Vehicle power supply system and control method for vehicle power supply system

Abstract

The present application relates to a vehicle power supply system and a control method for the vehicle power supply system. The vehicle power supply system includes a power supply control device (88) that performs processing that switches a connection state of a drive circuit (61a) with a main power supply (45) and an auxiliary power supply (81), the processing including processing that switches the connection state to transition to a backup state due to occurrence of a voltage drop of the main power supply (45), and processing that switches the connection state to transition to a normal state due to resolution of the voltage drop of the main power supply (45). After occurrence of the voltage drop of the main power supply (45), a turning side control device (60) of a turning control unit (1) sets an output limited state for a turning side motor (32). The output limited state is canceled when the power supply control device (88) completes switching of the connection state to transition.

Description

Technical Field

[0001] This invention relates to a vehicle power system and a control method for the vehicle power system. Background Technology

[0002] For example, a vehicle is equipped with a steering device as described in Japanese Unexamined Patent Application Publication No. 2020-83058 (JP 2020-83058A). The steering device described in JP 2020-83058A is a so-called steer-by-wire device, in which the power transmission path between the vehicle's steering wheel and the vehicle's turning wheels is interrupted. The power required for the steering device is supplied from a power supply unit. The power supply unit has a main power supply and a backup power supply. The power supply to the steering device is primarily supplied from the main power supply. When the main power supply fails due to a malfunction, the power supply state switches to a standby state, in which power is supplied from the backup power supply. Therefore, the backup power supply provides backup support for the power supply provided by the main power supply. The steering device is configured to set an output-limited state through output limiting processing while the power supply state is in standby state. The output limiting processing is a process used to limit, for example, the output of a rotation actuator that is a component of the steering device. Summary of the Invention

[0003] The output limiting state described in JP 2020-83058A is designed to ensure that the power required by the steering mechanism in standby mode does not exceed the performance limit of the backup power supply. Here, measures are needed to help prevent the output limiting state from being canceled during standby mode.

[0004] The vehicle power system related to this disclosure includes: a power control unit having a second power source separate from a first power source installed in the vehicle; and a steering control unit connected to the first power source via the power control unit and controlling a steering device installed in the vehicle. The steering control unit includes a steering control device configured to control the operation of a motor. The steering control device includes a drive circuit that is driven to supply power to the motor due to the drive circuit being connected to at least one of the first and second power sources, and the steering control device controls the operation of the motor by controlling the drive circuit. The power control unit includes a power control device that switches the connection state of the drive circuit with the first and second power sources. The connection state supplying power from the first power source is referred to as a first state, and the connection state supplying power from the second power source is referred to as a second state. The power control device is configured to perform state detection processing for detecting a change in the state of the first power source and switching processing for switching the connection state of the drive circuit with the first and second power sources. The switching process includes: a first switching process, which switches the connection state to transition to a second state due to a state detection process detecting an abnormality in the first power supply; and a second switching process, which, in the case where the connection state has transitioned to the second state due to the detection of an abnormality in the first power supply, switches the connection state to transition to the first state due to a state detection process detecting a recovery of the first power supply from the abnormality. The steering control device is configured to set an output-limited state after an abnormality in the first power supply is detected, limiting the torque that the motor can output compared to the torque before the abnormality was detected. The steering control device is configured to cancel the output-limited state upon completion of the second switching process executed simultaneously with the power supply control device setting the output-limited state after the abnormality in the first power supply is detected.

[0005] A method for controlling a vehicle power system that addresses the aforementioned challenges includes: a power control unit having a second power source separate from a first power source installed in the vehicle and a power control device; and a steering control unit connected to the first power source via the power control unit and controlling a steering device installed in the vehicle. The steering control unit includes a steering control device, and the steering control device includes a drive circuit. The method for controlling the vehicle power system includes: supplying power to a motor via the drive circuit, which is supplied due to the drive circuit being connected to at least one of the first and second power sources; controlling the operation of the motor by the steering control device through controlling the drive of the drive circuit; and performing the following processes by the power control device. The processes performed by the power control device include: performing a state detection process that detects a change in the state of the first power source; and performing a switching process that switches the connection state of the drive circuit with the first and second power sources. The connection state supplying power from the first power source is referred to as a first state, and the connection state supplying power from the second power source is referred to as a second state. The switching process includes: a first switching process, which switches the connection state to transition to a second state due to a state detection process detecting an abnormality in the first power supply; and a second switching process, which, when the connection state has transitioned to the second state due to a detected abnormality in the first power supply, switches the connection state to transition to the first state due to a detected recovery of the first power supply from the abnormality. The control method for the vehicle power system further includes: setting an output limiting state by the steering control device after an abnormality in the first power supply is detected, for limiting the torque that the motor can output compared to the torque before the abnormality was detected; and canceling the output limiting state by the steering control device when the second switching process, executed simultaneously by the power control device when the output limiting state is set after the abnormality in the first power supply is detected, is completed.

[0006] According to the above configuration and method, the power control device is configured such that, if the connection state has transitioned to the second state due to a detected anomaly in the first power supply, the power control device switches the connection state back to the first state upon detecting a recovery of the first power supply from the anomaly. Here, the first state of the power supply to the steering device is the original state of the power supply state, and the second state is a standby state. That is, in the standby state, when the power control device detects a recovery of the first power supply from the anomaly, the power control device can restore the power supply state to the original state by completing the switch from the first state to the second state. In this case, the steering control device cancels the output-limited state after the power state is restored to the original state. Therefore, even when a recovery of the first power supply from the anomaly is detected, the output-limited state is maintained unless the recovery of the power state to the original state is completed. This helps prevent the output-limited state from being canceled before the recovery of the power state to the original state is completed.

[0007] In the aforementioned vehicle power system, the state detection process may include: an anomaly condition determination process, which determines whether an anomaly condition for detecting an anomaly in the first power supply is met; an anomaly resolution condition determination process, which, after the anomaly condition is met, determines whether an anomaly resolution condition for not meeting the anomaly condition is met; and a recovery condition determination process, which, after the anomaly resolution condition is met, determines whether a recovery condition for detecting that the first power supply has recovered from the anomaly is met. The anomaly condition may include a condition based on voltage parameters indicating the voltage state of the first power supply. The recovery condition may include a condition based on state parameters indicating that the anomaly condition can remain in a state that is not met.

[0008] According to this configuration, if the abnormal condition is no longer met and the abnormality resolution condition is met, the power control device can determine that the recovery condition has been met if the abnormality condition is not a transient event but persists for a period of time. Therefore, even when the abnormal condition is no longer met and the abnormality resolution condition is met, if it is a transient event, the recovery of the first power supply from the abnormality will not be detected. This can improve the accuracy of detecting the recovery of the first power supply from the abnormality after detecting the abnormality of the first power supply.

[0009] In the aforementioned vehicle power system, the voltage parameter can be the output voltage of the first power supply. Abnormal conditions can include conditions based on a comparison between the output voltage and a voltage threshold. The state parameter can be the elapsed time since the abnormality resolution condition was met. Recovery conditions can include conditions based on a comparison between the elapsed time and a time threshold.

[0010] This configuration simplifies the determination of parameters required for recovery conditions. It is effective in easily implementing the processing related to determining recovery conditions. More specifically, in the aforementioned vehicle power system, the power control device can be configured to perform anomaly resolution condition determination processing for a time-limited period after the abnormal condition is met until the recovery condition is not met, or the power control device can be configured to continue performing anomaly resolution condition determination processing even after the abnormal condition is met but the recovery condition is not met.

[0011] According to the former configuration, the power control device performs the anomaly resolution condition determination process only during a time-limited period after the anomaly condition is met. Therefore, the power consumption required for the anomaly resolution condition determination process after the anomaly of the first power supply is detected can be reduced. This is effective in reducing the power consumption of the second power supply when its capacity is limited.

[0012] According to the latter configuration, even after the abnormal condition is met but the recovery condition is not, the abnormal resolution condition determination process continues, which increases the chance of the primary power supply recovering from the abnormality. This is effective in maintaining motor operation as much as possible when the primary power supply is not abnormal.

[0013] In the aforementioned vehicle power system, the power control unit and the steering control unit are communicatively connected to each other via a cable. The power control unit can output switching completion information to the steering control unit via this cable, indicating that the connection state transition has been completed when the connection state changes to a first or second state. The steering control unit can identify that the connection state transition initiated by the power control unit has been completed based on the switching completion information obtained from the power control unit via the cable.

[0014] In this configuration, the steering control unit can determine the power supply status based on information obtained from the power control unit via a line. Therefore, the steering control unit can operate while taking the power supply status into account.

[0015] In the aforementioned vehicle power system, an output-limited state can be a state in which the torque output by the motor is limited so as not to exceed an output limit value. When the power performance of the second power supply, as defined by its power capacity or output voltage, is lower than that of the first power supply, the output limit value can be a value lower than the limit of the power performance of the second power supply.

[0016] This configuration helps prevent situations where the power supply performance of the second power source exceeds that of the first power source in standby mode. Therefore, even if an anomaly is detected in the first power source, motor operation can continue appropriately. This is particularly effective when the power supply performance of the second power source is lower than that of the first power source.

[0017] The vehicle power system and control method of the present invention help prevent the cancellation of the output-limited state during standby. Attached Figure Description

[0018] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, in which the same reference numerals denote the same elements, and in the drawings:

[0019] Figure 1 This is a diagram showing the configuration of the steering device according to the first embodiment;

[0020] Figure 2 This is a diagram showing the configuration of the vehicle power system according to the first embodiment;

[0021] Figure 3 It is shown Figure 2 A block diagram of the electrical configuration of the vehicle's power system;

[0022] Figure 4 It is a description of Figure 2 The table shows the processing performed by the power control unit of the power control device;

[0023] Figure 5 It is a description of Figure 2 The table shows the processing performed by the power control unit of the power control device;

[0024] Figure 6 It is shown by Figure 2 A block diagram of the processing performed by the steering control unit's rotational side control device;

[0025] Figure 7 It is a description of Figure 6 A table limiting the processing performed by the control unit;

[0026] Figure 8 It is a description of Figure 6 A table limiting the processing performed by the control unit; and

[0027] Figure 9 It is a graph showing the status of the start switch, the output voltage of the main power supply, the output voltage of the power control unit, the communication status of the power supply status signal, the reception status of the power supply status signal, and the output limit value in relation to the first embodiment. Detailed Implementation

[0028] First Implementation Method

[0029] A vehicle power supply system according to a first embodiment will be described. For example... Figure 1As shown, the steering control unit 1 controls the steering device 2, which is the target. The steering device 2 is configured as a steer-by-wire vehicle steering device. The steering device 2 includes a steering unit 4 and a rotation unit 6. The steering unit 4 is steered by the driver via the steering wheel 3, which serves as the steering component of the vehicle. The rotation unit 6 rotates the left and right turning wheels 5 of the vehicle according to the steering input by the driver into the steering unit 4. The steering device 2 of this embodiment has a structure in which the power transmission path between the steering unit 4 and the rotation unit 6 is always mechanically cut off. In this structure, the power transmission path between the steering actuator 12, which will be described later, and the rotation actuator 31, which will be described later, is always mechanically cut off.

