Vehicle control device

Abstract

The vehicle-mounted control device (1) includes a first relay (20) between the high-voltage battery (10) and the high-voltage load (12), a first voltage conversion unit (21) between the first relay (20) and the low-voltage load (13), a second voltage conversion unit (22) provided in parallel with the first relay (20) and the first voltage conversion unit (21), and a control unit (23). The first voltage conversion unit (21) performs a first conversion operation of converting a voltage input from the high-voltage battery (10) via the first relay (20) to a low voltage lower than the output voltage of the high-voltage battery (10) and outputting the low-voltage load (13). The second voltage conversion unit (22) performs a second conversion operation of converting a voltage input from the high-voltage battery (10) to a low voltage and outputting the low-voltage load (13). The control unit (23) controls the first relay (20) to an on state while the vehicle is traveling, and causes the first voltage conversion unit (21) to perform a first conversion operation, and causes the second voltage conversion unit (22) to perform a second conversion operation while the vehicle is parked.

Description

[Technical field]

[0001] The present disclosure relates to an in-vehicle control device. [Background technology]

[0002] Patent Document 1 discloses a configuration in which power is supplied from a lithium ion battery to a lead battery and a group of electric loads via a step-up / step-down converter (voltage conversion unit). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-159784 A Summary of the Invention [Problem to be solved by the invention]

[0004] The group of electrical loads in Patent Document 1 includes electrical loads that operate in a parked state. The configuration in Patent Document 1 is such that power is supplied from a lithium-ion battery to a lead battery, and power is supplied from the lead battery to the electrical loads that operate in a parked state. In such a configuration, the lead battery is repeatedly charged and discharged even when the vehicle is parked, and there is a concern that the lead battery may be easily deteriorated. Furthermore, in a configuration in which a system main relay (relay) is provided between the step-up / step-down converter and the lithium-ion battery, there is a concern that the system main relay may also be easily deteriorated in the same manner as the lead battery.

[0005] The present disclosure has been made in light of the above-mentioned circumstances, and aims to provide an in-vehicle control device that can at least suppress excessive deterioration of a relay. [Means for solving the problem]

[0006] The in-vehicle control device of the present disclosure includes: An in-vehicle control device for use in an in-vehicle system including a high-voltage battery, a high-voltage load, and a low-voltage load, a relay provided between the high-voltage battery and the high-voltage load; a first voltage conversion unit provided between the relay and the low-voltage load; A second voltage conversion unit provided in parallel with the relay and the first voltage conversion unit; a control unit that controls the relay, the first voltage conversion unit, and the second voltage conversion unit, the first voltage conversion unit performs a first conversion operation of converting a voltage input from the high-voltage battery side through the relay into a low voltage lower than an output voltage from the high-voltage battery and outputting the low-voltage load side; the second voltage conversion unit performs a second conversion operation of converting a voltage input from the high-voltage battery side into the low-voltage and outputting the low-voltage load side; The control unit controls the relay to an on state while the vehicle is traveling, while causing the first voltage conversion unit to perform the first conversion operation, and causes the second voltage conversion unit to perform the second conversion operation while the vehicle is parked. Effect of the Invention

[0007] This configuration can prevent the relay from deteriorating excessively. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram illustrating an in-vehicle system including the in-vehicle control device according to the first embodiment. [Diagram 2] FIG. 2 is a circuit diagram showing an example of the configuration of the first voltage conversion unit and the second voltage conversion unit of the first embodiment. [Diagram 3] FIG. 3 is a graph showing an example of power supply efficiency with respect to the output current of each of the first voltage conversion unit and the second voltage conversion unit. [Figure 4] FIG. 4 is a flowchart showing an example of control by the control unit in the first embodiment. [Diagram 5]FIG. 5 is a block diagram illustrating an in-vehicle system including the in-vehicle control device according to the second embodiment. [Figure 6] FIG. 6 is a flowchart showing an example of control by the control unit in the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] [Description of the embodiments of the present disclosure] In the following, embodiments of the present disclosure are listed and illustrated.

