Control device for steering reaction force motor

Abstract

The present invention provides a control device for a steering reaction force motor, the control device enabling short-circuiting of a three-phase armature winding in which reaction force torque is generated by on / off control of a switching element in a power conversion circuit when a power supply for a control circuit is off, while making it possible to limit unnecessarily long periods of short-circuiting. Provided is a control device (30) for a steering reaction force motor, the control device (30) comprising: a stopped-state rotation detection circuit (33) that detects for the rotation of a motor in a state in which the supply of power to a control circuit (32) is stopped; a stopped-state short circuit (34) that is capable of shorting together terminals of an n-phase armature winding of the motor; and a stopped-state control circuit (35) that operates the stopped-state short circuit (34) to short together the terminals of the n-phase armature winding when rotation is detected by the stopped-state rotation detection circuit (33) in a state in which the supply of power to the control circuit (32) is stopped.

Description

Control apparatus for steering reaction force motor

[0001] The present disclosure relates to a control apparatus for a steering reaction force motor.

[0002] In a steer-by-wire system, it is required that an appropriate steering reaction force is applied to a steering wheel by a steering reaction force motor in response to a driver's steering operation on the steering wheel, and the steering angle of the steering wheel can be appropriately changed according to the driver's intention. Since steering information of the steering wheel is transmitted to a steering control device and used for controlling the steering angle of steered wheels by a steering motor, the characteristics of the steering reaction force are important for ensuring steering stability of a vehicle.

[0003] When an abnormality occurs in the control system of the steering reaction force motor and a normal steering reaction force cannot be generated, the steering feeling becomes excessively light, and steering wheel deviation is likely to occur. When steering wheel deviation occurs, the steering angle becomes unstable and vehicle behavior becomes unstable, so it is necessary to apply braking to the steering wheel by some means to suppress steering wheel deviation. Further, when the power supply of the vehicle is turned off and the operation of the control apparatus for the steering reaction force motor stops, there is no response to the driver's steering operation on the steering wheel, which gives a sense of discomfort during steering. Further, for example, when getting in or out of the vehicle, if the driver tries to support the body by placing a hand on the steering wheel with a feeling similar to that of a conventional steering device, there is a concern that the driver may lose balance due to the excessively light and wobbly behavior of the steering wheel.

[0004] To address this problem, in the technique of Patent Document 1, a steering reaction force motor is provided with three-phase armature windings whose terminals are mutually short-circuited, in addition to two main sets of three-phase armature windings that generate reaction torque through on-off control of switching elements of a power conversion circuit. The short-circuited three-phase armature windings generate brake torque by induced voltage generated according to the rotation of the rotor, and do not require on-off control of the power conversion circuit.

[0005] In the technology described in Patent Document 1, even when the vehicle's power is turned off and the control device for the steering reaction motor stops operating, the short-circuit winding generates electromagnetic braking torque in accordance with the rotation of the steering wheel, thereby suppressing the feeling of the steering wheel being pulled and providing a tactile response to steering. However, in addition to the main winding, a short-circuit winding is required. Furthermore, even when the main winding is operating, electromagnetic braking torque is generated by the short-circuit winding, which can cause the main winding to generate a torque that cancels out the electromagnetic braking torque of the short-circuit winding. This can lead to problems such as the steering reaction motor becoming larger, requiring a larger drive current, and thus the system becoming larger.

[0006] To address this problem, the technology described in Patent Document 2 includes a dedicated short-circuit circuit in addition to the power conversion circuit, which short-circuits the terminals of the main three-phase armature windings. When the vehicle's power is turned off, the short-circuit circuit is activated to short-circuit the three-phase armature windings, generating an electromagnetic braking torque in the three-phase armature windings. On the other hand, when the vehicle's power is turned on, the operation of the short-circuit circuit is stopped, and a reaction torque is generated in the three-phase armature windings by controlling the on / off state of the switching elements of the power conversion circuit. Therefore, since a dedicated winding for short-circuiting is not provided, the system can be kept from becoming too large.

[0007] US2024 / 0001986 A1US2023 / 0303156 A1

[0008] However, in the technology described in Patent Document 2, when the vehicle's power is turned off, the switching element (e.g., MOSFET) of the short-circuit circuit is kept constantly on. Normally, the period during which the vehicle's power is off in its lifespan is considerably longer than the period during which it is on, so the control terminal (e.g., gate terminal) of the switching element is exposed to applied voltage for a very long time. Applying voltage to the gate oxide film raises reliability concerns in terms of the durability degradation of the oxide film, and degradation progresses as the voltage increases and the duration increases. If the oxide film degrades and breaks down, the switching element will short-circuit, hindering power transmission between the power conversion circuit and the armature winding when the vehicle's power is on, and thus preventing the generation of normal reaction torque. In addition, power consumption when the vehicle's power is off increases.

[0009] Therefore, the present disclosure aims to provide a control device for a steering reaction motor that enables short-circuiting of the three-phase armature windings, which generate reaction torque by on / off control of the switching elements of the power conversion circuit, when the control circuit is powered off, while suppressing unnecessary short-circuiting for extended periods.

[0010] The steering reaction motor control device according to the present disclosure is a steering reaction motor control device that controls a motor that provides steering reaction force to a steering wheel operated by a driver, and comprises: a power conversion circuit having a plurality of switching elements that converts the power supplied to the motor; a control circuit that controls the motor by turning on and off the plurality of switching elements of the power conversion circuit; a stop rotation detection circuit that detects the rotation of the motor when the power supply to the control circuit is stopped; a stop short circuit that can short-circuit the terminals of the n-phase armature windings of the motor (where n is a natural number of 2 or more); and a stop control circuit that operates the stop short circuit and short-circuits the terminals of the n-phase armature windings when rotation is detected by the stop rotation detection circuit when the power supply to the control circuit is stopped.

[0011] According to the steering reaction motor control device described herein, the rotation detection circuit at stop can detect the motor's rotation and the steering wheel's rotation when the power supply to the control circuit is stopped. The control circuit at stop activates the short-circuit circuit at stop when rotation is detected by the rotation detection circuit at stop when the power supply to the control circuit is stopped, thereby short-circuiting the terminals of the n-phase armature windings and generating electromagnetic braking torque in the steering reaction motor. Therefore, when the control circuit is stopped due to the vehicle's power being turned off, the short-circuit circuit at stop is activated and the terminals of the n-phase armature windings are short-circuited only when the steering wheel is turned. Thus, when the control circuit is stopped, the short-circuit is only activated when it is necessary to generate electromagnetic braking torque, and unnecessary long-term short-circuiting is suppressed. Therefore, when the vehicle's power is turned off, the progression of durability deterioration due to the switching element of the short-circuit circuit being constantly on can be suppressed, and the increase in power consumption can be suppressed.

