Power supply control device

Abstract

A power supply control device (20) includes a first control circuit (30) and a second control circuit (40). The first control circuit (30) controls a voltage converting unit (25) by periodic processing that is performed each time a predetermined interval elapses. The second control circuit (40) switches an element unit (24) from a shut-off state to an allowing state when the supply of power from a power supply unit (10) to a power path (12) enters a failure state. If the failure state arises while the voltage converting unit (25) is being caused to perform a second conversion operation, the first control circuit (30) performs, separately from the periodic processing, advancement processing for advancing the control timing of the voltage converting unit (25), stops the second conversion operation performed by the voltage converting unit (25) at the control timing that has arrived as a result of the advancement processing, and causes the voltage converting unit (25) to perform a first conversion operation.

Description

Power supply control device

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

[0002] Patent Document 1 discloses a power supply control device. The power supply control device includes a first conductive path, an element unit, a second conductive path, a voltage conversion unit, a third conductive path, and a control unit. A voltage based on the output of the power storage unit is applied to the first conductive path. One end of the element unit is electrically connected to the first conductive path. The other end of the element unit is electrically connected to the second conductive path. The second conductive path forms an energization path between the element unit and the power path. The voltage conversion unit is connected in parallel to the element unit between the power storage unit and the power path. The third conductive path is electrically connected to the voltage conversion unit between the voltage conversion unit and the power path. The element unit has a reverse current prevention switch. The element unit allows current to flow to the power path side through itself when the reverse current prevention switch is in the on state, and blocks the flow of current to the power path side through itself when the reverse current prevention switch is in the off state. The voltage conversion unit performs a first conversion operation of boosting or降压 the voltage applied to the first conductive path and applying the output voltage to the third conductive path, and a second conversion operation of boosting or降压 the voltage applied to the third conductive path and applying the output voltage to the first conductive path.

[0003] In the normal state, the control unit causes the voltage conversion unit to perform the second conversion operation and sets the reverse current prevention switch to the off state. This prevents the current supplied from the voltage conversion unit to the first conductive path from flowing into the second and third conductive paths through the element unit. When a fault occurs, the control unit switches the reverse current prevention switch to the on state and starts the first conversion operation of the voltage conversion unit. This immediately starts the power supply to the power path through the element unit.

[0004] International Publication No. 2024 / 105905

[0005] In the above configuration, if it is assumed that the reverse current prevention switch and the voltage conversion unit are controlled by separate control circuits, a state may occur where the current supply from the voltage conversion unit to the first conductive path continues when the reverse current prevention switch is switched to the on state. In this case, there is a risk that the current supplied to the first conductive path may flow into the second and third conductive paths through the element unit.

[0006] The present disclosure aims to provide a technology that can suppress the leakage of output current from the voltage conversion unit to the energy storage unit through the element unit when switching from the charging state of the energy storage unit by the voltage conversion unit to the discharge state of the energy storage unit via the element unit.

[0007] The power supply control device of the present disclosure is included in an in-vehicle system comprising a power supply unit that supplies power, a power path which is a path through which power from the power supply unit is transmitted, and a power storage unit different from the power supply unit, and is a power supply control device that controls the power supply from the power storage unit, comprising: a first conductive path to which a voltage based on the output of the power storage unit is applied; an element unit whose one end is electrically connected to the first conductive path; a second conductive path electrically connected to the other end of the element unit and forming a current-carrying path between the element unit and the power path; a voltage conversion unit connected in parallel to the element unit between the power storage unit and the power path; a third conductive path electrically connected to the voltage conversion unit between the voltage conversion unit and the power path; a first control circuit for controlling the voltage conversion unit; and a second control circuit provided separately from the first control circuit. The voltage conversion unit performs a first conversion operation to boost or lower the voltage applied to the first conductive path and apply the output voltage to the third conductive path, and a second conversion operation to boost or lower the voltage applied to the third conductive path and apply the output voltage to the first conductive path. The element unit is capable of preventing current from flowing through it to the energy storage unit, and switches between a shut-off state that blocks current flowing through it to the power path and an allowable state that allows current to flow through it to the power path. The first control circuit controls the voltage conversion unit by periodic processing performed after a predetermined period has elapsed. The second control circuit controls the element unit, and when the power supply from the power supply unit to the power path is lost, it switches the element unit from the shut-off state to the allowable state. If the first control circuit occurs in the state in which the voltage conversion unit is performing the second conversion operation, it performs an advancement process to advance the control timing of the voltage conversion unit, separate from the periodic processing, and stops the second conversion operation by the voltage conversion unit at the control timing that has arrived as a result of the advancement process, causing the voltage conversion unit to perform the first conversion operation.

