Onboard control device

Abstract

This onboard control device (10) is included in an onboard system (1). The onboard system (1) comprises a power supply unit (2), a conductive path (3) through which power from the power supply unit (2) is supplied via a switch unit (11), and a power storage unit (4) that is electrically connected to the conductive path (3). The onboard control device (10) has a control circuit (13) that operates on the basis of the voltage impressed across the conductive path (3). The control circuit (13) switches the switch unit (11) to OFF when the output voltage of the power supply unit (2) exceeds an overvoltage threshold value, and then transitions from a first state to a second state in which less power is consumed than in the first state when the voltage of the conductive path (3) is equal to or less than a threshold value.

Description

In-vehicle control device

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

[0002] Patent Document 1 discloses an electronic device with a built-in overvoltage protection circuit. The overvoltage protection circuit is configured by connecting a voltage blocking circuit that blocks the power supply voltage and a constant voltage circuit that outputs a constant voltage in parallel between a power input terminal and an internal power supply terminal that supplies power to the internal circuitry of the electronic device. When a high voltage is applied to the power input terminal, the voltage blocking circuit blocks this voltage, and only the constant voltage output by the constant voltage circuit is supplied to the internal power supply terminal.

[0003] Japanese Patent Application Laid-Open No. 2008-5582

[0004] In the configuration of Patent Document 1, backup is achieved by a constant voltage circuit. In contrast, when backup is achieved by a power storage unit provided separately from the power source that supplies power to the power input terminal, the voltage of the power storage unit gradually drops during backup. This can lead to a problem caused by an excessive drop in the voltage of the power storage unit. Possible problems include, for example, insufficient input voltage to the supply destination or deterioration of the power storage unit.

[0005] The present disclosure aims to provide a technique capable of preventing the voltage of a power storage unit from dropping excessively during backup by the power storage unit.

[0006] The vehicle control device disclosed herein is an vehicle control device included in an vehicle system having a power supply unit, a conduction path to which power from the power supply unit is supplied via a switch unit, and a storage unit electrically connected to the conduction path, and has a control circuit that operates based on a voltage applied to the conduction path, and the control circuit switches the switch unit to an off state when the output voltage of the power supply unit exceeds an overvoltage threshold, and then transitions from a first state to a second state that consumes less power than the first state when the voltage of the conduction path becomes equal to or lower than the threshold.

[0007] The technology according to the present disclosure can prevent the voltage of the power storage unit from dropping excessively during backup by the power storage unit.

[0008] Fig. 1 is a configuration diagram of an in-vehicle system including an in-vehicle control device of a first embodiment. Fig. 2 is a flowchart of processing performed by a control circuit of the in-vehicle control device of the first embodiment. Fig. 3 is a timing chart showing changes over time in the output voltage of the power supply unit, the voltage of the conduction path, the on / off state of the switch unit, and the state of the control circuit when the voltage of the conduction path falls below the threshold after the output voltage of the power supply unit exceeds the overvoltage threshold and the switch unit is switched to the off state. Fig. 4 is a timing chart showing changes over time in the output voltage of the power supply unit, the voltage of the conduction path, the on / off state of the switch unit, and the state of the control circuit when the output voltage of the power supply unit exceeds the overvoltage threshold and the switch unit is switched to the off state, and the output voltage of the power supply unit falls below the recovery voltage.

[0009] [Description of Embodiments of the Present Disclosure] In the following, embodiments according to the present disclosure are listed and exemplified.

[0010] [1] An in-vehicle control device included in an in-vehicle system having a power supply unit, a conductive path to which power from the power supply unit is supplied via a switch unit, and a storage unit electrically connected to the conductive path, the in-vehicle control device having a control circuit that operates based on a voltage applied to the conductive path, the control circuit switching the switch unit to an off state when the output voltage of the power supply unit exceeds an overvoltage threshold, and thereafter transitioning from a first state to a second state that consumes less power than the first state when the voltage of the conductive path becomes equal to or lower than the threshold.