[0010] (1) An in-vehicle control device for use in an in-vehicle system including a high-voltage battery, a high-voltage load, and a low-voltage load, a relay provided between the high-voltage battery and the high-voltage load; a first voltage conversion unit provided between the relay and the low-voltage load; A second voltage conversion unit provided in parallel with the relay and the first voltage conversion unit; a control unit that controls the relay, the first voltage conversion unit, and the second voltage conversion unit, the first voltage conversion unit performs a first conversion operation of converting a voltage input from the high-voltage battery side through the relay into a low voltage lower than an output voltage from the high-voltage battery and outputting the low-voltage load side; the second voltage conversion unit performs a second conversion operation of converting a voltage input from the high-voltage battery side into the low-voltage and outputting the low-voltage load side; The control unit controls the relay to an on state while the vehicle is traveling, while causing the first voltage conversion unit to perform the first conversion operation, and causes the second voltage conversion unit to perform the second conversion operation while the vehicle is parked.

[0011] The in-vehicle control device of (1) uses the second voltage conversion unit when the vehicle is parked, thereby making it possible to avoid using a relay provided between the high-voltage battery and the high-voltage load, thereby suppressing deterioration of the relay and extending the service life of the relay.

[0012] (2) The in-vehicle control device according to (1), wherein an output current when the power supply efficiency of the second voltage conversion unit is maximized is smaller than an output current when the power supply efficiency of the first voltage conversion unit is maximized.

[0013] It is expected that the power consumption of the low-voltage load will be smaller when the vehicle is parked than when the vehicle is moving. For this reason, the in-vehicle control device of (2) is configured to make the output current when the power supply efficiency of the second voltage conversion unit is at its maximum smaller than the output current when the power supply efficiency of the first voltage conversion unit is at its maximum, thereby making it easier to supply power appropriate to the operating state of the low-voltage load when the vehicle is moving and when the vehicle is parked.

[0014] (3) the first voltage conversion unit has a first transformer that converts a voltage, the second voltage conversion unit has a second transformer that converts a voltage; The in-vehicle control device according to (2), wherein an outer shape of the second transformer is smaller than an outer shape of the first transformer.

[0015] (3) The in-vehicle control device is configured such that the output current when the power supply efficiency of the second voltage conversion unit is at its maximum is smaller than the output current when the power supply efficiency of the first voltage conversion unit is at its maximum, so that the second voltage conversion unit can be made smaller than the first voltage conversion unit.

[0016] (4) The vehicle-mounted system includes a low-voltage battery; the low-voltage battery is capable of supplying power to the low-voltage load; The control unit adjusts the output voltage of the second voltage conversion unit so that power supply from the second voltage conversion unit to the low-voltage load is prioritized over power supply from the low-voltage battery to the low-voltage load.

[0017] The on-board control device (4) can reduce the number of times the low-voltage battery is charged and discharged, thereby slowing down the deterioration of the low-voltage battery.

[0018] (5) the relay is a first relay; a second relay provided between the high-voltage battery and the second voltage conversion unit; a battery case that houses the high-voltage battery, The control unit controls the second relay, the second relay and the second voltage conversion unit are provided in parallel with the first relay and the first voltage conversion unit, The vehicle-mounted control device according to (1) or (2), wherein the first relay and the second relay are provided inside the battery case.

[0019] (5) The vehicle-mounted control device can reliably disconnect the inside and outside of the battery case by using the first relay and the second relay, making it easier to prevent the output voltage of the high-voltage battery from being exposed outside the battery case.

[0020] (6) Further comprising a battery case for accommodating the high voltage battery, The vehicle-mounted control device according to (1) or (2), wherein the relay and the second voltage conversion unit are provided inside the battery case.

[0021] (6) The vehicle-mounted control device can construct a power supply unit that outputs two different voltages: an output voltage from the high-voltage battery and a low voltage converted by the second voltage conversion unit, by providing a high-voltage battery, a relay, and a second voltage conversion unit within a battery case.

