.

[0027] <First Embodiment>

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

[0029] Shown in Figure 1 is an in-vehicle power supply system 100 including an in-vehicle power supply device 10. The in-vehicle power supply system 100 is used in a vehicle (not shown). The vehicle can be an electric vehicle, a motor vehicle, or a hybrid vehicle. In addition to the in-vehicle power supply device 10, the in-vehicle power supply system 100 further includes a storage battery 20, a power line 21, and a capacitor 22.

[0030] The storage battery 20 can be a lithium-ion storage battery, a lead storage battery, or other storage batteries.

[0031] The power line 21 is an electrical path for supplying power based on the storage battery 20. The power line 21 has a positive-side power line 30 and a negative-side power line 31. The positive-side terminal of the storage battery 20 is electrically connected to the positive-side power line 30. The negative-side terminal of the storage battery 20 is electrically connected to the negative-side power line 31. The negative-side power line 31 is electrically connected to the ground. The output voltage of the storage battery 20 is applied to the power line 21 (more specifically, the positive-side power line 30). In addition, in this specification, the voltage refers to the potential difference with the ground potential as the reference, and refers to the potential difference with the negative-side power line 31 as the reference.

[0032] The capacitor 22 is electrically connected to the power line 21. The capacitor 22 is provided between the positive-side power line 30 and the negative-side power line 31. One end of the capacitor 22 is electrically connected to the positive-side power line 30. The other end of the capacitor 22 is electrically connected to the negative-side power line 31. Power based on the storage battery 20 is supplied to the capacitor 22 via the power line 21. The capacitor 22 smoothes the voltage based on the storage battery 20.

[0033] In the present embodiment, the capacitor 22 is configured to be provided as a part of the drive unit 40 of the in-vehicle power supply system 100. In addition to the capacitor 22, the drive unit 40 includes an inverter 41 and a motor 42. The capacitor 22 is provided on the side closer to the battery 20 than the inverter 41. The capacitor 22 smoothes the voltage based on the battery 20 and supplies it to the inverter 41. The inverter 41 is electrically connected to the power line 21. The inverter 41 generates an AC voltage (e.g., three-phase AC) based on the DC voltage based on the voltage supplied from the battery 20 and supplies it to the motor 42. The motor 42 is, for example, a main system motor. The motor 42 is a device that rotates based on the power supplied from the battery 20 and imparts a rotational force to the wheels of the vehicle.

[0034] The in-vehicle power supply device 10 is used in the in-vehicle power supply system 100. The in-vehicle power supply device 10 includes a relay circuit 50, a pre-charge circuit 60, and a second relay 70.

[0035] The relay circuit 50 is an example of the "second circuit". The relay circuit 50 forms a structure in which a plurality of first relays 51 (more specifically, first relays 51A, 51B, 51C) are connected in parallel. The first relay 51 is an example of the "relay". The first relay 51 is a system main relay. The first relay 51 is a mechanical relay. The first relay 51 has contacts.

[0036] The ends of the plurality of first relays 51 on the battery 20 side are short-circuited to each other. The ends of the plurality of first relays 51 on the side opposite to the battery 20 side are short-circuited to each other. One end of each first relay 51 is electrically connected to the positive electrode of the battery 20 and is short-circuited to the positive electrode of the battery 20. The other end of each first relay 51 is electrically connected to one end of the capacitor 22 and is short-circuited to one end of the capacitor 22. The relay circuit 50 cuts off the flow of current from the battery 20 to the capacitor 22 via the relay circuit 50 when all the first relays 51 are in the off state. The relay circuit 50 conducts the positive electrode of the battery 20 and one end of the capacitor 22 when at least one of the first relays 51 is in the on state. The relay circuit 50 allows current to flow from the battery 20 to the capacitor 22 via the relay circuit 50 when at least one of the first relays 51 is in the on state.