[0008] According to the technology disclosed herein, when switching from the charging state of the energy storage unit by the voltage conversion unit to the discharge state of the energy storage unit via the element unit, it is possible to suppress the output current from the voltage conversion unit to the energy storage unit side flowing back through the element unit.

[0009] Figure 1 is a schematic diagram showing an in-vehicle system equipped with a power supply control device according to the first embodiment. Figure 2 is a schematic diagram showing the voltage conversion unit of the first embodiment. Figure 3 is a flowchart of the processing performed by the first control circuit of the first embodiment. Figure 4 is a timing chart showing the operation of the first control circuit, voltage conversion unit, second control circuit, and element unit of the first embodiment before and after the failure state occurs. Figure 5 is a flowchart showing the processing performed by the first control circuit of the second embodiment. Figure 6 is a timing chart showing the operation of the first control circuit, voltage conversion unit, second control circuit, and element unit of the second embodiment before and after the failure state occurs. Figure 7 is a schematic diagram showing an in-vehicle system equipped with a power supply control device according to the third embodiment.

[0010] [Description of Embodiments of the Disclosure] First, embodiments of the Disclosure will be listed and described.

[0011] [1] A power supply control device included in an in-vehicle system comprising a power supply unit that supplies power, a power path which is a path through which power from the power supply unit is transmitted, and a power storage unit different from the power supply unit, the power supply control device for controlling the power supply from the power storage unit, comprising: a first conductive path to which a voltage based on the output of the power storage unit is applied; an element unit whose one end is electrically connected to the first conductive path; a second conductive path electrically connected to the other end of the element unit and forming a current-carrying path between the element unit and the power path; a voltage conversion unit connected in parallel to the element unit between the power storage unit and the power path; a third conductive path electrically connected to the voltage conversion unit between the voltage conversion unit and the power path; a first control circuit for controlling the voltage conversion unit; and a second control circuit provided separately from the first control circuit, The voltage conversion unit performs a first conversion operation to boost or lower the voltage applied to the first conductive path and apply the output voltage to the third conductive path, and a second conversion operation to boost or lower the voltage applied to the third conductive path and apply the output voltage to the first conductive path. The element unit is capable of preventing current from flowing through it to the energy storage unit, and switches between a shut-off state that blocks current flowing through it to the power path and an allowable state that allows current to flow through it to the power path. The first control circuit controls the voltage conversion unit by periodic processing performed after a predetermined period has elapsed. The second control circuit controls the element unit, and when the power supply from the power supply unit to the power path is lost, it switches the element unit from the shut-off state to the allowable state. The first control circuit, when the failure state occurs while the voltage conversion unit is performing the second conversion operation, performs an advancement process to advance the control timing of the voltage conversion unit, separate from the periodic processing, and stops the second conversion operation by the voltage conversion unit at the control timing that has arrived as a result of the advancement process, causing the voltage conversion unit to perform the first conversion operation.

[0012] In the above-described power supply control device, when a power failure occurs, the second control circuit switches the element unit from an interrupted state to an enabled state. As a result, power is immediately supplied from the energy storage unit to the power line via the element unit. However, if the voltage conversion unit is performing a second conversion operation at the time of the power failure, and the first control circuit waits for the predetermined period to elapse before stopping the second conversion operation of the voltage conversion unit, there is a concern that the element unit will turn on before the second conversion operation stops, causing the current supplied from the voltage conversion unit to the energy storage unit to flow back through the element unit. In this regard, the first control circuit of the above-described power supply control device performs an early detection process when a power failure occurs while the voltage conversion unit is performing a second conversion operation, and stops the second conversion operation by the voltage conversion unit at the control time that has arrived as a result of the early detection process, causing the voltage conversion unit to perform a first conversion operation. Therefore, compared to the case where the second conversion operation of the voltage conversion unit is stopped after waiting for the predetermined period to elapse without performing an early detection process, the second conversion operation by the voltage conversion unit can be stopped earlier. As a result, either no current flows back through the element, or the time it takes for current to flow back through the element is shortened. In other words, with this configuration, when switching from the charging state of the energy storage unit by the voltage conversion unit to the discharge state of the energy storage unit via the element, it is possible to suppress the flow of output current from the voltage conversion unit to the energy storage unit side through the element.

