Vehicle-mounted backup control device and vehicle-mounted backup device

Abstract

Provides a vehicle-mounted backup control device and a vehicle-mounted backup device. Provides support more quickly in case of power failure. The vehicle-mounted backup control device (1) has a switch (e.g., a second switch (12A, 12B)), a control unit (15), a low voltage detection circuit (20), and a latching circuit (30). The switch is disposed between the energy storage unit (93) and the load (e.g., a second load (92)). The control unit (15) controls the switch. The low voltage detection circuit (20) detects a low voltage state in the power path supplied with power from the power supply unit (91). The latching circuit (30) switches to a latching state that keeps the switch in the on state when the low voltage detection circuit (20) detects a low voltage state. When a low voltage state occurs, the control unit (15) releases the latching state and controls the switch to the on state.

Description

Technical Field

[0001] This disclosure relates to a vehicle-mounted backup control device and a vehicle-mounted backup device. Background Technology

[0002] Patent Document 1 discloses an energy storage device that supplies power from an energy storage unit to a load when the main power supply voltage drops. The control circuit of this energy storage device controls the charging circuit to charge the energy storage unit when the main power supply is normal. Furthermore, when the main power supply voltage drops (e.g., when the engine starts after idling stops), the control circuit connects a switch located between the energy storage unit and the load to supply power to the load. Additionally, Patent Document 1 describes that this energy storage device can also be used in a power backup system when the main power supply is abnormal.

[0003] Existing technical documents

[0004] Patent Document 1: Japanese Patent Application Publication No. 2009-296808 Summary of the Invention

[0005] The problem that the invention aims to solve

[0006] Sometimes it is preferable to quickly support the load that is intended as a backup. However, in the energy storage device of Patent Document 1, the control circuit periodically determines whether there is an abnormality in the main power supply within the range that does not interfere with other processes. Therefore, there are limits to how long it is possible to shorten the time from when the main power supply becomes abnormal until the switch is turned on.

[0007] Therefore, the purpose of this disclosure is to provide technology that enables more rapid support in the event of power failure.

[0008] Solution for solving the problem

[0009] The vehicle-mounted backup control device disclosed herein, in a vehicle-mounted power system comprising a power supply unit, a storage unit, and a load, performs a backup operation of supplying power from the storage unit to the load when the power path supplied with power from the power supply unit becomes low-voltage. The vehicle-mounted backup control device includes: a switch unit disposed between the storage unit and the load; a control unit for controlling the switch unit; a low-voltage detection circuit for detecting the low-voltage state; and a latching circuit that, when the low-voltage detection circuit detects the low-voltage state, switches to a latching state that keeps the switch unit in an on state, and when the low-voltage state occurs, the control unit controls the switch unit to the on state.

[0010] The vehicle-mounted backup device disclosed herein includes the vehicle-mounted backup control device disclosed herein and the aforementioned energy storage unit.

[0011] Invention Effects

[0012] According to this disclosure, support can be provided more quickly in the event of a power failure. Attached Figure Description

[0013] Figure 1 This is a circuit diagram that schematically illustrates the structure of an on-board power supply system according to the first embodiment of this disclosure.

[0014] Figure 2 It is a circuit diagram that roughly shows the structure of the switch control circuit.

[0015] Figure 3 This is a flowchart representing the backup processing procedures performed by the control department. Detailed Implementation

[0016] [Description of embodiments of this disclosure]

[0017] First, the embodiments described herein will be illustrated.

[0018] [1] A vehicle-mounted backup control device, in a vehicle-mounted power system comprising a power supply unit, a storage unit, and a load, performs a backup operation of supplying power from the storage unit to the load when the power path supplied with power from the power supply unit becomes low voltage. The vehicle-mounted backup control device comprises: a switch unit disposed between the storage unit and the load; a control unit for controlling the switch unit; a low voltage detection circuit for detecting the low voltage state; and a latching circuit that, when the low voltage detection circuit detects the low voltage state, switches to a latching state that keeps the switch unit in an on state, and when the low voltage state occurs, the control unit controls the switch unit to the on state.

[0019] According to this structure, when the power path becomes low-voltage, the latching circuit can be immediately switched to a latching state, thus turning the switch on and supplying power to the load. Therefore, power can be supplied to the load immediately without waiting for the switch to be turned on through periodic processing by the control unit.

[0020] [2] In the vehicle-mounted backup control device described in [1], when the low voltage state is not mentioned above, the control unit releases the latch state and controls the switch unit to be in the open state.

[0021] According to this structure, the control unit can release the latching state and restore the switch unit to the open state when the latching circuit becomes latched due to erroneous operation or when it becomes latched due to a temporary low voltage state.

[0022] [3] In the vehicle-mounted backup control device described in [1] or [2], the low voltage detection circuit is configured to receive a low voltage signal when the low voltage state is reached. The vehicle-mounted backup control device has a fault checking circuit that provides the low voltage signal to the low voltage detection circuit as a check signal. The control unit performs fault checking processing to determine whether the latching circuit has reached the latching state after the fault checking circuit performs the operation of providing the check signal to the low voltage detection circuit.