[0037] The above-mentioned positive electrode side power line 30 includes: a first positive electrode side power line 32 provided on the battery 20 side with respect to the relay circuit 50; and a second positive electrode side power line 33 provided on the side opposite to the battery 20 side with respect to the relay circuit 50.

[0038] The precharge circuit 60 performs a precharge operation, and the precharge operation precharges the capacitor 22. The precharge circuit 60 is provided in parallel with respect to the relay circuit 50. One end of the precharge circuit 60 is electrically connected to the first positive-side power line 32 and is short-circuited with the first positive-side power line 32. The other end of the precharge circuit 60 is electrically connected to the second positive-side power line 33 and is short-circuited with the second positive-side power line 33. The precharge circuit 60 forms a structure in which the precharge relay 61 and the resistor section 62 are connected in series.

[0039] The precharge relay 61 is a mechanical relay. The precharge relay 61 has contacts. The resistor section 62 is constituted by a known resistor, for example.

[0040] The second relay 70 is provided in the power path 21 on the side of the battery 20 with respect to the capacitor 22. The second relay 70 is provided in the negative-side power line 31. One end of the second relay 70 is electrically connected to the negative-side terminal of the battery 20 and is short-circuited with the negative-side terminal of the battery 20. The other end of the second relay 70 is electrically connected to the other end of the capacitor 22 and is short-circuited with the other end of the capacitor 22. The second relay 70 is a system main relay. The second relay 70 is a mechanical relay. The second relay 70 has contacts.

[0041] 2. Structure of the control unit 71

[0042] The in-vehicle power supply device 10 includes a control unit 71, a current detection unit 72, an individual current detection unit 73, a first voltage detection unit 74, a second voltage detection unit 75, and a temperature detection unit 76.

[0043] The control unit 71 is configured to include a control circuit such as an integrated circuit, for example. The control unit 71 includes a processing unit such as a CPU, a storage unit such as a memory, an input / output unit, and the like.

[0044] The current detection unit 72 is configured as a known current sensor, for example. The current detection unit 72 detects the value of the current flowing through a path (more specifically, the negative-side power line 31) in the power path 21 other than the part where the relay circuit 50 and the precharge circuit 60 are connected in parallel. That is, when the current flows only through the relay circuit 50 among the relay circuit 50 and the precharge circuit 60, the current detection unit 72 detects the current flowing through the relay circuit 50. Further, when the current flows only through the precharge circuit 60 among the relay circuit 50 and the precharge circuit 60, the current detection unit 72 detects the current flowing through the precharge circuit 60. The current detection unit 72 outputs a signal capable of determining the detection value. The control unit 71 determines the value of the current flowing through the power path 21 (more specifically, the negative-side power line 31) based on the output signal of the current detection unit 72. The control unit 71 determines the current flowing through the precharge circuit 60 by determining the detection value when the precharge circuit 60 performs the precharge operation.

[0045] The individual current detection unit 73 is configured as a known current sensor, for example. The individual current detection unit 73 is provided separately for each of the first relays 51. Each individual current detection unit 73 detects the value of the current flowing through the corresponding first relay 51 when the corresponding first relay 51 is in the on state. Each individual current detection unit 73 outputs a signal capable of determining the detected value. The control unit 71 determines the value of the current flowing through each first relay 51 based on the output signals of the individual current detection units 73.

[0046] The first voltage detection unit 74 is configured as a known voltage detection circuit, for example. The first voltage detection unit 74 detects the potential difference across the relay circuit 50 (more specifically, the first relay 51). The first voltage detection unit 74 outputs a signal capable of determining the detected value. The control unit 71 determines the potential difference across the first relay 51 based on the output signal of the first voltage detection unit 74.

[0047] The second voltage detection unit 75 is configured as a known voltage detection circuit, for example. The second voltage detection unit 75 detects the voltage of the capacitor 22. The second voltage detection unit 75 outputs a signal capable of determining the detected value. The control unit 71 determines the voltage of the capacitor 22 based on the output signal of the second voltage detection unit 75.