[0013] [2] The acceleration process is a process that shortens the predetermined cycle, as described in [1].

[0014] The above-mentioned power supply control device can shorten a predetermined cycle when a power failure occurs, thereby accelerating the control timing of the voltage conversion unit.

[0015] [3] The acceleration process is a process to cause the first control circuit to perform an interrupt process to immediately execute the control of the voltage conversion unit, as described in [1].

[0016] The above power supply control device can accelerate the control timing of the voltage conversion unit by performing an interrupt process when a power failure occurs.

[0017] [4] The power supply control device according to any one of [1] to [3], wherein the first control circuit temporarily stops the output of the voltage conversion unit before allowing the voltage conversion unit to perform the first conversion operation when stopping the second conversion operation by the voltage conversion unit.

[0018] If the voltage conversion unit switches directly from the second conversion operation to the first conversion operation, there is a risk that current may continue to flow from the voltage conversion unit to the energy storage unit for a while even after switching to the first conversion operation. The power supply control device temporarily stops the output of the voltage conversion unit before switching the voltage conversion unit to the first conversion operation, thereby preventing current leakage immediately after stopping the second conversion operation.

[0019] [Details of Embodiments of the Disclosure] 1. First Embodiment 1-1. Configuration of the In-Vehicle System 1 The in-vehicle system 1 shown in Figure 1 comprises a power supply unit 10, a load 11, a power line 12, a diode 13, a power storage unit 14, and a power supply control device 20.

[0020] The power supply unit 10 is a power source that supplies power to the load 11. The power supply unit 10 is composed of, for example, a battery. The power path 12 is the path through which power from the power supply unit 10 is transmitted. The power path 12 is provided between the power supply unit 10 and the load 11. The diode 13 is provided in the power path 12. The diode 13 allows current to flow from the power supply unit 10 to the load 11 through itself, and prevents current from flowing from the load 11 to the power supply unit 10 through itself. The energy storage unit 14 is a power source separate from the power supply unit 10. The energy storage unit 14 is composed of, for example, a lithium-ion battery or a lithium-ion capacitor.

[0021] The power supply control device 20 controls the power supply from the energy storage unit 14. The power supply control device 20 includes a first conductive path 21, a second conductive path 22, a third conductive path 23, an element unit 24, a voltage conversion unit 25, a voltage detection unit 26, a first control circuit 30, and a second control circuit 40.

[0022] A voltage based on the output of the energy storage unit 14 is applied to the first conductive path 21. The first conductive path 21 is electrically connected to the positive terminal of the energy storage unit 14. One end of the element unit 24 is electrically connected to the first conductive path 21. The other end of the element unit 24 is electrically connected to the second conductive path 22. The second conductive path 22 forms the current path between the element unit 24 and the power path 12. The second conductive path 22 is electrically connected to the power path 12 on the load 11 side of the diode 13. The voltage conversion unit 25 is connected in parallel to the element unit 24 between the energy storage unit 14 and the power path 12. The third conductive path 23 is electrically connected to the voltage conversion unit 25 between the voltage conversion unit 25 and the power path 12.

[0023] The element section 24 includes a reverse current prevention switch 24A and a diode 24B. The reverse current prevention switch 24A and the diode 24B are connected in series between the first conductive path 21 and the second conductive path 22. When the reverse current prevention switch 24A is in the off state, it blocks the current flowing through it from the first conductive path 21 to the second conductive path 22, and when it is in the on state, it allows current to flow through it from the first conductive path 21 to the second conductive path 22. The diode 24B prevents current from flowing through it from the second conductive path 22 to the first conductive path 21, and allows current to flow through it from the first conductive path 21 to the second conductive path 22.

[0024] The element 24 prevents current from flowing through it to the energy storage unit 14 by the diode 24B. When the reverse current prevention switch 24A is in the off state, the element 24 is in a blocking state that blocks the current flowing through it to the power line 12, and when the reverse current prevention switch 24A is in the on state, it is in a tolerance state that allows current to flow through it to the power line 12. The element 24 is in a blocking state when a blocking signal (specifically, an off signal) is input, and is in a tolerance state when a tolerance signal (specifically, an on signal) is input. The reverse current prevention switch 24A is composed of, for example, a MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor).

