Power supply system and power supply device

Abstract

A power supply system (1) comprises: a power feed subject (20) that operates by consuming power from a main power source (30) of a vehicle; and a power supply device (10) that backs up power feeding to the power feed subject (20). Upon recognition of turning off of a power supply switch (31) of the vehicle, the power feed subject (20) generates a stop permission signal (S2). When all of a first determination condition, a second determination condition, and a third determination condition are satisfied, the power supply device (10) determines that an abnormality has occurred in a power supply line (L2) that is provided with the power supply switch (31), among power feeding paths (L1-L8) between the main power source (30) and the power feed subject (20). The first determination condition is that a voltage (V1) generated in a power supply line (l2) is less than a voltage threshold value (V1th). The second determination condition is that the power supply device (10) has not received the stop permission signal (S2). The third determination condition is that the communication state between the power supply device (10) and the power feed subject (20) is normal.

Description

Power Systems and Power Supplies

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

[0002] Conventionally, power supply devices are known that use an auxiliary power supply to back up power supply to a power supply target when the main power supply fails. For example, the power supply device disclosed in Patent Document 1 is provided in a power supply path between a main power supply of a vehicle and a steering control device. The power supply device has an auxiliary power supply. When the main power supply is normal, when the vehicle's power switch is turned on, power from the main power supply is supplied to the steering control device via the power supply device. When the main power supply fails, the main power supply is disconnected from the power supply path, and power from the auxiliary power supply is supplied to the steering control device.

[0003] Japanese Patent Application Laid-Open No. 2022-39399

[0004] The power supply device disclosed in Patent Document 1 has the following concerns: A power supply voltage may drop due to an abnormality in the power supply path. In this case, the power supply device may mistakenly recognize the drop in power supply voltage due to the abnormality in the power supply path as a drop in power supply voltage caused by the power switch being turned off, and may stop operation.

[0005] A power supply system according to one aspect of the present disclosure includes a power supply target configured to operate by consuming power from a main power supply of a vehicle, and a power supply device configured to back up power supply to the power supply target. The power supply target is configured to generate a stop permission signal to permit the power supply device to stop operating when it recognizes that a power switch of the vehicle has been turned off. The power supply device is configured to determine that an abnormality has occurred in a power line on which the power switch is provided, within a power supply path between the main power supply and the power supply target, when all of a first determination condition, a second determination condition, and a third determination condition are met. The first determination condition is that a voltage generated in the power line is less than a voltage threshold. The second determination condition is that the power supply device has not received the stop permission signal. The third determination condition is that communication between the power supply device and the power supply target is normal.

[0006] A power supply device according to one aspect of the present disclosure includes an auxiliary power supply configured to back up power supply to a power supply target configured to operate by consuming power from a vehicle's main power supply, and a control circuit configured to control charging and discharging of the auxiliary power supply. The power supply target is configured to generate a stop permission signal to permit stopping of operation of the power supply device when it recognizes that a power switch of the vehicle has been turned off. The control circuit is configured to determine that an abnormality has occurred in a power line in a power supply path between the main power supply and the power supply target, the power supply line including the power switch, when all of a first determination condition, a second determination condition, and a third determination condition are met. The first determination condition is that a voltage generated in the power line is less than a voltage threshold. The second determination condition is that the control circuit has not received the stop permission signal. The third determination condition is that communication between the control circuit and the power supply target is normal.

[0007] Fig. 1 is a block diagram of a power supply system according to an embodiment of the present invention, and Fig. 2 is a circuit diagram of the power supply device shown in Fig. 1.

[0008] A power supply system 1 according to one embodiment will be described. As shown in Fig. 1, the power supply system 1 has a power supply device 10 and a steering control device 20 to which power is supplied. The power supply device 10 is provided on a power supply path between a main power supply 30 and the steering control device 20. The main power supply 30 is, for example, a lithium-ion battery or a nickel-metal hydride battery. Power from the main power supply 30 is supplied to the steering control device 20 via the power supply device 10. The power supply device 10 backs up the power supply to the steering control device 20.

[0009] The steering control device 20 is one of the vehicle control devices. The steering control device 20 controls a motor that is a drive source for the vehicle's steering device. The steering device is, for example, a steer-by-wire type steering device in which power transmission between the steering wheel and the steered wheels is separated. The motor includes a reaction force motor 21C and a steering motor 22C.

[0010] The reaction force motor 21C is a source of a steering reaction force. The steering reaction force is a force in the direction opposite to the steering direction of the steering wheel. The reaction force motor 21C is, for example, a three-phase brushless motor and has two winding groups. The winding groups include a first winding group N11 and a second winding group N12. The torque of the reaction force motor 21C is applied to the steering shaft via a reducer.

[0011] The steering motor 22C is a source of steering force. The steering force is a force for steering the steered wheels of the vehicle. The steering motor 22C is, for example, a three-phase brushless motor and has two winding groups. The winding groups include a first winding group N21 and a second winding group N22. The torque of the steering motor 22C is applied to a steering shaft via a reducer. The steering shaft steers the steered wheels.