[0023] Based on this structure, it is possible to check whether the low voltage detection circuit and latching circuit are operating normally.

[0024] [4] In the vehicle-mounted backup control device described in [3], there is a charging unit that performs the charging operation of the above-mentioned energy storage unit. When the vehicle is started, the control unit performs charging control to make the charging unit perform the charging operation until the charging voltage of the energy storage unit becomes the target voltage. After the vehicle is started, the fault check and processing is performed before the charging control is started or in parallel with the charging control.

[0025] This structure enables rapid fault diagnosis and handling after the vehicle is started.

[0026] <First Implementation>

[0027] [Structure of vehicle-mounted power supply system]

[0028] Figure 1 The vehicle power system 100 shown includes: a power supply unit 90, a first load 91, a second load 92, an energy storage unit 93, and a vehicle-mounted backup control device 1 (hereinafter also referred to as control device 1). Figure 1 The vehicle-mounted backup device 2 shown includes a control device 1 and an energy storage unit 93. A power supply unit 90 is electrically connected to a first load 91 and a second load 92 via a power path 80. Power from the power supply unit 90 is supplied to the first load 91 and the second load 92 via the power path 80. The control device 1 performs a backup operation to supply power from the energy storage unit 93 to the first load 91 and the second load 92 when the power path 80 becomes low-voltage. A low-voltage state refers to, for example, a state where the voltage of the power path 80 is below a threshold value.

[0029] The power supply unit 90 functions as the main power source. The power supply unit 90 is a DC power source that generates DC voltage, such as a lead-acid battery. The high-potential side terminals of the power supply unit 90 are electrically connected to the power path 80 and the first conductive path 81, while the low-potential side terminals of the power supply unit 90 are electrically connected to ground, for example. The power supply unit 90 is configured to apply a predetermined output voltage to the first conductive path 81.

[0030] The first load 91 is a backup electrical component with a lower urgency than the second load 92, such as an electric motor or other vehicle-mounted actuator. There may be one or more first loads 91. In this embodiment, the first load 91 is configured to receive power from the power supply unit 90 when the power path 80 is not in a low-voltage state, but it may also be configured not to receive power from the power supply unit 90.

[0031] The second load 92 is equivalent to a "load" and is a backup electrical component with a higher urgency than the first load 91. Examples include the ECU or actuator in an electric parking brake system, or the ECU or actuator in a shift-by-wire control system. There can be one or more second loads 92. In this embodiment, the second load 92 is configured to receive power from the power supply unit 90 when the power path 80 is not in a low-voltage state, but it can also be configured not to receive power from the power supply unit 90.

[0032] The energy storage unit 93 functions as an auxiliary power source. The energy storage unit 93 is a DC power source that outputs DC voltage, such as a double-layer capacitor. The energy storage unit 93 is electrically connected to the charging / discharging unit 14 via the fifth conductive path 85, and is charged and discharged via the charging / discharging unit 14. The output voltage of the energy storage unit 93 remains below the standby voltage when the vehicle is stationary. When the vehicle is started, it charges until it reaches a target voltage higher than the standby voltage. When the vehicle is stationary, it discharges until it falls below the standby voltage.

[0033] The control device 1 includes: a first conductive path 81, a second conductive path 82, a third conductive path 83, a fourth conductive path 84, a fifth conductive path 85, a first switch unit 11, second switch units 12A and 12B, a third switch unit 13A and 13B, a charging and discharging unit 14, a control unit 15, a switch control circuit 16, an OR circuit 17, and voltage detection units 18A, 18B, 18C, and 18D.

[0034] The first conductive path 81 is electrically connected to the high-potential terminal of the power supply unit 90 and to the power path 80. The voltage of the first conductive path 81 reflects the voltage of the power path 80. For example, if the power path 80 is not in a low-voltage state, the voltage of the first conductive path 81 is greater than the aforementioned threshold; if the power path 80 is in a low-voltage state, the voltage of the first conductive path 81 is less than the aforementioned threshold. The second conductive path 82 is disposed closer to the first load 91 and the second load 92 than the first conductive path 81, and branches midway into paths corresponding to the first load 91 and the second load 92, respectively. The third conductive path 83 is electrically connected to the first load 91 and to the power path 80. The fourth conductive path 84 is electrically connected to the second load 92. The fifth conductive path 85 is electrically connected to the charging / discharging unit 14 and the energy storage unit 93.

[0035] The first switch section 11, the second switch sections 12A and 12B, and the third switch sections 13A and 13B are configured as switching elements, and more specifically, as N-channel MOSFETs (Metal-Oxide-Semiconductor Field Effect Transistors). The first switch section 11, the second switch section 12A and 12B, and the third switch sections 13A and 13B are controlled to be in an ON state by receiving an ON signal from the control section 15, and are controlled to be in an OFF state by receiving an OFF signal.