[0012] This is a schematic diagram of the steer-by-wire device according to Embodiment 1. This is a schematic diagram of the steering reaction motor according to Embodiment 1. This is a schematic diagram of the control device for the steering reaction motor according to Embodiment 1. This is a circuit diagram of the rotation detection circuit when stopped according to Embodiment 1. This is a time chart explaining the behavior of the rotation detection circuit when stopped according to Embodiment 1. This is a circuit diagram of the short-circuit circuit when stopped according to Embodiment 1. This is a circuit diagram of the control circuit when stopped according to Embodiment 1. This is a schematic block diagram of the control circuit according to Embodiment 1. This is a schematic hardware diagram of the control circuit according to Embodiment 1. This is a flowchart for explaining the processing of the control device for the steering reaction motor according to Embodiment 1. This is a schematic diagram of the control device for the steering reaction motor according to Embodiment 2. This is a circuit diagram of the short-circuit circuit when stopped according to Embodiment 2.

[0013] 1. Embodiment 1 The control device 30 (hereinafter simply referred to as the control device 30) for the steering reaction motor according to Embodiment 1 will be described with reference to the drawings. The control device 30 constitutes the steer-by-wire device 1. The steer-by-wire device 1 is a steer-by-wire type electric power steering device. Figure 1 shows a schematic configuration diagram of the steer-by-wire device 1.

[0014] The steer-by-wire system 1 includes a steering input mechanism 22, a steering reaction motor 7 (hereinafter simply referred to as motor 7), a control device 30, a steering motor 12, a steering control device 15, and a steering mechanism 27. The control device 30 and the steering control device 15 may be integrated into a single unit.

[0015] The steering input mechanism 22 includes a steering wheel 4 operated by the driver, a steering shaft 5 connected to the steering wheel 4, and a steering angle sensor 6 and a torque sensor 20 attached to the steering shaft 5. The steering angle sensor 6 detects the steering angle of the steering wheel 4 by the driver. The torque sensor 20 detects the steering torque by the driver.

[0016] The motor 7 provides steering reaction force to the steering wheel 4. As shown in Figure 2, the rotating shaft 74 of the motor 7 is connected to the steering wheel 4 via a reduction gear 75 and a steering wheel shaft 5. Alternatively, the reduction gear 75 may be omitted, and the rotating shaft 74 of the motor 7 and the steering wheel shaft 5 may be directly connected. The control device 30 controls the motor 7.

[0017] The steering mechanism 27 steers the steering wheels using the steering force of the steering motor 12. In this embodiment, the steering wheels are the left and right wheels 8a and 8b. Tie rods 10a and 10b are connected to the knuckle arms 9a and 9b of the left and right wheels 8a and 8b, and the tie rods 10a and 10b are connected to the rack shaft 11. The movement of the rack shaft 11 is transmitted to the left and right wheels 8a and 8b via the tie rods 10a and 10b and the knuckle arms 9a and 9b, thereby steering the left and right wheels 8a and 8b.

[0018] A steering motor 12 is connected to the rack shaft 11, and the rack shaft 11 is driven by the driving force of the steering motor 12. In this example, two steering motors 12a and 12b are mounted on the left and right sides of the rack shaft 11. The steering control device 15 has a power conversion circuit for steering, and controls the steering motor 12 by controlling the on / off state of the switching elements of the power conversion circuit for steering. The steering control device 15 calculates the target steering angle of the steering wheels based on the steering angle of the steering wheel detected by the steering angle sensor 6, and controls the rotation angle of the steering motor 12 so that the steering angle of the steering wheels approaches the target steering angle. The configuration of the steering control device 15 and the steering motor 12 use various known general motors and control devices, so a detailed explanation is omitted.

[0019] 1-1. Motor 7 As shown in Figure 2, the motor 7 comprises a stator 71 and a rotor 72 positioned radially inward of the stator 71. The stator 71 is provided with n-phase armature windings (where n is a natural number of 2 or more). In this embodiment, three-phase armature windings of U-phase, V-phase, and W-phase are provided. The three-phase armature windings are delta-connected. They may also be star-connected. The rotor 72 is provided with permanent magnets 73. The rotor's rotation axis 74 is connected to the handle shaft 5 via a reduction gear 75. The handle shaft 5 is connected to the handle 4. The rotor's rotation axis 74 may also be directly connected to the handle shaft 5.

[0020] The rotor 72 is equipped with a rotation sensor 2 for detecting the rotation angle of the rotor. The output signal of the rotation sensor 2 is input to the control circuit 32. Various types of sensors such as resolvers, Hall elements, or encoders can be used as the rotation sensor 2.

[0021] 1-2. Control device 30 As shown in Figure 3, the control device 30 includes a power conversion circuit 31, a control circuit 32, a rotation detection circuit when stopped 33, a short circuit circuit when stopped 34, a control circuit when stopped 35, a power supply circuit 36, and a communication interface 37 (communication IF).

[0022] 1-2-1. Power Conversion Circuit 31 The power conversion circuit 31 has multiple switching elements and converts the power supplied to the motor 7. The power conversion circuit 31 has three sets of series circuits (legs) in which a high-potential switching element SP and a low-potential switching element SN are connected in series, corresponding to the armature windings of each phase. The connection points of the two switching elements SP and SN in the series circuit of each phase are connected to the terminal T of the armature winding of the corresponding phase. The high-potential switching element SP is connected to the high-potential side of the DC power supply 41, and the low-potential switching element SN is connected to the low-potential side (ground) of the DC power supply 41.

[0023] Specifically, in a U-phase series circuit, the high-potential switching element SPu and the low-potential switching element SNu of the U-phase are connected in series, and the connection point of the two switching elements SPu and SNu is connected to the terminal Tu of the U-phase armature winding. In a V-phase series circuit, the high-potential switching element SPv and the low-potential switching element SNv of the V-phase are connected in series, and the connection point of the two switching elements SPv and SNv is connected to the terminal Tv of the V-phase armature winding. In a W-phase series circuit, the high-potential switching element SPw and the low-potential switching element SNw of the W-phase are connected in series, and the connection point of the two switching elements is connected to the terminal Tw of the W-phase armature winding.