[0012] The steering control device 20 has a reaction force control device 21. The reaction force control device 21 controls the power supply to a reaction force motor 21C. The reaction force control device 21 has a first reaction force control unit 21A and a second reaction force control unit 21B. The first reaction force control unit 21A controls the power supply to a first system winding group N11 of the reaction force motor 21C. The second reaction force control unit 21B controls the power supply to a second system winding group N12 of the reaction force motor 21C.

[0013] Steering control device 20 has a steering control device 22. Steering control device 22 controls the power supply to steering motor 22C. Steering control device 22 has a first steering control section 22A and a second steering control section 22B. First steering control section 22A controls the power supply to a first system winding group N21 of steering motor 22C. Second steering control section 22B controls the power supply to a second system winding group N22 of steering motor 22C.

[0014] The reaction force control device 21 and the steering control device 22 are connected to each other via an in-vehicle network 41. The communication standard of the in-vehicle network 41 is, for example, CAN (Controller Area Network). The reaction force control device 21 and the steering control device 22 exchange information with each other via the in-vehicle network 41. The reaction force control device 21 and the steering control device 22 can also exchange information with various in-vehicle systems via the in-vehicle network 41. Communication via the in-vehicle network 41 is called, for example, global CAN communication.

[0015] The reaction force control device 21 is connected to the power supply device 10 via a communication line 42. The communication line 42 is a dedicated communication path that connects the reaction force control device 21 and the power supply device 10 one-to-one, and is separated from the in-vehicle network 41. The reaction force control device 21 and the power supply device 10 exchange information with each other via the communication line 42. The communication standard between the reaction force control device 21 and the power supply device 10 is, for example, CAN. One-to-one communication via the communication line 42 is called, for example, local CAN communication.

[0016] <Power Supply Path> Next, the power supply path between the main power supply 30 and the steering control device 20 will be described. The first reaction force control unit 21A is connected to the main power supply 30 via a first power supply line L1. The first reaction force control unit 21A is also connected to the main power supply 30 via a second power supply line L2. The first power supply line L1 and the second power supply line L2 connect the first reaction force control unit 21A and the main power supply 30 via the power supply device 10.

[0017] The second power line L2 branches off from a first connection point P1 set on the first power line L1. The first connection point P1 is set on the first power line L1 between the main power supply 30 and the power supply device 10. A power switch 31 is provided on the second power line L2. The power switch 31 includes, for example, an ignition switch, and is operated when the vehicle is running. Through operation of the power switch 31, the conduction of the second power line L2 is switched between on and off. Turning on the power switch 31 turns on the power to the steering control device 20. Turning off the power switch 31 turns off the power to the steering control device 20.

[0018] Power from the main power supply 30 is supplied to a power circuit of the first reaction force control unit 21A via a first power line L1. The power circuit is an electric circuit that handles larger power and includes, for example, an inverter that converts DC power from the main power supply 30 to AC power. Power from the main power supply 30 is also supplied to a control circuit of the first reaction force control unit 21A via a second power line L2. The control circuit is an electric circuit for controlling the reaction force motor 21C and includes, for example, a CPU (Central Processing Unit) and memory. The memory includes RAM (Random Access Memory) and ROM (Read Only Memory).

[0019] The second reaction force control unit 21B is connected to the main power supply 30 without going through the power supply unit 10. The second reaction force control unit 21B is connected to a second connection point P2 set on the first power supply line L1 via a third power supply line L3. The second connection point P2 is set between the first connection point P1 on the first power supply line L1 and the power supply unit 10. Power from the main power supply 30 is supplied to the power circuit of the second reaction force control unit 21B via the third power supply line L3.

[0020] The second reaction force control unit 21B is connected to a third connection point P3 set on the second power supply line L2 via a fourth power supply line L4. The third connection point P3 is set on the second power supply line L2 between the power switch 31 and the power supply device 10. Power from the main power supply 30 is supplied to the control circuit of the second reaction force control unit 21B via the fourth power supply line L4.

[0021] First steering control unit 22A is connected to main power supply 30 via power supply device 10. First steering control unit 22A is connected to a fourth connection point P4 set on first power supply line L1 via a fifth power supply line L5. Fourth connection point P4 is set on first power supply line L1 between power supply unit 10 and first reaction force control unit 21A. Power from main power supply 30 is supplied to a power circuit of first steering control unit 22A via fifth power supply line L5.

[0022] First steering control unit 22A is connected to a fifth connection point P5 set on second power supply line L2 via a sixth power supply line L6. Fifth connection point P5 is set on second power supply line L2 between power supply device 10 and first reaction force control unit 21A. Power from main power supply 30 is supplied to the control circuit of first steering control unit 22A via the sixth power supply line L6.