[0048] The temperature detection unit 76 is configured as a known temperature sensor, for example. The temperature detection unit 76 is provided separately for each of the first relays 51. Each temperature detection unit 76 detects the temperature of the contact of the corresponding first relay 51. Each temperature detection unit 76 outputs a signal capable of determining the detected value. The control unit 71 determines the temperature of the contact of each first relay 51 based on the output signals of the temperature detection units 76.

[0049] The control unit 71 controls the relay circuit 50, the precharge circuit 60, and the second relay 70. That is, the control unit 71 controls the plurality of first relays 51, the precharge relay 61, and the second relay 70.

[0050] The control unit 71 performs the first control when the start condition for starting the charge and discharge of the storage battery 20 is satisfied. At the time when the start condition is satisfied, all of the first relays 51, the precharge relay 61, and the second relay 70 are in the off state. The first control is a control for causing the precharge circuit 60 to perform a precharge operation. More specifically, as Figure 2As shown, the first control is a control for switching the precharge relay 61 and the second relay 70 to the ON state while maintaining all the first relays 51 in the OFF state. In the state where the first control is performed, power from the storage battery 20 is supplied to the capacitor 22 via the precharge circuit 60. According to this configuration, the current flowing through the power path 21 is suppressed by the resistance portion 62 of the precharge circuit 60. Therefore, it is possible to increase the voltage of the capacitor 22 while suppressing damage to the first relay 51, the precharge relay 61, and the second relay 70. As the voltage of the capacitor 22 increases, the difference between the voltage of the capacitor 22 and the voltage of the storage battery 20 becomes smaller. As a result, the potential difference across the first relay 51 becomes smaller.

[0051] When the first switching condition is satisfied during the execution of the first control, the control unit 71 executes the second control. The second control is a control for stopping the precharge operation generated by the precharge circuit 60 and switching a part of the plurality of first relays 51, which are the switching targets, to the ON state. More specifically, as Figure 3 shown, the second control is the following control: while maintaining the second relay 70 in the ON state, the precharge relay 61 is switched to the OFF state, and the first relay 51, which is the switching target, is switched to the ON state. In the state where the second control is performed, the positive electrode of the storage battery 20 is conducted to one end of the capacitor 22 via the relay circuit 50 (more specifically, the first relay 51), and the positive electrode of the storage battery 20 is short-circuited with one end of the capacitor 22. As a result, the voltage of the storage battery 20 becomes the same as the voltage of the capacitor 22 in a short time, and the potential difference across the first relay 51 approaches 0V.

[0052] The first switching condition may be that the potential difference across the first relay 51 becomes equal to or less than a specified value, or the value of the current flowing through the precharge circuit 60 becomes equal to or less than a specified value, or a specified time has elapsed since the start of the first control, or the voltage of the capacitor 22 becomes equal to or greater than a specified value, or other conditions.

[0053] The number of the first relays 51 that are the switching targets only needs to be a part of the first relays 51 that constitute the relay circuit 50, and may be one or two or more.

[0054] The control unit 71 selects the first relay 51 to be switched in a specified order. For example, the control unit 71 may select the first relay 51 to be switched in the order of the first relay 51A, the first relay 51B, and the first relay 51C. In this case, for example, the control unit 71 selects the first relay 51A in the current second control and selects the first relay 51B in the next second control. In this case, whenever the first switching condition is satisfied, the control unit 71 switches the first relay 51 to be switched. In contrast, the control unit 71 may switch the first relay 51 to be switched whenever a specified condition is satisfied. The specified condition may be, for example, that the first relay 51 to be switched is switched to the on state a specified number of times continuously, that the degree of deterioration of the first relay 51 to be switched exceeds a threshold value, or other conditions. Details of the degree of deterioration will be described later. The specified order may also be changeable.