[0024] A MOSFET (Metal Oxide Semiconductor Field Effect Transistor) is used as the switching element. However, various other switching elements may be used, such as an IGBT (Insulated Gate Bipolar Transistor) with diodes connected in antiparallel, or a bipolar transistor with diodes connected in antiparallel. Various switching elements may also be used in the switching elements of the following circuits. The control terminal (gate terminal) of each switching element is connected to the control circuit 32 via a gate drive circuit. Each switching element is turned on or off by a switching signal output from the control circuit 32.

[0025] The DC power supply 41 outputs a DC voltage to the power conversion circuit 31. The DC power supply 41 can be any device that outputs a DC voltage, such as a battery, DC-DC converter, diode rectifier, or PWM rectifier. The DC power supply 41 is located outside the control device 30.

[0026] A current sensor 42 is provided for detecting the current flowing through the terminals Tu, Tv, and Tw of the armature windings of each phase. In this embodiment, the current sensor 42 has a shunt resistor connected in series with the low-potential side of the low-potential switching element SN of each phase. The voltage across the shunt resistor of each phase is input to the control circuit 32. The current sensor 42 may also be provided on the wire connecting the series circuit of each phase and the armature winding of each phase. A Hall element may be used for the current sensor 42.

[0027] 1-2-2. Rotation Detection Circuit 33 When Stopped The rotation detection circuit 33 when stopped is a rotation detection circuit that detects the rotation of the motor 7, at least when the power supply to the control circuit 32 is stopped.

[0028] The rotation detection circuit 33 is supplied with power even when the power supply to the control circuit 32 is stopped, and is capable of detecting rotation. For example, the rotation detection circuit 33 is constantly supplied with a voltage Vdc2 obtained by stepping down the voltage of the DC power supply 41 using a step-down converter 43.

[0029] In this embodiment, the rotation detection circuit 33 detects the rotation of the motor 7 by the fluctuation of the terminal voltages Vu, Vv, and Vw of the armature windings of each phase caused by the induced voltage generated by the rotation of the motor 7. The rotation detection circuit 33 detects that the motor 7 has rotated when the terminal voltages Vu, Vv, and Vw of the armature windings of each phase exceed the determination voltage Vth.

[0030] For example, the circuit shown in Figure 4 is used. The rotation detection circuit 33 at rest includes phase comparators 331, 332, and 333 that compare the terminal voltages Vu, Vv, and Vw of the armature windings of each phase with a threshold voltage Thv. These phase comparators 331, 332, and 333 are constantly supplied with a supply voltage Vdc2 obtained by stepping down the voltage of the DC power supply 41 using a step-down converter 43.

[0031] The non-inverting input (+) of each phase comparator receives a determination voltage Vth (0.23V in this example), which is generated by stepping down the supply voltage Vdc2 (12V in this example) using a voltage divider resistor. The inverting input (-) is connected to the terminals Tu, Tv, and Tw of the armature winding of each phase, receiving the terminal voltages Vu, Vv, and Vw of the armature winding of each phase. The phase comparators 331, 332, and 333 output a High voltage (supply voltage Vdc2 in this example) if the terminal voltages Vu, Vv, and Vw of the armature winding of each phase fall below the determination voltage Vth, and output a Low voltage (0V) if they fall above the determination voltage Vth. The outputs of the phase comparators 331, 332, and 333 are connected to each other, and the total output voltage Vrt is obtained by circuit design considerations such as configuring the comparator output section as an open-drain or open-collector output. The total output voltage Vrt is output as a negative logic rotation detection signal Vrt.

[0032] As shown in Figure 5, if the terminal voltages Vu, Vv, and Vw of any phase armature winding exceed the determination voltage Vth, the total output voltage Vrt becomes a Low voltage (0V). If the terminal voltages Vu, Vv, and Vw of all phase armature windings fall below the determination voltage Vth, the voltage becomes a High voltage (supply voltage Vdc2).

[0033] Therefore, the rotation detection circuit 33 turns on (Low) the rotation detection signal Vrt output to the outside when the terminal voltage Vu, Vv, Vw of any phase of armature winding exceeds the determination voltage Vth, and turns off (High) the rotation detection signal Vrt output to the outside when the terminal voltage Vu, Vv, Vw of all phases of armature winding fall below the determination voltage Vth. Since the terminal voltages Vu, Vv, Vw of all phases of armature winding are monitored, the rotation detection timing can be advanced. Note that it is not necessary to monitor the terminal voltage of all phases of armature winding; it is sufficient to monitor the terminal voltage of one or more phases of armature winding. Also, a circuit different from that shown in Figure 4 may be used; for example, an IC may be used.

[0034] 1-2-3. Short-circuit circuit 34 during shutdown The short-circuit circuit 34 is a circuit that can short-circuit the terminals Tu, Tv, and Tw of the three-phase armature windings. When the terminals of the three-phase armature windings are short-circuited, an electromagnetic braking torque is generated in the rotor due to the induced voltage generated in the armature windings by the rotation of the rotor. Electromagnetic braking torque is a torque that resists the rotation of the rotor, and is a so-called braking torque. The short-circuit circuit 34 can operate even when the power supply to the control circuit 32 is stopped.

[0035] <Dedicated Short-Circuit Circuit 341> In this embodiment, the shutdown short-circuit circuit 34 has a dedicated short-circuit circuit 341 that is provided separately from the power conversion circuit 31 and short-circuits the terminals Tu, Tv, and Tw of the three-phase armature windings.

[0036] As shown in Figure 6, the dedicated short-circuit circuit 341 is equipped with switching elements SSCu, SSCv, and SSCw (MOSFETs in this example) for short-circuiting each phase, which switch the connection between the terminals Tu, Tv, and Tw of the armature windings of each phase and the connection section 342 on and off. The connection section 342 is ground, and the terminals of each phase are short-circuited to each other via ground. Specifically, the terminal Tu of the U-phase armature winding is connected to the connection section 342 (ground) via the U-phase short-circuiting switching element SSCu, the terminal Tv of the V-phase armature winding is connected to the connection section 342 (ground) via the V-phase short-circuiting switching element SSCv, and the terminal Tw of the W-phase armature winding is connected to the connection section 342 (ground) via the W-phase short-circuiting switching element SSCw.

