MOTOR CONTROL DEVICE, MOTOR CONTROL METHOD, AND ELECTRIC POWER STEERING DEVICE

Abstract

To appropriately reduce torque ripples generated in an AC motor while suppressing the number of functional units more than before.SOLUTION: A motor drive device includes: first calculation means for calculating a first two-phase current command value corresponding to a torque command value of a synchronous motor based on angular velocity of the synchronous motor; second calculation means for calculating a second two-phase current command value corresponding to a sixth phase component in a dq-rotation coordinate system based on the torque command value and a rotation angle of the synchronous motor; and derivation means for deriving a two-phase voltage command value by using difference between the two-phase current command value obtained by superimposing the first two-phase current command value and the second two-phase current command value and an actual two-phase current value of the synchronous motor. The derivation means derives the two-phase voltage command value so that the sixth order component of the actual two-phase current value does not delay.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a motor control device, a motor control method, and an electric power steering device. [Background technology]

[0002] Conventionally, an AC motor such as an AC motor provided in an electric power steering device (EPS) or the like is supplied with power from a power source capable of controlling the frequency, voltage, current, phase, etc., to control the operation of the motor. For example, in an electric power steering device, feedback control of the motor current is performed to appropriately generate torque for assisting steering. In the feedback control, the motor applied voltage is adjusted so that the difference between a current command value and an actual current value becomes small. In general, the motor applied voltage is adjusted by PWM (Pulse Width Modulation) control.

[0003] In addition, a synchronous motor can be used as a motor in an electric power steering device. As a synchronous motor, a brushless motor, which has excellent durability and maintainability and produces little noise and noise, is generally used. As a driving method for a brushless motor, vector control is known, which controls the motor current in a dq rotating coordinate system defined by the d-axis and the q-axis.

[0004] The motor current flowing through a brushless motor contains harmonic components in addition to fundamental components. Torque ripples caused by these harmonic components are one of the causes of vibration and noise. In order to reduce this torque ripple, for example, Patent Document 1 describes a method of superimposing harmonic components with frequencies that are integer multiples of the fundamental component on a current command value of a fundamental component on a dq rotating coordinate system, and controlling the current based on the current command value on which the harmonic components are superimposed.

[0005] Furthermore, Patent Document 2 describes that in order to reduce torque ripple that occurs in the high rotation range of a motor in an electric power steering device, a superimposed component for reducing torque ripple is superimposed on the motor current during a period corresponding to the high rotation range. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 4484325 [Patent Document 2] JP 2019-88130 A Summary of the Invention [Problem to be solved by the invention]

[0007] In Patent Document 1 and Patent Document 2, many functional units for feedback signals are provided for the purpose of reducing torque ripple. The functional units for feedback signals include a functional unit for extracting each harmonic component from the motor current flowing through the motor and converting it to a rotating coordinate system, a functional unit for adjusting the harmonic components obtained from the motor current using a gain so as to perform tracking control, and a functional unit for inversely converting the adjusted harmonic components and reflecting them in the fundamental wave component. Furthermore, to improve the accuracy of extracting harmonic components from the motor current, a functional unit equipped with a low-pass filter is further required.

[0008] Increasing the number of functional units reduces the responsiveness of the entire device. For example, in a conventional configuration, if an attempt is made to improve the accuracy of extracting harmonic components from the motor current using a low-pass filter or the like, a trade-off inevitably occurs between the accuracy and responsiveness in control. From the viewpoint of responsiveness, a configuration is required that can reduce torque ripple while suppressing the number of functional units in the device.

[0009] In view of the above problems, an object of the present invention is to appropriately reduce torque ripple generated in an AC motor while reducing the number of functional units in an apparatus compared to conventional methods. [Means for solving the problem]

[0010] In order to solve the above problems, the present invention has the following configuration. That is, a motor control device comprising: a first calculation means for calculating a first two-phase current command value corresponding to a torque command value of the synchronous motor based on an angular velocity of the synchronous motor; a second calculation means for calculating a second two-phase current command value corresponding to a 6n-th order component in a dq rotating coordinate system based on the torque command value and a rotation angle of the synchronous motor; a first conversion means for converting a three-phase current value supplied to the synchronous motor into a two-phase current value based on a rotation angle of the synchronous motor; a derivation means for deriving a first two-phase voltage command value by using a difference between a two-phase current command value obtained by superimposing the first two-phase current command value and the second two-phase current command value and the two-phase current value converted by the first conversion means; a second conversion means for converting the first two-phase voltage command value into a three-phase voltage command value; a supply means for supplying a three-phase voltage to the synchronous motor based on the three-phase voltage command value; Equipped with The derivation means is PI control is performed using the difference to calculate a second two-phase voltage command value; calculating a correction value for the second two-phase voltage command value based on the difference and a rotation angle of the synchronous motor; The second two-phase voltage command value is corrected by the correction value to derive the first two-phase voltage command value.

[0011] Another aspect of the present invention has the following configuration. That is, a motor control method comprising: a first calculation step of calculating a first two-phase current command value corresponding to a torque command value of the synchronous motor based on an angular velocity of the synchronous motor; a second calculation step of calculating a second two-phase current command value corresponding to a 6n-th order component in a dq rotating coordinate system based on the torque command value and a rotation angle of the synchronous motor; a first conversion step of converting a three-phase current value supplied to the synchronous motor into a two-phase current value based on a rotation angle of the synchronous motor; a derivation step of deriving a first two-phase voltage command value by using a difference between a two-phase current command value obtained by superimposing the first two-phase current command value and the second two-phase current command value and the two-phase current value converted in the first conversion step; a second conversion step of converting the first two-phase voltage command value into a three-phase voltage command value; a supply step of supplying a three-phase voltage to the synchronous motor based on the three-phase voltage command value; having In the deriving step, PI control is performed using the difference to calculate a second two-phase voltage command value; calculating a correction value for the second two-phase voltage command value based on the difference and a rotation angle of the synchronous motor; The second two-phase voltage command value is corrected by the correction value to derive the first two-phase voltage command value.

