Electric power steering device

Abstract

The first motor control unit (110) transmits a first command (A1) for driving control of the motor (101) to the second motor control unit (120) in the case of steering assist control, and performs driving control of the motor and assists driving of the motor in accordance with a second command (T2) for driving control of the motor transmitted from the second motor control unit in the case of automatic driving assist control. The second motor control unit transmits a second command to the first motor control unit in the case of automatic driving assist control, and performs driving control of the motor in accordance with the first command in the case of steering assist control.

Description

Technical Field

[0001] This disclosure relates to electric power steering systems. Background Technology

[0002] Conventionally, electric power steering systems that utilize the driving force of an electric motor to assist steering have known devices that perform steering assist control and automatic driving assistance control (for example, see Patent Document 1). Steering assist control is the control that provides steering assistance force through the driving force of the electric motor when the driver steers. Automatic driving assistance control is the control that changes the vehicle's forward direction by changing the steering angle in a manner independent of the driver's steering (e.g., parking assist system or path following control). Existing technical documents Patent documents

[0003] Patent Document 1: Japanese Patent Application Publication No. 2012-56404 Summary of the Invention The technical problem that the invention aims to solve

[0004] In Patent Document 1, the first motor control circuit for steering assist control and the second motor control circuit for autonomous driving assist control are configured independently. Therefore, if an anomaly occurs when the first motor control circuit is performing steering assist control, steering assist cannot continue; similarly, if an anomaly occurs when the second motor control circuit is performing autonomous driving assist control, autonomous driving assist cannot continue.

[0005] This disclosure was made in view of the following circumstances, and its object is to provide an electric power steering device that can continue steering assistance even when an anomaly occurs during steering assist control, and can continue autonomous driving assistance even when an anomaly occurs during autonomous driving assist control. Technical means for solving technical problems

[0006] One aspect of this disclosure is an electric power steering device, comprising: a vehicle status sensor that detects the vehicle's status and external information; an autonomous driving assistance control unit that generates a steering angle command for the vehicle's steering gear based on the detection results of the vehicle status sensor; a torque sensor that detects the steering torque of the steering gear; a first electric motor control unit that performs steering assistance control by driving the electric motor to assist steering based on the detection results of the torque sensor; and a second electric motor control unit that performs autonomous driving assistance control by driving the electric motor to automatically steer the steering gear based on the steering angle command. When performing steering assistance control, the first electric motor control unit sends a first command to the second electric motor control unit to drive the electric motor; and when performing autonomous driving assistance control, it performs drive control of the electric motor based on a second command sent from the second electric motor control unit to drive the electric motor, thereby assisting the driving of the electric motor. Conversely, when performing autonomous driving assistance control, the second electric motor control unit sends the second command to the first electric motor control unit; and when performing steering assistance control, it performs drive control of the electric motor based on the first command, thereby assisting the driving of the electric motor. Invention Effects

[0007] As described above, according to this disclosure, steering assistance can be performed even if an anomaly occurs during steering assist control, and autonomous driving assistance can continue even if an anomaly occurs during autonomous driving assist control. Attached Figure Description

[0008] Figure 1 This is a structural diagram of the steering system of a vehicle equipped with the electric power steering device according to Embodiment 1. Figure 2 This is a block diagram of the motor controller according to Embodiment 1. Figure 3 This is a simplified structural diagram of the electric motor drive unit and the electric motor drive unit according to Embodiment 1. Figure 4 This is a diagram illustrating the mapping of vehicle speed and steering torque involved in Implementation Method 1. Figure 5 This is a diagram illustrating the method for generating auxiliary steering commands according to Embodiment 1. Figure 6 This is a block diagram of the current control unit according to Embodiment 1. Figure 7 This is a block diagram of the steering angle indicator according to Embodiment 1. Figure 8 This is a block diagram showing the electric motor angle control unit according to Embodiment 1. Figure 9 This is a structural diagram of the steering system of a vehicle equipped with the electric power steering device according to Embodiment 2. Figure 10 This is a block diagram of the motor controller involved in Implementation Method 2. Figure 11 This is a structural diagram of the steering system of a vehicle equipped with the electric power steering device according to Embodiment 3. Figure 12 This is a block diagram of the motor controller involved in Implementation Method 3. Figure 13 This is a block diagram showing the motor angle control unit involved in Embodiment 3. Figure 14 This is a structural diagram of the steering system of a vehicle equipped with the electric power steering device according to Embodiment 4. Figure 15 This is a block diagram of the motor controller involved in embodiment 4. Figure 16 This is a structural diagram of the steering system of a vehicle equipped with the electric power steering device according to Embodiment 5. Figure 17 This is a block diagram of the motor controller according to embodiment 5. Figure 18 This is a block diagram showing the motor angle control unit involved in Embodiment 5. Detailed Implementation

[0009] Hereinafter, the electric power steering device according to Embodiment 5 of this disclosure will be described with reference to the accompanying drawings.

[0010] <Implementation Method 1> Figure 1 This is a structural diagram illustrating the steering system of a vehicle equipped with an electric power steering device according to Embodiment 1. (As shown...) Figure 1 As shown, the electric power steering system 1 according to Embodiment 1 includes a torque sensor 3, a steering shaft 4, a reducer 5, a rack and pinion 6, a vehicle status sensor 10, an automatic driving assistance control device 20 (automatic driving assistance control unit), and an electric motor control unit 100. The electric power steering system 1 has automatic driving assistance control, which enables the vehicle to continue driving automatically even in the event of an anomaly.

[0011] The torque sensor 3 detects the steering torque Ts generated on the steering shaft 4 when the driver turns the steering wheel 2. For example, the torque sensor 3 is installed on the steering shaft 4. The torque sensor 3 is connected to the motor control unit 100 and outputs the steering torque Ts to the motor control unit 100.

[0012] One end of the steering shaft 4 is connected to the steering wheel 2, and the other end is connected to the rack and pinion 6. The steering shaft 4 and the steering wheel 2 rotate together.

[0013] The reducer 5 increases the motor torque from the motor control unit 100 according to the gear reduction ratio. The reducer 5 then transmits the increased motor torque to the steering shaft 4.

[0014] The electric motor control unit 100 includes a control unit and an electric motor for controlling the steering operation of the vehicle. The electric motor torque from the electric motor control unit 100, along with the steering torque, is applied from the driver to the steering shaft 4 via a reducer 5. The electric motor torque and steering torque applied to the steering shaft 4 are transmitted to the tires 7 via a rack and pinion 6 to steer the vehicle.

[0015] The vehicle status sensor 10 is electrically connected to the motor control unit 100. The vehicle status sensor 10 detects the vehicle's status and external information. For example, the vehicle status sensor 10 is a type of sensor used to detect the vehicle's surrounding environment and determine the vehicle's motion state. The vehicle's surrounding environment is an example of external information. The vehicle's motion state is an example of the vehicle's status.

[0016] The vehicle state sensor 10 includes, for example, a first sensor that detects information about the vehicle's surrounding environment and a second sensor that measures the vehicle's motion state. The first sensor may include, for example, an image sensor and a radar sensor. The second sensor may include, for example, a vehicle speed sensor, a yaw rate sensor, a lateral acceleration sensor, and a steering angle sensor. The vehicle state sensor 10 outputs the surrounding environment information detected by the first sensor (hereinafter referred to as "surrounding environment information") and the vehicle's motion state information measured by the second sensor (hereinafter referred to as "vehicle state information") to the automated driving assistance control device 20. The vehicle state sensor 10 outputs the vehicle state information (e.g., vehicle speed signal, etc.) to the electric motor control unit 100.

[0017] The automated driving assistance control device 20 performs automated driving assistance control to enable the vehicle to travel along a target trajectory. Examples of automated driving assistance control include path following control, lane departure mitigation control, and parking assistance systems. To automatically operate the vehicle's steering for autonomous driving, the automated driving assistance control device 20 generates an automated driving steering angle command As, which is the target value for the vehicle's steering, based on information from the vehicle state sensor 10.