[0055] When the second switching condition is satisfied during the execution of the second control, the control unit 71 executes the third control. The third control is a control for increasing the first relay 51 in the on state. More specifically, the third control is a control for switching at least a part of the first relay 51 in the off state to the on state. For example, as Figure 4 shown, the control unit 71 switches all of the first relays 51 in the off state to the on state in the third control. That is, the control unit 71 controls all of the first relays 51 to be in the on state in the third control. In the state where the third control has been performed, current flows through the plurality of first relays 51 controlled to be in the on state to the power path 21.

[0056] The second switching condition is preferably a condition that is satisfied when the potential difference across the first relay 51 becomes near 0V. The second switching condition may be that the potential difference across the first relay 51 becomes equal to or less than a specified value, that the value of the current flowing through the precharge circuit 60 becomes equal to or less than a specified value, that a specified time has elapsed since the start of the first control, that the voltage of the capacitor 22 becomes equal to or greater than a specified value, or other conditions.

[0057] 3. Regarding the degree of deterioration

[0058] The degree of deterioration of each first relay 51 is determined, for example, based on the potential difference across the first relay 51 that is the object when all other first relays 51 are in the off state and the first relay 51 that is the object is in the on state (hereinafter, also referred to as "the potential difference across the first relay 51 that is the object"), the value of the current flowing through the first relay 51, the resistance value when the first relay 51 is in the on state, the number of operations of the first relay 51, the temperature of the contacts when the first relay 51 is in the on state, and a combination of a plurality of them. The degree of deterioration of each first relay 51 may be the values exemplified above themselves, or may be values obtained by substituting the exemplified values into an arithmetic expression. The temperature of the contacts when the first relay 51 is in the on state depends not only on the degree of deterioration of the first relay 51 (for example, the resistance value) but also on the value of the current flowing through the first relay 51. Therefore, in a configuration in which the degree of deterioration of the first relay 51 is determined based on the temperature of the contacts when the first relay 51 is in the on state, it is preferable to determine the degree of deterioration of the first relay 51 based on the temperature of the contacts when the first relay 51 is in the on state and the value of the current flowing through the first relay 51.

[0059] The greater the potential difference across the first relay 51 that is the object, the greater the degree of deterioration of the first relay 51. The smaller the value of the current flowing through the first relay 51, the greater the degree of deterioration of the first relay 51. The greater the resistance value when the first relay 51 is in the on state, the greater the degree of deterioration of the first relay 51. The greater the number of operations of the first relay 51, the greater the degree of deterioration of the first relay 51. Assuming that the value of the current flowing through the first relay 51 is constant, the greater the temperature of the contacts when the first relay 51 is in the on state, the greater the degree of deterioration of the first relay 51.

[0060] As a method for determining the potential difference across the first relay 51 that is the object, the control unit 71, for example, sequentially switches the first relay 51 set to the on state and determines the potential difference across the first relay 51 when each first relay 51 is set to the on state. The determination start time may also be, for example, during the execution of the third control.

[0061] As a method for determining the value of the current flowing through each first relay 51, the control unit 71, for example, determines the value of the current flowing through each first relay 51 based on the output signals of the individual current detection units 73. As another example, the control unit 71 sequentially switches the first relay 51 set to the on state and determines the value of the current flowing through each first relay 51 based on the output signal of the current detection unit 72 when each first relay 51 is made to be in the on state. The determination start time may also be, for example, during the execution of the third control.

[0062] As a method for determining the resistance value when the first relay 51 is in the on state, the control unit 71 determines, for example, the potential difference across the first relay 51 that is the target and the value of the current flowing through each first relay 51 by the method described above. Then, the control unit 71 determines the resistance value of each first relay 51 based on the determined potential difference and current value. The determination start time can also be, for example, during the execution of the third control.

[0063] As a method for determining the number of operations of the first relay 51, the control unit 71 counts, for example, the number of times each first relay 51 is switched to the on state in the second control.

[0064] As a method for determining the temperature of the contacts when the first relay 51 is in the on state, the control unit 71 determines, for example, the temperature of the contacts when each first relay 51 is in the on state based on the output signals of the respective temperature detection units 76.