[0025] The voltage conversion unit 25 performs a first conversion operation in which it increases or decreases the voltage applied to the first conductive path 21 and applies the output voltage to the third conductive path 23, and a second conversion operation in which it increases or decreases the voltage applied to the third conductive path 23 and applies the output voltage to the first conductive path 21. The voltage conversion unit 25 is configured, for example, by a DC-DC converter.

[0026] The voltage conversion unit 25 is, for example, an H-bridge type buck-boost converter as shown in Figure 2. The voltage conversion unit 25 includes switches 25A, 25B, 25C, and 25D, and an inductor 25E. Switch 25A is a high-side switch on the first conductive path 21 side. Switch 25B is a low-side switch on the first conductive path 21 side. Switch 25C is a high-side switch on the third conductive path 23 side. Switch 25D is a low-side switch on the third conductive path 23 side. One end of the inductor 25E is electrically connected to the conductive path between switches 25A and 25B. The other end of the inductor 25E is electrically connected to the conductive path between switches 25C and 25D.

[0027] The voltage detection unit 26 detects the voltage of the power line 12 and outputs a signal indicating the voltage of the power line 12. The voltage detection unit 26 detects the voltage of the power line 12 on the power supply unit 10 side of the diode 13. The voltage detection unit 26 is configured, for example, by a known voltage detection circuit.

[0028] The first control circuit 30 controls the voltage conversion unit 25. The first control circuit 30 has an MCU 31 (Micro Controller Unit). The MCU 31 controls the voltage conversion unit 25 by periodic processing performed after a predetermined period has elapsed. In this embodiment, the predetermined period is the time between the start times of the periodic processing, but it may also be the time from the end time of one periodic processing to the start time of the next periodic processing.

[0029] The second control circuit 40 is provided separately from the first control circuit 30. The second control circuit 40 controls the element unit 24 (specifically, the reverse current prevention switch 24A). When the power supply from the power supply unit 10 to the power line 12 is lost, the second control circuit 40 switches the element unit 24 from the shut-off state to the allow state.

[0030] A power failure state is an abnormal state in which the power supply from the power supply unit 10 to the power line 12 has decreased to a predetermined standard or has stopped. In this embodiment, a power failure state is a state in which the voltage of the power line 12 (i.e., the value detected by the voltage detection unit 26) has decreased to a threshold Vth or lower. The threshold Vth is a value that is less than the output voltage of the power supply unit 10 when fully charged and is 0V or greater.

[0031] The second control circuit 40 determines whether or not a failure has occurred based on the voltage of the power line 12. In this embodiment, the second control circuit 40 is composed of hardware circuits. Specifically, the second control circuit 40 has a comparator 41. The comparator 41 receives a signal output from the voltage detection unit 26 (i.e., a signal indicating the voltage of the power line 12) and a threshold Vth as input. When the voltage of the power line 12 is greater than the threshold Vth, the comparator 41 outputs a cutoff signal (specifically, an off signal) to the reverse current prevention switch 24A. In other words, the second control circuit 40 controls the element unit 24 to the cutoff state in the normal state when there is no failure. The comparator 41 also outputs an allow signal (specifically, an on signal) to the reverse current prevention switch 24A when the voltage of the power line 12 falls below the threshold Vth. In other words, the second control circuit 40 controls the element unit 24 to the allow state when a failure has occurred.

[0032] When the MCU 31 of the first control circuit 30 fails, it causes the voltage conversion unit 25 to perform a first conversion operation, supplying power from the energy storage unit 14 to the load 11.

[0033] The MCU 31 causes the voltage conversion unit 25 to perform a second conversion operation when the charging conditions are met under normal conditions. For example, the charging conditions are met during the period from when the voltage of the power line 12 falls below the charging start voltage to when it rises above the charging end voltage. The charging start voltage is a value that is lower than the output voltage of the power supply unit 10 when fully charged and greater than the threshold voltage Vth. The charging end voltage is a value that is less than or equal to the output voltage of the power supply unit 10 when fully charged and greater than the charging start voltage.

[0034] If the MCU 31 experiences a failure while the voltage conversion unit 25 is performing a second conversion operation, it performs an advancement process to advance the control timing of the voltage conversion unit 25, separate from the periodic processing. At the control timing that has arrived due to the advancement process, the MCU 31 stops the second conversion operation by the voltage conversion unit 25 and causes the voltage conversion unit 25 to perform the first conversion operation.