[0022] <Embodiment 1> A first embodiment of the present disclosure will be described below. The in-vehicle system 100 shown in Fig. 1 is a power supply system mounted on a vehicle. The in-vehicle system 100 includes a high-voltage battery 10 for high voltage, a battery case 30 that houses the high-voltage battery 10, a high-voltage load 12, a low-voltage battery 11, and a low-voltage load 13. The high-voltage load 12 operates with power supplied from the high-voltage battery 10. The low-voltage battery 11 outputs a voltage lower than the output voltage of the high-voltage battery 10. The in-vehicle control device 1 of the present disclosure is used in the in-vehicle system 100. The in-vehicle control device 1 includes a first relay 20 which is a relay, a second relay 24 which is a relay, a first voltage conversion unit 21, a second voltage conversion unit 22, and a control unit 23.

[0023] [In-vehicle system configuration] The high-voltage battery 10 is, for example, an assembled battery configured by combining a plurality of unit cells, such as lithium-ion batteries or nickel-metal hydride batteries, in series, and outputs an output voltage of, for example, about 400 V. The high-voltage battery 10 is housed in a battery case 30. The battery case 30 is configured to cover the entire high-voltage battery 10. The battery case 30 is provided with a first terminal 30A and a second terminal 30B. A first conductive path 16 is electrically connected to the high-voltage side terminal of the high-voltage battery 10.

[0024] In the present disclosure, "electrically connected" preferably means a configuration in which the connection objects are connected in a mutually conductive state (a state in which a current can flow) so that the potentials of both connection objects are equal. However, this is not limited to this configuration. For example, "electrically connected" may mean a configuration in which the two connection objects are connected in a state in which the two connection objects can be conductive with an electric component interposed between them.

[0025] The high voltage load 12 receives the output voltage of the high voltage battery 10 as is via a first relay 20 described later. The high voltage load 12 corresponds to, for example, a motor that drives the wheels of a vehicle. Thus, the high voltage load 12 is a load that operates while the vehicle is traveling. Here, the concept of the vehicle being traveling also includes a state in which the vehicle is temporarily stopped while traveling. The high voltage load 12 is electrically connected to the first relay 20 via a second conductive path 17.

[0026] The low-voltage battery 11 may be, for example, a lead storage battery, or a configuration using the same type of unit cells as the high-voltage battery 10 but with a smaller number of cells connected in series than the high-voltage battery 10. The low-voltage battery 11 can output an output voltage of, for example, about 12 V. The low-voltage battery 11 is configured separately from the high-voltage battery 10. The low-voltage battery 11 is electrically connected to a first voltage conversion unit 21, which will be described later, via a third conductive path 18.

[0027] The low-voltage load 13 includes a first low-voltage load 13A and a second low-voltage load 13B. The first low-voltage load 13A is, for example, a load that operates only while the vehicle is traveling. The first low-voltage load 13A corresponds to, for example, a sensor that operates while the vehicle is traveling to assist driving the vehicle. The second low-voltage load 13B is a load that operates not only while the vehicle is traveling but also while the vehicle is parked. The second low-voltage load 13B corresponds to, for example, an air conditioner compressor, a display disposed on the dashboard, an interior light, etc. The low-voltage load 13 is electrically connected to a third conductive path 18. The low-voltage load 13 can be supplied with power from the low-voltage battery 11. The low-voltage load 13 can also be supplied with power from the high-voltage battery 10 via a first relay 20 and a first voltage conversion unit 21, which will be described later.

[0028] [Configuration of on-board control device] The first relay 20 is a so-called system main relay (SMR). The operation of the first relay 20 is controlled by a control unit 23 described later. The first relay 20 is switched between an on state and an off state by the control unit 23. When the first relay 20 is in the on state, the first conductive path 16 and the second conductive path 17 are electrically connected via the first relay 20. As a result, the voltage of the high-voltage battery 10 applied via the first conductive path 16 is directly applied to the second conductive path 17. When the first relay 20 is in the off state, the first conductive path 16 and the second conductive path 17 are cut off. At this time, the voltage of the high-voltage battery 10 applied via the first conductive path 16 is not applied to the second conductive path 17. The first relay 20 is provided in a battery case 30. The high-voltage load 12 is electrically connected to the second conductive path 17.