[0030] The steering unit 4 includes a steering shaft 11 and a steering actuator 12. The steering shaft 11 is connected to the steering wheel 3. The steering actuator 12 has a steering-side motor 13 and a steering-side reduction mechanism 14. The steering-side motor 13 is a reaction force motor that applies a steering reaction force as a force against steering to the steering wheel 3 via the steering shaft 11. The steering-side motor 13 is connected to the steering shaft 11 via the steering-side reduction mechanism 14, which is formed, for example, by a worm and a worm wheel. As the steering-side motor 13 in this embodiment, for example, a three-phase brushless motor is used. In this embodiment, the steering-side motor 13 is an example of the drive source for the steering actuator 12.

[0031] The rotating unit 6 includes a pinion shaft 21, a rack shaft 22, and a rack housing 23. The pinion shaft 21 and the rack shaft 22 are connected together at a predetermined intersection angle. The pinion teeth 21a formed on the pinion shaft 21 and the rack teeth 22a formed on the rack shaft 22 mesh with each other to form a rack and pinion mechanism 24. The pinion shaft 21 is a rotational shaft corresponding to the rotation angle of its rotation, which can be converted into the rotational position of the rotating wheel 5. The rack housing 23 houses the rack and pinion mechanism 24. In this embodiment, the rack shaft 22 is an example of a rotational shaft.

[0032] One end of the pinion shaft 21, opposite to the side connected to the rack shaft 22, protrudes from the rack housing 23. Both ends of the rack shaft 22 protrude axially from both ends of the rack housing 23. The tie rod 26 is connected to both ends of the rack shaft 22 via rack ends 25 formed by ball joints. The front end of the tie rod 26 is connected to steering knuckles (not shown) on which left and right rotating wheels 5 are respectively mounted.

[0033] The rotation unit 6 includes a rotation actuator 31. The rotation actuator 31 includes a rotation-side motor 32, a transmission mechanism 33, and a conversion mechanism 34. The rotation-side motor 32 is a rotational motor that applies rotational force to the rack shaft 22 to rotate the rotating wheel 5 via the transmission mechanism 33 and the conversion mechanism 34. The rotation of the rotation-side motor 32 is transmitted to the conversion mechanism 34 via the transmission mechanism 33, which is formed by, for example, a belt drive mechanism. The transmission mechanism 33 converts the rotation of the rotation-side motor 32 into the reciprocating motion of the rack shaft 22 via the conversion mechanism 34, which is formed by, for example, a ball screw mechanism. As the rotation-side motor 32 in this embodiment, for example, a three-phase brushless motor is used. In this embodiment, the rotation-side motor 32 is an example of the motor, i.e., the drive source, of the rotation actuator 31.

[0034] In the steering mechanism 2, according to the driver's steering operation, as the motor torque is applied as a rotational force from the rotary actuator 31 to the rack shaft 22, the rotation angle of the rotating wheel 5 changes. Simultaneously, a steering reaction force resisting the driver's steering is applied from the steering actuator 12 to the steering wheel 3. Therefore, in the steering mechanism 2, the steering torque Th required to steer the steering wheel 3 is changed by the steering reaction force, which is the motor torque applied from the steering actuator 12.

[0035] The reason for providing the pinion shaft 21 is to support the rack shaft 22 together with the pinion shaft 21 inside the rack housing 23. The rack shaft 22 is supported by a support mechanism (not shown) provided in the steering device 2 so that it can move in its axial direction and is pressed against the pinion shaft 21. Therefore, the rack shaft 22 is supported inside the rack housing 23. However, another support mechanism can be provided to support the rack shaft 22 on the rack housing 23 without using the pinion shaft 21.

[0036] Electrical configuration of steering system

[0037] like Figure 1 As shown, the steering-side motor 13 and the rotation-side motor 32 are connected to the steering control unit 1. The steering control unit 1 controls the operation of each of the motors 13 and 32.

[0038] The detection results from various sensors are input to the steering control unit 1. Examples of various sensors include a torque sensor 41, a steering side rotation angle sensor 42, a turning side rotation angle sensor 43, and a vehicle speed sensor 44.

[0039] A torque sensor 41 is mounted on the steering shaft 11 at the portion between the steering wheel 3 and the steering-side deceleration mechanism 14. The torque sensor 41 detects the steering torque Th, which is the value indicating the torque applied to the steering shaft 11 by the driver's steering operation. The steering torque Th is detected by the torsion of a torsion bar 41a located at the middle portion of the steering shaft 11 between the steering wheel 3 and the steering-side deceleration mechanism 14 within the steering shaft 11. A steering-side rotation angle sensor 42 is mounted on the steering-side motor 13. The steering-side rotation angle sensor 42 detects the rotation angle θα, which is the angle of the rotation axis of the steering-side motor 13, within a 360-degree range. A rotation-side rotation angle sensor 43 is mounted on the rotation-side motor 32. The rotation-side rotation angle sensor 43 detects the rotation angle θb, which is the angle of the rotation axis of the rotation-side motor 32, within a 360-degree range. A vehicle speed sensor 44 detects the vehicle speed SPD, which is the vehicle's travel speed.

[0040] Electrical configuration of the steering control unit

[0041] like Figure 2 As shown, the steering control unit 1 has a steering-side control device 50 and a rotation-side control device 60. The steering-side control device 50 controls the power supply to the steering-side motor 13. The rotation-side control device 60 controls the power supply to the rotation-side motor 32. The steering-side control device 50 and the rotation-side control device 60 send and receive information to each other via a local network 70, such as serial communication. The steering-side control device 50 forms part of the steering unit 4. The rotation-side control device 60 forms part of the rotation unit 6.

[0042] The steering-side control unit 50 includes a central processing unit (CPU) and a memory (neither shown), and the CPU executes a program stored in the memory at predetermined arithmetic operation cycles. The CPU and memory constitute a microcomputer as processing circuitry. Similarly, the turn-side control unit 60 includes a central processing unit (CPU) and a memory (neither shown), and the CPU executes a program stored in the memory at predetermined arithmetic operation cycles. The CPU and memory constitute a microcomputer as processing circuitry. The memory includes computer-readable media, such as random access memory (RAM) and read-only memory (ROM). However, implementing various processes in software is one example. The processing circuitry of the steering-side control unit 50 can be configured such that at least some of the processing is implemented by hardware circuitry, such as logic circuitry. The same applies to the turn-side control unit 60.

[0043] The arithmetic cycle of the steering side control device 50 is set based on the arithmetic cycle of the power control device 88, which will be described later, or the communication cycle of the signal line 90, i.e., the dedicated line, which will be described later. For example, the arithmetic cycle of the steering side control device 50 is shorter than the arithmetic cycle of the power control device 88, which will be described later, or the communication cycle of the dedicated signal line 90, which will be described later.

[0044] The steering-side control unit 50 has a dual control system formed by combinations of individual CPUs and memories to perform various processes. The dual control system includes a system formed by a main control unit 50a and a system formed by sub-control units 50b. The same applies to the turn-side control unit 60. That is, the turn-side control unit 60 also has a dual control system formed by combinations of individual CPUs and memories to perform various processes. The dual control system includes a system formed by a main control unit 60a and a system formed by sub-control units 60b. The steering-side control unit 50 and the turn-side control unit 60 are configured to communicate via a local network 70.

[0045] The steering-side control unit 50 calculates the reaction force control amount based on various information. Examples of this information include the detection results of the various sensors mentioned above and information obtained from the steering-side control unit 60 via the local network 70. The reaction force control amount is the target value of the steering reaction force that the steering wheel 3 should generate through the steering-side motor 13. The steering-side control unit 50 controls the power supply to the steering-side motor 13 based on this reaction force control amount. The steering-side control unit 60 calculates the rotation control amount based on various information. Examples of this information include the detection results of the various sensors mentioned above and information obtained from the steering-side control unit 50 via the local network 70. The rotation control amount is the target value of the rotational force that should be generated by the rotation-side motor 32. The steering-side control unit 60 controls the power supply to the rotation-side motor 32 based on this rotation control amount.

[0046] Path of power supply to the steering device

[0047] The steering system 2 has a power control unit 80. The power control unit 80 is connected to a main power supply 45. The steering control unit 1 is connected to the main power supply 45 via the power control unit 80. The main power supply 45 is, for example, a secondary battery installed in the vehicle as a DC power source. The main power supply 45 is the source of electricity required for the operation of, for example, the steering control unit 1, motors 13 and 32, and the power control unit 80, which are components of the steering system 2. Therefore, the steering control unit 1, motors 13 and 32, the power control unit 80, etc., operate by consuming electricity from the main power supply 45. The main power supply 45 is connected to a generator 46, which is an alternator or the like. The generator 46 uses the rotation of the engine, which is the driving source for the vehicle, as a power source to generate alternating current. The alternating current generated by the generator 46 is converted into direct current and stored in the main power supply 45. In this embodiment, the main power supply 45 is an example of a first power source.

[0048] The power control unit 80 is connected to the main power supply 45 via two power lines L1 and L2. Power line L2 branches off from the connection point P0 of power line L1. A start switch 47 is provided in power line L2. The start switch 47 is, for example, an ignition switch or a power switch. The start switch 47 is operated to start or stop the vehicle's drive system. The operation of the start switch 47 is a trigger used to switch the conduction of power line L2 between on and off. The conduction of power line L1 is essentially always on. However, the steering system 2 has a configuration for internally switching the conduction of power line L1 on and off in conjunction with the operation of the start switch 47. Therefore, the state of power supply to the steering system 2 is related to the operation of the start switch 47, i.e., the operating state of the vehicle's drive system.