[0035] The MCU 31 includes an acceleration processing unit 32 and a control unit 33. The acceleration processing unit 32 determines whether or not a failure state has occurred based on the signal output from the second control circuit 40 (specifically, the comparator 41) to the element unit 24. The acceleration processing unit 32 determines that a failure state has not occurred when an off signal is output from the comparator 41, and determines that a failure state has occurred when an on signal is output from the comparator 41. If the acceleration processing unit 32 determines that a failure state has occurred, it performs the acceleration processing described above. In this embodiment, the acceleration processing is a process that shortens a predetermined period for periodic processing. For example, the predetermined period in the normal state is the first period, and the acceleration processing is a process that changes the predetermined period to a second period which is shorter than the first period.

[0036] The control unit 33 controls the voltage conversion unit 25. In normal conditions, when the charging conditions are met, the control unit 33 causes the voltage conversion unit 25 to perform a second conversion operation. If a failure occurs while the voltage conversion unit 25 is performing the second conversion operation, the control unit 33 receives instructions from the acceleration process and performs periodic processing in the second cycle. When the second cycle has elapsed, the control unit 33 stops the second conversion operation by the voltage conversion unit 25 in the periodic processing and causes the voltage conversion unit 25 to perform the first conversion operation.

[0037] When the control unit 33 stops the second conversion operation by the voltage conversion unit 25, it temporarily stops the output of the voltage conversion unit 25 before allowing the voltage conversion unit 25 to perform the first conversion operation. In other words, the control unit 33 stops the second conversion operation by the voltage conversion unit 25 by stopping the output of the voltage conversion unit 25, and then allows the voltage conversion unit 25 to perform the first conversion operation. The control unit 33 stops the output of the voltage conversion unit 25 by controlling at least one of the switches 25A, 25B, 25C, 25D that constitute the voltage conversion unit 25 (for example, switch 25A) to the OFF state.

[0038] Furthermore, if the MCU 31 fails while the voltage conversion unit 25 is not performing the second conversion operation, the MCU 31 may temporarily stop the output of the voltage conversion unit 25 before allowing the voltage conversion unit 25 to perform the first conversion operation, or it may allow the voltage conversion unit 25 to perform the first conversion operation without providing a period of time to stop the output of the voltage conversion unit 25.

[0039] The MCU 31 performs the processing shown in Figure 3, for example. In step S11, the MCU 31 performs periodic processing. After performing periodic processing, in step S12, the MCU 31 determines whether a predetermined period (specifically, the first period) has elapsed since the start of the previous periodic processing. If the MCU 31 determines that the predetermined period has elapsed (step S12: Yes), it returns to the processing in step S11 and performs periodic processing.

[0040] If the MCU 31 determines that a predetermined period has not elapsed (step S12: No), it determines in step S13 whether or not it has entered a lost state. If the MCU 31 determines that it has not entered a lost state (step S13: No), it returns to the process in step S12. In other words, under normal conditions, the MCU 31 performs periodic processing each time the first period has elapsed.

[0041] Under normal conditions, power is supplied from the power supply unit 10 to the load 11. The second control circuit 40 outputs an off signal to the reverse current prevention switch 24A of the element unit 24, controlling the element unit 24 to an off state. In this state, when the charging conditions are met, the MCU 31 causes the voltage conversion unit 25 to perform a second conversion operation in a periodic process. As a result, power from the power supply unit 10 is supplied to the load 11, and power from the power supply unit 10 is charged to the energy storage unit 14 via the voltage conversion unit 25.

[0042] When a failure occurs, the second control circuit 40 outputs an ON signal to the reverse current prevention switch 24A of the element unit 24, switching the element unit 24 to an allowable state. Also, when the second control circuit 40 outputs an ON signal, the MCU 31 determines that a failure has occurred (step S13: Yes), and in step S14, shortens the predetermined period to the second period. Then, the MCU 31 returns to the process of step S12, and when it determines that the second period has elapsed, it performs period processing in step S11. In this period processing, the MCU 31 stops the output of the voltage conversion unit 25. As a result, with the output of the voltage conversion unit 25 stopped, power is supplied from the energy storage unit 14 to the load 11 via the element unit 24. After stopping the output of the voltage conversion unit 25, the MCU 31 causes the voltage conversion unit 25 to perform the first conversion operation in the period processing after a predetermined time has elapsed.