[0029] The second relay 24 is a so-called system sub-relay (SSR). The operation of the second relay 24 is controlled by the control unit 23. The second relay 24 is switched between an on state and an off state by the control unit 23. When the second relay 24 is in the on state, the first conductive path 16 and the fourth conductive path 19 are electrically connected via the second relay 24. As a result, the voltage of the high-voltage battery 10 applied via the first conductive path 16 is directly applied to the fourth conductive path 19. When the second relay 24 is in the off state, the first conductive path 16 and the fourth conductive path 19 are disconnected. As a result, the voltage of the high-voltage battery 10 applied via the first conductive path 16 is not applied to the fourth conductive path 19. The second relay 24 is provided in the battery case 30.

[0030] 2, the first voltage conversion unit 21 has a first transformer 21A having a function of converting voltage, and is a known isolated step-down DCDC converter capable of stepping down voltage. The first voltage conversion unit 21 has a configuration in which two switch elements 21B are connected in a half bridge configuration. A semiconductor switch such as a MOSFET is used for the switch element 21B. The first voltage conversion unit 21 is a so-called LLC resonant type DCDC converter.

[0031] The first voltage conversion unit 21 performs a step-down operation to convert the voltage of the high-voltage battery 10 applied to the second conductive path 17 into a low voltage lower than the output voltage of the high-voltage battery 10 and apply the low voltage to the third conductive path 18. The first voltage conversion unit 21 and the first relay 20 are electrically connected in series. The first voltage conversion unit 21 is provided outside the battery case 30. Therefore, the second conductive path 17 is configured to be drawn out from the battery case 30 to the outside of the battery case 30. The first terminal 30A of the battery case 30 is provided on the second conductive path 17. In other words, the first relay 20 is provided between the first terminal 30A and the high-voltage battery 10.

[0032] The voltage applied from the first voltage conversion unit 21 to the third conductive path 18 is slightly higher than the charging voltage of the low-voltage battery 11 when it is fully charged. In this configuration, the step-down operation performed by the first voltage conversion unit 21 (operation of converting the voltage input from the high-voltage battery 10 side via the first relay 20 to a low voltage lower than the output voltage of the high-voltage battery 10 and applying the low voltage to the low-voltage load 13 side) corresponds to an example of a first conversion operation. The first relay 20 is provided between the high-voltage battery 10 and the high-voltage load 12.

[0033] The second voltage conversion unit 22 has a similar configuration to the first voltage conversion unit 21. As shown in FIG. 2, the second voltage conversion unit 22 has a second transformer 22A having a function of converting voltage, and is a known isolated step-down DCDC converter capable of stepping down. The outer shape of the second transformer 22A is smaller than that of the first transformer 21A. The second voltage conversion unit 22 has a configuration in which two switch elements 22B are connected in a half bridge configuration. A MOSFET semiconductor switch or the like is used for the switch element 22B. The second voltage conversion unit 22 is a so-called LLC resonant type DCDC converter.

[0034] The second voltage conversion unit 22 performs a step-down operation to convert the voltage of the high-voltage battery 10 applied to the fourth conductive path 19 into a low voltage lower than the output voltage of the high-voltage battery 10 and apply the low voltage to the third conductive path 18. The second voltage conversion unit 22 and the second relay 24 are electrically connected in series. The second voltage conversion unit 22 is provided outside the battery case 30. Therefore, the fourth conductive path 19 is configured to be drawn out from the battery case 30 to the outside of the battery case 30. The second terminal 30B of the battery case 30 is provided on the fourth conductive path 19. That is, the second relay 24 is provided between the second terminal 30B and the high-voltage battery 10. The second relay 24 and the second voltage conversion unit 22 are provided in parallel with the first relay 20 and the first voltage conversion unit 21.