[0049] The main control unit 50a is connected to power lines L1 and L2 via the power control unit 80. Therefore, the main control unit 50a is connected to the main power supply 45 via the power control unit 80 and power lines L1 and L2. The same applies to the main control unit 60a. The main control unit 60a is connected to power lines L1 and L2 via the power control unit 80. Therefore, the main control unit 60a is connected to the main power supply 45 via the power control unit 80 and power lines L1 and L2.

[0050] Sub-control unit 50b is directly connected to power lines L1 and L2 without being inserted into power control unit 80. Therefore, sub-control unit 50b is connected to main power supply 45 without being inserted into power control unit 80. The same applies to sub-control unit 60b. Sub-control unit 60b is directly connected to power lines L1 and L2 without being inserted into power control unit 80. Therefore, sub-control unit 60b is connected to main power supply 45 without being inserted into power control unit 80. In this embodiment, the steering-side control device 50 and the rotation-side control unit 60 share a single power control unit 80. Power control unit 80 can communicate with steering-side control device 50 via signal line 90. Power control unit 80 can communicate with rotation-side control device 60 via signal line 90.

[0051] Figure 3 The configuration of the power supply path is shown in detail. Here, the description will focus on the configuration of the steering side control device 60. The configuration of the steering side control device 50 is substantially the same as that of the steering side control device 60.

[0052] like Figure 3 As shown, the main control unit 60a has a drive circuit 61a and a control circuit 62a. The sub-control unit 60b has a drive circuit 61b and a control circuit 62b. The drive circuits 61a and 61b are circuits that process large amounts of electricity and include, for example, an inverter that converts the direct current from the main power supply 45 into alternating current. The control circuits 62a and 62b are circuits for controlling the steering-side motor 13 and include, for example, a CPU and a memory.

[0053] Power from the main power supply 45 is supplied to the drive circuit 61a via power line L11, which branches off from connection point P11 of power line L1. Power from the main power supply 45 is supplied to the control circuit 62a via power line L21, which branches off from connection point P12 of power line L2. Power from the main power supply 45 is supplied to the drive circuit 61b via power line L12, which branches off from connection point P11 of power line L1. Power from the main power supply 45 is supplied to the control circuit 62b of the sub-control unit 60b via power line L22, which branches off from connection point P12 of power line L2.

[0054] The steering-side control device 50 has a configuration corresponding to that of the rotation-side control device 60. That is, the main control unit 50a has a configuration corresponding to that of the drive circuit 61a and the control circuit 62a. The sub-control unit 50b has a configuration corresponding to that of the drive circuit 61b and the control circuit 62b.

[0055] Configuration of power control unit

[0056] like Figure 3As shown, the power control unit 80 includes an auxiliary power supply 81, a circuit 82, switches 83, 84, 85, diodes 86, 87, and a power control device 88.

[0057] The auxiliary power supply 81 is, for example, a capacitor that functions similarly to a secondary battery. The auxiliary power supply 81 is a source of electricity required for the operation of components of the steering device 2, such as the steering control unit 1 and motors 13 and 32. The auxiliary power supply 81 supplies power to components of the main power supply 45, including the main control units 50a and 60a, motors 13 and 32, and the power control device 88. Therefore, the main control units 50a and 60a, motors 13 and 32, and the power control device 88 can operate by consuming power not only from the main power supply 45 but also from the auxiliary power supply 81.

[0058] Auxiliary power supply 81 is connected to connection point P11 of power supply line L11 via power supply line L111 branching from connection point P13 of power supply line L11. Auxiliary power supply 81 is connected to connection point P11 of power supply line L11 via power supply line L112 branching from connection point P14 of power supply line L11. Connection point P14 is the connection point of power supply line L11 located downstream of connection point P13, more specifically, on the side closer to the rotation-side control device 60.

[0059] In this embodiment, the power supply to the steering device 2 is primarily supplied from the main power supply 45. When the main power supply 45 fails due to a malfunction or other reasons, the power supply state switches to a standby state, in which power is supplied from the auxiliary power supply 81. Therefore, the auxiliary power supply 81 provides backup support for the power supply provided by the main power supply 45. The auxiliary power supply 81 provides backup support for the power supply to some of the components to which the main power supply 45 supplies power, such as the main control units 50a and 60a, motors 13 and 32, and the power control device 88.

[0060] Compared to the power performance of the main power supply 45, the power performance of the auxiliary power supply 81 in this embodiment, as defined by, for example, power capacity and output voltage, is low. That is, compared to the power capacity of the main power supply 45, the power capacity of the auxiliary power supply 81, representing the amount of charge, is small. Compared to the output voltage of the main power supply 45, the output voltage of the auxiliary power supply 81, representing the amount of power supplied, is low. In this embodiment, the auxiliary power supply 81 is an example of a second power supply.

[0061] As shown in Equation (A), the output voltage V2 of the auxiliary power supply 81 is set to be higher than the voltage V0 required for proper operation of motors 13, 32, control devices 50, 60, etc., and lower than the output voltage V1 of the main power supply 45.

[0062] V1>V2>V0…(A)

[0063] A failure of the main power supply 45 is detected when the output voltage Vb of the main power supply 45 actually drops. The output voltage Vb is a voltage parameter indicating the voltage state of the main power supply 45. A drop in the output voltage Vb indicates that the main power supply 45 is in a state where it cannot maintain the output voltage V1.

[0064] The power capacity C2 of the auxiliary power supply 81 is set to be greater than the power capacity C0 required for the proper operation of the motors 13, 32, control devices 50, 60, etc., and less than the power capacity C1 of the main power supply 45.

[0065] Circuit 82 switches the connection state between auxiliary power supply 81 and power line L11, causing auxiliary power supply 81 to be in a charging, discharging, or holding state. For example, when auxiliary power supply 81 is in the holding state, circuit 82 switches the connection state to power line L11 to disconnect auxiliary power supply 81.

[0066] Switch 83 is located at the midpoint of power line L11. Switch 83 is upstream of connection point P13, more specifically, located closer to the main power supply 45. Switch 83 turns power on and off via power line L11. Switch 84 is located at the midpoint of power line L111. Switch 84 turns power on and off via power line L111. Switch 85 is located at the midpoint of power line L112. Switch 85 turns power on and off via power line L112.

[0067] A connection point P15 is provided in power line L112. Connection point P15 of power line L112 and connection point P16 of power line L21 are connected to each other via power line L113. Diode 86 is located at the midpoint of power line L113. The cathode of diode 86 is connected to connection point P16 of power line L21. The anode of diode 86 is connected to connection point P15 of power line L112.

[0068] Diode 87 is positioned at the midpoint of power line L21. The cathode of diode 87 is connected to connection point P16 of power line L21. The anode of diode 87 is connected to connection point P12 of power line L21.

[0069] Diodes 86 and 87 allow power to flow from the anode to the cathode while restricting power flow from the cathode to the anode. Diodes 86 and 87 form an OR circuit that supplies the control circuit 62a with the higher voltage of the power from the main power supply 45 and the auxiliary power supply 81. The OR circuit formed by diodes 86 and 87 is a so-called wired OR circuit. The OR circuit formed by diodes 86 and 87 corresponds to a selection circuit that selects the power from the main power supply 45 and the auxiliary power supply 81 with the higher supply voltage to supply power to the rotation-side control device 60. In this embodiment, the OR circuit is an example of a connecting circuit.

[0070] Functions of power control device

[0071] The power control device 88 includes a central processing unit (CPU) and a memory (neither shown), and the CPU executes a program stored in the memory at predetermined arithmetic operation cycles. The CPU and memory constitute a microcomputer as processing circuitry. The memory includes computer-readable media, such as random access memory (RAM) and read-only memory (ROM). However, implementing various processes in software is one example. The processing circuitry of the power control device 88 can be configured such that at least some of the processing is implemented by hardware circuitry, such as logic circuitry.

[0072] More specifically, the power control device 88 switches the connection state of the control circuit 82 and controls the opening and closing of switches 83, 84, and 85. The power control device 88 monitors the voltage of the main power supply 45. The power control device 88 detects the voltage of the power supplied to the power control unit 80 through the power line L11 as the output voltage Vb of the main power supply 45. The output voltage Vb is the voltage detected at the connection point P11 of the power line L11.

[0073] As shown in equation (B), when the output voltage Vb of the main power supply 45 is lower than the voltage threshold Vth, the power control device 88 determines that the output voltage Vb of the main power supply 45 has dropped. The voltage threshold Vth is a criterion used to determine the voltage drop of the main power supply 45, and is set based on the voltage V0 required for proper operation of the motors 13, 32 or the control devices 50, 60. In this embodiment, the voltage threshold Vth is set to the same value as the voltage V0:

[0074] Vb <Vth…(B)。

[0075] When no voltage drop in the main power supply 45 is detected, the power control device 88 keeps switches 83 and 84 in the ON (closed) state and switch 85 in the OFF (open) state. When a voltage drop in the main power supply 45 is detected, the power control device 88 switches switches 83 and 84 from the ON (closed) state to the OFF (open) state. Subsequently, the power control device 88 switches switch 85 from the OFF (open) state to the ON (closed) state.

[0076] More specifically, when the output voltage Vb of the main power supply 45 does not drop, switches 83 and 84 remain in the closed state (on), while switch 85 remains in the open state (off). For example, for the rotating unit 6, power from the main power supply 45 is supplied to the drive circuit 61a via power line L11. Power from the main power supply 45 is also supplied to the auxiliary power supply 81 via power line L111.

[0077] When the start switch 47 is turned on, and the output voltage Vb does not drop, power from the main power supply 45 is supplied to the control circuit 62a through power supply line L21. The output voltage Vb is set to be higher than the output voltage V2 (output voltage V1), so that power from the auxiliary power supply 81 is substantially not supplied to the control circuit 62a through power supply line L113 and a portion of power supply line L21. Diode 86 restricts the flow of main power supply 45 power that has already flowed through power supply line L21 into the auxiliary power supply 81 through power supply line L113.

[0078] When the main power supply 45 fails and the output voltage Vb drops below the output voltage V2, power from the auxiliary power supply 81 is immediately supplied to the control circuit 62a through power supply line L113 and a portion of power supply line L21. This is because the output voltage V2 becomes higher than the voltage occurring in power supply line L2. Even when the power supply from the main power supply 45 to the control circuit 62a is interrupted due to a failure of the main power supply 45, the power supply to the control circuit 62a is supported by backup from the auxiliary power supply 81.