[0065] 4. Examples of effects

[0066] The in-vehicle power supply device 10 switches the first relay 51 to the on state after pre-charging the capacitor 22 through the pre-charge circuit 60, thereby being able to suppress the inrush current from flowing into the first relay 51. Moreover, the in-vehicle power supply device 10 can selectively use any one of the plurality of first relays 51. Therefore, the in-vehicle power supply device 10 can easily achieve the long life of the device including the first relay 51.

[0067] The in-vehicle power supply device 10 can limit the first relays 51 through which the inrush current flows to a part by switching only a part of the first relays 51 to the on state in the second control, and conduct the battery 20 and the capacitor 22 via the first relay 51. In addition, the in-vehicle power supply device 10 can increase the first relays 51 in the on state by switching at least a part of the first relays 51 in the off state to the on state in the state where the battery 20 and the capacitor 22 are conducted via the first relay 51. As a result, the in-vehicle power supply device 10 can reduce the current flowing through each first relay 51.

[0068] The in-vehicle power supply device 10 selects the first relay 51 to be switched as a target in a predetermined order, so it is easy to deteriorate each first relay 51 evenly.

[0069] As a determination of the degree of deterioration, the in-vehicle power supply device 10 can measure the resistance value when the first relay 51 is in the on state for each first relay 51. With this configuration, the in-vehicle power supply device 10 can use the resistance value when each first relay 51 is in the on state as the degree of deterioration.

[0070] <Second Embodiment>

[0071] In the first embodiment, the structure is such that the first relay 51 to be switched is selected in a prescribed order. In contrast, in the second embodiment, a structure will be described in which the degradation degree of each first relay 51 is determined and compared, and based on the comparison result, the first relay 51 to be switched is selected. In the second embodiment, mainly the points different from the first embodiment will be described. In addition, the in-vehicle power supply system of the second embodiment is the same as that described in the first embodiment Figure 1 in structure. Therefore, reference is made to Figure 1 for the description of the second embodiment.

[0072] In the second embodiment, the control unit 71 determines the degradation degree of each first relay 51. Then, the control unit 71 compares the determined degradation degrees and selects the first relay 51 to be switched based on the comparison result. More specifically, the control unit 71 selects the first relay 51 with the smallest degradation degree as the first relay 51 to be switched. In addition, when the number of relays to be switched is two or more, the control unit 71 selects two or more first relays 51 in ascending order of degradation degree. For example, when the number of relays to be switched is two, the control unit 71 selects the two first relays 51 with the smallest degradation degrees.

[0073] The in-vehicle power supply device 10 of the second embodiment can reflect the comparison result of the degradation degrees in the selection of the first relay 51 to be switched. In addition, the in-vehicle power supply device 10 of the second embodiment easily causes each first relay 51 to deteriorate evenly, so the long life of the device including the first relay 51 can be realized more reliably.

[0074] <Third Embodiment>

[0075] In the third embodiment, a structure will be described in which the control unit 71 switches two or more first relays 51 to the on state at the same time. In the third embodiment, mainly the points different from the first embodiment will be described. In addition, the in-vehicle power supply system of the third embodiment is the same as that described in the first embodiment Figure 1 in structure. Therefore, reference is made to Figure 1 for the description of the third embodiment.

[0076] In the third embodiment, the control unit 71 stops the pre-charge operation generated by the pre-charge circuit 60 during the second control, and switches two or more first relays 51 to be switched on at the same time. That is, when the start condition for starting the charge and discharge of the storage battery 20 is satisfied, the control unit 71 causes the pre-charge circuit 60 to perform the pre-charge operation. When the first switching condition is satisfied during the pre-charge operation, the control unit 71 stops the pre-charge operation and switches two or more first relays 51 to be switched on at the same time.

[0077] In the first and second embodiments, the number of first relays 51 to be switched is a part of the first relays 51 constituting the relay circuit 50. In contrast, in the third embodiment, the number of first relays 51 to be switched may be all of the first relays 51 constituting the relay circuit 50.