[0035] The control unit 23 adjusts the output voltage of the second voltage conversion unit 22 so that the power supply from the second voltage conversion unit 22 to the low-voltage load 13 is prioritized over the power supply from the low-voltage battery 11 to the low-voltage load 13. Specifically, the output voltage of the second voltage conversion unit 22 is applied to the third conductive path 18 by the control unit 23 at a voltage slightly higher than the charging voltage of the low-voltage battery 11 when fully charged. In this configuration, the step-down operation performed by the second voltage conversion unit 22 (the operation of converting the voltage input from the high-voltage battery 10 side to a low voltage lower than the output voltage of the high-voltage battery 10 and applying the low voltage to the low-voltage load 13 side) corresponds to an example of the second conversion operation. The second relay 24 is provided between the high-voltage battery 10 and the second voltage conversion unit 22. When the first relay 20 and the second relay 24 are in the off state, the voltage of the high-voltage battery 10 is not applied to the second conductive path 17 and the fourth conductive path 19. Therefore, by turning off the first relay 20 and the second relay 24, the voltage of the high voltage battery 10 can be prevented from being exposed to the outside of the battery case 30.

[0036] As shown in Fig. 3, the output current P2 when the power supply efficiency of the second voltage conversion unit 22 (the dotted line graph in Fig. 3) is maximized is set to be smaller than the output current P1 when the power supply efficiency of the first voltage conversion unit 21 (the solid line graph in Fig. 3) is maximized. Here, the power supply efficiency is the ratio of the power received by the load to the power output from the voltage conversion unit. In other words, the second voltage conversion unit 22 can supply power more efficiently to a load that consumes less power than the first voltage conversion unit 21. In contrast, the first voltage conversion unit 21 can supply power more efficiently to a load that consumes more power than the second voltage conversion unit 22.

[0037] The control unit 23 is configured as, for example, a microcomputer, and includes a CPU, a ROM, a RAM, a non-volatile memory, and the like. The control unit 23 is configured to receive, for example, a signal indicating that the vehicle is running (a signal indicating that the start switch is on) or a signal indicating that the vehicle is parked (a signal indicating that the start switch is off) from an external ECU (not shown). The control unit 23 is also configured to receive a signal requesting power supply to the second low-voltage load 13B from the external ECU. The control unit 23 has a function of operating either the first voltage conversion unit 21 or the second voltage conversion unit 22 based on this signal. The control unit 23 can control the first relay 20 and the second relay 24 to be individually switched between an on state and an off state based on the signal indicating that the vehicle is running (a signal indicating that the start switch is on) or a signal indicating that the vehicle is parked (a signal indicating that the start switch is off).

[0038] The control unit 23 is also configured to acquire the voltage and current values ​​of each unit cell of the high-voltage battery 10, and detect the SOC (State of Charge) of the high-voltage battery 10 based on these values. The control unit 23 can detect the SOC of the high-voltage battery 10 using various known methods.

[0039] For example, when a signal indicating that the vehicle is running (a signal indicating that the start switch is on) is input from the external ECU, the control unit 23 controls the first relay 20 to the on state and causes the first voltage conversion unit 21 to perform the first conversion operation. At this time, the control unit 23 keeps the second relay 24 in the off state and does not cause the second voltage conversion unit 22 to perform the second conversion operation.

[0040] For example, when a signal indicating that the vehicle is parked (a signal indicating that the start switch is in an OFF state) is input from an external ECU, the control unit 23 controls the second relay 24 to an ON state and causes the second voltage conversion unit 22 to perform the second conversion operation. At this time, the control unit 23 keeps the first relay 20 in an OFF state and does not cause the first voltage conversion unit 21 to perform the first conversion operation. In this way, the control unit 23 controls the operations of the first relay 20, the second relay 24, the first voltage conversion unit 21, and the second voltage conversion unit 22.

[0041] [Regarding control in the control section] Next, an example of the control executed by the control unit 23 will be described with reference to FIG.

[0042] When a signal indicating that the start switch is in the on state is input from the external ECU (Yes in step S1), the process proceeds to step S2, where the control unit 23 switches the first relay 20 to the on state. The start switch being in the on state corresponds to an instruction to switch the first relay 20 to the on state. As a result, the voltage of the high-voltage battery 10 is applied to the first voltage conversion unit 21. Then, the process proceeds to step S3, where the control unit 23 operates the first voltage conversion unit 21. As a result, the first voltage conversion unit 21 applies a low voltage to the low-voltage battery 11 and the low-voltage load 13. At this time, the control unit 23 switches the second relay 24 to the off state, while not operating the second voltage conversion unit 22. Then, the process shown in FIG. 4 is terminated. In this way, the high-voltage load 12 and the low-voltage load 13 are supplied with power while the vehicle is traveling.