[0036] A first switch section 11 is disposed between the energy storage section 93 and the first load 91, and between the second conductive path 82 and the third conductive path 83. The first switch section 11 has a parasitic diode 11A. The anode of the parasitic diode 11A is electrically connected to the third conductive path 83, and the cathode of the parasitic diode 11A is electrically connected to the second conductive path 82. When the first switch section 11 is in the ON state, power supply from the second conductive path 82 side to the third conductive path 83 side is permitted. When the first switch section 11 is in the OFF state, power supply from the second conductive path 82 side to the third conductive path 83 side is prohibited.

[0037] The second switching units 12A and 12B, equivalent to "switching units," are disposed between the energy storage unit 93 and the second load 92, and between the second conductive path 82 and the fourth conductive path 84. The second switching units 12A and 12B have parasitic diodes 12C and 12D. The second switching units 12A and 12B are connected in series and in reverse order of each other. When the second switching units 12A and 12B are in the ON state, power supply from the second conductive path 82 side to the fourth conductive path 84 side is permitted. When the second switching units 12A and 12B are in the OFF state, power supply from the second conductive path 82 side to the fourth conductive path 84 side is prohibited.

[0038] The third switch sections 13A and 13B are disposed between the power supply section 90 and the energy storage section 93, and between the first conductive path 81 and the second conductive path 82. The third switch sections 13A and 13B have parasitic diodes 13C and 13D. The third switch sections 13A and 13B are connected in series and in reverse order of each other. When the third switch sections 13A and 13B are in the ON state, power supply from the first conductive path 81 side to the second conductive path 82 side is permitted. When the third switch sections 13A and 13B are in the OFF state, power supply from the first conductive path 81 side to the second conductive path 82 side is prohibited.

[0039] The charging / discharging unit 14 is equivalent to a "charging unit" and is configured as a voltage conversion circuit, such as a DC-DC converter. The charging / discharging unit 14 is disposed between the second conductive path 82 and the fifth conductive path 85. The charging / discharging unit 14 performs charging and discharging operations on the energy storage unit 93. The charging / discharging unit 14 performs a charging operation by allowing the energy storage unit 93 to charge. More specifically, the charging / discharging unit 14 performs a charging operation by increasing or decreasing the voltage applied to the second conductive path 82 and applying it to the fifth conductive path 85. The charging / discharging unit 14 performs a discharging operation by allowing the energy storage unit 93 to discharge. More specifically, the charging / discharging unit 14 performs a discharging operation by increasing or decreasing the voltage applied to the fifth conductive path 85 and applying it to the second conductive path 82. The charging / discharging unit 14 charges the energy storage unit 93 by performing the charging operation while the third switch units 13A and 13B are in the closed state. The charging and discharging unit 14 discharges the energy storage unit 93 by performing a discharge operation when the first switch unit 11 and the second switch units 12A and 12B are in the closed state, and can supply power to the first load 91 and the second load 92.

[0040] Voltage detection units 18A, 18B, 18C, and 18D are configured, for example, as a voltage detection circuit. Voltage detection unit 18A detects the voltage of the first conductive path 81. Voltage detection unit 18B detects the voltage of the second conductive path 82. Voltage detection unit 18C detects the voltage of the fourth conductive path 84. The voltages on both sides of the second switching units 12A and 12B are detected by voltage detection units 18B and 18C. Voltage detection unit 18D detects the voltage of the fifth conductive path 85, i.e., the charging voltage of the energy storage unit 93.

[0041] The control unit 15 is, for example, composed of a microcomputer and includes an arithmetic unit such as a CPU (Central Processing Unit), a memory such as ROM (Read Only Memory) or RAM (Random Access Memory), an A / D converter, etc.

[0042] The control unit 15 is electrically connected to voltage detection units 18A, 18B, 18C, and 18D. The control unit 15 can obtain the voltage applied to the first conductive path 81, the voltages on both sides of the second switching units 12A and 12B, and the charging voltage of the energy storage unit 93 based on signals from the voltage detection units 18A, 18B, 18C, and 18D. The control unit 15 determines that the power path 80 is not in a low-voltage state if the voltage of the first conductive path 81 is greater than a threshold, and determines that the power path 80 is in a low-voltage state if the voltage of the first conductive path 81 is less than the threshold.

[0043] The control unit 15 is electrically connected to the second load 92 and can receive signals output from the second load 92. In this embodiment, the control unit 15 is configured to not supply power to the second load 92 when the power path 80 is not in a low voltage state, but to supply power to the second load 92 even when it is not in a low voltage state, based on a request from the second load 92.