[0043] Figure 4 shows a timing chart illustrating the operation of the first control circuit 30, voltage conversion unit 25, second control circuit 40, and element unit 24 before and after the failure state. Timings t1 to t2 represent the normal state. In the normal state, the first control circuit 30 performs periodic processing after the first cycle has elapsed, the voltage conversion unit 25 performs the second conversion operation, the second control circuit 40 outputs an off signal, and the element unit 24 is controlled to a cutoff state.

[0044] When a breakdown state occurs at timing t2, the output signal of the second control circuit 40 switches to an on signal, and the element unit 24 switches to an allowable state. Then, the predetermined period of the periodic processing performed by the first control circuit 30 is changed to a second period. When the second period elapses at timing t3, the first control circuit 30 performs periodic processing, stops the second conversion operation by the voltage conversion unit 25, and stops the output of the voltage conversion unit 25. After the first control circuit 30 stops the second conversion operation by the voltage conversion unit 25, when the discharge start condition is satisfied, the first conversion operation is caused to be performed on the voltage conversion unit 25 in the periodic processing (timing t4). The discharge start condition may be, for example, that a predetermined interval time has elapsed since the second conversion operation by the voltage conversion unit 25 stopped, or other conditions.

[0045] 1-2. Effects of the first embodiment In the power supply control device 20, when a power failure occurs, the second control circuit 40 switches the element unit 24 from the shut-off state to the allow state. As a result, power is immediately supplied from the energy storage unit 14 to the power line 12 via the element unit 24. However, if the voltage conversion unit 25 is performing the second conversion operation at the time the power failure occurs, and the first control circuit 30 waits for the predetermined period to elapse before stopping the second conversion operation of the voltage conversion unit 25, there is a concern that the element unit 24 will turn ON before the second conversion operation stops, and the current supplied from the voltage conversion unit 25 to the energy storage unit 14 will leak back through the element unit 24. If such current leakage occurs, there is a concern that a loop current will be generated through the voltage conversion unit 25 and the element unit 24, causing an overcurrent. In this regard, the first control circuit 30 of the power supply control device 20 performs an acceleration process when a failure occurs while the voltage conversion unit 25 is performing the second conversion operation. The first control circuit 30 then stops the second conversion operation by the voltage conversion unit 25 at the control time that has arrived as a result of the acceleration process, and causes the voltage conversion unit 25 to perform the first conversion operation. Therefore, compared to the case where the second conversion operation of the voltage conversion unit 25 is stopped after waiting for a predetermined cycle to elapse without performing the acceleration process, the second conversion operation of the voltage conversion unit 25 can be stopped earlier. As a result, either no current flows back through the element unit 24, or the time it takes for current to flow back through the element unit 24 is shortened. In other words, with this configuration, when switching from the charging state of the energy storage unit 14 by the voltage conversion unit 25 to the discharge state of the energy storage unit 14 via the element unit 24, it is possible to suppress the flow of output current from the voltage conversion unit 25 to the energy storage unit 14 side via the element unit 24.

[0046] The power supply control device 20 can shorten a predetermined cycle when a power failure occurs, thereby accelerating the control timing of the voltage conversion unit 25.

[0047] The power supply control device 20 temporarily stops the output of the voltage conversion unit 25 before switching the voltage conversion unit 25 to the first conversion operation, thereby preventing current leakage immediately after stopping the second conversion operation.

[0048] 2. Second Embodiment In the first embodiment, an example of shortening a predetermined period as initialization processing has been described. In the second embodiment, an example of causing the first control circuit to perform an interrupt process as initialization processing will be described. Note that since the in-vehicle system of the second embodiment has the same configuration as that shown in FIG. 1 described in the first embodiment, the description will be made with reference to FIG. 1.

[0049] In the second embodiment, the operation of the first control circuit 30 is different from that in the first embodiment. Specifically, the initialization processing unit 32 of the MCU 31 causes the control unit 33 to perform an interrupt process as initialization processing. The interrupt process is a process that immediately executes the control of the voltage conversion unit even if a predetermined period has not elapsed. When the control unit 33 receives an interrupt instruction from the initialization processing unit 32, the control unit 33 performs an interrupt process. Specifically, the control unit 33 stops the second conversion operation by the voltage conversion unit 25 in such a manner as to stop the output of the voltage conversion unit 25. After the control unit 33 stops the output of the voltage conversion unit 25, the control unit 33 causes the voltage conversion unit 25 to perform the first conversion operation in the periodic process after a predetermined time has elapsed.