[0043] When a signal indicating that the start switch is in the OFF state is input from the external ECU (No in step S1), the process proceeds to step S4, where control unit 23 switches first relay 20 to the OFF state. Then, the process proceeds to step S5, where control unit 23 stops the operation of first voltage conversion unit 21.

[0044] Next, when the process proceeds to step S6, the control unit 23 judges whether or not it is possible and necessary to supply power to the low-voltage load 13 via the second voltage conversion unit 22. Specifically, the control unit 23 judges whether or not a signal requesting power supply to the second low-voltage load 13B has been input from the external ECU. When the control unit 23 judges in step S6 that it is possible and necessary to supply power to the low-voltage load 13 via the second voltage conversion unit 22 (i.e., a signal requesting power supply to the second low-voltage load 13B has been input from the external ECU) (Yes in step S6), the process proceeds to step S7, where the control unit 23 switches the second relay 24 to an on state. Then, the process proceeds to step S8, where the control unit 23 operates the second voltage conversion unit 22, and ends the process shown in FIG. 4. In this way, the second low-voltage load 13B is supplied with power and operates while the vehicle is parked.

[0045] In step S6, when the control unit 23 determines that the supply to the low-voltage load 13 via the second voltage conversion unit 22 is possible but not necessary (i.e., a signal requesting the power supply to the second low-voltage load 13B is not input from the external ECU) (No in step S6), the process proceeds to step S9, where the control unit 23 switches the second relay 24 to the OFF state. Then, the process proceeds to step S10, where the control unit 23 stops the operation of the second voltage conversion unit 22 and ends the process shown in FIG. 4. At this time, since both the first relay 20 and the second relay 24 are turned off, the voltage of the high-voltage battery 10 is not exposed to the outside of the battery case 30. And, the second low-voltage load 13B does not operate because it is not supplied with power. Since the voltage of the high-voltage battery 10 is not exposed to the outside of the battery case 30, No in step S6 is suitable for the case where the vehicle is maintained or the detected SOC of the high-voltage battery 10 is in an unexpected state.

[0046] Next, the effects of this configuration will be illustrated. The vehicle-mounted control device 1 is used in a vehicle-mounted system 100 including a high-voltage battery 10, a high-voltage load 12, and a low-voltage load 13. The vehicle-mounted control device 1 includes a first relay 20, a first voltage conversion unit 21, a second voltage conversion unit 22, and a control unit 23. The first relay 20 is provided between the high-voltage battery 10 and the high-voltage load 12. The first voltage conversion unit 21 is provided between the first relay 20 and the low-voltage load 13. The second voltage conversion unit 22 is provided in parallel with the first relay 20 and the first voltage conversion unit 21. The control unit 23 controls the first relay 20, the first voltage conversion unit 21, and the second voltage conversion unit 22. The first voltage conversion unit 21 performs a first conversion operation of converting a voltage input from the high-voltage battery 10 side via the first relay 20 into a low voltage lower than the output voltage from the high-voltage battery 10 and outputting the low-voltage load 13 side. Second voltage conversion unit 22 performs a second conversion operation of converting the voltage input from high-voltage battery 10 to a low voltage and outputting it to low-voltage load 13. Control unit 23 causes first voltage conversion unit 21 to perform the first conversion operation while controlling first relay 20 to the on state while the vehicle is traveling, and causes second voltage conversion unit 22 to perform the second conversion operation while the vehicle is parked.

[0047] According to this configuration, by using the second voltage conversion unit 22 while the vehicle is parked, it is possible to avoid using the first relay 20 provided between the high-voltage battery 10 and the high-voltage load 12. Therefore, deterioration of the first relay 20 can be suppressed, and the usage period of the first relay 20 can be extended.

[0048] The output current P2 when the power supply efficiency of the second voltage conversion unit 22 is maximum is smaller than the output current P1 when the power supply efficiency of the first voltage conversion unit 21 is maximum. It is expected that the power consumption of the low-voltage load 13 is smaller when the vehicle is parked than when the vehicle is running. For this reason, the in-vehicle control device 1 is configured to make the output current P2 when the power supply efficiency of the second voltage conversion unit 22 is maximum smaller than the output current P1 when the power supply efficiency of the first voltage conversion unit 21 is maximum, thereby making it easier to supply power suitable for each operating state of the low-voltage load 13 when the vehicle is running and when the vehicle is parked.

