Power supply control device

Abstract

This technology provides a way to 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 via the voltage conversion unit to the discharge state of the energy storage unit via the element unit. [Solution] The power supply control device 20 comprises a first control circuit 30 and a second control circuit 40. The first control circuit 30 stops the second conversion operation by the voltage conversion unit 25 and causes the voltage conversion unit 25 to perform the first conversion operation when the power supply from the power supply unit 10 to the power line 12 is lost while the voltage conversion unit 25 is performing the second conversion operation. The second control circuit 40 comprises a failure detection circuit 41 and a delay circuit 42. The failure detection circuit 41 outputs a cutoff signal when it determines that there is no failure, and outputs an allow signal when it determines that there is a failure. The delay circuit 42 delays the signal output from the failure detection circuit 41 and outputs it to the element unit 24.

Description

Technical Field

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

Background Art

[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 a current conduction 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 bucking 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 bucking the voltage applied to the third conductive path and applying the output voltage to the first conductive path.

[0003] 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 in the normal state. Thereby, it is possible to prevent the current supplied from the voltage conversion unit to the first conductive path from flowing into the second conductive path and the third conductive path 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. Thereby, the power supply to the power path through the element unit is immediately started.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] In the above configuration, assuming that the reverse current prevention switch and the voltage conversion unit are controlled by separate control circuits, a situation may occur where current is continuously supplied from the voltage conversion unit to the first conductive path 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 leak back into the second and third conductive paths via 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. [Means for solving the problem]

[0007] The power supply control device disclosed herein is A power supply control device 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 controls the power supply from the power storage unit, A first conductive path to which a voltage based on the output of the energy storage unit is applied, An element portion having one end electrically connected to the first conductive path, A second conductive path is electrically connected to the other end of the element portion and forms a current-carrying path between the element portion and the power line, A voltage conversion unit connected in parallel to the element unit between the energy storage unit and the power line, Between the voltage conversion unit and the power line, a third conductive path electrically connected to the voltage conversion unit, A first control circuit for controlling the voltage conversion unit, The system comprises a second control circuit provided separately from the first control circuit, The voltage conversion unit performs a first conversion operation to increase or decrease the voltage applied to the first conductive path and apply the output voltage to the third conductive path, and a second conversion operation to increase or decrease the voltage applied to the third conductive path and apply the output voltage to the first conductive path. The element is capable of preventing current from flowing through it to the energy storage unit, and when a cutoff signal is input, it enters a cutoff state that cuts off the current flowing through it to the power line, and when an allow signal is input, it enters an allowable state that allows current to flow through it to the power line. The first control circuit, when the supply of power from the power supply unit to the power line is lost while the voltage conversion unit is performing the second conversion operation, stops the second conversion operation by the voltage conversion unit and causes the voltage conversion unit to perform the first conversion operation. The second control circuit has a failure detection circuit and a delay circuit, The failure detection circuit outputs the cutoff signal when it determines that the failure state is not present, and outputs the allow signal when it determines that the failure state is present. The delay circuit delays the signal output from the failure detection circuit and outputs it to the element section. [Effects of the Invention]

[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. [Brief explanation of the drawing]