[0018] The automated driving assistance control device 20, for example as path following control, determines the center position of the lane divider in the road width direction based on the driving path width information obtained from the first sensors (image sensor and radar sensor), which is one of the surrounding environment information, and sets this determined center position as the target driving line. Furthermore, based on the set target driving line, the lateral position of the vehicle relative to the lane determined by the image sensor, and the vehicle state information determined by the second sensors (vehicle speed sensor, yaw rate sensor, lateral acceleration sensor, and steering angle sensor), the automated driving assistance control device 20 generates an automated driving steering angle command As for causing the vehicle to follow the target driving line.

[0019] The autonomous driving assistance control device 20, for example as lane departure suppression control, detects the lane dividing line of the driving lane based on the surrounding environment information from the first sensor, and generates an autonomous driving steering angle command As to suppress deviation from the driving lane to other lanes, so as to keep the vehicle from leaving the driving lane.

[0020] Figure 2 This is a block diagram of the motor control unit 100 according to Embodiment 1. Figure 2 As shown, the motor control unit 100 includes a motor 101, a motor angle sensor 102, motor drive units 105 and 106, a first CPU 110 (first motor control unit), and a second CPU 120 (second motor control unit).

[0021] Motor 101 is a motor that rotates to obtain the steering angle of the steering gear. Motor 101 has three-phase windings U1, V1, W1 and three-phase windings U2, V2, W2. Motor 101 can be a motor with two three-phase windings, such as a permanent magnet synchronous motor, induction motor, or synchronous reluctance motor, or it can be a motor with more phase windings or a 2-pole, 2-pair brushed motor. The motor windings of motor 101 can be distributed windings or concentrated windings.

[0022] The motor 101 can be a series motor with two stators. The windings of the two sets of motors do not need to be the same and can have different winding specifications. However, as long as the motor 101 has a structure that can output the desired rotation angle and torque, it can have only one set of windings or two sets working together. Hereinafter, we will explain the case where the motor 101 is a non-salient pole permanent magnet synchronous motor for a rotating machine, that is, a three-phase brushless motor with three-phase windings of U-phase winding, V-phase winding, and W-phase winding.

[0023] The motor angle sensor 102 detects the rotation angle θ of the motor 101 as θ1 (=θ) and θ2 (=θ). The motor angle sensor 102 outputs the detected rotation angle θ1 to the first CPU 110 (described later) and the detected rotation angle θ2 to the second CPU 120. Additionally, in Figure 2 In this document, the motor angle sensor 102 is described as a single sensor, but two redundant angle sensors, each independently input to the first CPU 110 and the second CPU 120, can also be configured. Examples of the motor angle sensor 102 include a rotary transformer, an encoder, or a magnetic sensor, but the design is not limited to these examples; any sensor capable of detecting the rotation angle of the motor 101 is acceptable regardless of its form. Furthermore, the rotation angle of the motor 101 will sometimes be referred to as the motor angle below.

[0024] Figure 3 This is a simplified structural diagram of the motor drive unit 105 and motor drive unit 106 according to Embodiment 1. Figure 3 As shown, the motor drive unit 105 includes a current sensor 103, an inverter circuit 130, and a DC power supply 200.

[0025] The current sensor 103 detects the current flowing through each phase of the motor 101 and outputs the detected current values ​​iu, iv, and iw for each phase. The current sensor 103 outputs the detected current values ​​iu, iv, and iw for each phase to the first CPU 110. Examples of the current sensor 103 include sensors utilizing a current transformer (CT) method that measures the magnetic flux generated by the current or sensors using a current-sensing resistive element, but it is not limited to these examples; any sensor capable of detecting the current flowing through each phase of the motor is acceptable, regardless of its form. Furthermore, Figure 3 The current sensor 103 shown is connected in series with the lower arm switching element of the inverter circuit 130, but is not limited to... Figure 3 The location shown can be any location where the current flowing through each phase of the motor 101 can be detected.

[0026] DC power supply 200 generates DC voltage Vdc. For example, DC power supply 200 can be a battery installed in a vehicle, or it can boost or buck the power from the battery to generate DC voltage Vdc.

[0027] The inverter circuit 130 applies voltages to the three-phase windings U1, V1, and W1 of the motor 101 by performing PWM modulation with a carrier period Tc1 and a duty cycle corresponding to the first drive command, based on the first drive command generated by the first CPU 110 and the DC voltage Vdc from the DC power supply 200.

[0028] The switching elements Sup1 to Swn1 are, for example, semiconductor switching elements such as IGBT (Insulated Gate Bipolar Transistor), bipolar transistor, and MOS (Metal Oxide Semiconductor) power transistor. The switching elements Sup1 to Swn1 perform switching operations according to the first drive command, thereby applying the desired voltage to the motor 101.

[0029] like Figure 3 As shown, the motor drive unit 106 includes an inverter circuit 140. In Figure 3 In the example shown, the inverter circuit 140 applies a DC voltage Vdc from the DC power supply 200. However, it is not limited to this; the motor drive unit 106 may also have a DC power supply different from the DC power supply 200. That is, the DC power supply 200 may be used as the DC power supply for the motor drive unit 105, and a separate DC power supply different from the DC power supply 200 may be provided as the DC power supply for the motor drive unit 106.

[0030] The inverter circuit 140 applies voltages to the three-phase windings U2, V2, and W2 of the motor 101 by performing PWM modulation with a carrier period Tc2 and a duty cycle corresponding to the second drive command, based on the second drive command generated by the second CPU 120 and the DC voltage Vdc from the DC power supply 200. Switching elements Sup2 to Swn2, like switching elements Sup1 to Swn1, are semiconductor switching elements, applying the desired voltage to the motor 101 by switching according to the second drive command. Furthermore, since the rotation angle of the motor 101 is controlled by feedback in the motor drive unit 106, no current sensor is provided.

[0031] The first CPU 110 performs steering assistance control by driving the electric motor 101 based on the detection result of the torque sensor 3. The first CPU 110 is input with the steering torque Ts detected by the torque sensor 3 and the vehicle speed V detected by the vehicle speed sensor (an example of the vehicle state sensor 10). Hereinafter, using... Figure 2 The structure of the first CPU 110 is described. Furthermore, the first CPU 110 and the second CPU 120 can exchange data through communication. Figure 2 In the example shown, the auxiliary torque Ta and steering angle torque command T2 are replaced. Auxiliary torque Ta is an example of the first command. Steering angle torque command T2 is an example of the second command.

[0032] like Figure 2As shown, the first CPU 110 includes an auxiliary control unit 111, a steering angle indicator unit 112, a current switching unit 113, a current control unit 114, a PWM conversion unit 115, and an abnormality detection unit 116.

[0033] The auxiliary control unit 111 calculates the auxiliary torque Ta to be applied to the steering shaft 4 based on the steering torque Ts and the vehicle speed V. For example, the auxiliary control unit 111... Figure 4 As shown, the auxiliary torque Ta is calculated based on the mapping between vehicle speed V and steering torque Ts. Alternatively, the auxiliary control unit 111 may also calculate the auxiliary torque Ta using known techniques based on vehicle speed V and steering torque Ts.

[0034] The steering angle indicator 112 obtains the auxiliary torque Ta calculated by the auxiliary control unit 111 and the steering angle detection value Am from a steering angle sensor, which is an example of a vehicle state sensor 10. The steering angle detection value Am is the detected value of the steering angle in the actual steering state. The steering angle indicator 112 calculates the auxiliary steering angle command A1 based on the auxiliary torque Ta and the steering angle detection value Am. The auxiliary steering angle command A1 is the target value of the steering angle (target steering angle) and is an example of a first command.

[0035] Here, as Figure 5 As shown, the steering torque Ts detected by the torque sensor 3 causes the torsion angle Ad of the steering wheel 2 and the steering shaft 4 to be proportional to the torsion spring speed k through the torsion bar. The torsion angle Ad is the angle deviation between the steering wheel 2 (i.e., the steering angle As) and the steering shaft 4. Therefore, the steering torque Ts is as shown in equation (1).