[0049] The first voltage conversion unit 21 has a first transformer 21A that converts voltage, and the second voltage conversion unit 22 has a second transformer 22A that converts voltage, and the outer shape of the second transformer 22A is smaller than the outer shape of the first transformer 21A. According to this configuration, the output current P2 when the power supply efficiency of the second voltage conversion unit 22 is maximized is smaller than the output current P1 when the power supply efficiency of the first voltage conversion unit 21 is maximized, so that the second voltage conversion unit 22 can be made smaller than the first voltage conversion unit 21.

[0050] The in-vehicle system 100 includes a low-voltage battery 11. The low-voltage battery 11 is capable of supplying power to a low-voltage load 13, and a control unit 23 adjusts the output voltage of the second voltage conversion unit 22 so that power supply from the second voltage conversion unit 22 to the low-voltage load 13 is prioritized over power supply from the low-voltage battery 11 to the low-voltage load 13. With this configuration, the number of times the low-voltage battery 11 is charged and discharged can be reduced, and deterioration of the low-voltage battery 11 can be delayed.

[0051] The battery case 30 further includes a second relay 24 provided between the high voltage battery 10 and the second voltage conversion unit 22, and a battery case 30 that houses the high voltage battery 10, and the control unit 23 controls the second relay 24. The second relay 24 and the second voltage conversion unit 22 are provided in parallel with the first relay 20 and the first voltage conversion unit 21. The first relay 20 and the second relay 24 are provided inside the battery case 30. With this configuration, the first relay 20 and the second relay 24 can reliably cut off the connection between the inside and outside of the battery case 30, and it is easy to prevent the output voltage of the high voltage battery 10 from being exposed to the outside of the battery case 30.

[0052] <Embodiment 2> 5, the in-vehicle control device 2 of the second embodiment is different from the first embodiment in that it does not include a second relay and that the second voltage conversion unit 22 is provided in the battery case 30, but is otherwise common. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals and detailed description will be omitted. The in-vehicle system 200 is a power supply system mounted on a vehicle.

[0053] The first relay 20 is provided in the battery case 30 together with the second voltage conversion unit 22. The first voltage conversion unit 21 is provided outside the battery case 30. The second voltage conversion unit 22 performs a step-down operation to convert the voltage of the high-voltage battery 10 applied to the first conductive path 16 into a low voltage lower than the output voltage of the high-voltage battery 10 and apply a constant voltage to the third conductive path 18. The second voltage conversion unit 22 is accommodated in the battery case 30. Therefore, the third conductive path 18 electrically connected to the second voltage conversion unit 22 is configured to be drawn out from the battery case 30 to the outside of the battery case 30. The second terminal 30B of the battery case 30 is provided on the third conductive path 18. The second voltage conversion unit 22 is provided between the second terminal 30B and the high-voltage battery 10. The second voltage conversion unit 22 is provided in parallel with the first relay 20 and the first voltage conversion unit 21.

[0054] [Regarding control in the control section] Next, an example of the control executed by the control unit 23 will be described with reference to FIG.

[0055] Steps S1 to S5 execute the same processes as those in the first embodiment. Specifically, when a signal indicating that the start switch is in the OFF state is input from the external ECU (No in step S1), the process proceeds to step S4. When the process proceeds to step S4, the control unit 23 switches the first relay 20 to the OFF state, and the process proceeds to step S5, where the control unit 23 stops the operation of the first voltage conversion unit 21.

[0056] Then, when the process proceeds to step S11, the control unit 23 operates the second voltage conversion unit 22. In this way, while the vehicle is parked, the second low-voltage load 13B is supplied with power and operates.

[0057] The battery case 30 is provided to house the high-voltage battery 10, and the first relay 20 and the second voltage conversion unit 22 are provided inside the battery case 30. According to this configuration, by providing the high-voltage battery 10, the first relay 20, and the second voltage conversion unit 22 inside the battery case 30, it is possible to construct a power supply unit that outputs two different voltages, the output voltage output from the high-voltage battery 10 and a low voltage converted by the second voltage conversion unit 22.