[0044] The control unit 15 is electrically connected to the gates of the first switch unit 11, the second switch units 12A and 12B, and the third switch units 13A and 13B. The control unit 15 controls the switches to an ON state by providing an ON signal to the gates of the first switch unit 11, the second switch units 12A and 12B, and the third switch units 13A and 13B, and controls them to an OFF state by providing an OFF signal. In this embodiment, a high-level signal is the ON signal, and a low-level signal is the OFF signal. The control unit 15 is electrically connected to the gate of the first switch unit 11 and the first input terminal 17A of the OR circuit 17 via the first output path 86. The output terminal 17C of the OR circuit 17 is electrically connected to the gates of the second switch units 12A and 12B. The control unit 15 provides ON or OFF signals to the first switch unit 11 and the second switch units 12A and 12B by applying an ON or OFF signal to the first output path 86.

[0045] The control unit 15 is electrically connected to the charging / discharging unit 14. The control unit 15 performs charging control to charge the battery storage unit 93 and discharging control to discharge the battery storage unit 93. Charging control involves turning on the third switches 13A and 13B and causing the charging / discharging unit 14 to perform a charging operation to charge the battery storage unit 93. Discharging control involves turning on the first switch 11 and the second switches 12A and 12B and causing the charging / discharging unit 14 to perform a discharging operation to discharge the battery storage unit 93 to the first load 91 and the second load 92. The control unit 15 begins charging control when the vehicle's start switch (not shown) is turned on, and ends charging control when the output voltage of the battery storage unit 93 reaches or exceeds the target voltage. After ending charging control, the control unit 15 turns off the third switches 13A and 13B, causing the charging / discharging unit 14 to perform a discharging operation. At this time, the first switch 11 and the second switches 12A and 12B remain in the off state. This results in a state where a voltage based on the output voltage of the energy storage unit 93 is applied to the second conductive circuit 82. The control unit 15 can immediately supply power to the first load 91 and the second load 92 by switching the first switch unit 11 and the second switch units 12A and 12B to the on state from this state. In addition, even when the second switch units 12A and 12B are switched to the on state by the latching circuit 30 described later, power is immediately supplied to the second load 92.

[0046] [Structure of the switch control circuit]

[0047] The switch control circuit 16 is a different circuit from the control unit 15, and it controls the second switch units 12A and 12B. For example... Figure 2 As shown, the switch control circuit 16 includes: a low voltage detection circuit 20, a latch circuit 30, a latch release circuit 40, and a fault detection circuit 50.

[0048] The low-voltage detection circuit 20 is a circuit that detects the low-voltage state of the power path 80. The low-voltage detection circuit 20 determines that the power path 80 is not in a low-voltage state if the voltage of the first conductive path 81 is greater than a threshold. The low-voltage detection circuit 20 determines that the power path 80 is in a low-voltage state if the voltage of the first conductive path 81 is below the threshold, and thus detects the low-voltage state. The low-voltage detection circuit 20 is electrically connected to the latching circuit 30 via the conductive path 62, and provides a low-voltage detection signal to the latching circuit 30 when a low-voltage state is detected in the power path 80.

[0049] The latching circuit 30 is a circuit that switches to a latching state, keeping the second switches 12A and 12B in the ON state, when the low-voltage detection circuit 20 detects a low-voltage state in the power path 80. The latching circuit 30 is electrically connected to the second input terminal 17B of the OR circuit 17 via the conductive path 63. When a low-voltage detection signal is provided, the latching circuit 30 provides an ON signal to the second input terminal 17B of the OR circuit 17 via the conductive path 63, and switches to a latching state, keeping the second switches 12A and 12B in the ON state.

[0050] The latch release circuit 40 is a circuit that releases the latch state of the latch circuit 30. The latch release circuit 40 is electrically connected to the control unit 15 via conductive path 64 and to the latch circuit 30 via conductive path 65. The latch release circuit 40 releases the latch state of the latch circuit 30 when a release instruction signal is provided from the control unit 15.

[0051] The fault detection circuit 50 is used to detect faults in the low-voltage detection circuit 20 and the latching circuit 30. The fault detection circuit 50 is electrically connected to the control unit 15 via the second output path 87 and to the low-voltage detection circuit 20 via the conductive path 66. When a check instruction signal is provided from the control unit 15, the fault detection circuit 50 provides a low-voltage signal as a check signal to the low-voltage detection circuit 20. When a check signal is provided, the low-voltage detection circuit 20 provides a low-voltage detection signal to the latching circuit 30. When a low-voltage detection signal is provided, the latching circuit 30 provides a signal to the second input terminal 17B of the OR circuit 17. As a result, an on signal is provided from the OR circuit 17 to the second switches 12A and 12B, and the second switches 12A and 12B are turned on.

[0052] If the control unit 15 provides a check indication signal to the fault check circuit 50 and turns on the second switches 12A and 12B, it determines that the low voltage detection circuit 20 and the latching circuit 30 are not faulty. Conversely, if the second switches 12A and 12B remain off, the control unit 15 determines that the low voltage detection circuit 20 or the latching circuit 30 is faulty. For example, if the voltage difference between the two sides of the second switches 12A and 12B is less than a predetermined value, the control unit 15 determines that the second switches 12A and 12B are on; if it is greater than or equal to the predetermined value, the control unit 15 determines that the second switches 12A and 12B are off.