[0023] The second steering control unit 22B is connected to the main power supply 30 without going through the power supply device 10. The second steering control unit 22B is connected to the first power supply line L1 via the seventh power supply line L7. Specifically, the second steering control unit 22B is connected to a sixth connection point P6 set on the third power supply line L3 via the seventh power supply line L7. Power from the main power supply 30 is supplied to the power circuit of the second steering control unit 22B via the seventh power supply line L7.

[0024] The second steering control unit 22B is connected to the second power supply line L2 via the eighth power supply line L8. Specifically, the second steering control unit 22B is connected to a seventh connection point P7 set on the fourth power supply line L4 via the eighth power supply line L8. Power from the main power supply 30 is supplied to the control circuit of the second steering control unit 22B via the eighth power supply line L8.

[0025] The power of the main power supply 30 is also supplied to various in-vehicle systems via power lines (not shown). The power lines include a service line that draws power from the main power supply 30 and a service line that draws power from the load side of the power switch 31. The load side is the side of the power switch 31 opposite the main power supply 30, to which a load is connected. The steering control device 20 is one of the loads that consumes power from the main power supply 30.

[0026] <Configuration of Power Supply Device 10> Next, a description will be given of the configuration of the power supply device 10. As shown in Fig. 2, the power supply device 10 has a charging circuit 11, an auxiliary power supply 12, a boost circuit 13, and a control circuit 14. The power supply device 10 also has a first switch 15A, a second switch 15B, a third switch 15C, a first diode 16A, a second diode 16B, and a voltage sensor 17.

[0027] The charging circuit 11 is a circuit for charging the auxiliary power supply 12 using power from the main power supply 30. The input terminal of the charging circuit 11 is connected to an eighth connection point P8 set on the first power supply line L1 via a ninth power supply line L9. The output terminal of the charging circuit 11 is connected to the auxiliary power supply 12 via a tenth power supply line L10.

[0028] The auxiliary power supply 12 is used to back up the power supply to the steering control device 20. The auxiliary power supply 12 is a power storage device that can be charged and discharged, and examples of such a power storage device include a lithium ion capacitor or a lithium ion battery. The voltage of the auxiliary power supply 12 is set lower than the voltage of the main power supply 30. The voltage of the auxiliary power supply 12 and the voltage of the main power supply 30 are terminal voltages, and are actual output voltages.

[0029] The boost circuit 13 is a circuit for boosting the output voltage of the auxiliary power supply 12. The boost circuit 13 boosts the output voltage of the auxiliary power supply 12 to a voltage that is higher than the terminal voltage of the auxiliary power supply 12 and lower than the terminal voltage of the main power supply 30, for example.

[0030] An input terminal of the boost circuit 13 is connected to the auxiliary power supply 12 via an eleventh power line L11. The boost circuit 13 has two output terminals. A first output terminal of the boost circuit 13 is connected to a ninth connection point P9 set on the second power line L2 via a twelfth power line L12. A second output terminal of the boost circuit 13 is connected to a tenth connection point P10 set on the first power line L1 via a thirteenth power line L13. The tenth connection point P10 is set between the eighth connection point P8 on the first power line L1 and the steering control device 20.

[0031] The first switch 15A is provided on the ninth power line L9. The first switch 15A opens and closes the ninth power line L9. The second switch 15B is provided on the twelfth power line L12. The second switch 15B opens and closes the twelfth power line L12. The third switch 15C is provided on the thirteenth power line L13. The third switch 15C opens and closes the thirteenth power line L13.

[0032] The first diode 16A is provided in a portion of the twelfth power line 12 between the second switch 15B and the ninth connection point P9. The cathode of the first diode 16A is connected to the ninth connection point P9. The anode of the first diode 16A is connected to the second switch 15B. The second diode 16B is provided in a portion of the second power line L2 between the power switch 31 and the ninth connection point P9. The cathode of the second diode 16B is connected to the ninth connection point P9. The anode of the second diode 16B is connected to the power switch 31. The first diode 16A and the second diode 16B are diodes for preventing backflow.

[0033] The voltage sensor 17 is provided between the power switch 31 and the second diode 16B in the second power line L2. The voltage sensor 17 detects the voltage V １ Detect.

[0034] The control circuit 14 is connected to an eleventh connection point P11 set on the ninth power supply line L9 via a fourteenth power supply line L14. The eleventh connection point P11 is set between the first switch 15A on the ninth power supply line L9 and the charging circuit 11. The control circuit 14 is also connected to a twelfth connection point P12 set on the second power supply line L2 via a fifteenth power supply line L15. The twelfth connection point P12 is set between the ninth connection point P9 on the second power supply line L2 and the steering control device 30.

[0035] The ninth power supply line L9 and the tenth power supply line L10 constitute a charging path between the main power supply 30 and the auxiliary power supply 12. The eleventh power supply line L11, the twelfth power supply line L12, and the thirteenth power supply line L13 constitute a discharging path between the auxiliary power supply 12 and the steering control device 20. The control circuit 14 controls the opening and closing of the charging path and the discharging path by controlling the on and off of the first switch 15A, the second switch 15B, and the third switch 15C.