[0036] Ts=k·Ad…(1)

[0037] Furthermore, the relationship between the sum of the steering torque Ts, motor torque Tm1, and motor torque Tm2, ​​and the reduction ratio N, and the road reaction force Tp transmitted from tire 7, is shown in equation (2) below. Additionally, motor torque Tm1 is the motor torque of motor 101 driven by motor drive unit 105. Motor torque Tm2 is the motor torque of motor 101 driven by motor drive unit 106.

[0038] Ts+N(Tm1+Tm2)=Tp…(2)

[0039] Here, when the output motor torque Tm2 is expressed by the following equation (3), equation (2) is as shown in equation (4).

[0040] N·Tm2=Ts…(3)

[0041] 2Ts+N·Tm1=Tp…(4)

[0042] Compared to when the motor torque Tm1 is output solely through the motor drive unit 105, when the motor torque Tm2 is output as shown in equation (3), the steering torque Ts input to the auxiliary control unit 111 is used as 1 / 2Ts input, which reduces the auxiliary torque Ta. In this case, the auxiliary steering angle command A1 is expressed as equation (5) using equations (1) and (3). For example, the steering angle indicator unit 112 calculates the auxiliary steering angle command A1 using equation (5). The steering angle indicator unit 112 sends the calculated auxiliary steering angle command A1 to the second CPU 120.

[0043] A1=Ts / k+Am…(5)

[0044] The current switching unit 113 obtains the auxiliary torque Ta from the auxiliary control unit 111. The current switching unit 113 obtains the steering angle torque command T2 from the second CPU 120. The current switching unit 113 selects either the auxiliary torque Ta or the steering angle torque command T2. For example, in an auxiliary state where steering assistance control is performed when the driver is steering, the current switching unit 113 selects the auxiliary torque Ta from the steering angle torque command T2. In an autonomous driving assistance state where the autonomous driving steering angle command As is generated by the autonomous driving assistance control device 20 based on information from the vehicle state sensor 10, the current switching unit 113 selects the steering angle torque command T2 from the auxiliary torque Ta and the steering angle torque command T2.

[0045] The current switching unit 113 calculates the target current (i.e., current command Itq) for the q-axis and the target current (i.e., current command Itd) for the d-axis, based on the selected auxiliary torque Ta or steering angle torque command T2, as a current command to suppress the increase of the induced voltage of the motor. The current command Itd for the d-axis can be generated by known control methods, for example, it can be generated based on maximum torque / current (MTPA) control.

[0046] The current control unit 114 obtains the target current values ​​(i.e., current commands Itd and Itq) of the dq axis from the current switching unit 113. The current control unit 114 obtains the current detection values ​​iu, iv, and iw from the current sensor 103. The current control unit 114 converts the current detection values ​​iu, iv, and iw into the current detection values ​​Id and Iq of the dq axis. The current control unit 114 performs general vector control by calculating drive commands based on the current commands Itd and Itq of the dq axis and the current detection values ​​Id and Iq of the dq axis.

[0047] Figure 6 This is a block diagram of the current control unit 114 according to Embodiment 1. The current control unit 114 includes a coordinate converter 131, a deviation calculator 132, a current controller 133, a deviation calculator 134, a current controller 135, and a coordinate converter 136.

[0048] The coordinate converter 131 converts the rotation angle θ1 detected by the motor angle sensor 102 into a two-phase coordinate system using the three-phase current detection values ​​Iu, Iv, and Iw of the motor 101, thereby obtaining the q-axis current detection value Id and the d-axis current detection value Iq. The coordinate converter 131 outputs the q-axis current detection value Iq to the deviation calculator 132 and the d-axis current detection value Id to the deviation calculator 134.

[0049] Deviation calculator 132 calculates the deviation between the q-axis current command Itq and the q-axis current detection value Iq, and outputs the calculated deviation to the current controller 133. Deviation calculator 134 calculates the deviation between the d-axis current command Itd and the d-axis current detection value Id, and outputs the calculated deviation to the current controller 135.

[0050] Based on the deviation output from the deviation calculator 132, the current controller 133 calculates the target voltage Vq for the q-axis as a drive command. The current controller 133 outputs the target voltage Vq to the coordinate converter 136. Based on the deviation output from the deviation calculator 134, the current controller 135 calculates the target voltage Vd for the d-axis as a drive command. The current controller 133 outputs the target voltage Vd to the coordinate converter 136.

[0051] Coordinate converter 136 converts the target voltages Vd and Vq along the dq axis into three-phase drive voltages Vu1, Vv1, and Vw1 based on the rotation angle θ1. Coordinate converter 136 then outputs the drive voltages Vu1, Vv1, and Vw1 to PWM converter 115.

[0052] Current controller 133 is a feedback controller that ensures the deviation between the q-axis current command Itq and the current detection value Iq is zero. Current controller 135 is a feedback controller that ensures the deviation between the d-axis current command Itd and the current detection value Id is zero. Current controllers 133 and 135 can use proportional-integral control (PIC) commonly used in motor control, or they can use any combination of known proportional, integral, and derivative control, or other known control methods, or a combination of multiple known control methods.

[0053] The PWM conversion unit 115, as a known pulse width modulation, outputs a first drive command of the duty cycle to the switching elements Sup1 to Swn1 in accordance with the carrier period Tc1 and the drive voltages Vu1, Vv1, and Vw1, thereby controlling the switching elements Sup1 to Swn1 to be in an on or off state.

[0054] The second CPU 120 performs automatic steering assistance control by driving the control motor 101 to automatically steer the steering gear according to the automatic driving steering angle command As. The second CPU 120 includes a steering angle indicator 122, a steering angle switching unit 123, a motor angle control unit 124, a PWM conversion unit 125, and an anomaly detection unit 126.

[0055] Figure 7 This is a block diagram of the steering angle indicator 122 according to Embodiment 1. The steering angle indicator 122 generates a steering angle torque command T2 based on the autonomous driving steering angle command As generated by the autonomous driving assistance control device 20 and the steering angle detection value Am of the actual steering state from the steering angle sensor of the vehicle state sensor 10. (As...) Figure 7 As shown, the steering angle indicator 122 includes a deviation calculator 141 and a steering angle controller 142.

[0056] Deviation calculator 141 calculates the deviation between the autonomous driving steering angle command As and the detected steering angle value Am. Deviation calculator 141 outputs the calculated deviation to steering angle controller 142. Steering angle controller 142 is a controller that performs feedback control to generate a steering angle torque command T2 that makes the deviation between the autonomous driving steering angle command As and the detected steering angle value Am zero. Steering angle torque command T2 is the target value of the motor torque that makes the deviation between the autonomous driving steering angle command As and the detected steering angle value Am zero. Steering angle controller 142 can use any combination of known proportional control, integral control, and derivative control, or other known control methods, or a combination of multiple known control methods.

[0057] The steering angle switching unit 123 obtains the autonomous driving steering angle command As from the autonomous driving assistance control device 20 and the auxiliary steering angle command A1 from the steering angle indicator unit 112. In the assisted state, the steering angle switching unit 123 selects the auxiliary steering angle command A1 as the steering angle command At from the autonomous driving steering angle command As and the auxiliary steering angle command A1. The steering angle command At is the command value of the rotation angle of the motor 101. In the autonomous driving assistance state where autonomous driving assistance control is performed based on information from the vehicle state sensor 10, the steering angle switching unit 123 selects the autonomous driving steering angle command As from the autonomous driving steering angle command As and the auxiliary steering angle command A1 as the steering angle command At. The steering angle switching unit 123 outputs the steering angle command At to the motor angle control unit 124.

[0058] Figure 8 This is a block diagram showing the motor angle control unit 124 according to Embodiment 1. The motor angle control unit 124 includes a deviation calculator 151, a steering angle controller 152, and a drive waveform generator 153.

[0059] Deviation calculator 151 calculates the deviation between the steering angle command At output from steering angle switching unit 123 and the steering angle detection value Am from steering angle sensor of vehicle status sensor 10. Deviation calculator 151 outputs the calculated deviation to steering angle controller 152.

[0060] The steering angle controller 152 is a controller that performs feedback control to generate a command voltage V2 that makes the deviation between the steering command At and the steering angle detection value Am zero. The steering angle controller 152 can use any combination of known proportional control, integral control, and derivative control, or other known control methods, or a combination of multiple known control methods.