[0053] The detailed structure of the low voltage detection circuit 20, latch circuit 30, latch release circuit 40, and fault detection circuit 50 is described.

[0054] The low-voltage detection circuit 20 includes a comparator 21 and resistors R1, R2, and R3. The inverting input terminal 22 of the comparator 21 is electrically connected to a constant voltage source Vcc. One end of resistor R1 is electrically connected to a first conductive path 81, and the other end of resistor R1 is electrically connected to one end of resistor R2. The other end of resistor R2 is electrically connected to ground. The connection portion 25 between the other end of resistor R1 and one end of resistor R2 is electrically connected to the non-inverting input terminal 23 of the comparator 21 via a conductive path 61. The output terminal 24 of the comparator 21 is electrically connected to a conductive path 62. One end of resistor R3 is electrically connected to the constant voltage source Vcc, and the other end of resistor R3 is electrically connected to a conductive path 62.

[0055] The latch-up circuit 30 includes: a diode 31, a PNP transistor 32, an NPN transistor 33, and resistors R4, R5, R6, and R7. The emitter of the PNP transistor 32 and one end of resistor R5 are electrically connected to a constant voltage source Vcc. The base of the PNP transistor 32 is electrically connected to one end of resistor R4 and the other end of resistor R5. The collector of the PNP transistor 32 is electrically connected to one end of resistor R6 and the conductive path 63.

[0056] The other end of resistor R6 is electrically connected to the base of NPN transistor 33 and one end of resistor R7. The other end of resistor R7 and the emitter of NPN transistor 33 are electrically connected to ground. The collector of NPN transistor 33 is electrically connected to the connection portion 34 between the other end of resistor R4 and the anode of diode 31. The cathode of diode 31 is electrically connected to conductive circuit 62.

[0057] The latch-off circuit 40 includes an NPN transistor 41 and resistors R8 and R9. One end of resistor R8 is electrically connected to the conductive path 64. The other end of resistor R8 is electrically connected to the base of the NPN transistor 41 and one end of resistor R9. The other end of resistor R9 and the emitter of the NPN transistor 41 are electrically connected to ground. The collector of the NPN transistor 41 is electrically connected to the collector of the PNP transistor 32 in the latch-off circuit 30, one end of resistor R6, and the connection portion 35 of the conductive path 63. Furthermore, the conductive path 64 is electrically connected to the first output path 86. Thus, an on or off signal applied from the control unit 15 to the first output path 86 is provided to one end of resistor R8 in the latch-off circuit 40 via the conductive path 64.

[0058] The fault detection circuit 50 includes an NPN transistor 51 and resistors R10 and R11. One end of resistor R10 is electrically connected to the second output circuit 87. The other end of resistor R10 is electrically connected to the base of the NPN transistor 51 and one end of resistor R11. The other end of resistor R11 and the emitter of the NPN transistor 51 are electrically connected to ground. The collector of the NPN transistor 51 is electrically connected to the conductive circuit 61 via conductive circuit 66.

[0059] Next, the operation of the switch control circuit 16 will be explained. When the voltage of the first conductive path 81 is greater than a threshold value, the comparator 21 in the low-voltage detection circuit 20 outputs a high-level signal from the output terminal 24. At this time, the voltage on the anode side of the diode 31 in the latch-up circuit 30 is lower than the voltage on the cathode side, so current does not flow from the latch-up circuit 30 side to the low-voltage detection circuit 20 side. Then, when the voltage of the first conductive path 81 falls below the threshold value due to a break in the power path 80, the comparator 21 outputs a low-level signal from the output terminal 24. As a result, the voltage on the anode side of the diode 31 is higher than the voltage on the cathode side, and current flows from the latch-up circuit 30 side to the low-voltage detection circuit 20 side. As a result, the PNP transistor 32 switches from the off state to the on state, providing an on signal to the second input terminal 17B of the OR circuit 17 via the conductive path 63. Furthermore, the gates of the second switching units 12A and 12B are provided with on signals, and the second switching units 12A and 12B become on.

[0060] Furthermore, by switching PNP transistor 32 to the ON state, current flows from the base to the emitter of NPN transistor 33, and NPN transistor 33 switches to the ON state. As a result, current continues to flow from the emitter to the base of PNP transistor 32, and PNP transistor 32 remains in the ON state. Therefore, latch-up circuit 30 becomes a latch-up state that keeps the second switching parts 12A and 12B in the ON state.

[0061] After the latching circuit 30 is in the latched state, when one end of the resistor R8 in the latch-off circuit 40 is supplied with an on signal from the control unit 15, current flows from the base to the emitter of the NPN transistor 41, and the NPN transistor 41 switches to the on state. As a result, the voltage of the connection 35 decreases, the NPN transistor 33 becomes the off state, and the PNP transistor 32 becomes the off state. Therefore, the latching state of the latching circuit 30 is released. In addition, as described later, the second switches 12A and 12B are kept in the on state by the on signal from the control unit 15.