[0036] The control circuit 14 has a processing circuit including one of the following three components A1, A2, and A3: A1. One or more processors that operate according to a computer program, which is software. The processor includes a CPU and a memory.

[0037] A2: One or more dedicated hardware circuits such as an application specific integrated circuit (ASIC) that executes at least some of the various processes. A3: A hardware circuit that combines the two configurations A1 and A2.

[0038] The memory is a computer-readable medium that stores a program that describes processes or instructions for the computer. In this embodiment, the computer is a CPU. The memory includes RAM and ROM. The CPU executes the program stored in the memory at a predetermined calculation cycle to perform various controls.

[0039] The control circuit 14 detects the voltage V １ The control circuit 14 detects whether the power switch 31 is on or off based on the voltage V１ When the value of the voltage V is less than the first voltage threshold, the control circuit 14 determines that the power switch 31 is turned off. １ When the value of is equal to or greater than the first voltage threshold, it is determined that the power switch 31 is turned on.

[0040] Control circuit 14 monitors the voltage of main power supply 30. Control circuit 14 determines whether the voltage of main power supply 30 has dropped based on the value of the voltage of main power supply 30. Control circuit 14 determines that the voltage of main power supply 30 has dropped when the value of the voltage of main power supply 30 is less than a second voltage threshold. Control circuit 14 determines that the voltage of main power supply 30 has not dropped when the value of the voltage of main power supply 30 is equal to or greater than the second voltage threshold. The second voltage threshold is set, for example, based on the lower limit of the voltage required to properly operate reaction force motor 21C, turning motor 22C, first reaction force control unit 21A, and first turning control unit 22A.

[0041] <Operation of power supply device 10 when power is turned on> Next, a description will be given of the operation of the power supply device 10 when power is turned on, i.e., when the power switch 31 is turned on. In the initial state, the power switch 31, the first switch 15A, the second switch 15B, and the third switch 15C are all turned off.

[0042] When the power switch 31 is turned on, power from the main power supply 30 is supplied to the control circuit 14 via the fifteenth power line L15. The control circuit 14 starts up when the power is turned on and performs an initial check. The initial check is an initial inspection before the power supply device 10 is put into operation, and includes, for example, a hardware check, initialization of the CPU, and initialization of variables or flags.

[0043] When the initial check is completed normally, the control circuit 14 performs processing to transition the state of the power supply device 10 to a backup standby state for the steering control device 20. That is, the control circuit 14 turns on the first switch 15A and the second switch 15B, while maintaining the third switch 15C in an off state. When the first switch 15A is turned on, power from the main power supply 30 is charged into the auxiliary power supply 12 via the charging circuit 11. The charging circuit 11 controls charging while monitoring, for example, the charging current and the charging voltage.

[0044] The backup standby state is a state in which the power supply device 10 is able to back up the power supply to the steering control device 20, that is, a state in which the power supply device 10 is on standby to back up the power supply to the steering control device 20. When the power supply device 10 is maintained in the backup standby state, the voltage of the main power supply 30 does not drop, and power is supplied from the main power supply 30 to the steering control device 20 via the first power supply line L1 and the second power supply line L2.

[0045] The output voltage of the auxiliary power supply 12 is boosted by the boost circuit 13. When the voltage of the main power supply 30 does not drop, the voltage V ２ is lower than the voltage of the main power supply 30. Therefore, the voltage V ２ However, the voltage V boosted by the boost circuit 13 is not supplied to the steering control device 20 via the twelfth power line L12. In addition, the third switch 15C is maintained in the OFF state. ２ However, it is not supplied to the steering control device 20 via the thirteenth power line L13.

[0046] A first diode 16A for preventing backflow is provided between the ninth connection point P9 on the twelfth power supply line L12 and the second switch 15B. The first diode 16A prevents power from flowing from the main power supply 30 to the boost circuit 13 via the second power supply line L2 and the twelfth power supply line L12.

[0047] When the voltage of the main power supply 30 drops, power from the boost circuit 13 is immediately supplied to the steering control device 20 via the twelfth power supply line L12 and the second power supply line L2. This is because, as the voltage of the main power supply 30 drops, the voltage V boosted by the boost circuit 13 ２ is higher than the voltage of the main power supply 30, and therefore the voltage generated on the second power supply line L2.

[0048] Specifically, power from boost circuit 13 is supplied to the control circuit of first reaction force control unit 21A via the twelfth power supply line L12 and the second power supply line L2. Power from boost circuit 13 is also supplied to the control circuit of first turning control unit 22A via the twelfth power supply line L12, the second power supply line L2, and the sixth power supply line L6. Therefore, even if the power supply from main power supply 30 to steering control device 20 is interrupted, the power supply to the control circuit of first reaction force control unit 21A and the control circuit of first turning control unit 22A will be backed up by auxiliary power supply 12.

[0049] A second diode 16B for preventing backflow is provided between the voltage sensor 17 and the ninth connection point P9 on the second power supply line L2. The second diode 16B prevents power from flowing from the boost circuit 13 to the main power supply 30 via the twelfth power supply line L12 and the second power supply line L2.