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

[0010] [Description of Embodiments in this Disclosure] First, the embodiments of this 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 line 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, which controls the power supply from the power storage unit, A first conductive path to which a voltage based on the output of the energy storage unit is applied, An element portion having one end electrically connected to the first conductive path, A second conductive path is electrically connected to the other end of the element portion and forms a current-carrying path between the element portion and the power line, A voltage conversion unit connected in parallel to the element unit between the energy storage unit and the power line, Between the voltage conversion unit and the power line, a third conductive path electrically connected to the voltage conversion unit, A first control circuit for controlling the voltage conversion unit, The system comprises a second control circuit provided separately from the first control circuit, The voltage conversion unit performs a first conversion operation to increase or decrease the voltage applied to the first conductive path and apply the output voltage to the third conductive path, and a second conversion operation to increase or decrease the voltage applied to the third conductive path and apply the output voltage to the first conductive path. The element unit can prevent current from flowing to the power storage unit side through itself, and enters a blocking state where it blocks the current flowing to the power path side through itself when a blocking signal is input, and enters an allowable state where it allows current to flow to the power path side through itself when an allowable signal is input. When power supply from the power supply unit to the power path is lost while the first control circuit is causing the voltage conversion unit to perform the second conversion operation, the first control circuit stops the second conversion operation by the voltage conversion unit and causes the voltage conversion unit to perform the first conversion operation. The second control circuit includes a fault detection circuit and a delay circuit. When the fault detection circuit determines that it is not in a fault state, it outputs the blocking signal, and when it determines that it is in a fault state, it outputs the allowable signal. The delay circuit delays the signal output from the fault detection circuit and outputs it toward the element unit. Power supply control device.

[0012] In the above power supply control device, when a fault state occurs while the voltage conversion unit is performing the second conversion operation, the first control circuit stops the second conversion operation by the voltage conversion unit, and the second control circuit switches the element unit to the allowable state. However, the timing at which the second control circuit switches the element unit to the allowable state is delayed by the delay circuit. For this reason, it becomes easier for the voltage conversion unit to stop the second conversion operation before the element unit switches to the allowable state. As a result, the current flowing in through the element unit is prevented from occurring, or the time during which the current flows in through the element unit is shortened. That is, according to this configuration, it is possible to suppress the output current from the voltage conversion unit to the power storage unit side from flowing in through the element unit when switching from the charging state of the power storage unit by the voltage conversion unit to the discharging state of the power storage unit through the element unit.

[0013] 〔2〕The first control circuit controls the voltage conversion unit by periodic processing performed every time a predetermined period elapses. The power supply control device according to 〔1〕.

[0014] In a configuration where the first control circuit controls the voltage conversion unit through periodic processing, if a failure occurs, the second conversion operation of the voltage conversion unit is stopped after waiting for the start of the periodic processing. Therefore, the timing at which the voltage conversion unit stops the second conversion operation tends to be delayed. In this configuration, if we assume that the second control circuit immediately switches the element unit to an acceptable state when a failure occurs, there is a high probability that the element unit will switch to an acceptable state before the second conversion operation by the voltage conversion unit stops. In this regard, in the above power supply control device, the timing at which the second control circuit switches the element unit to an acceptable state is delayed by a delay circuit. Therefore, even in a configuration where the first control circuit controls the voltage conversion unit through periodic processing, the voltage conversion unit is more likely to stop the second conversion operation before the element unit switches to an acceptable state.

[0015] [3] The delay circuit delays the signal output from the failure detection circuit for a predetermined time and outputs it to the element section. The predetermined time is longer than or equal to the predetermined period. The power supply control device described in [2].

[0016] With this configuration, the element section is more likely to switch to an acceptable state after the second conversion operation by the voltage conversion section stops, thus reducing the likelihood of current flowing back through the element section.

[0017] [4] When the first control circuit stops the second conversion operation by the voltage conversion unit, it temporarily stops the output of the voltage conversion unit and then allows the voltage conversion unit to perform the first conversion operation. A power supply control device as described in any of [1] to [3].

[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 the embodiments of this disclosure] 1. First Embodiment 1-1. Configuration of 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] The first conductive path 21 receives a voltage based on the output of the energy storage unit 14. 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 line 12. The second conductive path 22 is electrically connected to the power line 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 line 12. The third conductive path 23 is electrically connected to the voltage conversion unit 25 between the voltage conversion unit 25 and the power line 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 includes an MCU 31 (Micro Controller Unit). The MCU 31 controls the voltage conversion unit 25 by periodic processing performed at predetermined intervals. In this embodiment, the predetermined period is the time between the start and end times of the periodic processing, but it may also be the time from the end of one periodic processing to the start of the next periodic processing. When the power supply from the power supply unit 10 to the power line 12 is lost, the MCU 31 causes the voltage conversion unit 25 to perform a first conversion operation and supply power from the energy storage unit 14 to the load 11.