[0011] When the output voltage of the power supply unit exceeds an overvoltage threshold, the control circuit switches the switch unit to an off state, thereby cutting off the overvoltage output from the power supply unit and switching the power supply source for the control circuit to the power storage unit. Furthermore, when the voltage of the power storage unit drops and the voltage of the conduction path becomes equal to or lower than the threshold, the control circuit transitions from the first state to a second state that consumes less power than the first state. This suppresses a voltage drop in the power storage unit. In other words, the above-described on-board control device can suppress an excessive drop in the voltage of the power storage unit during backup by the power storage unit.

[0012] [2] The in-vehicle control device according to [1], further comprising a power supply circuit that generates and outputs a power supply voltage based on a voltage applied to the conductive path, and the control circuit operates by receiving the power supply voltage output from the power supply circuit.

[0013] The above-described on-vehicle control device can generate the power supply voltage input to the control circuit by the power supply circuit.

[0014] [3] The in-vehicle control device described in [2], wherein the control circuit transitions from the first state to the second state and switches the switch unit to an on state when the voltage of the conductive path becomes equal to or lower than the threshold value.

[0015] The control circuit switches the switch unit to the on state when the voltage of the conduction path falls below a threshold. This allows power from the power supply unit to be supplied to the conduction path, thereby suppressing a voltage drop in the power storage unit. However, when the output voltage of the power supply unit is in an overvoltage state, there is a concern that an overcurrent will be supplied from the power supply unit, causing the power supply circuit to heat up. In this regard, by transitioning the control circuit to the second state, the current supplied from the power supply unit to the control circuit is suppressed. In other words, when the voltage of the conduction path falls below a threshold, the above-mentioned on-board control device can supply power from the power supply unit to the conduction path while suppressing heat generation in the power supply circuit, and can also suppress an excessive drop in the voltage of the power storage unit.

[0016] [4] The vehicle-mounted control device according to [2] or [3], wherein the threshold value is set to a value greater than a minimum operating voltage of the power supply circuit.

[0017] This configuration can prevent the power supply circuit from being unable to generate the power supply voltage due to a voltage drop in the power storage unit.

[0018] [5] The vehicle-mounted control device according to any one of [1] to [4], wherein the threshold value is set to a value greater than a lower limit usable voltage of the power storage unit.

[0019] According to this configuration, the discharge of the power storage unit is suppressed before the voltage of the power storage unit becomes equal to or lower than the lower limit usable voltage, and a voltage drop of the power storage unit is suppressed.

[0020] [6] The vehicle-mounted control device according to any one of [1] to [5], wherein the control circuit switches the switch unit to an on state when the output voltage of the power supply unit becomes equal to or lower than a recovery voltage.

[0021] According to this configuration, when the output voltage of the power supply unit drops below the recovery voltage, the power supply source for the control circuit can be returned to the power supply unit.

[0022] [Details of the embodiment of the present disclosure] 1. First embodiment An in-vehicle system 1 according to the first embodiment is a system mounted on a vehicle, as shown in Fig. 1. The in-vehicle system 1 includes a power supply unit 2, a conductive path 3, and a power storage unit 4.

[0023] The power supply unit 2 is configured to be able to output an overvoltage. The power supply unit 2 may be configured to include a voltage converter such as a DC-DC converter.

[0024] The conductive path 3 is an electrical path to which power from the power supply unit 2 is supplied via the switch unit 11. The switch unit 11 is provided between the power supply unit 2 and the conductive path 3. The switch unit 11 switches between an ON state in which it allows current to flow from the power supply unit 2 side to the conductive path 3 side through itself, and an OFF state in which it blocks current flowing from the power supply unit 2 side to the conductive path 3 side through itself. When in the ON state, the switch unit 11 may allow current to flow from the conductive path 3 side to the power supply unit 2 side. When in the OFF state, the switch unit 11 may block current flowing from the conductive path 3 side to the power supply unit 2 side. The switch unit 11 may be configured as a mechanical switch or a semiconductor switch.

[0025] The power storage unit 4 is configured by, for example, a battery such as a lithium ion battery or a capacitor such as a lithium ion capacitor. The power storage unit 4 is electrically connected to the conductive path 3 via a branch path 5.

[0026] When the switch unit 11 is in the on state, the output voltage of the power supply unit 2 is applied to the conductive path 3. When the switch unit 11 is in the off state, the voltage of the power storage unit 4 is applied to the conductive path 3.

[0027] The in-vehicle system 1 includes an in-vehicle control device 10. The in-vehicle control device 10 has the switch unit 11, the power supply circuit 12, and the control circuit 13 described above.