[0079] When the output voltage Vb drops further and falls below the voltage threshold Vth, switches 83 and 84 switch from the closed (conducting) state to the open (off) state. After this, switch 85 switches from the open (off) state to the closed (conducting) state. Therefore, power from the auxiliary power supply 81 is supplied to the drive circuit 61a through power supply lines L112 and a portion of power supply line L11. This is because the output voltage V2 becomes higher than the voltage occurring in power supply line L11 due to a fault in the main power supply 45. Therefore, even when the power supply from the main power supply 45 to the drive circuit 61a is interrupted due to the output voltage Vb falling below the voltage threshold Vth, the power supply to the drive circuit 61a is supported by backup power from the auxiliary power supply 81.

[0080] When the output voltage Vb drops below the voltage threshold Vth and then becomes equal to or higher than the voltage threshold Vth, switch 85 switches from the on (closed) state to the off (open) state. After this, switches 83 and 84 switch from the off (open) state to the on (closed) state. Therefore, power from the main power supply 45 is supplied to the drive circuit 61a via power supply line L11. Power from the main power supply 45 is not immediately supplied to the control circuit 62a via power supply lines L113 and a portion of power supply line L21. This is because the output voltage V2 becomes higher than the voltage occurring in power supply line L2 until the output voltage Vb, which has already become equal to or higher than the voltage threshold Vth, further exceeds the output voltage V2. Therefore, when the power supply to the drive circuit 61a is restored due to the recovery from the state where the output voltage Vb is below the voltage threshold Vth, the power supply from the main power supply 45 to the drive circuit 61a will be restored.

[0081] It is conceivable to replace switch 85 with a diode on power supply line L112. Then, when the main power supply 45 fails, power from auxiliary power supply 81 is immediately supplied to drive circuit 61a. However, power loss occurs in the diode. Therefore, from the perspective of reducing the consumption of auxiliary power supply 81, switch 85 is used instead of diode on power supply line L112 to supply power to drive circuit 61a, which requires a larger amount of power.

[0082] It is also conceivable to replace diode 86 with a switch on power supply line L113. However, this raises the following concerns. Specifically, after a power supply from main power supply 45 is interrupted due to a failure of main power supply 45, the switch in power supply line L113 takes a short time—albeit a brief one—to switch from the off state to the on state. Therefore, during the period until the switch in power supply line L113 switches from off to on, the power supply to control circuit 62a is momentarily interrupted, which could cause control circuit 62a to reset. In this respect, when diode 86 is provided in power supply line L113, in the event of a failure of main power supply 45, power from auxiliary power supply 81 is immediately supplied to control circuit 62a through power supply line L113 and a portion of power supply line L21. Since the power supply to control circuit 62a is not interrupted, control circuit 62a does not reset.

[0083] Monitoring via power control device

[0084] The power control device 88 monitors the state changes of the main power supply 45 by detecting the output voltage Vb. Therefore, the power control device 88 switches the connection state of the drive circuit 61a with the main power supply 45 and the auxiliary power supply 81 based on the state changes of the main power supply 45. The state change of the main power supply 45 is determined based on the detection result of the output voltage Vb. When the power control device 88 detects that the output voltage Vb is equal to or higher than the voltage threshold Vth, the power control device 88 determines that no voltage drop has occurred in the main power supply 45, i.e., the main power supply 45 is normal. When the power control device 88 detects that the output voltage Vb is lower than the voltage threshold Vth, the power control device 88 determines that the voltage of the main power supply 45 is low, i.e., the main power supply 45 is abnormal. In this embodiment, whether the voltage of the main power supply 45 is low is determined based on whether the power supply from the main power supply 45 to the drive circuit 61a is feasible. That is, even if the main power supply 45 fails, if the output voltage Vb is equal to or higher than the voltage threshold Vth, the power control device 88 determines that no voltage drop has occurred in the main power supply 45. In this embodiment, the process by which the power control device 88 monitors the state changes of the main power supply 45 by detecting the output voltage Vb is an example of state detection processing. The process by which the power control device 88 switches the connection state of the drive circuit 61a with the main power supply 45 and the auxiliary power supply 81 based on the state changes of the main power supply 45 is an example of switching processing.

[0085] More specifically, Figure 4 The state changes of the main power supply 45 are shown from the state where the output voltage Vb is equal to or higher than the voltage threshold Vth. The power control device 88 determines that no voltage drop of the main power supply 45 has occurred. The connection state refers to the following connection state: in which switches 83 and 84 are in the closed state (conducting) and switch 85 is in the open state (off), and in which power is supplied from the main power supply 45 to the drive circuit 61a.

[0086] like Figure 4 As shown, when the output voltage Vb is detected to be equal to or higher than the voltage threshold Vth, the power control device 88 maintains the determination that no voltage drop has occurred in the main power supply 45. The power control device 88 maintains a connection state in which switches 83 and 84 are in the closed state (conducting) and switch 85 is in the open state (off). This connection state is a normal state, which is the original state of the power supply to the steering device 2, and in this normal state, power is supplied from the main power supply 45 to the drive circuit 61a. In this embodiment, the connection state in which power is supplied from the main power supply 45 to the drive circuit 61a is an example of a first state.

[0087] like Figure 4As shown, when the output voltage Vb is detected to be lower than the voltage threshold Vth, the power control device 88 determines that a voltage drop in the main power supply 45 has occurred. The power control device 88 switches the connection state to a connection state in which switches 83 and 84 are in the off (open) state and switch 85 is in the on (closed) state. This connection state is a standby state for the power supply to the steering device 2, in which power is supplied from the auxiliary power supply 81 to the drive circuit 61a. In this embodiment, the connection state in which power is supplied from the auxiliary power supply 81 to the drive circuit 61a is an example of a second state. The output voltage Vb being lower than the voltage threshold Vth is an example of an abnormal condition being met. The process by which the power control device 88 determines whether a voltage drop in the main power supply 45 has occurred by detecting the output voltage Vb is an example of an abnormal condition determination process.

[0088] Figure 5 The state changes of the main power supply 45 are shown from the point where the output voltage Vb is lower than the voltage threshold Vth. The power control device 88 determines that the voltage of the main power supply 45 is low. The connection state refers to the following connection state: in which switches 83 and 84 are in the off open state and switch 85 is in the on closed state, and in which power is supplied from the auxiliary power supply 81 to the drive circuit 61a.

[0089] like Figure 5 As shown, when the output voltage Vb is detected to be lower than the voltage threshold Vth, the power control device 88 maintains the determination that the main power supply 45 has a low voltage. The power control device 88 maintains the connection state in which switches 83 and 84 are in the off state and switch 85 is in the on state. That is, the power control device 88 maintains the standby state as the power supply state.

[0090] like Figure 5 As shown, when the output voltage Vb is detected to be equal to or higher than the voltage threshold Vth, the power control device 88 determines that the voltage drop of the main power supply 45 has been resolved. Simultaneously, the power control device 88 determines the following state: the output voltage Vb being equal to or higher than the voltage threshold Vth is maintained. In this embodiment, the output voltage Vb being equal to or higher than the voltage threshold Vth, representing a state change of the main power supply 45 from a state where the output voltage Vb is lower than the voltage threshold Vth, is an example of satisfying an anomaly resolution condition; under this anomaly resolution condition, the anomaly condition is not satisfied. The process by which the power control device 88 determines that the voltage drop of the main power supply 45 has been resolved by detecting the output voltage Vb is an example of an anomaly resolution condition determination process.

[0091] When the power control device 88 determines that the voltage drop of the main power supply 45 has been resolved, but the determination time Tst has not reached the time threshold Tth1, the power control device 88 is not certain that the main power supply 45 has recovered from the voltage drop. The determination time Tst is the time during which the power control device 88 maintains the detected output voltage Vb at or above the voltage threshold Vth. The time threshold Tth1 is a value obtained experimentally within a range that ensures the detected output voltage Vb at or above the voltage threshold Vth is not an instantaneous event. The power control device 88 maintains a connected state in which switches 83 and 84 are in the off (open) state and switch 85 is in the on (closed) state. Therefore, even when the power control device 88 determines that the voltage drop of the main power supply 45 has been resolved, the power control device 88 maintains the standby state as a power supply state until the determination time Tst reaches the time threshold Tth1.

[0092] On the other hand, when the power control device 88 determines that the voltage drop of the main power supply 45 has been resolved, and furthermore, when the determination time Tst reaches the time threshold Tth1, the power control device 88 determines that the main power supply 45 has recovered from the voltage drop, that is, the standby state is cancelled. The power control device 88 switches the connection state to a connected state in which switches 83 and 84 are in the closed state (conducting) and switch 85 is in the open state (off). Therefore, after the power control device 88 determines that the determination time Tst from the time the voltage drop of the main power supply 45 has been resolved has reached the time threshold Tth1, it restores the power supply state from the standby state to the normal state.

[0093] In this embodiment, the determination time Tst is an example of a state parameter indicating that the resolution of the voltage drop in the main power supply 45 can be maintained. The determination time Tst reaching a time threshold Tth1 after determining that the voltage drop in the main power supply 45 has been resolved is an example of a recovery condition. The process by which the power control device 88 determines whether the determination time Tst has reached the time threshold Tth1 and thus determines the state that the output voltage Vb is equal to or higher than the voltage threshold Vth is maintained is an example of a recovery condition determination process.

[0094] like Figure 5As shown, after the time Ter elapsed since the output voltage Vb falls below the voltage threshold Vth reaches the time limit Tth2, the power control device 88 does not perform the process for determining whether the voltage drop has been resolved. The elapsed time Ter is the time during which the power control device 88 maintains the detection that the output voltage Vb is below the voltage threshold Vth. From the perspective of not preventing the auxiliary power supply 81 from supplying power to the rotating side motor 32, the time limit Tth2 is a value greater than the time threshold Tth1. The power control device 88 maintains a connected state in which switches 83 and 84 are in the off state and switch 85 is in the on state. Therefore, after the time Ter elapsed since the voltage drop of the main power supply 45 occurs reaches the time limit Tth2, the power control device 88 determines that the voltage of the main power supply 45 is low and maintains a standby state as the power supply state.

[0095] When the connection status of the drive circuit 61a with the main power supply 45 and the auxiliary power supply 81 is switched according to the status change of the main power supply 45, the power control device 88 generates a power supply status signal FLG indicating the power supply status when the switching is completed.