[0050] Note that when the MCU 31 enters a defective state while the voltage conversion unit 25 is not performing the second conversion operation, when stopping the second conversion operation by the voltage conversion unit 25, the MCU 31 may temporarily stop the output of the voltage conversion unit 25 and then cause the voltage conversion unit 25 to perform the first conversion operation, or may cause the voltage conversion unit 25 to perform the first conversion operation without providing a time for stopping the output of the voltage conversion unit 25.

[0051] The MCU 31 performs, for example, the process shown in FIG. 5. The MCU 31 performs a periodic process in step S21. After performing the periodic process, the MCU 31 determines in step S22 whether or not a predetermined period has elapsed since the previous periodic process. When the MCU 31 determines that the predetermined period has elapsed (step S22: Yes), the MCU 31 returns to the process of step S21 and performs a periodic process.

[0052] If the MCU 31 determines that a predetermined period has not elapsed (step S22: No), it determines in step S23 whether or not it has entered a lost state. If the MCU 31 determines that it has not entered a lost state (step S23: No), it returns to the process in step S22. In other words, under normal conditions, the MCU 31 performs periodic processing each time a predetermined period has elapsed.

[0053] When a failure occurs, the second control circuit 40 outputs an ON signal to the reverse current prevention switch 24A of the element unit 24, switching the element unit 24 to an allowable state. Also, when the second control circuit 40 outputs an ON signal, the MCU 31 determines that a failure has occurred (step S23: Yes), and performs interrupt processing in step S24. In other words, the MCU 31 stops the second conversion operation by the voltage conversion unit 25 and stops the output of the voltage conversion unit 25. After that, the MCU 31 returns to the processing in step S22. After stopping the output of the voltage conversion unit 25, the MCU 31 causes the voltage conversion unit 25 to perform the first conversion operation in the periodic processing after a predetermined time has elapsed.

[0054] Figure 6 shows a timing chart illustrating the operation of the first control circuit 30, voltage conversion unit 25, second control circuit 40, and element unit 24 before and after the failure state. Timings t21 to t22 represent the normal state. In the normal state, the first control circuit 30 performs periodic processing every predetermined period, the voltage conversion unit 25 performs the second conversion operation, the second control circuit 40 outputs an off signal, and the element unit 24 is controlled to a cutoff state.

[0055] In this state, if a failure occurs at timing t22, the output signal of the second control circuit 40 switches to an ON signal, and the element unit 24 switches to an OK state. The first control circuit 30 then performs an interrupt process, stopping the second conversion operation by the voltage conversion unit 25 and stopping the output of the voltage conversion unit 25 (timing t23). After stopping the second conversion operation by the voltage conversion unit 25, when the discharge start condition is met (timing t24), the first control circuit 30 causes the voltage conversion unit 25 to perform the first conversion operation in the subsequent periodic processing (timing t25).

[0056] The power supply control device 20 of the second embodiment can advance the control timing of the voltage conversion unit 25 by performing an interrupt process when a power failure occurs.

[0057] 3. Third Embodiment The third embodiment differs from the first embodiment only in the configuration of the element section. In the third embodiment, the same reference numerals are used for components that are the same as in the first embodiment, and detailed explanations are omitted.

[0058] The in-vehicle system 301 of the third embodiment shown in Figure 7 includes a power supply control device 320 instead of the power supply control device 20 described in the first embodiment. The power supply control device 320 includes an element unit 324 instead of the element unit 24 described in the first embodiment. The element unit 324 has a MOSFET 324A. The MOSFET 324A is oriented in the opposite direction to the reverse current prevention switch 24A described in the first embodiment. The source of the MOSFET 324A is electrically connected to the first conductive path 21. The drain of the MOSFET 324A is electrically connected to the second conductive path 22.

[0059] The resistance of MOSFET 324A is adjusted so that when it is in the off state and the voltage conversion unit 25 is performing the second conversion operation, no current flows from the first conductive path 21 to the second conductive path 22 via its body diode 324B. Therefore, when MOSFET 324A is in the off state, element 324 is in a blocking state that blocks the current flowing to the power path 12 via itself, and when MOSFET 324A is in the on state, it is in a tolerance state that allows current to flow to the power path 12 via itself.