[0029] 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.

[0030] The MCU31 causes the voltage conversion unit 25 to perform a second conversion operation when the charging conditions are met in a normal state that is not a failure state. 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.

[0031] If the MCU31 experiences a failure while the voltage conversion unit 25 is performing the second conversion operation, it stops the second conversion operation by the voltage conversion unit 25 and causes the voltage conversion unit 25 to perform the first conversion operation.

[0032] When the MCU31 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 MCU31 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 MCU31 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.

[0033] Furthermore, if the MCU31 fails 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 MCU31 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 time to stop the output of the voltage conversion unit 25.

[0034] The MCU31 performs the process shown in Figure 3, for example, by repeatedly performing periodic processing. In the process shown in Figure 3, the MCU31 determines in step S11 whether or not the charging conditions are met. If the MCU31 determines that the charging conditions are met (step S11: Yes), it causes the voltage conversion unit 25 to perform a second conversion operation in step S12. If the MCU31 determines that the charging conditions are not met (step S11: No), it stops the output of the voltage conversion unit 25 in step S13.

[0035] After step S12 or S13, in step S14, the MCU31 determines whether or not it has entered a failure state. If the MCU31 determines that it has not entered a failure state (step S14: No), it returns to the process in step S11. In other words, in the normal state, the MCU31 causes the voltage conversion unit 25 to perform a second conversion operation when the charging conditions are met, and stops the output of the voltage conversion unit 25 when the charging conditions are not met.

[0036] If the MCU31 determines that a failure has occurred (step S14: Yes), in step S15, it temporarily stops the output of the voltage conversion unit 25. Then, in step S16, the MCU31 causes the voltage conversion unit 25 to perform the first conversion operation.

[0037] The second control circuit 40 is provided separately from the first control circuit 30. The second control circuit 40 is composed of hardware circuits. The second control circuit 40 includes a failure detection circuit 41 and a delay circuit 42.

[0038] The failure detection circuit 41 outputs a cutoff signal (specifically, an off signal) when it determines that there is no failure, and outputs an allow signal (specifically, an on signal) when it determines that there is a failure. The failure detection circuit 41 is composed of, for example, a comparator. The failure detection circuit 41 receives the signal output from the voltage detection unit 26 (i.e., the signal indicating the voltage of the power line 12) and the threshold Vth as input. The failure detection circuit 41 outputs an off signal when the voltage of the power line 12 is greater than the threshold Vth. The failure detection circuit 41 outputs an on signal when the voltage of the power line 12 becomes less than or equal to the threshold Vth.

[0039] The delay circuit 42 is provided between the failure detection circuit 41 and the element unit 24 (specifically, the reverse current prevention switch 24A). The signal output from the failure detection circuit 41 is input to the delay circuit 42. The failure detection circuit 41 delays the signal output from the failure detection circuit 41 for a predetermined time and outputs it to the element unit 24. Specifically, when the failure detection circuit 41 outputs an off signal, it delays the off signal output from the failure detection circuit 41 and outputs it to the element unit 24. When the failure detection circuit 41 outputs an on signal, it delays the on signal output from the failure detection circuit 41 and outputs it to the element unit 24.

[0040] Figure 4 shows a timing chart illustrating the operation of the first control circuit 30, voltage conversion unit 25, failure detection circuit 41, delay circuit 42, 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 controls the voltage conversion unit 25 to perform the second conversion operation, the voltage conversion unit 25 performs the second conversion operation, the failure detection circuit 41 and delay circuit 42 output off signals, and the element unit 24 is controlled to a cutoff state.