[0037] The control terminals (gate terminals) of the short-circuit switching elements SSCu, SSCv, and SSCw for each phase are connected to the connection lines of the short-circuit control signal VSC of the shutdown control circuit 35, and are switched on and off by the short-circuit control signal VSC of the shutdown control circuit 35. When the short-circuit control signal VSC of the shutdown control circuit 35 is turned on, the short-circuit switching elements SSCu, SSCv, and SSCw for all phases are turned on, and the terminals Tu, Tv, and Tw of the three-phase armature windings are short-circuited to each other.

[0038] <Short-circuit release circuit 343> The shutdown short-circuit circuit 34 is controlled by the control circuit 32 and includes a short-circuit release circuit 343 for forcibly releasing the short circuit at the terminals Tu, Tv, and Tw of the three-phase armature windings by the dedicated short-circuit circuit 341. The short-circuit release circuit 343 is controlled by the control circuit 32. The short-circuit release circuit 343 includes switching elements Sstu, Sstv, and Sstw (transistors in this example) for each phase to forcibly turn off the switching elements SSCu, SSCv, and SSCw for short-circuiting each phase. Specifically, the control terminal (gate terminal) of the switching element SSCu for short-circuiting the U phase is connected to ground via the switching element Sstu for short-circuit release of the U phase, the control terminal (gate terminal) of the switching element SSCv for short-circuiting the V phase is connected to ground via the switching element Sstv for short-circuit release of the V phase, and the control terminal (gate terminal) of the switching element SSCw for short-circuiting the W phase is connected to ground via the switching element Sstw for short-circuit release of the W phase.

[0039] The control terminals (base terminals) of the switching elements Sstu, Sstv, and Sstw for short-circuit release in each phase are connected to the connection lines of the control circuit 32's control signals Vst2u, Vst2v, and Vst2w, which are turned on and off by the control signals Vst2u, Vst2v, and Vst2w. When the control signals Vst2u, Vst2v, and Vst2w of the stop control circuit 35 are turned on, the three-phase short-circuit release switching elements Sstu, Sstv, and Sstw are turned on, and the control terminals (gate terminals) of the three-phase short-circuit release switching elements SSCu, SSCv, and SSCw are connected to ground. Regardless of whether the control signal VSC of the stop control circuit 35 is on or off, the three-phase short-circuit release switching elements SSCu, SSCv, and SSCw are forcibly turned off, and the short circuits at the terminals Tu, Tv, and Tw of the three-phase armature windings are released.

[0040] 1-2-4. Stopping Control Circuit 35 The stopping control circuit 35 operates the stopping short circuit 34 when rotation is detected by the stopping rotation detection circuit 33 while the power supply to the control circuit 32 is stopped, thereby short-circuiting the terminals Tu, Tv, and Tw of the three-phase armature windings.

[0041] According to this configuration, when rotation of the steering wheel 4 is detected while the control circuit 32 is in a stopped state, the terminals of the three-phase armature windings are short-circuited to cause the motor 7 to generate electromagnetic braking torque, which can reduce a driver's uncomfortable feeling. When rotation of the steering wheel 4 is not detected, the stop short-circuit circuit 34 does not operate, and the terminals of the three-phase armature windings are not short-circuited. Therefore, unnecessary operation of the stop short-circuit circuit 34 can be suppressed, deterioration of durability of the stop short-circuit circuit 34 can be suppressed, and power consumption caused by operation of the stop short-circuit circuit 34 can be reduced.

[0042] In the present embodiment, the stop control circuit 35 turns on power supply to the control circuit 32 when rotation is detected by the stop rotation detection circuit 33 while power supply to the control circuit 32 is stopped. By operating the control circuit 32, the control circuit 32 can respond to an operation of the steering wheel 4 by a driver.

[0043] In the present embodiment, when rotation is first detected by the stop rotation detection circuit 33 while power supply to the control circuit 32 is stopped, the stop control circuit 35 turns on the short-circuit control signal VSC to operate the stop short-circuit circuit 34, so as to mutually short-circuit the terminals Tu, Tv, Tw of the three-phase armature windings. In addition, turning on the short-circuit control signal VSC turns on the power supply to the control circuit 32. Thereafter, when a short-circuit stop command is issued from the control circuit 32 which has started operating after the start of power supply, the stop control circuit 35 turns off the short-circuit control signal VSC, stops the operation of the stop short-circuit circuit 34, and releases the short-circuit of the terminals Tu, Tv, Tw of the three-phase armature windings.

[0044] As shown in FIG. 7, the stop control circuit 35 includes a latch circuit 351 and a short-circuit stop circuit 352. When the rotation detection signal Vrt turns on while the short-circuit control signal VSC output to the outside is off, the latch circuit 351 turns on the short-circuit control signal VSC output to the outside, and maintains (latches) it in the on state. Thereafter, when the short-circuit stop control signal Vst output from the control circuit 32 turns on, the short-circuit stop circuit 352 operates to release the latch of the latch circuit 351 and turn off the short-circuit control signal VSC.

[0045] The latch circuit 351 includes a PNP switching element 351a (a transistor in this example) and an NPN switching element 351b (a transistor in this example). A connection line for the rotation detection signal Vrt of the stop-time rotation detection circuit 33 is connected to the control terminal (base terminal) of the PNP switching element 351a. When the rotation detection signal Vrt turns on, the PNP switching element 351a turns on, and the short-circuit control signal VSC output to the outside turns on. The short-circuit control signal VSC is also input to the control terminal (base terminal) of the NPN switching element 351b. When the short-circuit control signal VSC turns on, the NPN switching element 351b turns on, and the short-circuit control signal VSC is maintained (latched) in an on state.

[0046] On the other hand, the short-circuit stop circuit 352 includes a short-circuit stop switching element 352a (a transistor in this example), and a connection line for the short-circuit stop control signal Vst of the control circuit 32 is connected to the control terminal (base terminal) of the short-circuit stop switching element 352a. The high-potential side terminal (collector terminal) of the short-circuit stop switching element 352a is connected to the control terminal (base terminal) of the NPN switching element 351b and the signal line of the short-circuit control signal VSC, and the low-potential side terminal (emitter terminal) of the short-circuit stop switching element 352a is connected to ground. When the short-circuit stop control signal Vst turns on, the short-circuit stop switching element 352a turns on, the control terminal (base terminal) of the NPN switching element 351b and the signal line of the short-circuit control signal VSC are connected to ground, the NPN switching element 351b is forcibly turned off, the latched state is released, and the short-circuit control signal VSC turns off.