[0061] The drive waveform generator 153 outputs drive voltages Vu2, Vv2, and Vw2 to the PWM converter 125 based on the command voltage V2 and the rotation angle θ2, thereby maximizing the motor torque. Although not shown, to make the motor 101 rotate to the commanded angle, for example, advance angle control, which controls the phase of the induced voltage of the motor 101 and the motor angle, can be used to generate the drive voltages Vu2, Vv2, and Vw2, thereby maximizing the torque extracted by the motor 101.

[0062] As a known pulse width modulation, the PWM converter 125 outputs a second drive command with a duty cycle corresponding to the carrier period Tc2 and the drive voltages Vu2, Vv2, Vw2 to the switching elements Sup2 to Swn2, thereby controlling the switching elements Sup2 to Swn2 to be in an on or off state.

[0063] Previously, as shown in Patent Document 2, in either the case of steering angle control as an automatic driving assistance control or the case of steering assistance control (assistance control) performed by the driver when steering, the current indication value was calculated based on the steering torque and vehicle speed, and current feedback control was performed so that the current flowing through the motor reached the current indication value.

[0064] The response time of a vehicle during steering is only around a few Hz, while the response time of the current, determined by the electrical characteristics of the electric motor, is over 100 Hz. Therefore, the required response time for a vehicle can be sufficiently low. Compared to the current response, since the response time during steering is low, current feedback control can be omitted, and angle feedback control that follows the target steering angle is sufficient. Therefore, in this embodiment, by omitting the current detection required for current feedback control, the device can be constructed inexpensively.

[0065] In Patent Document 2, when the electric motor is driven for steering assist control or when the electric motor is driven for autonomous driving assist control, the system for driving the electric motor 101 uses only one system to drive the motor, resulting in a relatively small motor output. The electric power steering device 1 of this embodiment has two systems for driving the electric motor 101, allowing one system to assist the other in driving the motor, thus achieving a larger motor output.

[0066] The electric power steering system disclosed in International Publication No. 2018 / 088465 has two independent motor drive circuits for steering assistance control. Therefore, each motor drive circuit requires an input circuit for a torque sensor and a current sensor. In this embodiment, as... Figure 2 As shown, the input circuit of the torque sensor 3 and the current sensor 103 are only set on one side of the motor drive circuit, which can reduce the cost of the device.

[0067] In International Publication No. 2018 / 088465, each motor drive circuit is equipped with a CPU, and these two CPUs need to have the same processing power. Compared with the first CPU 110, the second CPU 120 in this embodiment does not have the functions of inputting from the torque sensor 3, the auxiliary control unit 111, and the current control unit 114 starting from current detection. That is, the calculation and processing of the second CPU 120 is simplified compared with the first CPU 110. Therefore, the first CPU 110 and the second CPU 120 do not need to have the same processing power, and a CPU with lower processing power can be used as the second CPU 120 compared with the first CPU 110.

[0068] The following describes the operation and related details when the electric power steering device 1 according to Embodiment 1 malfunctions, specifically when the motor drive circuit fails.

[0069] The anomaly detection unit 116 detects an anomaly in which the motor 101 cannot be driven by the motor drive unit 105 due to some reason. Furthermore, the method for detecting the anomaly performed by the anomaly detection unit 116 and the method for determining the phase in which the anomaly has occurred can be achieved using known techniques. The anomaly in which the motor 101 cannot be driven by the motor drive unit 105 refers to an anomaly in the motor 101, an anomaly in the motor drive unit 105, an anomaly in the current sensor 103, an anomaly in the rotation angle θ1, or a situation where power is not supplied from the DC power supply 200 to the switching elements Sup1 to Swp1, etc.

[0070] For example, the anomaly detection unit 116 can determine that a phase is not flowing with current and determine it as an anomaly if the time length during which the current detection value of any phase is 0 (zero) reaches a predetermined value. The anomaly detection unit 116 can also determine anomalies based on the current detection value when the drive command for anomaly determination is output, and the potential difference between the high-potential side and the low-potential side of the switching elements Sup1 to Swn1.

[0071] If the anomaly detection unit 116 determines that motor drive cannot be performed, the first drive command from the PWM conversion unit 115 to the motor drive unit 105 is stopped. This suppresses motor drive in abnormal conditions. In this case, if the anomaly detection unit 126 (described later) does not detect an anomaly, the motor drive unit 106 operates normally. Therefore, the motor torque for steering assist control or automatic driving assist control can continue to be output by the motor drive unit 106. Thus, even in the event of an anomaly, driver steering assistance can be provided, and automatic driving assist control can continue.

[0072] The fault detection unit 126 detects the fault when, for some reason, the motor 101 cannot be driven by the motor drive unit 106. Furthermore, the fault detection method performed by the fault detection unit 126 and the method for determining the phase where the fault occurred can be performed using known techniques. The fault that the motor 101 cannot be driven by the motor drive unit 106 refers to faults in the motor 101, faults in the motor drive unit 106, faults in the rotation angle θ2, and situations where power is not supplied from the DC power supply 200 to the switching elements Sup2 to Swp2, etc.

[0073] The fault detection unit 126 can also detect the voltage supplied to the motor drive unit 106, and detect the occurrence of a fault if the detected voltage is inconsistent with the second drive command. The fault detection unit 126 can also detect the DC current flowing through the motor drive unit 106, and detect the occurrence of a fault if a DC current exceeding the motor output is detected.

[0074] If the anomaly detection unit 126 determines that motor drive cannot be performed, the second drive command from the PWM conversion unit 125 to the motor drive unit 106 is stopped. This suppresses motor drive in an abnormal state. At this time, if the anomaly detection unit 116 does not detect an anomaly, the motor drive unit 105 operates normally. Therefore, the motor torque during steering assist control or during automatic driving assist control can continue to be output by the motor drive unit 105. Thus, even in the event of an anomaly, steering assist control can be performed, and automatic driving assist control can continue.

[0075] Hereinafter, when the electric power steering device 1 according to Embodiment 1 malfunctions, the operation and related details will be explained when the instruction value exchanged between the first CPU 110 and the second CPU 120 is abnormal.

[0076] Due to malfunctions in the torque sensor 3, the steering angle sensor of the vehicle status sensor 10, and the first CPU 110, the anomaly detection unit 126 detects an anomaly when no auxiliary steering angle command A1 is input from the first CPU 110 to the second CPU 120. The absence of input of the auxiliary steering angle command A1 to the second CPU 120 indicates that the auxiliary steering angle command A1 was not generated correctly in the first CPU 110. For example, the anomaly detection unit 126 can also detect an anomaly when the second CPU 120 cannot receive the auxiliary steering angle command A1 or when the value of the auxiliary steering angle command A1 is abnormal.

[0077] In auxiliary mode, if the abnormality detection unit 126 determines that the auxiliary steering angle command A1 is abnormal, the steering angle switching unit 123 can also invalidate the switching to the auxiliary steering angle command A1 and stop the second drive command from the PWM conversion unit 125 to the motor drive unit 106. This suppresses motor drive in abnormal conditions.

[0078] Even when the first CPU 110 is functioning normally, and the communication failure is only in the communication from the first CPU 110 to the second CPU 120, the first CPU 110 operates normally and can output a first drive command to the motor drive unit 105. Therefore, even when the communication failure is only in the communication from the first CPU 110 to the second CPU 120, the first CPU 110 can drive the motor 101 and continue steering assist control. However, due to other abnormalities, such as abnormalities in the torque sensor 3, steering angle sensor, or the first CPU 110, the motor drive stops if the assist steering angle command A1 is not generated. However, the steering shaft 4 is engaged with the steering wheel 2, allowing the driver to steer manually.

[0079] In the automated driving assistance mode, if the anomaly detection unit 126 determines that the auxiliary steering angle command A1 is abnormal, the steering angle switching unit 123 invalidates the switching to the auxiliary steering angle command A1 and outputs the automated driving steering angle command As as the steering angle command At to the motor angle control unit 124. As a result, the second CPU 120 outputs a second drive command to the motor drive unit 106, which can then drive the motor 101 according to the second drive command. Therefore, even if the auxiliary steering angle command A1 is abnormal, automated driving assistance control can continue.