[0041] When a failure occurs at timing t2, the output signal of the failure detection circuit 41 switches to an ON signal. Then, the delay circuit 42, which receives the ON signal from the failure detection circuit 41, switches its output signal to an OFF signal after a predetermined time has elapsed. As a result, the element unit 24 switches to an acceptable state (timing t4). On the other hand, the first control circuit 30 stops the output of the voltage conversion unit 25 in the periodic processing immediately after the failure occurs (timing t3). The predetermined delay time by the delay circuit 42 is longer than the predetermined period. Therefore, even if the second conversion operation by the voltage conversion unit 25 is stopped in the periodic processing after the failure detection circuit 41 outputs an ON signal, the element unit 24 switches to an acceptable state after the second conversion operation by the voltage conversion unit 25 is stopped. As a result, power supply from the energy storage unit 14 to the load 11 via the element unit 24 begins with the second conversion operation by the voltage conversion unit 25 stopped.

[0042] After the first control circuit 30 stops the second conversion operation by the voltage conversion unit 25, if the discharge start condition is met, it causes the voltage conversion unit 25 to perform the first conversion operation in a periodic process (timing t5). The discharge start condition may be, for example, a predetermined interval time elapsed after the second conversion operation by the voltage conversion unit 25 has stopped, or it may be any other condition.

[0043] 1-2. Effects of the First Embodiment In the power supply control device 20, if a failure occurs while the voltage conversion unit 25 is performing the second conversion operation, the first control circuit 30 stops the second conversion operation by the voltage conversion unit 25, and the second control circuit 40 switches the element unit 24 to an acceptable state. However, the timing of the second control circuit 40 switching the element unit 24 to an acceptable state is delayed by the delay circuit 42. As a result, the voltage conversion unit 25 is more likely to stop the second conversion operation before the element unit 24 switches to an acceptable state. This either prevents current from flowing back through the element unit 24, or shortens the time during which current flows back through the element unit 24. 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. By suppressing such current flow, it is possible to suppress the generation of loop current through the voltage conversion unit 25 and the element unit 24, which would otherwise cause overcurrent.

[0044] The first control circuit 30 controls the voltage conversion unit 25 by periodic processing. In this configuration, when a failure occurs, the second conversion operation of the voltage conversion unit 25 is stopped after waiting for the start of the periodic processing. Therefore, the timing at which the voltage conversion unit 25 stops the second conversion operation tends to be delayed. In this configuration, if we assume that the second control circuit 40 immediately switches the element unit 24 to an acceptable state when a failure occurs, there is a high possibility that the element unit 24 will switch to an acceptable state before the second conversion operation by the voltage conversion unit 25 stops. In this respect, in the power supply control device 20, the timing at which the second control circuit 40 switches the element unit 24 to an acceptable state is delayed by the delay circuit 42. Therefore, even in the configuration in which the first control circuit 30 controls the voltage conversion unit 25 by periodic processing, the voltage conversion unit 25 is more likely to stop the second conversion operation before the element unit 24 switches to an acceptable state.

[0045] The predetermined delay time by the delay circuit 42 is longer than the predetermined period. With this configuration, the element section 24 is more likely to switch to the acceptable state after the second conversion operation by the voltage conversion section 25 stops, thus making it less likely for current to leak back through the element section 24.

[0046] If the voltage conversion unit 25 switches directly from the second conversion operation to the first conversion operation, there is a risk that current will continue to flow from the voltage conversion unit 25 to the energy storage unit 14 for a while even after switching to the first conversion operation. 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.

[0047] 2. Second Embodiment The second embodiment differs from the first embodiment only in the configuration of the element section. In the second embodiment, the same reference numerals are used for components that are the same as in the first embodiment, and detailed descriptions are omitted.