[0078] By switching two or more first relays 51 to be switched on at the same time, the in-vehicle power supply device 10 of the third embodiment can suppress the inrush current from flowing into each first relay 51.

[0079] <Fourth Embodiment>

[0080] In the fourth embodiment, an example in which the pre-charge operation is performed not through the pre-charge circuit 60 but through the DCDC converter will be described. In addition, the same reference numerals are given to the same structures as those in the first embodiment, and detailed descriptions thereof are omitted.

[0081] Figure 5 The in-vehicle power supply system 400 of the fourth embodiment shown is different from the in-vehicle power supply system 100 of the first embodiment in that it does not include the pre-charge circuit 60 but includes the low-voltage storage battery 90 and the DCDC converter 91, and is otherwise common.

[0082] The in-vehicle power supply system 400 of the fourth embodiment includes a storage battery 20, a power path 21, a capacitor 22, a low-voltage storage battery 90, and an in-vehicle power supply device 410.

[0083] The low-voltage storage battery 90 is a storage battery having an output voltage lower than that of the storage battery 20 when fully charged. That is, the storage battery 20 can be said to be a "high-voltage storage battery". The low-voltage storage battery 90 can be a lead storage battery, a lithium-ion storage battery, or other storage batteries.

[0084] The in-vehicle power supply device 410 includes a relay circuit 50, a second relay 70, a control unit 71, a current detection unit 72, a separate current detection unit 73, a first voltage detection unit 74, a second voltage detection unit 75, a temperature detection unit 76, and a DCDC converter 91.

[0085] The DCDC converter 91 is an example of the "first circuit". The DCDC converter 91 performs a first operation of converting (stepping down in this embodiment) the voltage applied to the first conductive path 92 and applying it to the second conductive path 93. In addition, the DCDC converter 91 performs a second operation of converting (stepping up in this embodiment) the voltage applied to the second conductive path 93 and applying it to the first conductive path 92. The first conductive path 92 is electrically connected to the power path 21 and is electrically connected to the capacitor 22 via the power path 21. The first conductive path 92 is short-circuited with the capacitor 22. The low-voltage battery 90 is connected to the second conductive path 93.

[0086] The control unit 71 controls the DCDC converter 91. When power is supplied from the battery 20 to the power path 21, the control unit 71 charges the low-voltage battery 90 by causing the DCDC converter 91 to perform the first operation. "When power is supplied from the battery 20 to the power path 21" means when at least one of the first relays 51 is in the on state and the second relay 70 is in the on state.

[0087] The control unit 71 causes the DCDC converter 91 to perform the second operation to boost the voltage based on the low-voltage battery 90 and apply it to the first conductive path 92. The capacitor 22 is applied with a voltage based on the voltage applied to the first conductive path 92. That is, the DCDC converter 91 can perform a pre-charging operation for pre-charging the capacitor 22. In the pre-charging operation, the DCDC converter 91 raises the voltage of the capacitor 22 to a voltage level similar to that of the battery 20. That is, the operation of raising the voltage of the capacitor 22 to a voltage level similar to that of the battery 20 by performing the second operation is the pre-charging operation.

[0088] When the start condition is satisfied, the control unit 71 causes the DCDC converter 91 to perform the pre-charging operation. After that, when the first switching condition described in the first embodiment is satisfied, the control unit 71 stops the pre-charging operation generated by the DCDC converter 91 and switches the first relay 51 and the second relay 70 to the on state. The first relay 51 switched to the on state can be a part or all of them. When a part of the first relays 51 switched to the on state, the third control described in the first embodiment may be executed later.

[0089] The in-vehicle power supply device 410 according to the fourth embodiment can pre-charge the capacitor 22 by using the DCDC converter 91 that charges the low-voltage battery 90. Therefore, the pre-charge circuit 60 described in the first embodiment is not required. Further, in the case of the pre-charge circuit 60, it is difficult for the voltage of the capacitor 22 to rise as it approaches the voltage of the battery 20. In contrast, in the configuration using the DCDC converter 91, the voltage of the capacitor 22 can be rapidly increased to the voltage of the battery 20.