[0062] The fault checking circuit 50 performs fault checking as described below. When one end of resistor R10 is supplied with an on signal from control unit 15, current flows from the base to the emitter of NPN transistor 51, turning NPN transistor 51 on. As a result, the voltage at the non-inverting input terminal 23 of comparator 21 in low-voltage detection circuit 20 is below the threshold. Furthermore, a low-level signal is output from output terminal 24 of comparator 21, latching circuit 30 is latched, and second switches 12A and 12B are turned on. Control unit 15 determines whether second switches 12A and 12B are turned on based on the voltages on both sides of second switches 12A and 12B, and determines whether low-voltage detection circuit 20 and latching circuit 30 are faulty.

[0063] [Operation of the vehicle-mounted backup control device]

[0064] Figure 3 This illustration shows an example of a standby process performed by the control unit 15. The control unit 15 initiates the standby process when the start condition for the standby process is met. The start condition for the standby process is, for example, when a start switch (e.g., ignition switch) not shown is in the ON state. The control unit 15 can detect when the start switch is in the ON state by, for example, receiving a start signal from an external ECU (Electronic Control Unit) indicating that the start switch is in the ON state.

[0065] When the control unit 15 begins standby processing, it performs a fault check (step S10). Additionally, although in Figure 3 (The text is omitted here.) The control unit 15 begins charging control when the start switch is turned on, and ends charging control when the output voltage of the energy storage unit 93 reaches or exceeds the target voltage. Preferably, the control unit 15 performs fault checking and processing before or in parallel with charging control. Furthermore, although in... Figure 3 (The text is omitted here.) After the charging control ends, the control unit 15 causes the charging / discharging unit 14 to begin discharging. This applies a voltage to the second conductive circuit 82 based on the output voltage from the energy storage unit 93.

[0066] During fault checking and processing, the control unit 15 provides an on signal to the fault checking circuit 50 via the second output path 87 as a check indication signal. Furthermore, the control unit 15 determines whether the second switches 12A and 12B are in an on state. As a result, if they are in an on state, the control unit 15 determines that the low voltage detection circuit 20 and the latching circuit 30 are not faulty; if they are in an off state, the control unit 15 determines that either the low voltage detection circuit 20 or the latching circuit 30 has faulted. When a fault is determined to have occurred, the control unit 15 performs fault handling. Fault handling may include, for example, notifying the fault handling via a notification unit (not shown) or informing external devices that a fault has occurred.

[0067] After the fault check and processing is completed, the control unit 15 determines whether the start conditions for the periodic processing are met (step S11). The start conditions for the periodic processing are, for example, the first periodic processing after the start switch is turned on, a predetermined time has elapsed since the start of the previous periodic processing, or a predetermined time has elapsed since the end of the previous periodic processing.

[0068] If the control unit 15 determines that the start condition for periodic processing is not met ("No" in step S11), it returns to the processing in step S11. That is, the control unit 15 enters a standby state until the start condition for periodic processing is met. When the control unit 15 determines that the start condition for periodic processing is met ("Yes" in step S11), it determines whether the latching circuit 30 is in a latched state (step S12). If the control unit 15 determines that the latching circuit 30 is in a latched state ("Yes" in step S12), it determines that the power path 80 is in a low voltage state, releases the latching state, and provides an on signal to the first switch unit 11 and the second switch units 12A and 12B. In this embodiment, the control unit 15 provides an on signal to the first switch unit 11 and the second switch units 12A and 12B by applying an on signal to the first output path 86, and also provides an on signal to the latch release circuit 40. As a result, the latching state of the latching circuit 30 is released, and the first switch section 11 and the second switch sections 12A and 12B become connected.

[0069] After step S13 or if the latching circuit 30 is not in a latched state ("No" in step S12), the control unit 15 determines whether it has controlled the first switch unit 11 and the second switches 12A and 12B to the on state (step S14). That is, the control unit 15 determines whether it is outputting an on signal from the first output path 86. If the control unit 15 determines that it has controlled the first switch unit 11 and the second switches 12A and 12B to the on state ("Yes" in step S14), it determines whether the power path 80 is in a low-voltage state (step S15). The control unit 15 determines that the power path 80 is not in a low-voltage state if the voltage of the first conductive path 81 based on the signal from the voltage detection unit 18A is greater than a threshold. Conversely, the control unit 15 determines that the power path 80 is in a low-voltage state if the voltage of the first conductive path 81 based on the signal from the voltage detection unit 18A is less than a threshold. If the control unit 15 determines that the power path 80 is not in a low-voltage state ("No" in step S15), it outputs a disconnect signal from the first output path 86, controlling the first switch unit 11 and the second switch units 12A and 12B to be in an open state (step S16). Therefore, if the low-voltage state of the power path 80 is temporary, the supply of backup power can be stopped when the low-voltage state of the power path 80 is eliminated.