[0080] If the autonomous driving steering angle command As cannot be generated normally due to a malfunction of the vehicle status sensor 10 or the autonomous driving assistance control device 20, or if the steering angle torque command T2 is not input to the first CPU 110 due to a malfunction of the steering angle sensor or the second CPU 120, the anomaly detection unit 116 detects the occurrence of an anomaly. The failure to generate the autonomous driving steering angle command As normally or the failure to input the steering angle torque command T2 to the first CPU 110 indicates that the steering angle torque command T2 cannot be generated normally in the second CPU 120. For example, the anomaly detection unit 116 can also detect the occurrence of an anomaly if the first CPU 110 cannot receive the steering angle torque command T2 or if the value of the steering angle torque command T2 is abnormal.

[0081] In the auxiliary mode, if the abnormality detection unit 116 determines that the steering angle torque command T2 is abnormal, the current switching unit 113 disables the switching to the steering angle torque command T2 and can output the auxiliary torque Ta to the current control unit 114. As a result, the first CPU 110 can drive the motor 101 by outputting a first drive command to the motor drive unit 105 to continue providing steering assistance.

[0082] In the automated driving assistance mode, if the anomaly detection unit 116 determines that the steering angle torque command T2 is abnormal, the first CPU 110 can still process the steering angle indicator unit 122. By processing the steering angle indicator unit 122, the first CPU 110 generates the steering angle torque command T2, and the current switching unit 113 selects the steering angle torque command T2 as the automated driving assistance control and outputs it to the current control unit 114. Consequently, the first CPU 110 outputs a first drive command to the motor drive unit 105, enabling the motor drive unit 105 to drive the motor 101 according to the first drive command.

[0083] Therefore, even if the anomaly detection unit 116 determines that the steering angle torque command T2 is abnormal, automatic driving assistance can continue. In the event of an anomaly in the electric power steering device 1, automatic driving assistance can be prioritized over steering by the driver.

[0084] The electric power steering device 1 described in Embodiment 1 above includes: a first motor control unit, which instructs the driving of the motor 101 based on the difference between the command value of the current supplied to the motor 101 and the current supplied to the motor 101; and a second motor control unit, which instructs the driving of the motor 101 based on the difference between the command value of the rotation angle of the motor 101 and the rotation angle of the motor 101.

[0085] When performing steering assist control, the first motor control unit sends a first command to the second motor control unit for driving control of motor 101, thereby assisting the second motor control unit in driving the motor. When performing automatic driving assist control, the first motor control unit performs drive control of motor 101 according to a second command sent from the second motor control unit for driving control of motor 101, thereby assisting the driving of motor 101.

[0086] When performing autonomous driving assistance control, the second motor control unit sends a second command to the first motor control unit. When performing steering assistance control, it performs drive control of motor 101 according to the first command to assist the drive of motor 101.

[0087] Therefore, the first motor control unit or the second motor control unit provides assistance to the motor torque of both the steering assist control and the automatic driving assist control. Even if the first motor control unit or the second motor control unit malfunctions, the other motor control unit can still assist the motor 101. That is, even if an anomaly occurs during steering assist control, steering assist can continue; even if an anomaly occurs during automatic driving assist control, automatic driving assist can continue.

[0088] In addition, no additional hardware is needed for abnormal situations. When performing steering assist control and autonomous driving assist control, the output of motor 101 can be superimposed by driving motor 101 with two motor drive circuits, thereby increasing the output of motor 101.

[0089] In the control method described in International Publication No. 2016 / 199839, an anomaly in the target value of the drive current flowing through the motor, i.e., the current indication value, can be addressed. However, the only way to address this anomaly is to change the current indication value. Therefore, in the control method described in International Publication No. 2016 / 199839, there is a problem that it cannot address the anomaly if the drive current flows through the motor drive unit or the motor itself malfunctions due to the current indication value being received.

[0090] Furthermore, in the control method disclosed in International Publication No. 2016 / 199839, it is not determined which structural element related to the generation of the current indication value has malfunctioned; a counter is simply used to suppress the yaw rate. Therefore, while it can prevent vehicle behavior from becoming unstable in the event of an anomaly, it suffers from the problem of not implementing appropriate control for the abnormal state and failing to continue following the target path in the form of automated driving assistance.

[0091] Even if the motor drive of the first motor control unit or the motor drive of the second motor control unit malfunctions, the electric power steering device 1 according to Embodiment 1 can still drive the motor 101 through another motor control unit. Therefore, the motor 101 can output torque as close as possible to normal, enabling continued autonomous driving assistance and providing peace of mind to the driver.

[0092] <Implementation Method 2> The electric power steering device 1A according to Embodiment 2 will be described. Figure 9 This is a structural diagram of the steering system of a vehicle equipped with the electric power steering device 1A according to Embodiment 2. The electric power steering device 1A according to Embodiment 2 differs from that in Embodiment 1 in that the electric motor control unit 100A contains a steering angle detection value Am obtained using the steering angle sensor of the vehicle state sensor 10. Furthermore, in the following description, parts having the same functions as those described in Embodiment 1 will be labeled with the same names and reference numerals, and specific descriptions of those functions will be omitted.

[0093] The electric power steering system 1A includes a torque sensor 3, a steering shaft 4, a reducer 5, a rack and pinion 6, a vehicle status sensor 10, an automatic driving assistance control device 20, and an electric motor control unit 100A. Similar to Embodiment 1, the electric power steering system 1A has automatic driving assistance control, enabling the vehicle to continue driving automatically even in the event of an anomaly.

[0094] Figure 10 This is a block diagram of the motor control unit 100A according to Embodiment 2. Figure 10 As shown, the motor control unit 100A includes a motor 101, a motor angle sensor 102, motor drive units 105 and 106, a first CPU 110A (first motor control unit), and a second CPU 120A (second motor control unit).

[0095] The first CPU 110A includes an auxiliary control unit 111, a steering angle indicator unit 112, a current switching unit 113, a current control unit 114, a PWM conversion unit 115, an abnormality detection unit 116, and a steering angle calculation unit 117.

[0096] The steering angle calculation unit 117 is connected to the motor angle sensor 102 and obtains the rotation angle θ1 from the motor angle sensor 102. The steering angle calculation unit 117 calculates the steering angle detection value Am by accumulating the rotation angle θ1. The steering angle detection value Am is a value converted into the steering angle equivalent to the steering shaft 4. The steering angle calculation unit 117 outputs the calculated steering angle detection value Am to the steering angle indicator unit 112.

[0097] The second CPU 120B includes a steering angle indicator 122, a steering angle switching unit 123, a motor angle control unit 124, a PWM conversion unit 125, and an abnormality detection unit 126.

[0098] The steering angle calculation unit 127 is connected to the motor angle sensor 102 and obtains the rotation angle θ2 from the motor angle sensor 102. The steering angle calculation unit 127 calculates the steering angle detection value Am by accumulating the rotation angle θ2. The steering angle calculation unit 127 outputs the calculated steering angle detection value Am to the steering angle indicator unit 122 and the motor angle control unit 124.

[0099] In addition to achieving the effects of Embodiment 1, the electric power steering device 1A described above in Embodiment 2 can be configured at a low cost without installing a steering angle sensor outside the motor control unit 100 by including the structure for calculating the steering angle detection value Am in the motor control unit 100 and calculating the steering angle detection value Am based on the motor angle from the motor angle sensor 102.

[0100] <Implementation Method 3> The electric power steering device 1B according to Embodiment 3 will be described. Figure 11 This is a structural diagram showing the steering system of a vehicle equipped with the electric power steering device 1B according to Embodiment 3. The difference between the electric power steering device 1B according to Embodiment 3 and Embodiment 2 is that the steering angle control based on the steering angle is replaced with motor angle control based on the deviation of the motor angle. Furthermore, in the following description, parts having the same functions as those described in Embodiment 1 or Embodiment 2 are labeled with the same names and reference numerals, and specific descriptions of those functions are omitted.