[0096] More specifically, such as Figure 4 As shown, when the power control device 88 determines that no voltage drop has occurred in the main power supply 45, the power control device 88 generates a power supply status signal FLGnm. When the power control device 88 determines that a voltage drop has occurred in the main power supply 45, the power control device 88 generates a power supply status signal FLGbu upon completing the switching of switches 83, 84, and 85 to the standby state. In this case, the power supply status signal FLGbu corresponds to the switching completion information indicating that the switching of switches 83, 84, and 85 to the standby state is complete.

[0097] In addition, such as Figure 5 As shown, when the power control device 88 determines that the voltage of the main power supply 45 remains low, the power control device 88 generates a power supply status signal FLGbu. When the power control device 88 determines that the voltage drop of the main power supply 45 has been resolved, the power control device 88 generates a power supply status signal FLGnm upon completing the switching of switches 83, 84, and 85 to the normal state. In this case, the power supply status signal FLGnm corresponds to the switching completion information indicating that the switching of switches 83, 84, and 85 to the normal state is complete.

[0098] When the power control device 88 generates a power supply status signal FLG, it outputs the generated signal to signal line 90. The output power supply status signal FLG is then transmitted to the rotation-side control device 60, i.e., the main control unit 60a, via signal line 90. While the power control device 88 determines that the voltage of the main power supply 45 remains low, it continuously outputs the power supply status signal FLGbu. While the power control device 88 detects that no voltage drop has occurred in the main power supply 45, it continuously outputs the power supply status signal FLGnm. The main control unit 60a identifies the connection status between the drive circuit 61a and the main power supply 45 and the auxiliary power supply 81—that is, whether the power supply status is normal or standby—by receiving the power supply status signal FLG.

[0099] Functions of the main control unit of the rotating side control device

[0100] Figure 6 Some of the processes performed by the rotation side control device 60 through the control circuit 62a of the main control unit 60a are shown. Figure 6 The processes shown are some of the processes implemented when the CPU executes a program stored in memory, and are depicted according to the type of process to be implemented. In this embodiment, the drive circuit 61a, the control circuit 62a, and the main control unit 60a including these circuits, i.e., the turn-side control device 60, are an example of a steering control device.

[0101] like Figure 6 As shown, a start signal Sig is input to control circuit 62a. The start signal Sig is a signal indicating the on or off state of start switch 47. Control circuit 62a determines the on or off state of start switch 47 based on the start signal Sig. When control circuit 62a determines that start switch 47 is in the off state, control circuit 62a disables control of the rotating side motor 32, that is, it puts the rotating side motor 32 in the off state. When start switch 47 is in the off state, the state of rotating unit 6 is a state that cannot reflect the state of steering unit 4.

[0102] When control circuit 62a determines that start switch 47 is in the ON state, control circuit 62a enables control of the rotating side motor 32, that is, puts rotating side motor 32 into the execution state. When start switch 47 is in the ON state, the state of rotating unit 6 is a state that reflects the state of steering unit 4. Therefore, during the period when current is applied to steering steer-by-wire device 2, control circuit 62a performs rotating side control. In this case, control circuit 62a performs the following processing.

[0103] Rotary side control during current application

[0104] In addition to the start signal Sig, the vehicle speed SPD, rotation angle θb, actual current value Ib on the rotating side, steering angle θs, output voltage Vbps, and power supply status signal FLG are input to the control circuit 62a.

[0105] The actual rotating side current value Ib is obtained from the drive circuit 61a. The drive circuit 61a has a current sensor (not shown). The current sensor detects the actual rotating side current value Ib, which is obtained from the current value in each phase of the rotating side motor 32 flowing through the connection line between the drive circuit 61a and the motor coils in each phase of the rotating side motor 32. The current sensor takes the voltage drop as current from the shunt resistor connected to the source side of each switching element in the inverter included in the drive circuit 61a, which is configured to correspond to the rotating side motor 32.

[0106] The steering angle θs is obtained from the steering-side control unit 50 via the local network 70. The steering-side control unit 50 converts the rotation angle θa into an integrated angle encompassing a range exceeding 360 degrees, for example, by counting the number of revolutions of the steering-side motor 13 from the steering neutral position—the position of the steering wheel 3 when the vehicle is moving straight forward. The steering-side control unit 50 calculates the steering angle θs by multiplying the integrated angle obtained through the conversion by a conversion factor based on the speed ratio of the steering-side reduction gear 14.

[0107] The output voltage Vbps is information obtained from the power control unit 80. Control circuit 62a monitors the output voltage Vbps of the power control unit 80, which varies according to the output voltage Vb of the main power supply 45. Control circuit 62a detects the voltage of the power supplied to the drive circuit 61a via power supply line L11 as the output voltage Vbps of the power control unit 80. The output voltage Vbps is the voltage detected at connection point P14 of power supply line L11.

[0108] Control circuit 62a controls the drive circuit 61a based on vehicle speed SPD, rotation angle θb, actual current value Ib on the rotating side, steering angle θs, output voltage Vbps, and power supply status signal FLG. More specifically, control circuit 62a includes a pinion angle calculation unit 101 and a pinion angle feedback control unit (…). Figure 6 The “pinion angle F / B control unit” 102, the limiting control unit 103, and the current application control unit 104 are included.

[0109] The rotation angle θb is input to the pinion angle calculation unit 101. The pinion angle calculation unit 101 converts the rotation angle θb into an integrated angle encompassing a range exceeding 360° by counting the number of revolutions of the rotating-side motor 32 from the rack neutral position—the position of the rack shaft 22 when the vehicle is moving forward straight. The pinion angle calculation unit 101 calculates the pinion angle θp, which is the actual rotation angle of the pinion shaft 21, by multiplying the integrated angle obtained through conversion by a conversion factor based on the speed ratio of the transmission mechanism 33, the lead of the conversion mechanism 34, and the speed ratio of the rack and pinion mechanism 24. The resulting pinion angle θp is then output to the pinion angle feedback control unit 102. In some cases, the pinion angle θp is also output to the steering-side control device 50.

[0110] Vehicle speed SPD, steering angle θs, and pinion angle θp are input to pinion angle feedback control unit 102. Pinion angle feedback control unit 102 calculates the rotational side motor torque command value Tt* by feedback control of the pinion angle θp, so that the pinion angle θp adapts to the pinion target angle θp*. Taking into account the steering angle ratio, which is the ratio between steering angle θs and pinion angle θp, the pinion target angle θp* is calculated as an angle scaled relative to the steering angle θs. The steering angle ratio changes, such that, for example, the change in pinion angle θp relative to steering angle θs is greater at low vehicle speed SPD compared to high vehicle speed SPD. The resulting rotational side motor torque command value Tt* is output to current application control unit 104.

[0111] The output voltage Vbps and the power supply status signal FLG are input to the limiting control unit 103. The limiting control unit 103 calculates the output limit value Ilim based on the output voltage Vbps and the power supply status signal FLG. The output limit value Ilim is a value used to limit the amount of current supplied to the rotating side motor 32. In other words, the output limit value Ilim is a value used to limit the torque output by the rotating side motor 32. The output limit value Ilim is calculated to change according to the connection status of the drive circuit 61a with the main power supply 45 and the auxiliary power supply 81—that is, the power supply status of the power control unit 80. The resulting output limit value Ilim is output to the current application control unit 104.

[0112] The rotation-side motor torque command value Tt*, rotation angle θb, actual rotation-side current value Ib, and output limit value Ilim are input to the current application control unit 104. The current application control unit 104 calculates the current command value Ib* for the rotation-side motor 32 based on the rotation-side motor torque command value Tt*. The current application control unit 104 performs a limiting process to limit the current command value Ib* based on the output limit value Ilim. The current application control unit 104 compares the current command value Ib* with the output limit value Ilim. When the absolute value of the current command value Ib* exceeds the value of the output limit value Ilim, the current application control unit 104 replaces the value obtained by limiting the current command value Ib* to the output limit value Ilim with the value obtained by limiting the current command value Ib* to the output limit value Ilim, calculating the final current command value Ib*. When the absolute value of the current command value Ib* is equal to or less than the value of the output limit value Ilim, the current application control unit 104 calculates the final current command value Ib* based on the value obtained by calculating based on the rotation-side motor torque command value Tt*.

[0113] The current application control unit 104 obtains the difference between the final current command value Ib* and the current value in the dq coordinate system obtained by converting the actual current value Ib on the rotating side based on the rotation angle θb, and calculates the drive signal Sm for driving the drive circuit 61a to eliminate this difference. The drive signal Sm is a gate on-off signal that specifies the on or off state of each switching element of the inverter included in the drive circuit 61a. The resulting drive signal Sm is output to the drive circuit 61a. Drive power based on the drive signal Sm is supplied from the drive circuit 61a to the rotating side motor 32. Therefore, the rotating side motor 32 rotates by a certain angle according to the rotating side motor torque command value Tt*.

[0114] Limit the function of the control unit

[0115] In control circuit 62a, limit control unit 103 monitors the state changes of power control unit 80 by detecting the output voltage Vbps. Therefore, limit control unit 103 switches the output limit value Ilim based on the state changes of power control unit 80. The state changes of power control unit 80 are determined based on the detected output voltage Vbps and the received state of power supply status signal FLG.

[0116] When the output voltage Vbps is equal to or lower than the output voltage V2 as expressed by the following formula (C), the limiting control unit 103 determines that the power supply state is not a normal state. When the limiting control unit 103 detects that the output voltage Vbps is higher than the output voltage V2, the limiting control unit 103 determines that the power supply state is not a standby state.

[0117] Vbps≤V2…(C).

[0118] In this embodiment, a power supply state determined to be abnormal includes a switch to a standby state. In this standby state, although the voltage of the main power supply 45 is determined to remain low, the power supply state is in the intermediate stage of switching from a normal state to a standby state. In the standby state, switches 83, 84, and 85 are switched to the standby state, i.e., a connection state where power is supplied from the auxiliary power supply 81 to the drive circuit 61a. Furthermore, a power supply state determined to be non-standby includes a switch to a normal state. In this normal state, although the voltage drop of the main power supply 45 is determined to have been resolved, the power supply state is in the intermediate stage of switching from a standby state to a normal state. In the normal state, switches 83, 84, and 85 are switched to the normal state, i.e., a connection state where power is supplied from the main power supply 45 to the drive circuit 61a.