[0048] The in-vehicle system 201 of the second embodiment shown in Figure 5 includes a power supply control device 220 instead of the power supply control device 20 described in the first embodiment. The power supply control device 220 includes an element unit 224 instead of the element unit 24 described in the first embodiment. The element unit 224 has a MOSFET 224A. The MOSFET 224A is oriented in the opposite direction to the reverse current prevention switch 24A described in the first embodiment. The source of the MOSFET 224A is electrically connected to the first conductive path 21. The drain of the MOSFET 224A is electrically connected to the second conductive path 22.

[0049] The resistance of MOSFET224A 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 through its body diode 224B. Therefore, when MOSFET224A is in the off state, element 224 is in a blocking state that blocks the current flowing through it to the power path 12, and when MOSFET224A is in the on state, it is in an allowable state that permits current to flow through it to the power path 12.

[0050] <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 each other. 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.

[0051] In each of the embodiments described above, 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.

[0052] In the embodiments described above, the predetermined time delayed by the delay circuit was longer than the predetermined period. In contrast, the predetermined time delayed by the delay circuit may be the same as the predetermined period, or it may be shorter than the predetermined period.

[0053] The first control circuit may be configured by a hardware circuit.

[0054] The element in the second 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 can be configured so that no current flows from the first conductive path to the second conductive path through the element when the MOSFET is in the off state and the voltage conversion unit is performing the second conversion operation.

[0055] 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 equivalent to the claims are intended to be included. [Explanation of Symbols]

[0056] 1…In-vehicle systems 10...Power supply section 11…Load 12…Power line 13…Diode 14…Energy storage unit 20... Power supply control device 21…First conductive path 22...Second conductive circuit 23…Third conductive circuit 24... Element section 24A…Backflow prevention switch 24B…diode 25...Voltage conversion section 25A…Switch 25B... Switch 25C…Switch 25D…Switch 25E...Inductor 26...Voltage detection unit 30...First control circuit 31…MCU 40...Second control circuit 41...Loss detection circuit 42... Delay Circuit 201... In-vehicle systems 220... Power supply control device 224... Element part 224A… MOSFET 224B...Body diode Vth... threshold

Claims

1. A power supply control device 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 controls the power supply from the power storage unit, A first conductive path to which a voltage based on the output of the energy storage unit is applied, An element portion having one end electrically connected to the first conductive path, A second conductive path is electrically connected to the other end of the element portion and forms a current-carrying path between the element portion and the power line, A voltage conversion unit connected in parallel to the element unit between the energy storage unit and the power line, Between the voltage conversion unit and the power line, a third conductive path is electrically connected to the voltage conversion unit, A first control circuit for controlling the voltage conversion unit, The system comprises a second control circuit provided separately from the first control circuit, The voltage conversion unit performs a first conversion operation to increase or decrease the voltage applied to the first conductive path and apply the output voltage to the third conductive path, and a second conversion operation to increase or decrease the voltage applied to the third conductive path and apply the output voltage to the first conductive path. The element is capable of preventing current from flowing through it to the energy storage unit, and when a cutoff signal is input, it enters a cutoff state that cuts off the current flowing through it to the power line, and when an allow signal is input, it enters an allowable state that allows current to flow through it to the power line. The first control circuit, when the supply of power from the power supply unit to the power line is lost while the voltage conversion unit is performing the second conversion operation, stops the second conversion operation by the voltage conversion unit and causes the voltage conversion unit to perform the first conversion operation. The second control circuit has a failure detection circuit and a delay circuit, The failure detection circuit outputs the cutoff signal when it determines that the failure state is not present, and outputs the allow signal when it determines that the failure state is present. The delay circuit delays the signal output from the failure detection circuit and outputs it to the element section. Power supply control device.

2. The first control circuit controls the voltage conversion unit by periodic processing performed each predetermined period. The power supply control device according to claim 1.

3. The delay circuit delays the signal output from the failure detection circuit for a predetermined time and outputs it to the element section. The predetermined time is longer than or equal to the predetermined period. The power supply control device according to claim 2.

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

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