[0101] The electric power steering system 1B includes a torque sensor 3, a steering shaft 4, a reducer 5, a rack and pinion 6, a vehicle status sensor 10, an automatic driving assistance control device 20, and an electric motor control unit 100B. Similar to Embodiment 1, the electric power steering system 1B has automatic driving assistance control, enabling the vehicle to continue driving automatically even in the event of an anomaly.

[0102] Figure 12 This is a block diagram of the motor control unit 100B according to Embodiment 3. Figure 12 As shown, the motor control unit 100B includes a motor 101, a motor angle sensor 102, motor drive units 105 and 106, a first CPU 110B (first motor control unit), and a second CPU 120B (second motor control unit).

[0103] The first CPU 110B includes an auxiliary control unit 111, a motor angle deviation indicator 112b, a current switching unit 112, a current control unit 114, a PWM conversion unit 115, an anomaly detection unit 116, and a steering angle calculation unit 117. The second CPU 120B includes a motor angle conversion unit 121, a steering angle indicator 122b, a motor angle deviation switching unit 123b, a motor angle control unit 124b, a PWM conversion unit 125, an anomaly detection unit 126, and a steering angle calculation unit 127.

[0104] The motor angle deviation indicator 112b acquires the auxiliary torque Ta calculated by the auxiliary control unit 111. The motor angle deviation indicator 112b notifies the motor angle deviation switching unit 123b of the deviation of the rotation angle, that is, the difference between the rotation angle θ1 relative to a certain moment and the rotation angle to be indicated, as an auxiliary angle deviation command θd. In addition, the rotation angle to be indicated is the rotation angle as the target. The relationship between the rotation angle θ (auxiliary angle deviation command θd) and the motor torque T is represented by the transfer function shown in equation (6).

[0105] [Mathematical Expression 1]

[0106] Here, s is the differential operator, Jm is the torque of inertia, and Dm is the coefficient of viscous friction. The rotation angle θ shown in equation (6) is the target value of the rotation angle relative to the rotation angle θ1 at a certain moment, which is used to rotate the motor by outputting auxiliary torque Ta to the motor, and is the auxiliary angle deviation command θd. The motor angle deviation indicator 112b uses the auxiliary torque Ta obtained from the auxiliary control unit 111 to calculate the auxiliary angle deviation command θd according to equation (6). The motor angle deviation indicator 112b outputs the calculated auxiliary angle deviation command θd to the motor angle deviation switching unit 123b. In addition, the auxiliary angle deviation command is an example of the first deviation.

[0107] The motor angle conversion unit 121 converts the autonomous driving steering angle command As output from the autonomous driving assistance control device 20 into the rotation angle of the motor 101 by dividing by the reduction ratio. The motor angle conversion unit 121 calculates the difference between the converted rotation angle and the rotation angle θ2 input from the motor angle sensor 102 as the autonomous driving motor angle deviation command θs. The motor angle conversion unit 121 outputs the calculated autonomous driving motor angle deviation command θs to the steering angle indicator unit 122b and the motor angle deviation switching unit 123b. In addition, the auxiliary angle deviation command (first deviation) is an example of the first command.

[0108] The steering angle indicator 122b generates a steering angle torque command T2 through feedback control, ensuring that the automatic driving motor angle deviation command θs obtained from the motor angle conversion unit 121 is zero. The feedback control executed by the steering angle indicator 122b can be any combination of known proportional control, integral control, and derivative control, or other known control methods, or a combination of multiple known control methods. The steering angle indicator 122b outputs the generated steering angle torque command T2 to the current switching unit 113.

[0109] The motor angle deviation switching unit 123b selects either the autonomous driving motor angle deviation command θs from the motor angle conversion unit 121 or the auxiliary angle deviation command θd from the motor angle deviation indicator unit 112b as the motor angle deviation command θt. For example, when the driver is steering, the motor angle deviation switching unit 123b selects the auxiliary angle deviation command θd as the motor angle deviation command θt. For example, when autonomous driving assistance is in operation, the motor angle deviation switching unit 123b selects the autonomous driving motor angle deviation command θs as the motor angle deviation command θt.

[0110] Figure 13 This is a block diagram showing the motor angle control unit 124b according to Embodiment 3. (As shown) Figure 13 As shown, the motor angle control unit 124b includes a motor angle controller 152b and a drive waveform generator 153.

[0111] The motor angle controller 152b obtains the motor angle deviation command θt from the motor angle deviation switching unit 123b and performs feedback control to generate the command voltage V2, so that the obtained motor angle deviation command θt is 0. The feedback control executed by the motor angle controller 152b can be any combination of known proportional control, integral control, and derivative control, or other known control methods, or a combination of multiple known control methods. The motor angle controller 152b outputs the generated command voltage V2 to the drive waveform generator 153.

[0112] The drive waveform generator 153 generates three-phase drive voltages Vu, Vv, and Vw based on the command voltage V2 obtained from the drive waveform generator 153 and the rotation angle θ2 obtained from the motor angle sensor 102, in a manner that maximizes the motor torque. The drive waveform generator 153 then outputs the drive voltages Vu, Vv, and Vw to the PWM converter 125. Although not shown, in order to move the motor angle of the motor 101 towards the commanded angle, the drive voltages Vu, Vv, and Vw can be generated, for example, using known advance angle control that controls the phase of the induced voltage of the motor 101 and the motor angle, so that the motor 101 extracts the maximum torque.

[0113] The steering angle calculation unit 127 is connected to the motor angle sensor 102 and obtains the rotation angle θ2 from the motor angle sensor 102. The steering angle calculation unit 127 calculates the steering angle detection value Am by accumulating the rotation angle θ2. The steering angle calculation unit 127 sends the steering angle detection value Am to the automatic driving assistance control device 20 in place of the steering angle sensor.

[0114] In addition to achieving the effects of Embodiment 1, the electric power steering device 1B described above in Embodiment 3 simplifies the angle conversion-related processing by replacing steering angle control based on steering angle with motor angle control based on the deviation of motor angle. That is, by replacing steering angle-dependent control with control based on angle information inside the motor control unit 100B.

[0115] <Implementation Method 4> The electric power steering device 1C according to Embodiment 4 will be described. Figure 14 This is a structural diagram showing the steering system of a vehicle equipped with the electric power steering device 1C according to Embodiment 4. Furthermore, in the following description, parts having the same functions as those described in Embodiments 1, 2, or 3 will be labeled with the same names and reference numerals, and specific descriptions of those functions will be omitted.

[0116] The electric power steering system 1C includes a torque sensor 3, a steering shaft 4, a reducer 5, a rack and pinion 6, a vehicle status sensor 10, an automatic driving assistance control device 20, and an electric motor control unit 100C. Similar to Embodiment 1, the electric power steering system 1C has automatic driving assistance control, enabling the vehicle to continue autonomous driving even in the event of an anomaly.

[0117] Figure 15 This is a block diagram of the motor control unit 100C according to Embodiment 4. Figure 15As shown, the motor control unit 100C includes a motor 101, a motor angle sensor 102, motor drive units 105 and 106, a first CPU 110C (first motor control unit), and a second CPU 120C (second motor control unit).

[0118] The first CPU 110C includes an auxiliary control unit 111, a current conversion unit 210, a current control unit 114, a target voltage switching unit 118, a PWM conversion unit 115, and an anomaly detection unit 116. The second CPU 120C includes a motor angle conversion unit 121, a motor angle control unit 124b, a target voltage switching unit 128, a PWM conversion unit 125, an anomaly detection unit 126, and a steering angle calculation unit 127.

[0119] The current conversion unit 210 obtains the auxiliary torque Ta from the auxiliary control unit 111. Based on the auxiliary torque Ta obtained from the auxiliary control unit 111, the current conversion unit 210 calculates current commands to suppress the increase of the induced voltage of the motor 101, which are respectively used as the q-axis current command Itq and the d-axis current command Itd. The d-axis current command Itd can be generated by known control methods, for example, it can be generated based on maximum torque / current (MTPA) control.