[0050] When the voltage of the main power supply 30 drops, the control circuit 14 turns on the third switch 15C. As a result, power from the boost circuit 13 is supplied to the steering control device 20 via the thirteenth power supply line L13 and the first power supply line L1. This is because, as the voltage of the main power supply 30 drops, the voltage V boosted by the boost circuit 13 ２ is higher than the voltage of the main power supply 30, and therefore the voltage generated on the first power supply line L1.

[0051] Specifically, power from boost circuit 13 is supplied to the power circuit of first reaction force control unit 21A via thirteenth power supply line L13 and first power supply line L1. Power from boost circuit 13 is also supplied to the power circuit of first turning control unit 22A via thirteenth power supply line L13, first power supply line L1, and fifth power supply line L5. Therefore, even if the power supply from main power supply 30 to steering control device 20 is interrupted, the power supply to the power circuit of first reaction force control unit 21A and the power circuit of first turning control unit 22A will be backed up by auxiliary power supply 12.

[0052] A third diode (not shown) for preventing backflow is provided between the eighth connection point P8 and the tenth connection point P10 on the first power supply line L1. The third diode prevents power from flowing from the boost circuit 13 to the main power supply 30 via the thirteenth power supply line L13 and the first power supply line L1.

[0053] <Operation of power supply device 10 when power is disconnected> Next, the operation of the power supply device 10 when power is disconnected, i.e., when the power switch 31 is turned off, will be described. In the initial state, the power switch 31, the first switch 15A, and the second switch 15B are on, and the third switch 15C is off. The voltage of the main power supply 30 has not dropped.

[0054] When the power switch 31 is turned off, the supply of power from the main power supply 30 to the control circuit 14 via the fifteenth power line L15 is stopped. However, the control circuit 14 keeps the first switch 15A and the second switch 15B in the on state even when the power switch 31 is turned off. Therefore, the supply of power from the main power supply 30 to the control circuit 14 via the fourteenth power line L14 continues. Therefore, the control circuit 14 can continue to operate even after the power switch 31 is turned off.

[0055] When the power switch 31 is turned off, the control circuit 14 executes a predetermined shutdown sequence. The shutdown sequence is a series of processes executed to properly terminate the functions of the power supply device 10. After the execution of the shutdown sequence is completed properly, the control circuit 14 turns off the first switch 15A and the second switch 15B. Turning off the first switch 15A cuts off the supply of power from the main power supply 30 to the control circuit 14 via the fourteenth power line L14. This stops the operation of the control circuit 14, and therefore the operation of the power supply device 10.

[0056] Note that even if the voltage of the main power supply 30 drops and the power switch 31 is turned off while the power supply device 10 is backing up the power supply to the steering control device 20, the control circuit 14 starts executing the termination sequence. After completing the execution of the termination sequence, the control circuit 14 turns off the first switch 15A, the second switch 15B, and the third switch 15C. This stops the operation of the power supply device 10.

[0057] <Abnormality in the Power Supply Path> The power supply device 10 configured as described above has the following concerns. That is, if an abnormality occurs in the second power supply line L2, the voltage V １ The abnormality includes a break in the second power supply line L2. The break is located, for example, in a portion of the second power supply line L2 between the voltage sensor 17 and the second diode 16B. In this case, the control circuit 14 determines whether the voltage V due to the abnormality in the second power supply line L2 is low. １ The decrease in voltage V due to the power switch 31 being turned off １ This may result in the power supply device 10 being mistakenly recognized as a drop in power supply voltage, causing the power supply device 10 to stop operating erroneously.

[0058] Therefore, in this embodiment, when the power switch 31 is turned off, the voltage V １ and the voltage V due to an abnormality in the second power line L2. １ In order to distinguish between a decrease in the power consumption and a decrease in the power consumption, the power supply system 1 employs the following configuration.

[0059] <Stop determination process of steering control device 20> First reaction force control unit 21A acquires power supply state signal S1 via in-vehicle network 41. Power supply state signal S1 is an electrical signal that indicates the state of power switch 31 recognized by various in-vehicle systems, i.e., the state of power supply to the various in-vehicle systems via power switch 31. First reaction force control unit 21A recognizes whether power switch 13 is on or off based on power supply state signal S1. Like first reaction force control unit 21A, second reaction force control unit 21B, first turning control unit 22A, and second turning control unit 22B also acquire power supply state signal S1 via in-vehicle network 41, and recognize whether power switch 13 is on or off based on the acquired power supply state signal S1.

[0060] When first reaction force control unit 21A, second reaction force control unit 21B, first steering control unit 22A, and second steering control unit 22B recognize that power switch 13 is off, they execute a stop determination process. The stop determination process is a process in which first reaction force control unit 21A, second reaction force control unit 21B, first steering control unit 22A, and second steering control unit 22B determine whether or not it is OK to stop their respective operations. The stop determination process includes a process in which first reaction force control unit 21A, second reaction force control unit 21B, first steering control unit 22A, and second steering control unit 22B confirm with each other whether or not they recognize that power switch 13 is off.