[0119] More specifically, Figure 7 The state change of the power supply control unit 80 from a state where the output voltage Vbps is higher than the output voltage V2 is shown. The power supply state of the power supply control unit 80 is normal. The power supply state signal FLGnm is transmitted through signal line 90. Therefore, the power supply state signal FLGbu has not yet been transmitted through signal line 90, and therefore, the power supply state signal FLGbu has not yet been received in the limiting control unit 103. The limiting control unit 103 calculates the output limiting value Ilim as the maximum value Imax. The maximum value Imax is a limiting value of the torque that can be output by the rotating side motor 32, for example, the rated current value. Therefore, the control circuit 62a performs rotating side control during current application without limitation, wherein the limiting control unit 103 allows the torque that can be output from the rotating side motor 32 to be up to the maximum value Imax, that is, the rated current value of the rotating side motor 32.

[0120] like Figure 7 As shown, when the output voltage Vbps is detected to be higher than the output voltage V2, the limit control unit 103 maintains the determination of the normal state. The limit control unit 103 maintains the output limit value Ilim as the maximum value Imax. Therefore, the control circuit 62a continues to perform rotational side control during the current application without limitation.

[0121] like Figure 7 As shown, when the output voltage Vbps is detected to be equal to or lower than the output voltage V2, the limiting control unit 103 determines that the power supply status is not normal. Simultaneously, the limiting control unit 103 determines the reception status of the power supply status signal FLGbu.

[0122] When the limiting control unit 103 determines that the power supply status is not normal, and the power supply status signal FLGbu has not yet been received, the limiting control unit 103 determines that the power supply status is to switch to standby. The limiting control unit 103 calculates the output limiting value Ilim as a minimum value Imin. Considering that the auxiliary power supply 81 cannot provide sufficient power to the rotating side motor 32, the minimum value Imin is, for example, a value of "0 (zero)". Therefore, while the limiting control unit 103 sets the output limiting state in which the torque that can be output from the rotating side motor 32 is limited to the minimum value Imin (i.e., "0"), the control circuit 62a performs rotating side control during the current application period.

[0123] On the other hand, when the limiting control unit 103 determines that the power supply state is not normal, and the power supply state signal FLGbu has been received, the limiting control unit 103 determines that the power supply state is in standby mode. That is, the limiting control unit 103 determines that the switch to standby mode has been completed. The limiting control unit 103 calculates the output limiting value Ilim as the standby mode limiting value Ibu. From the perspective of the power that can be supplied from the auxiliary power supply 81 to the rotating side motor 32, the standby mode limiting value Ibu is a value that is greater than the minimum value Imin and not greater than the maximum value Imax. Therefore, the control circuit 62a performs rotating side control during the current application while the limiting control unit 103 sets the output limited state in which the torque that can be output from the rotating side motor 32 is limited to the standby mode limiting value Ibu. Regarding the standby mode limiting value Ibu, a suitable value is calculated considering the state of the steering device 2. Examples of the state of the steering device 2 include the internal temperature of the steering control unit 1, the operating state of the rotating side motor 32, and the remaining power of the auxiliary power supply 81.

[0124] Figure 8 The state changes of the power control unit 80 from a state where the output voltage Vbps is equal to or lower than the output voltage V2 are shown. The power supply state of the power control unit 80 is a standby state. The power supply state signal FLGbu is transmitted through signal line 90. Therefore, the power supply state signal FLGnm has not yet been transmitted through signal line 90, and therefore, the power supply state signal FLGnm has not yet been received in the limiting control unit 103. The limiting control unit 103 calculates the output limiting value Ilim as the standby state limiting value Ibu. Therefore, while the output limiting state is set, the control circuit 62a performs rotational side control during the current application period.

[0125] like Figure 8As shown, when the output voltage Vbps is detected to be equal to or lower than the output voltage V2, the limiting control unit 103 maintains the determination of the standby state. The limiting control unit 103 maintains the output limiting value Ilim, which is the standby state limiting value Ibu. Therefore, the control circuit 62a maintains the execution of rotational side control during the current application period while the output limiting state is set.

[0126] like Figure 8 As shown, when the output voltage Vbps is detected to be higher than the output voltage V2, the limiting control unit 103 determines that the power supply status is not in standby mode. Simultaneously, the limiting control unit 103 determines the reception status of the power supply status signal FLGnm.

[0127] When the limiting control unit 103 determines that the power supply state is not in standby state, and the power supply state signal FLGnm has not yet been received, the limiting control unit 103 determines that the power supply state is transitioning to normal. The limiting control unit 103 maintains the output limiting value Ilim, which is the standby state limiting value Ibu. Therefore, the control circuit 62a performs rotational side control during current application while the output limiting state is set.

[0128] On the other hand, when the limiting control unit 103 determines that the power supply state is not in standby state, and has further received the power supply state signal FLGnm, the limiting control unit 103 determines that the power supply state has been restored from standby state. That is, the limiting control unit 103 determines that the switch to normal state has been completed. The limiting control unit 103 calculates the output limiting value Ilim as the maximum value Imax. Therefore, the control circuit 62a cancels the output limiting state, and thus performs rotational side control during current application without limitation.

[0129] When control circuit 62a sets an output-limited state by processing by limit control unit 103, control circuit 62a outputs a warning signal BE. Control circuit 62a transmits the warning signal BE to other control devices on the vehicle side via an in-vehicle network, such as CAN. Conversely, when control circuit 62a cancels the output-limited state by processing by limit control unit 103, control circuit 62a stops outputting the warning signal BE. Examples of other control devices on the vehicle side include devices controlling drive systems related to vehicle movement and devices controlling braking systems related to vehicle braking. The warning signal BE is information indicating that an output-limited state has been set. While the output-limited state is set, control circuit 62a continuously outputs the warning signal BE. The transmitted warning signal BE is received by other control devices on the vehicle side. Upon receiving the warning signal BE, the other control devices on the vehicle side control the following operation: notifying that an output-limited state has been set. Examples of this notification operation include: operation of a display device that notifies the driver by visual cues, operation of a warning device that notifies the driver by auditory cues, and operation of a motion-sensing device that notifies the driver by haptic feedback.

[0130] Output limit value

[0131] The power supply status signal FLGbu begins to be received by the limiting control unit 103 at the following input time: this input time is slightly later than the time when the limiting control unit 103 begins to determine that the power supply status is transitioning to a standby state. Similarly, the power supply status signal FLGnm begins to be received by the limiting control unit 103 at the following input time: this input time is slightly later than the time when the limiting control unit 103 begins to determine that the power supply status is transitioning to a normal state.

[0132] Communication via dedicated signal line 90 requires communication time, which can be attributed to line routing or communication cycles. In this relationship, communication time based on communication cycles is required after the power supply status signal FLG is transmitted to signal line 90 and before it begins to be received by the limiting control device 103. When the power control device 88 determines that a voltage drop has occurred or that the standby state needs to be cancelled, it requires multiple arithmetic operation cycles to complete the switching of switches 83, 84, and 85. In this relationship, after determining that a voltage drop has occurred or that the standby state needs to be cancelled, processing time based on multiple arithmetic operation cycles (e.g., "approximately tens of milliseconds") is required before the power supply status signal FLG, indicating the connection state at the time the switching of switches 83, 84, and 85 is completed, begins to be transmitted. The start of the switching of switches 83, 84, and 85 almost coincides with the moment when the power control device 88 determines that a voltage drop has occurred or that the standby state needs to be cancelled. The moment when the power control device 88 determines that a voltage drop has occurred or that the standby state needs to be cancelled almost coincides with the moment when the limiting control unit 103 begins to determine whether the power supply state is transitioning to a standby state or a normal state.

[0133] Therefore, the input time of the power supply status signal FLGbu is later than the time when the limiting control unit 103 begins to determine the power supply status as transitioning to standby mode, by the total time of the "communication time" and "processing time". Similarly, the input time of the power supply status signal FLGbu is later than the time when the limiting control unit 103 begins to determine the power supply status as transitioning to normal mode, by the delay time corresponding to the sum of the "communication time" and "processing time".

[0134] like Figure 7 As shown, even when the limiting control unit 103 detects that the output voltage Vbps is equal to or lower than the output voltage V2, the limiting control unit 103 does not immediately determine that the power supply state is in standby mode. Instead, when the limiting control unit 103 detects that the output voltage Vbps is equal to or lower than the output voltage V2, the limiting control unit 103 temporarily determines that the power supply state is transitioning to standby mode. The time for determining the power supply state to transition to standby mode corresponds to the aforementioned delay time. Therefore, when the limiting control unit 103 detects that the output voltage Vbps is equal to or lower than the output voltage V2, the limiting control unit 103 can immediately calculate the output limiting value Ilim as the minimum value Imin. That is, the limiting control unit 103 is configured such that when the output voltage Vbps is detected to be equal to or lower than the output voltage V2, unless the switch to standby mode is completed, the limiting control unit 103 does not calculate the output limiting value Ilim as the maximum value Imax or the standby mode limiting value Ibu.

[0135] like Figure 8As shown, even when the limiting control unit 103 detects that the output voltage Vbps is higher than the output voltage V2, the limiting control unit 103 does not immediately determine that the power supply state has recovered from the abnormality. Instead, when the limiting control unit 103 detects that the output voltage Vbps is higher than the output voltage V2, the limiting control unit 103 temporarily determines that the power supply state is transitioning to the normal state. The time for determining the power supply state to transition to the normal state corresponds to the aforementioned delay time. Therefore, even when the limiting control unit 103 detects that the output voltage Vbps is higher than the output voltage V2, the limiting control unit 103 can temporarily maintain the output limiting value Ilim as the standby state limiting value Ibu. That is, the limiting control unit 103 is configured such that even when the output voltage Vbps is detected to be higher than the output voltage V2, unless a switch for restoring to the normal state is completed, the limiting control unit 103 does not calculate the output limiting value Ilim as the maximum value Imax.

[0136] Unless the main power supply 45 fails, the sub-control unit 60b performs rotational-side control during current application through processing performed by control circuit 62b—similar to the processing performed by control circuit 62a. When the main power supply 45 fails and the output voltage Vb drops below the voltage threshold Vth, the sub-control unit 60b stops rotational-side control during current application. This is because the sub-control unit 60b is not connected to the auxiliary power supply 81.