[0120] The current control unit 114 obtains the dq-axis current commands Itd and Itq from the current switching unit 113. The current control unit 114 obtains the current detection values ​​iu, iv, and iw from the current sensor 103. The current control unit 114 converts the current detection values ​​iu, iv, and iw into the dq-axis current detection values ​​Id and Iq. Based on the dq-axis current commands Itd and Itq and the dq-axis current detection values ​​Id and Iq, the current control unit 114 calculates the three-phase drive voltages Vu1, Vv1, and Vw1.

[0121] Here, the drive voltages Vu1, Vv1, and Vw1 calculated by the current control unit 114 are referred to as auxiliary drive voltages Vua, Vva, and Vwa. The coordinate converter 136 outputs the auxiliary drive voltages Vua, Vva, and Vwa to the target voltage switching unit 118 and the target voltage switching unit 128. The auxiliary drive voltages Vua, Vva, and Vwa are target values ​​(first target voltages) for the voltage used to drive the motor 101, and are an example of the first command.

[0122] The target voltage switching unit 118 obtains the auxiliary drive voltages Vua, Vva, and Vwa calculated by the current feedback of the current control unit 114 from the current control unit 114. The target voltage switching unit 118 also obtains the autonomous driving angle drive voltages Vus, Vvs, and Vws calculated by the angle feedback of the motor angle control unit 124b from the motor angle control unit 124b. The target voltage switching unit 118 selects any one of the auxiliary drive voltages Vua, Vva, and Vwa and the autonomous driving angle drive voltages Vus, Vvs, and Vws as the drive voltages Vu1, Vv1, and Vw1. Furthermore, the autonomous driving angle drive voltages Vus, Vvs, and Vws are target values ​​for the voltage used to drive the motor 101, equivalent to the drive voltages Vu, Vv, and Vw generated by the motor angle control unit 124b. The autonomous driving angle drive voltages Vus, Vvs, and Vws are an example of a second target voltage and an example of a second command.

[0123] When performing steering assist control, the target voltage switching unit 118 selects auxiliary drive voltages Vua, Vva, and Vwa as drive voltages Vu1, Vv1, and Vw1. Conversely, when performing automatic driving assist control, the target voltage switching unit 118 selects automatic driving angle drive voltages Vus, Vvs, and Vws as drive voltages Vu1, Vv1, and Vw1. The target voltage switching unit 118 outputs the selected drive voltages Vu1, Vv1, and Vw1 to the PWM converter unit 115.

[0124] The target voltage switching unit 128 obtains the auxiliary drive voltages Vua, Vva, and Vwa calculated by the current feedback of the current control unit 114 from the current control unit 114. The target voltage switching unit 128 obtains the autonomous driving angle drive voltages Vus, Vvs, and Vws calculated by the angle feedback of the motor angle control unit 124b from the motor angle control unit 124b. The target voltage switching unit 128 selects any one of the auxiliary drive voltages Vua, Vva, and Vwa and the autonomous driving angle drive voltages Vus, Vvs, and Vws as the drive voltages Vu2, Vv2, and Vw2.

[0125] When performing steering assist control, the target voltage switching unit 128 selects the auxiliary drive voltages Vua, Vva, and Vwa as drive voltages Vu2, Vv2, and Vw2. Conversely, when performing automatic driving assist control, the target voltage switching unit 128 selects the automatic driving angle drive voltages Vus, Vvs, and Vws as drive voltages Vu2, Vv2, and Vw2. The target voltage switching unit 128 outputs the selected drive voltages Vu2, Vv2, and Vw2 to the PWM converter unit 125.

[0126] In embodiment 4, it is necessary to ensure that the output mode of the drive voltage of the motor drive unit 105 and the output mode of the drive voltage of the motor drive unit 106 are consistent. Therefore, the motor 101 is preferably configured with the same winding specification. However, the motor 101 can be configured on different stators, just like a series motor.

[0127] Figure 15 The structures of the motor control unit 100C shown are based on Figure 12 The motor control unit 100B shown is used to represent this, but it is not limited to this. The motor control unit 100C may also include a steering angle switching unit 123 and a motor angle control unit 124, replacing the motor angle conversion unit 121 and the motor angle control unit 124b. In this case, instead of inputting the motor angle deviation command θt (motor angle deviation) to the motor angle control unit 124, the automatic driving steering angle command As and the steering angle detection value Am may be input to generate the automatic driving angle drive voltages Vus, Vvs, and Vws.

[0128] Therefore, in Embodiment 4, the first CPU 110C switches to either the auxiliary drive voltage generated by the current control unit 114 from the auxiliary torque Ta, or the automatic driving angle drive voltage generated by the motor angle control unit 124b from the motor angle deviation command θt, as the drive voltage for the driver's steering command. Consequently, the second CPU 120C switches to either the auxiliary drive voltage generated by the current control unit 114 from the auxiliary torque Ta, or the automatic driving angle drive voltage generated by the motor angle control unit 124b from the motor angle deviation command θt, as the drive voltage for the driver's steering command.

[0129] In addition to achieving the effects of Embodiment 1, the electric power steering device 1C described above in Embodiment 4 further simplifies calculations by outputting either the auxiliary drive voltage generated from the auxiliary torque Ta or the automatic driving angle drive voltage generated from the motor angle deviation command θt to the PWM conversion unit, eliminating the need for processing by the steering angle indicator unit 122. As a result, the processing load applied to the CPU can be reduced.

[0130] <Implementation Method 5> The electric power steering device 1D according to Embodiment 5 will be described. Figure 16 This is a structural diagram showing the steering system of a vehicle equipped with the electric power steering device 1D according to Embodiment 5. Furthermore, in the following description, parts having the same functions as those described in Embodiments 1 to 4 will be labeled with the same names and reference numerals, and specific descriptions of those functions will be omitted.

[0131] The electric power steering system 1D includes a torque sensor 3, a steering shaft 4, a reducer 5, a rack and pinion 6, a vehicle status sensor 10, an automatic driving assistance control device 20, and an electric motor control unit 100D. Similar to Embodiment 1, the electric power steering system 1D has automatic driving assistance control, enabling the vehicle to continue autonomous driving even in the event of an anomaly.

[0132] Figure 17 This is a block diagram of the motor control unit 100D according to Embodiment 5. (As shown...) Figure 17 As shown, the motor control unit 100D includes a motor 101, a motor angle sensor 102, motor drive units 105 and 106, a first CPU 110D (first motor control unit), and a second CPU 120D (second motor control unit). The motor drive unit 106 according to Embodiment 5 includes an inverter circuit 140 and a current sensor 103. Therefore, the motor drive unit 106 according to Embodiment 5, like the motor drive unit 105, has a current sensor 103, outputting the three-phase current detection values ​​Iu2, Iv2, and Iw2 to the motor angle control unit 124c.

[0133] The first CPU 110D includes an auxiliary control unit 111, a motor angle deviation indicator unit 112b, a current switching unit 112, a current control unit 114, a PWM conversion unit 115, and an anomaly detection unit 116. The second CPU 120D includes a motor angle conversion unit 121, a steering angle indicator unit 122b, a motor angle deviation switching unit 123b, a motor angle control unit 124c, a PWM conversion unit 125, an anomaly detection unit 126, and a steering angle calculation unit 127.

[0134] Figure 18 This is a block diagram showing the motor angle control unit 124c according to Embodiment 5. (As shown) Figure 18 As shown, the motor angle control unit 124c includes a motor angle controller 152c, a motor speed calculator 154, a motor speed deviation calculator 155, a motor speed controller 156, a coordinate converter 157, deviation calculators 158 and 159, a current controller 160 and 161, and a coordinate converter 162.

[0135] The motor angle controller 152c acquires the motor angle deviation command θt from the motor angle deviation switching unit 123b. Based on the acquired motor angle deviation command θt, the motor angle controller 152c generates the target motor speed ωt. For example, the motor angle controller 152c performs feedback control to generate the target motor speed ωt, so that the motor angle deviation command θt is 0. This feedback control can use any combination of known proportional control, integral control, and derivative control, or other known control methods, or a combination of multiple known control methods.