[0070] After step S16, if the condition in step S14 is "No" or if the condition in step S15 is "Yes", the control unit 15 returns to the processing in step S11. Furthermore, the control unit 15 repeatedly performs this periodic processing.

[0071] Next, the effects of this structure will be illustrated. The vehicle-mounted backup control device 1 disclosed herein performs a backup operation in the vehicle-mounted power system 100, supplying power from the energy storage unit 93 to the first load 91 and the second load 92 when the power path 80, which is supplied with power from the power supply unit 90, becomes low-voltage. The control device 1 includes: a first switch unit 11, second switches 12A and 12B, a control unit 15, a low-voltage detection circuit 20, and a latching circuit 30. The first switch unit 11 is disposed between the energy storage unit 93 and the first load 91. The second switches 12A and 12B are disposed between the energy storage unit 93 and the second load 92. The control unit 15 controls the first switch unit 11 and the second switches 12A and 12B. The low-voltage detection circuit 20 detects the low-voltage state of the power path 80, which is supplied with power from the power supply unit 90. When the low voltage detection circuit 20 detects a low voltage state, the latching circuit 30 switches to a latching state that keeps the second switches 12A and 12B in the ON state. When a low voltage state is detected, the control unit 15 releases the latching state and controls the first switch 11 and the second switches 12A and 12B to the ON state.

[0072] According to this structure, when the power path 80 becomes low-voltage, the latching circuit 30 can be immediately switched to a latching state, turning on the second switches 12A and 12B to supply power to the second load 92. Therefore, power can be supplied to the second load 92 immediately without waiting for the periodic processing by the control unit 15 to turn on the first switch 11 and the second switches 12A and 12B. Furthermore, when a low-voltage state occurs, the control unit 15 releases the latching state of the latching circuit 30, turning on the first switch 11 and the second switches 12A and 12B. Thus, the main function of turning on the second switches 12A and 12B can be transferred from the latching circuit 30 to the control unit 15, allowing the control unit 15 to simultaneously maintain the first switch 11 and the second switches 12A and 12B in the on state.

[0073] Furthermore, when the voltage is not low, the control unit 15 releases the latching state and controls the second switches 12A and 12B to be in the open state. According to this structure, the control unit 15 can release the latching state and restore the second switches 12A and 12B to the open state when the latching circuit 30 is in a latching state due to erroneous operation or due to a temporary latching state.

[0074] Furthermore, the low-voltage detection circuit 20 is configured to receive a low-voltage signal when a low-voltage state is reached. The control device 1 includes a fault check circuit 50 that provides a low-voltage signal to the low-voltage detection circuit 20 as a check signal. The control unit 15 performs fault check processing to determine whether the latching circuit 30 is in a latching state after the fault check circuit 50 has performed the operation of providing a check signal to the low-voltage detection circuit 20.

[0075] Based on this structure, it is possible to check whether the low voltage detection circuit 20 and the latching circuit 30 are operating normally.

[0076] Furthermore, the control device 1 includes a charging / discharging unit 14 that performs charging operations on the battery storage unit 93. When the vehicle is started, the control unit 15 executes charging control, causing the charging / discharging unit 14 to perform charging operations until the charging voltage of the battery storage unit 93 reaches the target voltage. The control unit 15 performs fault checking processing after the vehicle is started, either before or in parallel with charging control. According to this structure, fault checking processing can be performed quickly after the vehicle is started.

[0077] <Other Implementation Methods>

[0078] This disclosure is not limited to the embodiments described above and in the accompanying drawings. For example, the features of the embodiments described above or later can be combined arbitrarily without contradiction. Furthermore, any feature in the embodiments described above or later can be omitted unless explicitly stated as essential. In addition, the above embodiments can also be modified in the following ways.

[0079] In the first embodiment described above, the power supply unit is a lead-acid battery, but it may not be a lead-acid battery. For example, it may be a lithium-ion battery, an alternator, a converter, etc.

[0080] In the first embodiment described above, the energy storage unit is a double-layer capacitor, but it is not limited to a double-layer capacitor. For example, it can also be a lithium-ion capacitor, a lead-acid battery, a lithium-ion battery, etc.

[0081] In the first embodiment described above, the charging / discharging unit is a DC-DC converter, but it can also be a switching element such as a FET. Furthermore, the vehicle-mounted backup control device can be configured without a charging / discharging unit.

[0082] In the first embodiment described above, the method for releasing the latching state and controlling the second switch to the open state when the voltage is not low is configured such that after the control unit releases the latching state, it determines whether the voltage is low, and if the voltage is not low, the second switch is controlled to the open state. Alternatively, the control unit may release the latching state and control the second switch to the open state after determining that the voltage is low.

[0083] In the first embodiment described above, the latching state is released when the control unit controls the first switch and the second switch to the ON state; however, the latching state may not be released. In other words, the control unit may also control the first switch and the second switch to the ON state while maintaining the latching state of the latching circuit.