[0028] The power supply circuit 12 is provided between the conductive path 3 and the control circuit 13. The power supply circuit 12 performs a power supply voltage generation operation by generating a power supply voltage based on a voltage applied to the conductive path 3 and outputting the generated power supply voltage to the control circuit 13. The power supply circuit 12 is configured as, for example, an integrated circuit. The power supply circuit 12 includes, for example, a voltage conversion unit 12A and a control unit 12B.

[0029] The voltage conversion unit 12A is provided between the conductive path 3 and the control circuit 13. The voltage conversion unit 12A performs a voltage conversion operation of increasing or decreasing the voltage applied to the conductive path 3 and applying the voltage to the output path 6 on the control circuit 13 side. The voltage conversion unit 12A is configured by, for example, a DC-DC converter.

[0030] The control unit 12B operates by receiving power from the conductive path 3 via the power line 12C. The control unit 12B controls the voltage conversion unit 12A. When the voltage input from the conductive path 3 is equal to or greater than the minimum operating voltage, the control unit 12B causes the voltage conversion unit 12A to perform a voltage conversion operation. When the voltage input from the conductive path 3 is less than the minimum operating voltage, the control unit 12B cannot cause the voltage conversion unit 12A to perform a voltage conversion operation.

[0031] The control circuit 13 operates based on the voltage applied to the conductive path 3. The control circuit 13 operates by receiving the power supply voltage output from the power supply circuit 12. In other words, the on-board control device 10 can generate the power supply voltage input to the control circuit 13 using the power supply circuit 12.

[0032] The on-board control device 10 has voltage detection units 21 and 22. The voltage detection unit 21 detects the output voltage of the power supply unit 2 on the side of the power supply unit 2 relative to the switch unit 11. The voltage detection unit 21 detects the voltage of the conductive path 3. The voltage detection units 21 and 22 are configured, for example, by known voltage detection circuits. Signals indicating the detection values ​​by the voltage detection units 21 and 22 are input to the control circuit 13.

[0033] The control circuit 13 determines the output voltage of the power supply unit 2 based on the signal output from the voltage detection unit 21. The control circuit 13 determines the voltage of the conductive path 3 based on the signal output from the voltage detection unit 22.

[0034] The control circuit 13 includes, for example, a microcomputer. The control circuit 13 switches between a first state and a second state in which power consumption is lower than that of the first state. The first state is, for example, a state in which the control circuit 13 controls a control target 90 other than the switch unit 11 and communicates with the communication device 91. The second state is, for example, a state in which the control circuit 13 does not control the control target 90 and only communicates with the communication device 91.

[0035] Control circuit 13 controls switch unit 11. Control circuit 13 switches switch unit 11 to the OFF state when the output voltage of power supply unit 2 exceeds an overvoltage threshold. The overvoltage threshold is set to a value greater than the full charge voltage of power storage unit 4 in the initial state.

[0036] After switching the switch unit 11 to the OFF state, when the voltage of the conductive path 3 becomes equal to or lower than the threshold, the control circuit 13 transitions from the first state to the second state and switches the switch unit 11 to the ON state.

[0037] The threshold value is set to a value greater than the minimum operating voltage of the power supply circuit 12. With the configuration in which the threshold value is set in this manner, it is possible to prevent the power supply circuit 12 from being unable to generate the power supply voltage due to a voltage drop in the power storage unit 4.

[0038] The threshold value is set to a value greater than the lower limit usable voltage of the power storage unit 4. With the configuration in which the threshold value is set in this manner, discharge of the power storage unit 4 is suppressed and a voltage drop of the power storage unit 4 is suppressed before the voltage of the power storage unit 4 falls below the lower limit usable voltage. The lower limit usable voltage is, for example, a voltage below which degradation of the power storage unit 4 begins.

[0039] The control circuit 13 switches the switch unit 11 to the on state when the output voltage of the power supply unit 2 becomes equal to or lower than the recovery voltage. The recovery voltage is set to be higher than 0 V, higher than the minimum operating voltage of the power supply circuit 12, and equal to or lower than the overvoltage threshold.