[0061] When it is determined through the execution of the stop determination process that it is OK to stop its own operation, the first reaction force control unit 21A permits the power supply device 10 to stop operating. That is, the first reaction force control unit 21A generates a stop permission signal S2 for the power supply device 10 and transmits the generated stop permission signal S2 to the power supply device 10 via the communication line 42. The stop permission signal S1 is an electrical signal for permitting the power supply device 10 to stop operating. After transmitting the stop permission signal S2, the first reaction force control unit 21A executes a predetermined termination sequence and stops operating upon completion of the termination sequence. The termination sequence is a series of processes executed by the first reaction force control unit 21A when stopping its operation.

[0062] When the second reaction force control unit 21B, the first steering control unit 22A, and the second steering control unit 22B determine that their own operation may be stopped through the execution of a stop determination process, they execute a termination sequence in the same manner as the first reaction force control unit 21A, and stop operation when the termination sequence is completed.

[0063] <Processing for Determining Abnormality of Power Supply Device 10> The control circuit 14 executes a processing for determining abnormality. １ and the voltage V due to an abnormality in the second power line L2. １ The control circuit 14 executes the abnormality determination process at a predetermined control period when the power switch 31 is turned on. The control circuit 14 determines whether the abnormality determination condition is met or not, and determines whether the voltage V １ It is determined whether the decrease in the voltage is due to turning off the power switch 31. The abnormality determination conditions include first to third determination conditions B1 to B3.

[0064] B1.V １ <V １ｔｈ B2. The stop permission signal S2 is not received. B3. The local CAN communication via the communication line 42 is normal.

[0065] However, "V １ｔｈ " is the first voltage threshold value, which is the voltage V of the second power line L2 when the power switch 31 is turned off. １ The control circuit 14 has a function of detecting errors in the local CAN communication. Examples of errors include bit errors, stuff errors, format errors, acknowledgement errors, and cyclic redundancy checksum errors (CRC errors). When no errors are detected in the local CAN communication, the control circuit 14 determines that the local CAN communication is normal.

[0066] When all of the first to third determination conditions B1 to B3 are met, the control circuit 14 determines whether the voltage V １It is determined that the drop in voltage V of the second power line L2 is not due to the power switch 31 being turned off, but due to an abnormality in the second power line L2. This is based on the following point of view. That is, even though the local CAN communication is normal and the stop permission signal S2 is not received from the first reaction force control unit 21A, the voltage V of the second power line L2 １ If the voltage drops, there is a high probability that an abnormality such as a break has occurred in the second power supply line L1.

[0067] When it is determined that an abnormality has occurred in the second power supply line L2, the control circuit 14 controls the voltage V １ is the voltage threshold V １ｔｈ Even if the voltage is less than 10 V, the power supply device 10 continues to operate.

[0068] The voltage V of the second power supply line L2 is １ When the voltage V of the second power line L2 drops, power from the boost circuit 13 is immediately supplied to the control circuit of the first reaction force control unit 21A via the twelfth power line L12 and the second power line L2. Also, power from the boost circuit 13 is immediately supplied to the control circuit of the first steering control unit 22A via the twelfth power line L12, the second power line L2 and the sixth power line L6. This is because the voltage V of the second power line L2 drops １ As the voltage V ２ is the voltage V of the second power supply line L2 １ Because it will be higher.

[0069] Therefore, even if the power supply via the second power line L2 is interrupted, the power supply to the control circuit of the first reaction force control unit 21A and the control circuit of the first turning control unit 22A is backed up by the auxiliary power supply 12. The control circuit 14 controls the voltage V １ Since the drop in voltage is not due to a drop in the voltage of the main power supply 30, the third switch 15C is maintained in the OFF state.

[0070] When it is determined that the second power supply line L2 is abnormal, the control circuit 14 may execute a predetermined process, such as notifying a vehicle occupant that an abnormality has occurred in the second power supply line L2.

[0071] When both the first determination condition B1 and the third determination condition B3 are satisfied and only the second determination condition B2 is not satisfied, the control circuit 14 determines whether the voltage V １ It is determined that the decrease in the voltage Vcc is due to the power switch 31 being turned off. The second determination condition B2 is not satisfied when the control circuit 14 receives the stop permission signal S2.

[0072] When the local CAN communication is normal and the stop permission signal S2 is received from the first reaction force control unit 21A, the voltage V １ If the signal S2 decreases, there is a high probability that the power switch 31 has been turned off. This is because the stop permission signal S2 is a highly reliable electrical signal that reflects the state of the power switch 31 recognized by various in-vehicle systems. The steering control device 20 generates the stop permission signal S2 when the various in-vehicle systems recognize that the power switch 31 is off.