[0060] <Other Embodiments> This disclosure is not limited to the embodiments described above and in the drawings. For example, any combination of the features of the embodiments described above or below is possible as long as it does not contradict the original. Furthermore, any feature of the embodiments described above or below may be omitted unless explicitly stated as essential. In addition, the embodiments described above may be modified as follows.

[0061] In each of the above embodiments, the first control circuit determined whether or not a failure state was occurring based on the output signal of the second control circuit, but the determination may be made by another method. For example, the first control circuit may determine whether or not a failure state is occurring based on the voltage of the power line.

[0062] In each of the above embodiments, the first control circuit was configured to temporarily stop the output of the voltage conversion unit before allowing the voltage conversion unit to perform the first conversion operation when stopping the second conversion operation by the voltage conversion unit. In contrast, the first control circuit may allow the voltage conversion unit to perform the first conversion operation without providing a time to stop the output of the voltage conversion unit when stopping the second conversion operation by the voltage conversion unit. In other words, the first control circuit may directly switch the voltage conversion unit from the second conversion operation to the first conversion operation.

[0063] The element section of the third embodiment described above may have a resistor connected in series with the MOSFET in addition to the MOSFET. With this configuration, by adjusting the resistance value of the resistor, the element section can be configured so that no current flows from the first conductive path side to the second conductive path side through the element section when the MOSFET is in the off state and the voltage conversion section is performing the second conversion operation.

[0064] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is not limited to the embodiments disclosed herein, but is indicated by the claims, and all modifications within the meaning and scope of the claims are intended to be included.

[0065] 1...In-vehicle system 10...Power supply unit 11...Load 12...Power line 13...Diode 14...Energy storage unit 20...Power supply control device 21...First conductive line 22...Second conductive line 23...Third conductive line 24...Element unit 24A...Reverse current prevention switch 24B...Diode 25...Voltage conversion unit 25A...Switch 25B...Switch 25C...Switch 25D...Switch 25E...Inductor 26...Voltage detection unit 30...First control circuit 31...MCU 32...Early processing unit 33...Control unit 40...Second control circuit 41...Comparator 301...In-vehicle system 320...Power supply control device 324...Element unit 324A...MOSFET 324B...Body diode Vth...Threshold

Claims

1. A power supply control device included in an in-vehicle system comprising a power supply unit that supplies power, a power path which is a path through which power from the power supply unit is transmitted, and a power storage unit different from the power supply unit, the power supply control device for controlling the power supply from the power storage unit, comprising: a first conductive path to which a voltage based on the output of the power storage unit is applied; an element unit whose one end is electrically connected to the first conductive path; a second conductive path electrically connected to the other end of the element unit and forming a current-carrying path between the element unit and the power path; a voltage conversion unit connected in parallel to the element unit between the power storage unit and the power path; a third conductive path electrically connected to the voltage conversion unit between the voltage conversion unit and the power path; a first control circuit for controlling the voltage conversion unit; and a second control circuit provided separately from the first control circuit, The voltage conversion unit performs a first conversion operation to boost or lower the voltage applied to the first conductive path and apply the output voltage to the third conductive path, and a second conversion operation to boost or lower the voltage applied to the third conductive path and apply the output voltage to the first conductive path. The element unit is capable of preventing current from flowing through it to the energy storage unit, and switches between a shut-off state that blocks current flowing through it to the power path and an allowable state that allows current to flow through it to the power path. The first control circuit controls the voltage conversion unit by periodic processing performed after a predetermined period has elapsed. The second control circuit controls the element unit, and when the power supply from the power supply unit to the power path is lost, it switches the element unit from the shut-off state to the allowable state. The first control circuit, when the failure state occurs while the voltage conversion unit is performing the second conversion operation, performs an advancement process to advance the control timing of the voltage conversion unit, separate from the periodic processing, and stops the second conversion operation by the voltage conversion unit at the control timing that has arrived as a result of the advancement process, causing the voltage conversion unit to perform the first conversion operation.

2. The power supply control device according to claim 1, wherein the acceleration process is a process for shortening the predetermined period.

3. The power supply control device according to claim 1, wherein the acceleration process is a process for causing the first control circuit to perform an interrupt process to immediately execute control of the voltage conversion unit.

4. The power supply control device according to any one of claims 1 to 3, wherein the first control circuit temporarily stops the output of the voltage conversion unit before allowing the voltage conversion unit to perform the first conversion operation when stopping the second conversion operation by the voltage conversion unit.

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