[0047] A circuit different from that shown in Fig. 7 may be used, for example, an IC may be used.

[0048] 1-2-5. Power supply circuit 36 The power supply circuit 36 turns on / off power supply from a power source to the control circuit 32. A voltage Vdc2 obtained by stepping down the voltage of a DC power source 41 by a step-down converter 43 is constantly supplied to the power supply circuit 36 as a power supply voltage.

[0049] The power supply circuit 36 ​​turns on the power supply to the control circuit 32 when the vehicle's power is turned on. When the power supply to the control circuit 32 is stopped, such as when the vehicle's power is turned off, the power supply circuit 36 ​​turns on the power supply to the control circuit 32 in response to a command from the stop control circuit 35 when rotation is detected by the stop rotation detection circuit 33.

[0050] With this configuration, normally, power can be supplied to the control circuit 32 when the vehicle is powered on. When the control circuit 32 stops operating due to the vehicle being powered off, power can be supplied to the control circuit 32 when the rotation of the steering wheel 4 is detected, enabling the control circuit 32 to process the steering of the steering wheel 4.

[0051] A power supply IC or the like is used in the power supply circuit 36. The power supply circuit 36 ​​is equipped with a start terminal, to which a start signal Vwk from an external device and a control signal VSC for short-circuiting the stop control circuit 35 are input. When either signal is turned on, the power supply circuit 36 ​​starts operating and begins supplying power to the control circuit 32. The power supply circuit 36 ​​communicates with the control circuit 32. The operation of the power supply circuit 36 ​​is stopped by a command from the control circuit 32. The start signal Vwk from the external device is output from the communication interface 37, which will be described later. That is, a start command is transmitted from the external control device to the power supply circuit 36 ​​via the communication interface 37. For example, when the vehicle's main power switch is turned on, the external control device transmits a start command to each control device of the vehicle, and each control device is started.

[0052] 1-2-6. Communication Interface 37 The communication interface 37 is connected to the in-vehicle network and communicates with external devices using a communication protocol. For example, the communication protocol may be CAN (Controller Area Network) or LIN (Local Interconnect Network). When the communication interface 37 receives a start command from an external control device, it turns on (High) the start signal Vwk output to the outside, and when it does not receive a start command from an external control device, it turns off (Low) the start signal Vwk output to the outside. When the vehicle's power is turned on, a specific control device sends a start command to the in-vehicle network.

[0053] 1-2-7. Control circuit 32 The control circuit 32 controls the motor by switching on and off multiple switching elements of the power conversion circuit 31.

[0054] As shown in Figure 8, the control circuit 32 includes functional units such as a steering angle detection unit 50, a rotation detection unit 51, a current detection unit 52, a steering detection control unit 53, and a reaction force torque control unit 54. Each function of the control circuit 32 is realized by the processing circuit provided in the control circuit 32. Specifically, as shown in Figure 9, the control circuit 32 includes a processing circuit such as a CPU (Central Processing Unit) or other arithmetic processing unit 90 (computer), a storage device 91 that exchanges data with the arithmetic processing unit 90, and an input / output device 92 that inputs and outputs external signals to and from the arithmetic processing unit 90.

[0055] The arithmetic processing unit 90 may include an ASIC (Application Specific Integrated Circuit), an IC (Integrated Circuit), an FPGA (Field Programmable Gate Array), various logic circuits, and various signal processing circuits. Furthermore, multiple arithmetic processing units 90 of the same or different types may be provided, with each processing unit being assigned to a specific task. The storage device 91 may include a RAM (Random Access Memory), ROM (Read Only Memory), EEPROM (Electrically Erasable Programmable Read Only Memory), etc. The input / output device 92 may include an A / D converter, a communication circuit, input / output ports, a drive circuit, a gate drive circuit, etc. The input / output device 92 is connected to a steering angle sensor 6, a torque sensor 20, a rotation sensor 2, a current sensor 42, a stop control circuit 35, a power supply circuit 36, a communication interface 37, and a power conversion circuit 31. Note that each part of the arithmetic processing unit 90, storage device 91, and input / output device 92 may be modularized into one or more modules.

[0056] <Each Detection Unit> The steering angle detection unit 50 detects the steering angle θs and steering angular velocity ωs of the steering wheel 4 based on the output signal of the steering angle sensor 6. The rotation detection unit 51 detects the rotation angle θm and rotation angular velocity ωm in electrical angles based on the output signal of the rotation sensor 2. The current detection unit 52 detects the winding currents Ius, Ivs, and Iws flowing through the three-phase armature windings based on the output signal of the current sensor 42.

[0057] <Steering detection control unit 53> When the stopping control circuit 35 starts supplying power to the control circuit 32, the steering detection control unit 53 transmits the steering information of the steering wheel 4 to other control devices.

[0058] With this configuration, when the vehicle stops, the control circuit 32, which is activated by the rotation of the steering wheel 4, transmits steering information of the steering wheel 4 to other control devices, allowing the other control devices to perform processing according to the steering information of the steering wheel 4. The steering information includes information that the steering wheel 4 has been turned, and information about the steering angle θs of the steering wheel 4.

[0059] For example, another control device may be one that has a vehicle anti-theft function. With this configuration, if the steering wheel is turned while the vehicle is not powered on, there is a possibility of theft, so the steering wheel information is transmitted to the anti-theft device and the anti-theft function is activated. For example, if a change in the steering angle is detected for a predetermined period of time or longer, an alarm will sound or the recording function of the drive recorder will be activated.

[0060] Other control devices may be devices other than the anti-theft device. For example, steering information from the steering wheel 4 may be transmitted to the interior light control device to turn on the interior light. Alternatively, steering information from the steering wheel 4 may be transmitted to the console device control device to activate the console device.

[0061] In this embodiment, when the steering detection control unit 53 starts the control circuit 32, if no start command is transmitted from an external control device via the communication interface 37, it determines that the stop control circuit 35 has started supplying power to the control circuit 32. On the other hand, when the steering detection control unit 53 starts the control circuit 32, if a start command is transmitted from an external control device via the communication interface 37, it determines that power is being supplied to the control circuit 32 by turning on the vehicle's power. Note that a short-circuit control signal VSC for the stop control circuit 35 may be input to the control circuit 32 and used for determination.