[0073] When the control circuit 14 recognizes that the power switch 31 is off, it determines that the situation allows the power supply device 10 to be stopped, and begins executing a predetermined shutdown sequence. The shutdown sequence is a series of processes executed to properly shut down the functions of the power supply device 10. After the execution of the shutdown sequence is completed properly, the control circuit 14 turns off the first switch 15A and the second switch 15B. Turning off the first switch 15A cuts off the supply of power from the main power supply 30 to the control circuit 14 via the fourteenth power line L14. This stops the operation of the control circuit 14, and ultimately the operation of the power supply device 10.

[0074] <Effects of the embodiment> The present embodiment has the following effects. (1) When all of the first to third determination conditions B1 to B3 are met, the power supply device 10 determines that an abnormality has occurred in the second power supply line L2, on which the power switch 31 is provided, among the power supply paths (L1 to L8) between the main power supply 30 and the steering control device 20 to be supplied with power. The abnormality includes, for example, a break in the second power supply line L2. The first determination condition B is that the voltage V generated in the second power supply line L2 is １ is the voltage threshold V １ｔｈThe second determination condition B2 is that the power supply device 10 does not receive the stop permission signal S2 from the steering control device 20. The third determination condition B3 is that the communication state between the power supply device 10 and the steering control device 20 is normal.

[0075] The voltage V of the second power line L2 on which the power switch 31 is provided １ If the voltage V drops and the stop permission signal S2 is not received from the steering control device 20, there is a high probability that an abnormality has occurred in the second power supply line L2. This is because the steering control device 20 generates the stop permission signal S2 when the various in-vehicle systems recognize that the power switch 31 is off. Therefore, the power supply device 10 can appropriately determine an abnormality in the second power supply line L2. In other words, the power supply device 10 detects that the voltage V １ and the voltage V due to an abnormality in the second power line L2. １ Therefore, it is possible to prevent the power supply device 10 from mistaking a drop in the power supply voltage due to an abnormality in the second power line L2, which is one of the power supply paths, for a drop in the power supply voltage due to the power switch 31 being turned off and stopping operation.

[0076] (2) When both the first and third determination conditions B1 and B3 are satisfied and only the second determination condition B2 is not satisfied, the power supply device 10 determines that the power switch 31 has been turned off. １ If the voltage drops and the power supply device 10 receives a stop permission signal S2 from the steering control device 20, there is a high probability that the power switch 31 has been turned off. This is because the steering control device 20 generates the stop permission signal S2 when the various in-vehicle systems recognize that the power switch 31 is off. Therefore, the power supply device 10 can appropriately determine that the power switch 31 has been turned off.

[0077] (3) The power supply device 10 and the steering control device 20 are connected one-to-one via a communication line 42 that is separated from the in-vehicle network 41. The power supply device 10 receives the stop permission signal S2 via the communication line 42. Therefore, an increase in the load on the in-vehicle network 41 can be suppressed compared to when the power supply device 10 receives the stop permission signal S2 via the in-vehicle network 41.

[0078] (4) The steering control device 20 acquires the power supply state signal S1 via the in-vehicle network 41, and recognizes that the power switch 31 has been turned off based on the acquired power supply state signal S1. The power supply state signal S1 is an electrical signal that indicates the state of the power supply switch 31 recognized by the various in-vehicle systems, i.e., the state of power supply to the various in-vehicle systems via the power supply switch 31. Therefore, the steering control device 20 can appropriately recognize that the power supply switch 31 has been turned off.

[0079] (5) The steering control device 20 controls the drive source of the steering device of the vehicle. Higher operational reliability is required for the steering control device 20. The power supply device 10 of this embodiment is suitable for the steering control device 20.

[0080] Other Embodiments This embodiment may be modified as follows: The abnormality determination conditions for the power supply device 10 may include the following fourth determination condition in addition to the first to third determination conditions B1 to B3.

[0081] B4. T>T ｔｈ Here, "T" is the time that has elapsed since the first to third determination conditions B1 to B3 were met. ｔｈ " is the time threshold. ｔｈ is set from the viewpoint of preventing the occurrence of an erroneous determination that an abnormality has occurred in the second power line L2 when, for example, the first to third determination conditions B1 to B3 are temporarily satisfied.

[0082] It is conceivable that the first reaction force control unit 21A, the second reaction force control unit 21B, the first turning control unit 22A, and the second turning control unit 22B recognize that the power switch 13 is off at different times. In this case, the timing of generating the stop permission signal S2 is delayed by the time difference for recognizing that the power switch 13 is off. This is one of the reasons why the first to third judgment conditions B1 to B3 are temporarily satisfied. For this reason, the time threshold value T ｔｈ is set taking into consideration the time difference for recognizing that the power switch 13 is turned off.

[0083] The power supply device 10 determines whether the elapsed time T after all of the first to third determination conditions B1 to B3 are satisfied is equal to or exceeds the time threshold T ｔｈ When the voltage V exceeds the threshold voltage V, it is determined that an abnormality has occurred in the second power supply line L2. That is, when all of the first to fourth determination conditions B1 to B4 are satisfied, the control circuit 14 determines that the voltage V １ This determines that the decrease in the voltage is due to an abnormality in the second power line L2, and not due to the power switch 31 being turned off. Therefore, if all of the first to third determination conditions B1 to B3 are temporarily satisfied, it is possible to prevent the power supply device 10 from erroneously determining that an abnormality has occurred in the second power line L2.