[0137] The steering-side control device 50 may have a main control unit 50a configured to include a limiting control unit similar to the limiting control unit of the main control unit 60a, or it may have a main control unit 50a configured not to include such a limiting control unit. When the main control unit 50a is configured to include a limiting control unit similar to the limiting control unit of the main control unit 60a, the main control unit 50a can perform steering-side control during current application through processing performed by the limiting control unit similar to the limiting control unit of the main control unit 60a. Like the main control unit 50a, the sub-control unit 50b performs steering-side control during current application unless the main power supply 45 fails. When the main power supply 45 fails and the output voltage Vb drops below the voltage threshold Vth, the sub-control unit 50b stops steering-side control during current application. This is because the sub-control unit 50b is not connected to the auxiliary power supply 81.

[0138] Work of this embodiment

[0139] For example, Figure 9The diagram shows the changes in output voltage Vb and output voltage Vbps over time when the start switch 47 is in the ON state. Output voltage Vb is the result detected by power control device 88. Output voltage Vbps is the result detected by control circuit 62a. When the start switch 47 is ON, unless the main power supply 45 fails, output voltage V1 is detected as output voltage Vb and output voltage Vbps.

[0140] In this case, such as Figure 9 As shown, the power supply status signal FLG is continuously transmitted as a transmission status. This is because the power control device 88 determines that the main power supply 45 is normal, and therefore outputs the power supply status signal FLGnm. For the same reason, as Figure 9 As shown, the power supply status signal FLG is continuously received as the receiving state.

[0141] like Figure 9 As shown, the output limit value Ilim is the maximum value Imax. This is because the limit control unit 103 determines that the power supply status is normal. Subsequently, as... Figure 9 As shown, after a mains power supply failure (45), the output voltages Vb and Vbps further decrease, causing both voltages to drop below the voltage threshold Vth and fall to, for example, "0 (zero)". Figure 9 (as indicated by "voltage drop" in the text). When the output voltage Vb drops below the voltage threshold Vth, the power control device 88 begins to switch switches 83, 84, and 85 to standby mode.

[0142] In this case, such as Figure 9 As shown, as the transmission state of the power supply status signal FLG, the power supply status signal FLGbu starts from "voltage drop occurs" with a certain delay ( Figure 9 The "processing time" in the text begins to be transmitted. This is because the power control device 88 begins to switch switches 83, 84, and 85 to the standby state and completes the switching ( Figure 9 The "start standby" process takes "approximately tens of milliseconds". For example... Figure 9 As shown, the reception status of the power supply status signal FLG, in addition to the reasons mentioned above, also has an additional delay from "start standby" due to delays based on communication cycles, etc. Figure 9 The “communication time” in the code begins to receive the power supply status signal FLGbu.

[0143] like Figure 9 As shown, during the period from "voltage drop occurs" until the power supply status signal FLGbu is received, the output limit value Ilim is the minimum value Imin. Figure 9(Setting output limited state). This is because, during the period from when "voltage drop occurs" until the power supply status signal FLGbu is first received, the limiting control unit 103 determines that the power supply status is to switch to standby.

[0144] like Figure 9 As shown, after receiving the power supply status signal FLGbu, the output limit value Ilim is the standby status limit value Ibu. This is because, upon receiving the power supply status signal FLGbu, the limit control unit 103 determines the power supply status to be standby. Figure 9 (The "Start Standby Restriction" in the text).

[0145] Subsequently, as Figure 9 As shown, when the main power supply 45 recovers from the fault, the output voltage Vb and the output voltage Vbps each reach the voltage threshold Vth or higher. Figure 9 (Voltage drop resolution). When the output voltage Vb is equal to or higher than the voltage threshold Vth and remains at the time threshold Tth1, the power control device 88 begins to switch switches 83, 84, and 85 to the normal state. Figure 9 (Cancel backup).

[0146] In this case, such as Figure 9 As shown, the power supply status signal FLG is transmitted with a certain delay after "cancel standby". Figure 9 The "processing time" in the data begins to be transmitted. This is because the power control device 88 begins to switch switches 83, 84, and 85 to the normal state. Figure 9 The process of canceling the standby switch and completing the handover takes approximately tens of milliseconds. Figure 9 As shown, the reception status of the power supply status signal FLG, in addition to the reasons mentioned above, also experiences an additional delay from "cancel standby" due to delays based on communication cycles, etc. Figure 9 The “communication time” in the text begins to receive the power supply status signal FLGnm.

[0147] like Figure 9 As shown, during the period from "voltage drop resolution" until the power supply status signal FLGnm is first received, the output limit value Ilim is the standby status limit value Ibu. This is because, during the period from "voltage drop resolution" until the power supply status signal FLGnm is first received, the limit control unit 103 determines that the power supply status is transitioning to the normal state.

[0148] like Figure 9As shown, after receiving the power supply status signal FLGnm, the output limit value Ilim is the maximum value Imax. This is because, upon receiving the power supply status signal FLGnm, the limit control unit 103 determines the power supply status to be normal. Figure 9 (In the "Cancel output restricted status" section).

[0149] According to this embodiment, when the power control device 88 determines that the voltage drop of the main power supply 45 in the standby state has been resolved, the power control device 88 can restore the power supply state to its original state by completing a connection state switch from the standby state to the normal state. In this case, after the power supply state is restored to its original state, the control circuit 62a cancels the output limiting state by calculating the output limit value Ilim, which is the maximum value Imax.

[0150] Advantages of the implementation method

[0151] 1-1

[0152] Even after it is determined that the voltage drop in mains power supply 45 has been resolved, the output-limited state continues until the power supply state is fully restored to its original state. This helps prevent the output-limited state from being canceled before the power supply state is fully restored to its original state.

[0153] 1-2

[0154] If it is determined that the voltage drop in main power supply 45 has been resolved, the power control device 88 can determine that main power supply 45 has recovered from the voltage drop if the resolution of the voltage drop is not an instantaneous event but lasts for a period of time. Therefore, even if the voltage drop in main power supply 45 has been resolved, it cannot be determined that main power supply 45 has recovered from the voltage drop if it is an instantaneous event. This improves the accuracy of determining whether main power supply 45 has recovered from the voltage drop after it has been determined that a voltage drop in main power supply 45 has occurred.

[0155] 1-3

[0156] The power control device 88 determines whether the main power supply 45 has recovered from a voltage drop based on the output voltage Vb and the determination time Tst. Therefore, the parameters required for determining whether the main power supply 45 has recovered from a voltage drop can be simplified. This is effective in easily implementing the processing related to determining whether the main power supply 45 has recovered from a voltage drop.

[0157] 1-4

[0158] After the power control device 88 determines that a voltage drop in the main power supply 45 has occurred, the power control device 88 performs the process of determining whether the voltage drop has been resolved only during the limitation time Tth2. Therefore, the power consumption required for the process of determining whether the voltage drop has been resolved after the voltage drop in the main power supply 45 has been determined can be reduced. This is effective in reducing the power consumption of the auxiliary power supply 81 when the capacity of the auxiliary power supply 81 is limited (as in this embodiment).

[0159] 1-5

[0160] Control circuit 62a can determine the power supply status based on information obtained from power control device 88 via signal line 90. Therefore, control circuit 62a can operate with reference to the power supply status of power control device 80.

[0161] 1-6

[0162] In this embodiment, it is unlikely that the power supply performance of the auxiliary power supply 81 will exceed that in standby mode. Therefore, even if a voltage drop in the main power supply 45 is determined to have occurred, the rotating side motor 32 can continue to operate appropriately. This is particularly effective when the power supply performance of the auxiliary power supply 81 is lower than that of the main power supply 45.

[0163] Second Implementation Method

[0164] Next, a vehicle power supply system according to the second embodiment will be described. For ease of description, the same components as in the first embodiment will be indicated by the same reference numerals as in the first embodiment, and their descriptions will be omitted.

[0165] After determining that a voltage drop in the main power supply 45 has occurred, the power control device 88 according to this embodiment performs a process to determine whether the voltage drop in the main power supply 45 has been resolved, regardless of the elapsed time. That is, after determining that a voltage drop in the main power supply 45 has occurred, the determination of whether the voltage drop in the main power supply 45 has been resolved continues until it is determined that the voltage drop in the main power supply 45 has been resolved. Therefore, after determining that a voltage drop in the main power supply 45 has occurred, even if the elapsed time Ter of the first embodiment has exceeded the time limit Tth2, the power control device 88 can determine whether the voltage drop in the main power supply 45 has been resolved.

[0166] Advantages of this implementation method

[0167] According to the second embodiment described above, the same operation as that of the first embodiment can be achieved, and the same advantages as those of (1-1) to (1-3), (1-5), and (1-6) of the first embodiment can be achieved. Furthermore, according to the second embodiment, the following advantages can also be achieved.

[0168] 2-1

[0169] Once it is determined that a voltage drop in the main power supply 45 has occurred, the determination of whether the voltage drop in the main power supply 45 has been resolved continues until it is determined that the voltage drop in the main power supply 45 has been resolved. This increases the chances of the main power supply 45 recovering from the voltage drop. This is effective in maintaining the operation of the rotating side motor 32 as much as possible.

[0170] Other implementation methods

[0171] Each of the above embodiments can be modified as follows. The following other embodiments can be combined with each other without causing technical inconsistencies.

[0172] In each of the above embodiments, diodes 86 and 87 can be formed or circuitted inside the rotation-side control device 60 (i.e., the steering control unit 1). Furthermore, in this case, power with the higher supply voltage is selected from the power from the main power supply 45 and the power from the auxiliary power supply 81 and supplied to the rotation-side control device 60.

[0173] In each of the above embodiments, the power performance of the auxiliary power supply 81 can be equivalent to or higher than that of the main power supply 45. For example, the power capacity of the auxiliary power supply 81 can be equivalent to or higher than that of the main power supply 45. For example, the output voltage V2 of the auxiliary power supply 81 can be set to the same value as or higher than that of the main power supply 45.

[0174] In each of the above embodiments, a double-layer capacitor or a secondary battery may be used as the auxiliary power source 81. In each of the above embodiments, in addition to providing backup support for the power supply provided by the main power source 45, the power control unit 80 may be able to supply power to the main power source 45 after increasing its voltage.

[0175] In each of the above embodiments, the configuration related to the power supply status signal FLG can be omitted. For example, when a voltage drop in the main power supply 45 is determined to have occurred, and the expected power control device 88 has completed the switching of switches 83, 84, 85 to standby mode, the limiting control unit 103 can determine that the power supply status is standby mode. The limiting control unit 103 can determine that the power supply status is standby mode when it detects that the output voltage Vbps is equal to or higher than the voltage threshold Vth.