[0062] The steering detection control unit 53 may transmit steering information to other control devices when the steering angular velocity ωs of the steering wheel exceeds a threshold after the stop control circuit 35 starts supplying power to the control circuit 32. Alternatively, the steering detection control unit 53 may transmit steering information to other control devices when the amount of change Δθs of the steering angle θs of the steering wheel exceeds a threshold after the stop control circuit 35 starts supplying power to the control circuit 32. The steering detection control unit 53 may also transmit steering information to the other control devices when the number of steering wheel movements exceeds a threshold after the stop control circuit 35 starts supplying power to the control circuit 32. For example, the number of steering wheel movements is counted as one change in the steering angle θs of the steering wheel in the same direction for consecutive changes. Multiple of these determinations may be combined. With this configuration, even though braking is applied to the rotation of the steering wheel due to the operation of electromagnetic braking control, the steering state is only transmitted to other control devices when predetermined steering conditions are met, thus suppressing unnecessary operation of other control devices.

[0063] When the steering detection control unit 53 starts supplying power to the control circuit 32 by the stop control circuit 35, it stores the steering history of the steering wheel in a non-volatile storage device 91 (for example, EEPROM).

[0064] With this configuration, after the vehicle's power is turned on and each of the vehicle's control devices is activated, the control circuit 32 can transmit the steering history stored in the non-volatile storage device 91 while the vehicle was powered off (stopped) to other control devices, which can be used for theft prevention functions and the like.

[0065] When the steering detection control unit 53 receives power from the stop control circuit 35, it continues to short-circuit the terminals of the three-phase armature windings using the stop short-circuit circuit 34. With this configuration, when the vehicle's power is off, electromagnetic braking torque can be easily generated in the motor 7 by short-circuiting the terminals of the three-phase armature windings using the stop short-circuit circuit 34. Power consumption due to the on / off control of multiple switching elements in the power conversion circuit 31 can be suppressed.

[0066] Furthermore, when the steering detection control unit 53 is activated by the stop control circuit 35 to start supplying power to the control circuit 32, it may stop the short-circuiting of the terminals of the three-phase armature winding by the stop short-circuit circuit 34, and generate a reaction torque by controlling the on / off state of multiple switching elements of the power conversion circuit 31 with the reaction torque control unit 54.

[0067] When the steering detection control unit 53 determines that steering of the steering wheel 4 has ceased after the stopping control unit 35 has started supplying power to the control unit 32, it stops the short circuit of the terminals of the three-phase armature winding by the stopping control unit 35, and then stops supplying power to the control unit 32.

[0068] With this configuration, when steering of the steering wheel 4 is stopped, unnecessary short circuits by the stop short circuit circuit 34 are prevented, thereby suppressing deterioration of the durability of the stop short circuit circuit 34. In addition, power supply to the control circuit 32 is stopped, reducing power consumption.

[0069] For example, the steering detection control unit 53 determines that steering of the steering wheel 4 has ceased if the steering angle θs of the steering wheel remains unchanged for the judgment period. The steering detection control unit 53 turns on the short-circuit stop control signal Vst output from the control circuit 32 to the stop control circuit 35 to stop the short circuit by the stop control circuit 35. The steering detection control unit 53 also turns on the short-circuit release control signals Vst2u, Vst2v, and Vst2w for each phase output from the control circuit 32 to the stop short circuit circuit 34 (short-circuit release circuit 343) to forcibly release the short circuit by the dedicated short circuit circuit 341. Note that if power is not supplied to the control circuit 32 and the control circuit 32 is not operating, the short-circuit stop control signal Vst and the short-circuit release control signals Vst2u, Vst2v, and Vst2w for each phase are automatically turned off. As a result, if the control circuit 32 is not operating, the stop control circuit 35 can initiate the short circuit.

[0070] Furthermore, when steering detection occurs, if power is supplied to the control circuit 32 due to the vehicle being powered on, the control unit 53 turns off the short-circuit stop control signal Vst and the short-circuit release control signals Vst2u, Vst2v, and Vst2w for each phase.

[0071] <Reaction Torque Control Unit 54> When power is supplied to the control circuit 32 due to the vehicle's power being turned on, the reaction torque control unit 54 controls the reaction torque generated by the motor 7 by switching on and off multiple switching elements of the power conversion circuit 31.

[0072] The reaction force torque control unit 54 calculates the d-axis current command value Idc and the q-axis current command value Iqc based on the reaction force output command value Oc, etc. In this embodiment, the reaction force torque control unit 54 calculates the reaction force output command value Oc based on the steering angle θs of the steering wheel, the steering angular velocity ωs of the steering wheel, and the vehicle speed Vs. The vehicle speed Vs is obtained by communication from an external device. The reaction force output command value Oc may also be calculated based on the steering torque detected by the torque sensor 20.

[0073] The reaction torque control unit 54 converts the three-phase winding current detection values ​​Ius, Ivs, and Iws into the d-axis current detection value Ids and the q-axis current detection value Iqs based on the rotation angle θm. The reaction torque control unit 54 calculates the d-axis voltage command value Vdc and the q-axis voltage command value Vqc by feedback control based on the deviation between the d-axis and q-axis current command values ​​Idc and Iqc and the d-axis and q-axis current detection values ​​Ids and Iqs. The reaction torque control unit 54 converts the d-axis voltage command value Vdc and the q-axis voltage command value Vqc into three-phase voltage command values ​​Vuc, Vvc, and Vwc based on the rotation angle θm. The reaction force torque control unit 54, based on the three-phase voltage command values ​​Vuc, Vvc, and Vwc, switches on and off multiple switching elements of the power supply circuit 36 ​​using known PWM control to apply voltage to the terminals Tu, Tv, and Tw of the three-phase armature windings.

[0074] 1-2-8. Using the flowchart in flowchart 10, the general processing and state transitions of the control device 30 described above will be explained.

[0075] Let's begin the explanation from step S01. In step S01, the power supply to the control circuit 32 is stopped because the vehicle's power is turned off. Since no power is being supplied to the control circuit 32, the control circuit 32 is not operating.