[0040] The control circuit 13 normally controls the switch unit 11 to the on state and starts the processing shown in Fig. 2. First, in step S10, the control circuit 13 determines whether the output voltage of the power supply unit 2 has exceeded the overvoltage threshold. If the control circuit 13 determines that the output voltage of the power supply unit 2 has not exceeded the overvoltage threshold, the control circuit 13 returns to the processing of step S10. That is, the control circuit 13 repeats the processing of step S10 until it determines that the output voltage of the power supply unit 2 has exceeded the overvoltage threshold. During this time, the power supply circuit 12 performs a power supply voltage generation operation, and the control circuit 13 is maintained in the first state.

[0041] When the control circuit 13 determines that the output voltage of the power supply unit 2 exceeds the overvoltage threshold, the control circuit 13 switches the switch unit 11 to the OFF state in step S11. As a result, the overvoltage output from the power supply unit 2 is cut off by the switch unit 11, and the voltage of the storage unit 4 is applied to the conductive path 3.

[0042] In step S12, the control circuit 13 determines whether the voltage of the conductive path 3 is equal to or lower than the threshold value. If the control circuit 13 determines that the voltage of the conductive path 3 is not equal to or lower than the threshold value, the control circuit 13 determines whether the output voltage of the power supply unit 2 is equal to or lower than the recovery voltage in step S13. If the control circuit 13 determines that the output voltage of the power supply unit 2 is not equal to or lower than the recovery voltage, the control circuit 13 returns to the processing of step S12. The control circuit 13 repeats the processing of steps S12 and S13 until it determines Yes in step S12 or step S13. During this time, the power of the power storage unit 4 is consumed by the power supply circuit 12 and the control circuit 13, and the voltage of the power storage unit 4 gradually decreases.

[0043] When the control circuit 13 determines in step S12 that the voltage of the conductive path 3 has become equal to or lower than the threshold value, the control circuit 13 transitions to the second state in step S14, and switches the switch unit 11 to the on state in step S15. Switching the switch unit 11 to the on state allows power from the power supply unit 2 to be supplied to the conductive path 3, thereby suppressing a voltage drop in the power storage unit 4. However, when the output voltage of the power supply unit 2 is in an overvoltage state, there is a concern that an overcurrent may be supplied from the power supply unit 2, causing the power supply circuit 12 to generate heat. In this regard, transitioning the control circuit 13 to the second state suppresses the current supplied from the power supply unit 2 to the control circuit 13. In other words, when the voltage of the conductive path 3 becomes equal to or lower than the threshold value, the on-board control device 10 can supply power from the power supply unit 2 to the conductive path 3 while suppressing heat generation in the power supply circuit 12, and can also suppress an excessive drop in the voltage of the power storage unit 4.

[0044] If the control circuit 13 determines in step S13 that the output voltage of the power supply unit 2 is equal to or lower than the recovery voltage, it controls the switch unit 11 to the on state in step S15. With this configuration, when the output voltage of the power supply unit 2 drops to or lower than the recovery voltage, the power supply source for the control circuit 13 can be returned to the power supply unit 2.

[0045] FIG. 3 shows a timing chart illustrating the changes over time in the output voltage of the power supply unit 2, the voltage of the conductive path 3, the on / off state of the switch unit 11, and the state of the control circuit 13 when the output voltage of the power supply unit 2 exceeds the overvoltage threshold, causing the switch unit 11 to switch to the off state, and then the voltage of the conductive path 3 falls below the threshold.

[0046] At timing T0, the output voltage of power supply unit 2 is lower than the overvoltage threshold, the voltage of conduction path 3 is lower than the overvoltage threshold and higher than the threshold, switch unit 11 is in the ON state, and control circuit 13 is in the first state. Thereafter, at timing T1, some abnormality causes the output voltage of power supply unit 2 to rise and exceed the overvoltage threshold. At timing T2, switch unit 11 is switched to the OFF state. This causes the voltage of conduction path 3 to fall below the overvoltage threshold. Thereafter, the voltage of power storage unit 4 gradually decreases, and at timing T3, when it falls below the threshold, control circuit 13 transitions to the second state, and switch unit 11 is returned to the ON state. As a result, the voltage of conduction path 3 exceeds the overvoltage threshold, but the current supplied to control circuit 13 is suppressed, and the current flowing through power supply circuit 12 is also suppressed. This suppresses heat generation in power supply circuit 12.