[0090] <Other Embodiments>

[0091] 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 hereinafter-described embodiments can be combined in their entirety within a non-contradictory range. Further, any feature in the above-described or hereinafter-described embodiments can be omitted as long as it is not explicitly stated as an essential feature. In addition, the above-described embodiments can be modified as follows.

[0092] In each of the above embodiments, the second relay 70 may not be provided.

[0093] Each of the above embodiments may also be configured not to execute the third control.

[0094] In the first embodiment described above, the relay circuit 50 and the pre-charge circuit 60 are provided on the positive-side power line 30, but the relay circuit 50 and the pre-charge circuit 60 may be provided on the negative-side power line 31.

[0095] 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.

[0096] Reference Numerals 10... In-vehicle power supply device 20... Battery 21... Power path 22... Capacitor 30... Positive-side power line 31... Negative-side power line 32... First positive-side power line 33... Second positive-side power line 40... Drive unit 41... Inverter 42... Motor 50... Relay circuit (second circuit) 51... First relay (relay) 51A…First relay 51B…First relay 51C…First relay 60…Pre - charge circuit (first circuit) 61…Pre - charge relay 62…Resistance section 70…Second relay 71…Control section 72…Current detection section 73…Separate current detection section 74…First voltage detection section 75…Second voltage detection section 76…Temperature detection section 90…Low - voltage battery 91…DCDC converter (first circuit) 92…First conducting path 93…Second conducting path 100…Vehicle - mounted power supply system 400…Vehicle - mounted power supply system 410…Vehicle - mounted power supply device.

Claims

1. A vehicle-mounted power supply device is used in a vehicle-mounted power supply system. The vehicle-mounted power supply system includes: a storage battery; a power circuit supplied with power based on the storage battery; and a capacitor electrically connected to the power circuit. Wherein, The vehicle-mounted power supply device includes: A first circuit that performs a pre-charging operation to pre-charge the capacitor; And A second circuit disposed in the power circuit on the storage battery side of the capacitor, The second circuit forms a structure in which a plurality of relays are connected in parallel.

2. The vehicle-mounted power supply device according to claim 1, Wherein, The vehicle-mounted power supply device includes a control unit that controls the first circuit and the plurality of relays. The control unit performs a first control when a start condition for starting the charge and discharge of the storage battery is satisfied. The first control causes the first circuit to perform the pre-charging operation. The control unit performs a second control when a first switching condition is satisfied during the execution of the first control. The second control stops the pre-charging operation and switches at least one of the relays to be switched among the plurality of relays to an on state. The control unit performs a third control when a second switching condition is satisfied during the execution of the second control. The third control switches at least a part of the relays in the off state to the on state.

3. The vehicle-mounted power supply device according to claim 1, Wherein, The vehicle-mounted power supply device includes a control unit that controls the first circuit and the plurality of relays. When a start condition for starting the charge and discharge of the storage battery is satisfied, the control unit causes the first circuit to perform the pre-charging operation. When a switching condition is satisfied during the pre-charging operation, the control unit stops the pre-charging operation and switches two or more relays to be switched to the on state at the same time.

4. The vehicle-mounted power supply device according to claim 2 or claim 3, Wherein, When the relay to be switched is a part of the plurality of relays, the control unit selects the relay to be switched in a prescribed order.

5. The vehicle-mounted power supply device according to claim 2 or claim 3, Wherein, When the relay to be switched is a part of the plurality of relays, the control unit determines and compares the degradation degrees of the respective relays, and selects the relay to be switched based on the comparison result.

6. The vehicle-mounted power supply device according to claim 5, Wherein, The control unit selects the relay with the smallest degradation degree as the relay to be switched.

7. The vehicle-mounted power supply device according to claim 5, Wherein, As the determination of the degradation degree, the control unit measures the resistance value in the on state for each of the relays.

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