[0076] In step S02, if power is supplied to the control circuit 32 when the vehicle is powered on, the process proceeds to step S11; otherwise, the process proceeds to step S03. In step S03, if the rotation detection circuit 33 detects motor rotation while power is not supplied to the control circuit 32, the process proceeds to step S04; otherwise, the process returns to step S02.

[0077] In step S04, the stop control circuit 35 is activated because, with power supply to the control circuit 32 stopped, rotation is detected by the stop rotation detection circuit 33, causing the terminals of the three-phase armature windings to short-circuit with each other.

[0078] In step S05, the stop control circuit 35, while the power supply to the control circuit 32 is stopped, detects rotation by the stop rotation detection circuit 33, and therefore turns on the power supply to the control circuit 32.

[0079] In step S06, the control circuit 32 detects the steering angle θs of the steering wheel and transmits the steering information to other control devices. The control circuit 32 also stores the steering history of the steering wheel in a non-volatile storage device 91.

[0080] In step S07, if the vehicle's power is turned on and a start command is received to supply power to the control circuit 32, the control circuit 32 proceeds to step S10; otherwise, it proceeds to step S08. In step S10, the control circuit 32 stops the short circuit of the three-phase armature winding terminals by the stop control circuit 35, and then proceeds to step S11.

[0081] In step S08, if the control circuit 32 determines that steering has ceased, it proceeds to step S09; otherwise, it returns to step S06.

[0082] In step S09, the control circuit 32 stops the short circuit of the three-phase armature winding terminals by the stop control circuit 35, and then stops the power supply to the control circuit 32. After that, the operation of the control circuit 32 stops, and the process returns to step S01.

[0083] Meanwhile, in step S11, the control circuit 32 is operating due to the vehicle's power being turned on, so it controls the on / off switching of multiple switching elements in the power conversion circuit 31 to control the reaction torque generated in the motor 7. In step S12, if the vehicle's power is turned off and there is a command to stop the power supply to the control circuit 32, the control circuit 32 proceeds to step S13; otherwise, it returns to step S11. In step S13, the control circuit 32 stops the power supply to the control circuit 32. After that, the operation of the control circuit 32 stops, and the process returns to step S01.

[0084] 2. Embodiment 2 The control device 30 for the steering reaction motor according to Embodiment 2 will be described. The same components as in Embodiment 1 will not be described. The basic configuration of the control device 30 according to this embodiment is the same as in Embodiment 1, but the configuration of the stop short circuit 34 is different from that of Embodiment 1. Figure 11 shows a schematic configuration diagram of the control device 30 according to this embodiment.

[0085] <Stop Short Circuit 34> In this embodiment, the stop short circuit 34 has a short-circuit signal generation circuit 344 that generates a signal to turn on the three-phase high-potential switching elements SPu, SPv, SPw, or the three-phase low-potential switching elements SNu, SNv, SNw. In this embodiment, the short-circuit signal generation circuit 344 generates a signal to turn on the three-phase low-potential switching elements SNu, SNv, SNw.

[0086] As shown in Figure 12, the short-circuit signal generation circuit 344 includes a short-circuit switching element SSC2 (a transistor in this example) that turns on and off a short-circuit gate signal VSC2 supplied to the control terminals (gate terminals) of the three-phase low-potential switching elements SNu, SNv, and SNw. The control terminal (base terminal) of the short-circuit switching element SSC2 is connected to the signal line of the short-circuit control signal VSC of the stop control circuit 35, and is turned on and off by the short-circuit control signal VSC. The high-potential side terminal (collector terminal) of the short-circuit switching element SSC2 is connected to the signal line of the short-circuit control signal VSC, and the low-potential side terminal (emitter terminal) of the short-circuit switching element SSC2 is connected to the control terminals (gate terminals) of the three-phase low-potential switching elements SNu, SNv, and SNw.

[0087] Therefore, when the short-circuit control signal VSC is turned on, the short-circuit switching element SSC2 is turned on, and the on short-circuit gate signal VSC2 is supplied to the control terminal (gate terminal) of the low-potential switching element of the three phases, turning on the low-potential switching element of the three phases, and short-circuiting the terminals of the three phase armature windings via ground. On the other hand, when the short-circuit control signal VSC is turned off, the short-circuit switching element SSC2 is turned off, and the off short-circuit gate signal VSC2 is supplied to the control terminal (gate terminal) of the low-potential switching element of the three phases, and the short-circuiting of the terminals of the three phase armature windings is released.

[0088] The shutdown short circuit 34 includes a short-circuit release circuit 345 for forcibly releasing the short circuit between the terminals Tu, Tv, and Tw of the three-phase armature windings, which is generated by the short-circuit signal generation circuit 344. The short-circuit release circuit 345 is controlled by the control circuit 32. The short-circuit release circuit 345 includes a short-circuit release switching element Sst2 (a transistor in this example) that forcibly turns off the short-circuit switching element SSC2. Specifically, the control terminal (base terminal) of the short-circuit switching element SSC2 is connected to ground via the short-circuit release switching element Sst2.

[0089] The control terminal (base terminal) of the short-circuit release switching element Sst2 is connected to the connection line of the short-circuit release control signal Vst2 of the control circuit 32, and is turned on and off by the short-circuit release control signal Vst2. When the short-circuit release control signal Vst2 of the stop control circuit 35 is turned on, the short-circuit release switching element Sst2 is turned on, the control terminal (base terminal) of the short-circuit switching element SSC2 is connected to ground, and regardless of whether the short-circuit release control signal VSC of the stop control circuit 35 is on or off, the short-circuit switching element SSC2 is forcibly turned off, an off signal is supplied to the control terminal (gate terminal) of the low-potential switching element of the three phases, and the short circuit at the terminals of the three-phase armature winding is released.

[0090] The stop-time short-circuit circuit 34 includes a disconnection circuit 346 for switching on and off the connection between the low-potential signal output terminals of the three phases of the gate drive circuit of the control circuit 32 and the control terminals (gate terminals) of the low-potential switching elements of the three phases. The disconnection circuit 346 is controlled by the control circuit 32. The disconnection circuit 346 includes switching elements Sopu, Sopv, and Sopw (MOSFETs in this example) for switching the connection lines of each phase on and off. The low-potential terminals (source terminals) of the switching elements for switching the connection lines of each phase are connected to the low-potential signal output terminals of each phase of the gate drive circuit of the control circuit 32, the high-potential terminals (drain terminals) of the switching elements for switching the connection lines of each phase are connected to the terminals of the armature windings of each phase, and the control terminals (gate terminals) of the switching elements for switching the connection lines of each phase are connected to the signal lines of the connection control signals Vopu, Vopv, and Vopw for each phase output from the connection control circuit 347.