[0136] The motor speed calculator 154 calculates the motor speed ωm by the difference between the current rotation angle θ2 detected by the motor angle sensor 102 and the rotation angle θ2z detected by the motor angle sensor 102 100μs ago. The motor speed calculator 154 outputs the calculated motor speed ωm to the motor speed deviation calculator 155.

[0137] The motor speed deviation calculator 155 obtains the target motor speed ωt from the motor angle controller 152c. The motor speed deviation calculator 155 obtains the motor speed ωm from the motor speed calculator 154. The motor speed deviation calculator 155 calculates the deviation between the target motor speed ωt and the motor speed ωm, and outputs the calculated deviation to the motor speed controller 156.

[0138] The motor speed controller 156 performs feedback control to generate the rotational torque of the target motor, so that the deviation between the target motor speed ωt and the motor speed ωm is 0. This feedback control can use any combination of known proportional control, integral control, and derivative control, or other known control methods, or a combination of multiple known control methods.

[0139] The motor speed controller 156 calculates the target motor rotational current Imq (q-axis) and target motor rotational current Imd (d-axis) based on the generated target motor rotational torque, as a current command to suppress the increase of induced voltage in motor 101. The target current Imd (d-axis) can be generated by known control methods, such as based on maximum torque-to-current (MTPA) control. The motor speed controller 156 outputs the target current Imq to the deviation calculator 158 and the target current Imd to the deviation calculator 159.

[0140] Based on the rotation angle θ2 detected by the motor angle sensor 102, the coordinate converter 157 converts the three-phase current detection values ​​Iu2, Iv2, and IW2 detected by the current sensor of the motor drive unit 106 into two-phase coordinates, thereby obtaining the two-phase current detection values ​​Iq2 and Id2 along the dq axis. The coordinate converter 157 outputs the current detection value Iq2 to the deviation calculator 158 and the current detection value Id2 to the deviation calculator 159.

[0141] Deviation calculator 158 calculates the deviation between the target current Imq and the current detection value Iq2, and outputs the calculated deviation to the current controller 160. Deviation calculator 159 calculates the deviation between the target current Imd and the current detection value Id2, and outputs the calculated deviation to the current controller 161.

[0142] Current controller 160 performs feedback control to make the deviation between the target current Imq and the current detection value Iq2 zero, thereby generating a target voltage Vq2 on the q-axis as a drive command. Current controller 160 outputs the target voltage Vq2 to coordinate converter 162. Current controller 161 performs feedback control to make the deviation between the target current Imd and the current detection value Id2 zero, thereby generating a target voltage Vd2 on the d-axis as a drive command. Current controller 161 outputs the target voltage Vq2 to coordinate converter 162.

[0143] The feedback control of current controller 160 and current controller 161 can use proportional-integral control used in general motor control, or can use any combination of known proportional control, integral control and derivative control, or other known control, or can combine multiple known control.

[0144] The coordinate converter 162 is connected to the motor angle sensor 102 and obtains the rotation angle θ2 from the motor angle sensor 102. Based on the rotation angle θ2, the coordinate converter 162 converts the target voltage Vq2 on the q-axis and the target voltage Vd2 on the d-axis into three-phase drive voltages Vu2, Vv2, and Vw2.

[0145] Autonomous driving assistance control assists the driver or controls the steering angle on behalf of the driver, assuming the steering wheel 2 is turned at the same speed as the driver's steering input. For example, when the autonomous driving assistance control device 20 wants to steer to avoid an obstacle ahead, the steering angle changes abruptly. When controlling the steering angle using feedback control based on the motor angle, its following ability is relatively low, making it difficult to ensure following ability when the steering angle changes suddenly. In such cases, the electric power steering device 1D according to Embodiment 5 not only uses feedback control based on the motor angle, but also uses feedback control based on the motor speed and feedback control based on the motor torque converted into the current supplied to the motor to control the steering angle, which improves responsiveness compared to feedback only on the motor angle.

[0146] In addition to achieving the effects of Embodiment 1, the electric power steering device 1D described above in Embodiment 5 improves responsiveness by controlling the steering angle through feedback control based on motor speed and feedback control of motor torque converted into current supplied to the motor. This is in contrast to feedback based solely on motor angle.

[0147] The embodiments of this disclosure have been described in detail above with reference to the accompanying drawings, but the specific structure is not limited to these embodiments, and designs that do not depart from the spirit of this disclosure are also included. Label Explanation

[0148] 1, 1A, 1B, 1C, 1D… Electric power steering system; 3… Torque sensor; 10… Vehicle status sensor; 100, 100A, 100B, 100C, 100D… Motor control unit; 110, 110A… 110B, 110C, 110D… First CPU, 120, 120A, 120B, 120C, 120D… Second CPU, 101… motor.

Claims

1. An electric power steering device, characterized in that, include: Vehicle status sensor, which detects the vehicle's status and external information; An autonomous driving assistance control unit generates steering angle commands for the vehicle's steering system based on the detection results from the vehicle state sensors. A torque sensor that detects the steering torque of the steering system; An electric motor that rotates to obtain the steering angle of the steering gear; The first motor control unit performs steering assistance control by driving and controlling the motor to assist steering based on the detection result of the torque sensor. as well as The second electric motor control unit performs automatic steering assistance control of the steering gear by driving and controlling the electric motor according to the steering angle command. When performing the steering assist control, the first motor control unit sends a first command to the second motor control unit to drive the motor. When performing the automatic driving assist control, it performs drive control of the motor according to a second command sent from the second motor control unit to drive the motor, thereby assisting in the drive of the motor. When performing the automatic driving assistance control, the second motor control unit sends the second instruction to the first motor control unit. When performing the steering assistance control, the second motor control unit performs drive control of the motor according to the first instruction to assist the drive of the motor.

2. The electric power steering device as described in claim 1, characterized in that, When performing the steering assist control, the first motor control unit calculates the target value of the steering angle, i.e., the target steering angle, and sends the calculated target steering angle as the first command to the second motor control unit. When performing the autonomous driving assistance control, the second motor control unit calculates the target value of the motor torque, i.e., the steering angle torque command, based on the deviation between the steering angle command and the detected steering angle, and sends the calculated steering angle torque command as the second command to the first motor control unit.

3. The electric power steering device as described in claim 1, characterized in that, When performing the steering assist control, the first motor control unit sends the deviation between the target rotation angle of the motor and the detected rotation angle of the motor, i.e., the first deviation, as the first command to the second motor control unit. When performing the autonomous driving assistance control, the second motor control unit converts the steering angle command into the rotation angle of the motor, drives the motor according to the deviation between the converted rotation angle of the motor and the detected rotation angle of the motor, i.e., the second deviation, and calculates the target value of the torque used to obtain the steering angle, i.e., the steering angle torque command, based on the second deviation, and sends the calculated steering angle torque command as the second command to the first motor control unit.

4. The electric power steering device as described in claim 1, characterized in that, When performing the automated driving assistance control, the first motor control unit calculates a target value for the voltage used to drive the motor, i.e., a first target voltage, and sends the calculated first target voltage as the first instruction to the second motor control unit. When performing the steering assist control, the second motor control unit calculates a target value for the voltage used to drive the motor, namely the second target voltage, and sends the calculated second target voltage as the second instruction to the first motor control unit.

5. The electric power steering device as described in any one of claims 1 to 4, characterized in that, When the steering assist control is in effect, if the first motor control unit is unable to drive and control the motor due to an malfunction, the drive control of the motor continues solely by the second motor control unit. In the case of the aforementioned autonomous driving assistance control, if the second motor control unit is unable to drive and control the motor due to an abnormality, the driving of the motor continues solely by the first motor control unit.

6. The electric power steering device as described in any one of claims 1 to 4, characterized in that, When the second motor control unit is performing the steering assist control, if it cannot receive the first command from the first motor control unit, it will stop the drive control of the motor. When the first motor control unit is performing the autonomous driving assistance control and cannot receive the second instruction from the second motor control unit, it calculates a target value of torque for obtaining the steering angle based on the deviation between the steering angle instruction output from the autonomous driving assistance control unit and the detected rotation angle of the motor, and performs drive control on the motor based on the calculated target value.

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