[0084] The control circuit 14 determines whether the time elapsed from when both the first determination condition B1 and the third determination condition B3 are satisfied and only the second determination condition B2 is not satisfied is equal to the time threshold T ｔｈ When it exceeds １ Alternatively, it may be determined that the decrease in the voltage is due to the power switch 31 being turned off.

[0085] The control circuit 14 may notify the steering control device 20 of the backup state of the power supply device 10 by local CAN communication via the communication line 42. The steering control device 20 is a higher-level device than the power supply device 10.

[0086] The second reaction force control unit 21, the first steering control unit 22A, or the second steering control unit 22B may generate a stop permission signal S2, and the generated stop permission signal S2 may be transmitted to the power supply unit 10 via the communication line 42.

[0087] Depending on the product specifications, stop permission signal S2 may be transmitted to power supply device 10 via in-vehicle network 41. Reaction force motor 21C and steering motor 22C may be configured to have a single system of winding groups. In this case, reaction force control device 21 may be configured to have only first reaction force control section 21A, for example. Also, a configuration may be adopted in which third power supply line L3 and fourth power supply line L4 are omitted from the power supply path between main power supply 30 and steering control device 20.

[0088] The steering motor 22C may be configured to have one winding group. In this case, the steering control device 22 may be configured to have, for example, only the first steering control unit 22A. Also, a configuration may be adopted in which the seventh power supply line L7 and the eighth power supply line L8 are omitted from the power supply path between the main power supply 30 and the steering control device 20.

[0089] The control target of the steering control device 20 may be an assist motor, which is a drive source of an electric power steering device. The assist motor is a source of assist force. The assist force is a force in the same direction as the steering wheel operation direction. A motor having one system of winding groups may be used as the assist motor, or a motor having two systems of winding groups may be used.

[0090] The power supply target of the power supply device 10 is not limited to the steering control device 20. The power supply target may be a control device that controls the drive of a traction motor of an electric vehicle or a hybrid electric vehicle. Furthermore, the power supply target of the power supply device 10 may be a control device that controls the brakes of the vehicle.

Claims

1. A power supply system comprising: a power supply target configured to operate by consuming power from a vehicle's main power supply; and a power supply unit configured to back up the power supply to the power supply target, wherein the power supply target is configured to generate a stop permission signal for permitting the power supply unit to stop operating when it recognizes that a power switch of the vehicle has been turned off, and the power supply unit is configured to determine that an abnormality has occurred in a power line in which the power switch is provided, of a power supply path between the main power supply and the power supply target, when a first judgment condition, a second judgment condition, and a third judgment condition are all satisfied, wherein the first judgment condition is that a voltage generated in the power line is less than a voltage threshold value, the second judgment condition is that the power supply unit has not received the stop permission signal, and the third judgment condition is that the communication state between the power supply unit and the power supply target is normal.

2. The power supply system of claim 1, wherein the power supply device is configured to determine that an abnormality has occurred in the power line when the elapsed time since all of the first judgment condition, the second judgment condition, and the third judgment condition are satisfied exceeds a time threshold taking into account the time difference for recognizing that the power switch is turned off.

3. A power supply system as described in claim 1 or claim 2, wherein the power supply device is configured to determine that the power switch is turned off when both the first judgment condition and the third judgment condition are satisfied and only the second judgment condition is not satisfied.

4. A power supply system as described in claim 1 or claim 2, wherein the power supply device and the power supply target are connected one-to-one via a communication line separated from an in-vehicle network, and the power supply device is configured to receive the stop permission signal via the communication line.

5. A power supply system as described in claim 1 or claim 2, wherein the power supply target is configured to acquire an electrical signal indicating a power supply state to the in-vehicle system via the power switch via an in-vehicle network, and recognize that the power switch has been turned off based on the acquired electrical signal.

6. The power supply system according to claim 1 or 2, wherein the power supply target is a steering control device configured to control a drive source of a steering device of the vehicle.

7. A power supply device having an auxiliary power source configured to back up power supply to a power supply object configured to operate by consuming power from a vehicle's main power source, and a control circuit configured to control charging and discharging of the auxiliary power source, wherein the power supply object is configured to generate a stop permission signal for permitting the operation of the power supply device to be stopped when it recognizes that a power switch of the vehicle has been turned off, and the control circuit is configured to determine that an abnormality has occurred in a power line in which the power switch is provided, of a power supply path between the main power source and the power supply object, when a first judgment condition, a second judgment condition, and a third judgment condition are all satisfied, wherein the first judgment condition is that a voltage generated in the power line is less than a voltage threshold value, the second judgment condition is that the control circuit has not received the stop permission signal, and the third judgment condition is that a communication state between the control circuit and the power supply object is normal.

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