[0058] <Other embodiments> The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is not limited to the embodiments disclosed herein, but is indicated by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

[0059] Unlike the first and second embodiments, the control unit may be housed in a battery box.

[0060] In the second voltage conversion unit, in addition to reducing the external dimensions of the second transformer, it is also possible to reduce the scale of the water-cooling or air-cooling configuration, narrow the width of the wiring pattern provided on the substrate, reduce the size of the heat dissipation sink, or reduce the size of the housing that houses the second voltage conversion unit.

[0061] The first voltage conversion unit and the second voltage conversion unit may be configured to be full-bridge connected, unlike the first and second embodiments. Also, the first voltage conversion unit and the second voltage conversion unit may adopt a forward type or a flyback type. [Explanation of symbols]

[0062] 1, 2... Vehicle control device 10...High voltage battery 11...Low voltage battery 12...High pressure load 13...Low pressure load 13A…First low voltage load 13B…Second low pressure load 16…First conductive path 17…Second conductive path 18…Third conductive path 19…Fourth conductive path 20…1st relay (relay) 21...First voltage conversion unit 21A…First transformer 21B...Switch element 22...Second voltage conversion unit 22A…Second transformer 22B...Switch element 23...Control section 24…Second relay 30…Battery case 30A…1st terminal 30B…2nd terminal 100,200…In-vehicle system P1: Output current when the power supply efficiency of the first voltage conversion unit is at its maximum P2: Output current when the power supply efficiency of the second voltage conversion section is at its maximum

Claims

1. An in-vehicle control device for use in an in-vehicle system including a high-voltage battery, a high-voltage load, and a low-voltage load, a relay provided between the high voltage battery and the high voltage load; A first voltage conversion unit provided between the relay and the low-voltage load; a second voltage conversion unit provided in parallel with the relay and the first voltage conversion unit; a control unit that controls the relay, the first voltage conversion unit, and the second voltage conversion unit, the first voltage conversion unit performs a first conversion operation of converting a voltage input from the high-voltage battery side through the relay into a low voltage lower than an output voltage from the high-voltage battery and outputting the low-voltage load side; the second voltage conversion unit performs a second conversion operation of converting a voltage input from the high-voltage battery side into the low-voltage and outputting the low-voltage load side; The control unit causes the second voltage conversion unit to perform the second conversion operation at least while the vehicle is parked.

2. The in-vehicle control device according to claim 1 , wherein the control unit causes the first voltage conversion unit to perform the first conversion operation while controlling the relay to an on state at least while the vehicle is traveling.

3. The vehicle-mounted system includes a low-voltage battery; the low-voltage battery is capable of supplying power to the low-voltage load; 3. The vehicle control device according to claim 1, wherein the control unit adjusts the output voltage of the second voltage conversion unit so that power supply from the second voltage conversion unit to the low-voltage load is prioritized over power supply from the low-voltage battery to the low-voltage load.

4. 3 . The in-vehicle control device according to claim 2 , wherein an output current when the power supply efficiency of the second voltage conversion unit is maximized is smaller than an output current when the power supply efficiency of the first voltage conversion unit is maximized.

5. the first voltage conversion unit has a first transformer that converts a voltage, the second voltage conversion unit includes a second transformer that converts a voltage; 5. The second transformer according to claim 4, wherein an outer size of the second transformer is smaller than an outer size of the first transformer. The in-vehicle control device described in

6. The relay is a first relay, a second relay provided between the high-voltage battery and the second voltage conversion unit; a battery case that houses the high-voltage battery, The control unit controls the second relay, the second relay and the second voltage conversion unit are provided in parallel with the first relay and the first voltage conversion unit, The vehicle-mounted control device according to claim 2 or 4, wherein the first relay and the second relay are provided inside the battery case.

7. Further comprising a battery case for accommodating the high voltage battery, The vehicle-mounted control device according to claim 2 , wherein the relay and the second voltage conversion unit are provided inside the battery case.

Images