[0047] FIG. 4 shows a timing chart illustrating the changes over time in the output voltage of the power supply unit 2, the voltage of the conductive path 3, the on / off state of the switch unit 11, and the state of the control circuit 13 when the output voltage of the power supply unit 2 exceeds the overvoltage threshold, causing the switch unit 11 to switch to the off state, and then the output voltage of the power supply unit 2 drops to or below the recovery voltage.

[0048] At timing T10, the output voltage of power supply unit 2 is lower than the overvoltage threshold, the voltage of conduction path 3 is lower than the overvoltage threshold and higher than the threshold, switch unit 11 is in the ON state, and control circuit 13 is in the first state. Thereafter, at timing T11, if some abnormality causes the output voltage of power supply unit 2 to rise and exceed the overvoltage threshold, switch unit 11 is switched to the OFF state at timing T12. This causes the voltage of conduction path 3 to fall below the overvoltage threshold. Thereafter, the voltage of power storage unit 4 gradually decreases, but when the output voltage of power supply unit 2 falls below the overvoltage threshold at timing T13, switch unit 11 is switched back to the ON state at timing T14. As a result, the output voltage of power supply unit 2 is applied to conduction path 3, and the voltage drop of power storage unit 4 is suppressed.

[0049] <Other Embodiments> The present disclosure is not limited to the embodiments described above and in the drawings. For example, any combination of features of the above-described or below-described embodiments is possible within a range that does not contradict. Furthermore, any feature of the above-described or below-described embodiments may be omitted unless explicitly stated as essential. Furthermore, the above-described embodiments may be modified as follows.

[0050] In the first embodiment, a power supply circuit is provided between the conductive path and the control circuit, but a power supply circuit may not be provided. For example, the voltage of the conductive path may be input to a series control circuit.

[0051] In the first embodiment, when the voltage of the conductive path becomes equal to or lower than the threshold value, the control circuit transitions to the second state and the switch unit returns to the on state. In contrast, when the voltage of the conductive path becomes equal to or lower than the threshold value, the control circuit may transition to the second state and the switch unit may remain in the off state. In this case, when the voltage of the conductive path becomes equal to or lower than a second threshold value that is lower than the threshold value, the switch unit may return to the on state.

[0052] It should be noted that the embodiments disclosed herein should be considered to be 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 indicated by the claims or within the scope equivalent to the claims.

[0053] REFERENCE SIGNS LIST 1... In-vehicle system 2... Power supply unit 3... Conduction path 4... Power storage unit 5... Branch path 6... Output path 10... In-vehicle control device 11... Switch unit 12... Power supply circuit 12A... Voltage conversion unit 12B... Control unit 12C... Power line 13... Control circuit 21... Voltage detection unit 22... Voltage detection unit 90... Control target 91... Communication device

Claims

1. An in-vehicle control device included in an in-vehicle system having a power supply unit, a conductive path to which power from the power supply unit is supplied via a switch unit, and a power storage unit electrically connected to the conductive path, the in-vehicle control device having a control circuit that operates based on a voltage applied to the conductive path, the control circuit switching the switch unit to an off state when the output voltage of the power supply unit exceeds an overvoltage threshold, and thereafter transitioning from a first state to a second state that consumes less power than the first state when the voltage of the conductive path becomes equal to or lower than the threshold.

2. The in-vehicle control device according to claim 1, further comprising a power supply circuit that generates and outputs a power supply voltage based on a voltage applied to the conductive path, and the control circuit operates by receiving the power supply voltage output from the power supply circuit.

3. The vehicle-mounted control device according to claim 2, wherein the control circuit transitions from the first state to the second state and switches the switch unit to an on state when the voltage of the conductive path becomes equal to or lower than the threshold value.

4. The vehicle control device according to claim 2 or 3, wherein the threshold value is set to a value greater than the minimum operating voltage of the power supply circuit.

5. The vehicle-mounted control device according to any one of claims 1 to 3, wherein the threshold value is set to a value greater than a lower limit usable voltage of the power storage unit.

6. The vehicle-mounted control device according to any one of claims 1 to 3, wherein the control circuit switches the switch unit to an on state when the output voltage of the power supply unit falls below a recovery voltage.

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