[0091] The disconnection circuit 346 includes a connection control circuit 347 that controls the on / off switching of the switching elements for each phase connection. Although the detailed circuit configuration is omitted, when the short-circuit release control signal Vst2 of the control circuit 32 is turned on, the connection control circuit 347 turns on the connection control signals Vopu, Vopv, and Vopw for each phase, and turns on the switching elements Sopu, Sopv, and Sopw for each phase connection. When the short-circuit release control signal Vst2 is turned off, the connection control signals Vopu, Vopv, and Vopw for each phase are turned off, and the switching elements Sopu, Sopv, and Sopw for each phase connection are turned off.

[0092] <Control circuit 32> In this embodiment, the control circuit 32 outputs a short-circuit release control signal Vst2 instead of the short-circuit release control signals Vst2u, Vst2v, and Vst2w for each phase in Embodiment 1. The processing of the control circuit 32 itself is the same as in Embodiment 1, so the explanation is omitted.

[0093] While this disclosure describes various exemplary embodiments and examples, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but are applicable individually or in various combinations to the embodiments. Accordingly, countless variations not illustrated are envisioned within the scope of the art disclosed in this disclosure. For example, these include modifying, adding or omitting at least one component, or extracting at least one component and combining it with a component from another embodiment.

[0094] θs: steering angle, ωs: steering angular velocity, 7: motor, 30: control device for steering reaction motor, 31: power conversion circuit, 32: control circuit, 33: rotation detection circuit when stopped, 34: short circuit when stopped, 35: control circuit when stopped, 36: power supply circuit, 341: dedicated short circuit, 344: short circuit signal generation circuit

Claims

1. A control device for a steering reaction motor that controls a motor that provides steering reaction force to a steering wheel operated by a driver, comprising: a power conversion circuit having a plurality of switching elements and converting power supplied to the motor; a control circuit that controls the motor by switching the plurality of switching elements of the power conversion circuit on and off; a stop rotation detection circuit that detects the rotation of the motor when the power supply to the control circuit is stopped; a stop short circuit that can short-circuit the terminals of the n-phase armature windings of the motor (where n is a natural number of 2 or more); and a stop control circuit that, when rotation is detected by the stop rotation detection circuit when the power supply to the control circuit is stopped, activates the stop short circuit and short-circuits the terminals of the n-phase armature windings.

2. The control device for a steering reaction motor according to claim 1, wherein the stop short circuit is a dedicated short circuit provided separately from the power conversion circuit, which short-circuits the terminals of the n-phase armature windings.

3. The control device for a steering reaction motor according to claim 1, wherein the power conversion circuit is provided with n sets of series circuits, each corresponding to the armature winding of each phase, in which the switching element on the high-potential side and the switching element on the low-potential side are connected in series, and the connection points of the two switching elements in the series circuit of each phase are connected to the terminals of the armature winding of the corresponding phase, and the stop short circuit is a short-circuit signal generation circuit that generates a signal to turn on the switching element on the high-potential side of the n-phase or the switching element on the low-potential side of the n-phase.

4. The control device for a steering reaction motor according to any one of claims 1 to 3, wherein the rotation detection circuit at rest detects the rotation of the motor by the fluctuation of the terminal voltage of the armature winding of each phase due to the induced voltage generated by the rotation of the motor.

5. The control device for a steering reaction motor according to claim 4, wherein the rotation detection circuit at rest detects that the motor has rotated when the terminal voltage of the armature winding of each phase exceeds a determination voltage.

6. The control device for a steering reaction motor according to any one of claims 1 to 5, wherein the stopping control circuit turns on the power supply to the control circuit when the rotation of the motor is detected by the stopping rotation detection circuit while the power supply to the control circuit is stopped.

7. The control device for a steering reaction motor according to claim 6, wherein the control circuit transmits steering information of the steering wheel to another control device when the power supply to the control circuit is started by the stop control circuit.

8. The control device for a steering reaction motor according to claim 7, wherein the control circuit transmits steering information of the steering wheel to the other control device when the steering angular velocity of the steering wheel exceeds a threshold after the power supply to the control circuit is started by the stop control circuit.

9. The control device for a steering reaction motor according to claim 7 or 8, wherein the control circuit transmits steering information of the steering wheel to the other control device when the amount of change in the steering angle of the steering wheel exceeds a threshold after the power supply to the control circuit is started by the stop control circuit.

10. The control device for a steering reaction motor according to any one of claims 7 to 9, wherein the control circuit transmits steering information of the steering wheel to the other control device when the number of steering wheel movements exceeds a threshold after the power supply to the control circuit is started by the stop control circuit.

11. The control device for a steering reaction force motor according to any one of claims 7 to 10, wherein the other control device is a control device having a vehicle anti-theft function.

12. The control device for a steering reaction motor according to any one of claims 6 to 11, wherein the control circuit stores the steering history of the steering wheel in a non-volatile storage device when the power supply to the control circuit is started by the stop control circuit.

13. The control device for a steering reaction motor according to any one of claims 6 to 12, wherein the control circuit continues to short-circuit the terminals of the n-phase armature winding by the stop short-circuit circuit when power supply to the control circuit is started by the stop control circuit, and controls the reaction torque generated in the motor by switching on and off a plurality of switching elements of the power conversion circuit when power supply to the control circuit is being performed by turning on the vehicle's power.

14. A control device for a steering reaction motor according to any one of claims 6 to 13, wherein the control circuit, after the stop control circuit has started supplying power to the control circuit, determines that steering of the steering wheel has ceased, stops the short circuit of the terminals of the n-phase armature winding by the stop control circuit, and then stops supplying power to the control circuit.

15. A control device for a steering reaction motor according to any one of claims 6 to 14, further comprising a power supply circuit for switching the power supply from a power source to the control circuit on and off, wherein the power supply circuit turns on the power supply to the control circuit when the vehicle is powered on, and when rotation is detected by the stop rotation detection circuit while the power supply to the control circuit is stopped due to the vehicle being powered off, the power supply to the control circuit is turned on by a command from the stop rotation control circuit.

Images