[0084] In the first embodiment described above, the control unit is mainly composed of a microcomputer, but it can also be implemented by multiple hardware circuits other than a microcomputer.

[0085] Furthermore, it should be considered that the embodiments disclosed herein are illustrative in all respects and not restrictive. The scope of the invention is not limited to the embodiments disclosed herein, and is intended to include all modifications within the scope set forth in the claims or equivalent to the claims.

[0086] Explanation of reference numerals in the attached figures

[0087] 1…Onboard backup control device

[0088] 2…Onboard backup device

[0089] 11…First Switch Section

[0090] 11A, 12C, 12C, 13C, 13D… Parasitic diodes

[0091] 12A, 12B… Second Switch Section (Switch Section)

[0092] 13A, 13B... Third Switch Section

[0093] 14…Charging / Discharging Section (Charging Unit)

[0094] 15…Control Department

[0095] 16…Switch control circuit

[0096] 17…OR circuit

[0097] 17A…First Input Terminal

[0098] 17B…Second Input Terminal

[0099] The output terminals of the 17C…OR circuit

[0100] 18A…Voltage Detection Section

[0101] 18B…Voltage Detection Section

[0102] 18C…Voltage Detection Section

[0103] 18D…Voltage Detection Section

[0104] 20…Low Voltage Detection Circuit

[0105] 21… Comparator

[0106] 22…Inverting input terminal

[0107] 23…Non-inverting input terminal

[0108] 24… Output terminals of the comparator

[0109] 25, 34, 35… connecting parts

[0110] 30… Latch circuit

[0111] 31… Diode

[0112] 32…PNP transistors

[0113] 33…NPN transistor

[0114] 40…Latch release circuit

[0115] 41…NPN transistor

[0116] 50… Fault Diagnosis Circuit

[0117] 51…NPN transistor

[0118] 61, 62, 63, 64, 65, 66… electrical circuits

[0119] 80… power path

[0120] 81…First Conductive Circuit

[0121] 82…Second Conductive Circuit

[0122] 83…Third conductive path

[0123] 84…Fourth conductive path

[0124] 85…Fifth Conductive Circuit

[0125] 86…First Output Lane

[0126] 87…Second Output Path

[0127] 90…Power Supply Section

[0128] 91…First Load

[0129] 92…Second load (load)

[0130] 93…Electric Storage Department

[0131] 100…Vehicle power system

[0132] Resistors R1, R2, R3, R4, R5, R6, R7, R8, R9, R10, R11…

[0133] Vcc… constant voltage source.

Claims

1. A vehicle-mounted backup control device, in a vehicle-mounted power system comprising a power supply unit, a power storage unit, and a load, performs a backup operation of supplying power from the power storage unit to the load when the power path supplied with power from the power supply unit becomes low-voltage. The vehicle-mounted backup control device has the following features: A switching unit is disposed between the energy storage unit and the load; The control unit controls the switching unit; A low voltage detection circuit detects the low voltage state; and The latching circuit, when the low-voltage detection circuit detects the low-voltage state, switches to a latching state that keeps the switch in the on state. When the control unit determines that the latching circuit is in the latching state, it releases the latching state and controls the switch unit to the on state.

2. The vehicle-mounted backup control device according to claim 1, wherein, If the voltage is not low, the control unit releases the latching state and controls the switch unit to be in the open state.

3. A vehicle-mounted backup control device, in a vehicle-mounted power system comprising a power supply unit, a power storage unit, and a load, performs a backup operation of supplying power from the power storage unit to the load when the power path supplied with power from the power supply unit becomes low-voltage. The vehicle-mounted backup control device has the following features: A switching unit is disposed between the energy storage unit and the load; The control unit controls the switching unit; A low voltage detection circuit detects the low voltage state; and The latching circuit, when the low-voltage detection circuit detects the low-voltage state, switches to a latching state that keeps the switch in the on state. When the voltage becomes low, the control unit controls the switch to the ON state. The low voltage detection circuit is configured to receive a low voltage signal when the low voltage state is reached. The on-board backup control device includes a fault checking circuit that provides the low voltage signal to the low voltage detection circuit as a check signal. The control unit performs the following fault check process: after the fault check circuit performs the operation of providing the check signal to the low voltage detection circuit, it determines whether the switch unit has become in the on state through the latching circuit based on the voltage on both sides of the switch unit, and determines whether the low voltage detection circuit and the latching circuit are faulty.

4. The vehicle-mounted backup control device according to claim 3, wherein, The on-board backup control device includes a charging unit for charging the battery storage unit. When the vehicle is started, the control unit performs charging control to cause the charging unit to perform the charging action until the charging voltage of the battery storage unit reaches the target voltage, and performs the fault check processing after the vehicle is started, before the charging control is started, or in parallel with the charging control.

5. A vehicle-mounted backup device, comprising: The vehicle-mounted backup control device according to any one of claims 1 to 4; and The energy storage unit.

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