[0176] In each of the above embodiments, the time threshold Tth1 can be changed taking into account system states, such as the power consumption of the steering device 2. In each of the above embodiments, when determining whether the voltage drop of the main power supply 45 has been resolved, the power control device 88 can also determine, for example, the operating state of the electricity generated by the generator 46, instead of maintaining a state where the detected output voltage Vb is equal to or higher than the voltage threshold Vth. The operating state of the generator 46 can be obtained from another control device on the vehicle side. The operating state of the generator 46 is a state parameter indicating that the resolution of the voltage drop of the main power supply 45 can be maintained.

[0177] In each of the above embodiments, when it is determined that the voltage drop of the main power supply 45 has been resolved, the power control device 88 can immediately determine that the main power supply 45 has recovered from the voltage drop, that is, the standby state should be cancelled.

[0178] In each of the above embodiments, the limiting control unit 103 may also monitor the state changes of the power control unit 80 by detecting the output voltage Vb instead of the output voltage Vbps. In this case, the limiting control unit 103 shall also determine the reception status of the power supply status signal FLG.

[0179] In each of the above embodiments, the control devices 50 and 60 may each be formed as a single system of main control unit 50a or 60a. For example, in this case, the main control unit 60a should have the same function as in each of the above embodiments.

[0180] In each of the above embodiments, the sub-control units 50b and 60b in the control devices 50 and 60 can be connected to the main power supply 45 via the power control unit 80. In each of the above embodiments, the limiting control unit 103 can also change the output limiting value Ilim so that the output limiting value Ilim changes gradually. This can be used only if the output limiting value Ilim becomes larger due to the change. Therefore, the impact of changes in the output limiting value Ilim on vehicle behavior can be mitigated, ensuring the comfort of the occupants in the vehicle.

[0181] In each of the above embodiments, the limiting control unit 103 can calculate the output limiting value Ilim by selecting one candidate value from a plurality of candidate values ​​that corresponds to a cause other than a drop in the main power supply 45 voltage. For example, the limiting control unit 103 can calculate the output limiting value Ilim by selecting the minimum value among a plurality of candidate values.

[0182] In each of the above embodiments, the power control unit 80 may include a power control unit for the steering unit and a power control unit for the rotation unit. For example, the power control unit for the steering unit should be connected only to the steering unit 4, which includes the steering side control device 50. The power control unit for the rotation unit should be connected only to the rotation unit 6, which includes the rotation side control device 60.

[0183] In each of the above embodiments, the control devices 50 and 60 may constitute a single control device, which integrates the functions of operating the steering-side motor 13 and operating the rotation-side motor 32.

[0184] In each of the above embodiments, the operating component operated by the driver to steer the vehicle is not limited to the steering wheel 3. For example, the operating component may be a joystick. In each of the above embodiments, the steering-side motor 13 mechanically coupled to the steering wheel 3 is not limited to a three-phase brushless motor. For example, the steering-side motor 13 may be a DC motor with brushes.

[0185] In each of the above embodiments, the rotation unit 6 transmits the rotation of the rotation-side motor 32 to the conversion mechanism 34 via the transmission mechanism 33. Not limited thereto, the rotation unit 6 can be configured to transmit the rotation of the rotation-side motor 32 to the conversion mechanism 34 via a gear mechanism. The rotation unit 6 can be configured such that the rotation-side motor 32 directly rotates the conversion mechanism 34. Furthermore, the rotation unit 6 can have a configuration including a second rack and pinion mechanism, and the rotation unit 6 can be configured to convert the rotation of the rotation-side motor 32 into the reciprocating motion of the rack shaft 22 via this second rack and pinion mechanism.

[0186] In each of the above embodiments, the rotating unit 6 is not limited to the configuration in which the right rotating wheel 5 and the left rotating wheel 5 rotate in combination with each other. In other words, the rotating device 6 can be configured to independently control the right rotating wheel 5 and the left rotating wheel 5.

[0187] In the above embodiment, the steering device 2 has a linkageless structure in which the steering unit 4 and the rotating unit 6 are always mechanically disconnected from each other. Not limited thereto, the steering device 2 may have a structure in which the steering unit 4 and the rotating unit 6 can be mechanically disconnected from each other, for example, by a clutch. The steering device 2 is not limited to a steer-by-wire device, but may be an electric steering device that applies the torque of a motor to the steering shaft 11 or the rack shaft 22.

Claims

1. A vehicle power system, the vehicle being equipped with a first power source (45), a steering device (2), and a motor (32), the vehicle power system being characterized in that it comprises: A power control unit (80) having a second power supply (81). as well as A steering control unit (1) is connected to the first power source (45) via the power control unit (80) and controls the steering device (2), wherein, The steering control unit (1) includes a steering control device (60) configured to control the operation of the motor (32). The steering control device (60) includes a drive circuit (61a) that drives to supply the motor (32) with power supplied due to the drive circuit (61a) being connected to at least one of the first power source (45) and the second power source (81). The steering control device (60) is configured to control the operation of the motor (32) by controlling the drive of the drive circuit (61a). The power control unit (80) includes a power control device (88) that switches the connection state of the drive circuit (61a) with the first power source (45) and the second power source (81). The connection state that supplies power from the first power source (45) is referred to as the first state, and the connection state that supplies power from the second power source (81) is referred to as the second state. The power control device (88) is configured to perform a state detection process that detects a state change of the first power source (45) and a switching process that switches the connection state. The switching process includes: The first switching process switches the connection state to transition to the second state because an abnormality in the first power supply (45) is detected by the state detection process; and The second switching process, in the case where the connection state has been changed to the second state due to the detection of an abnormality in the first power supply (45), switches the connection state to the first state because the recovery of the first power supply (45) from the abnormality is detected by the state detection process. The steering control device (60) is configured to set an output limiting state after an anomaly in the first power supply (45) is detected, for limiting the torque that the motor (32) can output compared to the torque before the anomaly is detected; and The steering control device (60) is configured to cancel the output limiting state when the second switching process performed by the power control device (88) is completed, coinciding with the setting of the output limiting state after an anomaly in the first power supply (45) is detected. The state detection process includes: Abnormal condition determination process, which determines whether the abnormal conditions used to detect the abnormality of the first power supply (45) are met; The exception resolution condition determination process, after the exception condition is met, determines whether the exception resolution conditions that would otherwise not be met are met; and The recovery condition determination process determines whether the recovery condition for detecting that the first power supply (45) has recovered from the anomaly is met after the anomaly resolution condition is met. The abnormal conditions include conditions based on voltage parameters indicating the voltage state of the first power supply (45); and The recovery conditions include conditions based on state parameters that indicate the abnormal conditions can remain in a state that is not satisfied. The voltage parameter is the output voltage of the first power supply (45); The abnormal conditions include those based on the result of a comparison between the output voltage and a voltage threshold. The state parameter is the elapsed time since the exception resolution condition was met; and The recovery conditions include conditions based on the result of a comparison between the elapsed time and a time threshold.

2. The vehicle power system according to claim 1, characterized in that, The power control device (88) is configured to perform the anomaly resolution condition determination process during a time-limited period after the anomaly condition is met until the recovery condition is not met.

3. The vehicle power system according to claim 1, characterized in that, The power control device (88) is configured to continue performing the exception resolution condition determination process after the exception condition is met but the recovery condition is not met.

4. The vehicle power system according to claim 1, characterized in that, The power control device (88) and the steering control device (60) can be communicatively connected to each other via a line (90); The power control device (88) outputs switching completion information to the steering control device (60) via the line (90), indicating that the switching of the connection state has been completed when the connection state changes to the first state or the second state; and The steering control device (60) is configured to identify that the switching of the connection state performed by the power control device (88) has been completed based on the switching completion information obtained from the power control device (88) via the line (90).

5. The vehicle power system according to any one of claims 1 to 4, characterized in that, The output-limited state refers to a state in which the torque output by the motor is limited so as not to exceed the output limit value; and When the power performance of the second power supply (81), as defined by its power capacity or output voltage, is lower than that of the first power supply (45), the output limit value is a value lower than the limit of the power performance of the second power supply (81).

6. A control method for a vehicle power system, the vehicle being equipped with a first power source (45), a steering device (2), and a motor (32), the vehicle power system comprising: A power control unit (80) having a second power supply (81) and a power control device (88). And a steering control unit (1), which is connected to the first power source (45) via the power control unit (80) and controls the steering device (2), the steering control unit (1) including a steering control device (60) including a drive circuit (61a). The control method is characterized by including: The drive circuit (61a) supplies power to the motor (32) because the drive circuit (61a) is connected to at least one of the first power source (45) and the second power source (81); The steering control device (60) controls the operation of the motor (32) by controlling the drive of the drive circuit; The following processing is performed by the power control device (88): Perform state detection processing to detect state changes in the first power supply (45); and The process of switching the connection state of the drive circuit (61a) with the first power supply (45) and the second power supply (81) is performed. The connection state in which power is supplied from the first power supply (45) is referred to as the first state, and the connection state in which power is supplied from the second power supply is referred to as the second state. The switching process includes: The first switching process switches the connection state to transition to the second state because an abnormality in the first power supply (45) is detected by the state detection process; and The second switching process, in the case where the connection state has been changed to the second state due to the detection of an abnormality in the first power supply (45), switches the connection state to the first state because the recovery of the first power supply (45) from the abnormality is detected by the state detection process. The steering control device (60) sets an output-limited state after an anomaly in the first power supply (45) is detected, limiting the torque that the motor (32) can output compared to the torque before the anomaly was detected; and The steering control device (60) performs the following operation: when the second switching process performed by the power control device (88) at the same time the output-limited state is set after an anomaly in the first power supply (45) is detected, the output-limited state is canceled. The state detection process includes: Abnormal condition determination process, which determines whether the abnormal conditions used to detect the abnormality of the first power supply (45) are met; The exception resolution condition determination process, after the exception condition is met, determines whether the exception resolution conditions that would otherwise not be met are met; and The recovery condition determination process determines whether the recovery condition for detecting that the first power supply (45) has recovered from the anomaly is met after the anomaly resolution condition is met. The abnormal conditions include conditions based on voltage parameters indicating the voltage state of the first power supply (45); and The recovery conditions include conditions based on state parameters that indicate the abnormal conditions can remain in a state that is not satisfied. The voltage parameter is the output voltage of the first power supply (45); The abnormal conditions include those based on the result of a comparison between the output voltage and a voltage threshold. The state parameter is the elapsed time since the exception resolution condition was met; and The recovery conditions include conditions based on the result of a comparison between the elapsed time and a time threshold.

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