[0012] Another aspect of the present invention has the following configuration: That is, an electric power steering device including a motor control device and a synchronous motor controlled by the motor control device, The motor control device includes: a first calculation means for calculating a first two-phase current command value corresponding to a torque command value of the synchronous motor based on an angular velocity of the synchronous motor; a second calculation means for calculating a second two-phase current command value corresponding to a 6n-th order component in a dq rotating coordinate system based on the torque command value and a rotation angle of the synchronous motor; a first conversion means for converting a three-phase current value supplied to the synchronous motor into a two-phase current value based on a rotation angle of the synchronous motor; a derivation means for deriving a first two-phase voltage command value by using a difference between a two-phase current command value obtained by superimposing the first two-phase current command value and the second two-phase current command value and the two-phase current value converted by the first conversion means; a second conversion means for converting the first two-phase voltage command value into a three-phase voltage command value; a supply means for supplying a three-phase voltage to the synchronous motor based on the three-phase voltage command value; Equipped with The derivation means is PI control is performed using the difference to calculate a second two-phase voltage command value; calculating a correction value for the second two-phase voltage command value based on the difference and a rotation angle of the synchronous motor; The second two-phase voltage command value is corrected by the correction value to derive the first two-phase voltage command value. Effect of the Invention

[0013] According to the present invention, it is possible to appropriately reduce torque ripple generated in an AC motor while reducing the number of functional parts in an apparatus compared to conventional techniques. [Brief description of the drawings]

[0014] [Figure 1] 1 is a configuration diagram showing an example of a schematic configuration of an electric power steering device according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a diagram showing an example of the functional configuration of a control system according to an embodiment of the present invention. [Diagram 3] FIG. 4 is a diagram for explaining an example of a transfer function of a feedback equation according to an embodiment of the present invention. [Figure 4] FIG. 13 is a diagram for explaining another example of the transfer function of the feedback equation according to the embodiment of the present invention. [Diagram 5] 4 is a flowchart showing a control process according to an embodiment of the present invention. [Figure 6] FIG. 11 is a diagram for explaining another example of the transfer function of the feedback equation according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, the embodiment for carrying out the present invention will be described with reference to the drawings. Note that the embodiment described below is one embodiment for explaining the present invention, and is not intended to be interpreted as limiting the present invention, and all configurations described in each embodiment are not necessarily essential configurations for solving the problems of the present invention. In addition, in each drawing, the same components are given the same reference numbers to indicate their correspondence.

[0016] <First embodiment> A first embodiment of the present invention will be described below. Note that the configuration of the electric power steering device shown below is just one example, and the present invention is applicable to electric power steering devices as well as electric motors in general, including AC motors.

[0017] [Configuration overview] An example of the configuration of an electric power steering device according to this embodiment is shown in Fig. 1. The steering wheel 1 is a steerable wheel that is used by a driver to perform steering operation. A steering shaft 2 of the steering wheel 1 is connected to steered wheels 8L, 8R via a reduction gear (worm gear) 3, universal joints 4a, 4b, a pinion rack mechanism 5, and tie rods 6a, 6b that constitute a reduction mechanism, and further via hub units 7a, 7b.

[0018] The steering shaft 2 is configured by connecting an input shaft on the steering wheel 1 side and an output shaft on the pinion rack mechanism 5 side via a torsion bar 9. The pinion rack mechanism 5 has a pinion 5a connected to a pinion shaft (not shown) to which steering force is transmitted from the universal joint 4b, and a rack 5b meshing with the pinion 5a. The rotational motion transmitted to the pinion 5a is converted into linear motion in the vehicle width direction by the rack 5b.

[0019] The steering shaft 2 is provided with a steering torque T dctThe steering shaft 2 is provided with a torque sensor 10 for detecting a steering angle θ 2 , which indicates a rotation angle of the steering shaft 2 around the axis on the steering wheel 1 side (input shaft side). h The steering shaft 2 is provided with a steering angle sensor 14 for detecting an output shaft angle θ , which indicates a rotation angle of the steering shaft 2 around the axis on the pinion rack mechanism 5 side (output shaft side). c In other words, the steering angle sensor 14 detects the rotation angle of the input shaft side with respect to the torsion bar 9 as the steering angle θ h The output shaft angle sensor 15 detects the rotation angle of the output shaft side relative to the torsion bar 9 as the output shaft angle θ c The torque sensor 10 detects the steering angle θ h and output shaft angle θ c Based on the torsion of the torsion bar 9 caused by the difference between dct Detect.

[0020] The steering angle sensor 14 and the output shaft angle sensor 15 may be an integrated sensor. In FIG. 1, the steering shaft 2 and the torque sensor 10 are shown separately for ease of explanation, but they may be integrated. The structure of the torque sensor 10 is not particularly limited, and for example, a sleeve type or a ring type that detects torque from the twist of the torsion bar 9 may be used. In the above-mentioned structure, the steering torque T dct is the steering angle θ h and output shaft angle θ c However, the present invention is not limited to this. For example, the torque value may be detected using the difference between the angle signal on the steering wheel 1 side of the torsion bar 9 and the angle signal on the pinion rack mechanism 5 side. In the following description, the steering wheel 1 side of the steering shaft 2 is also referred to as the upstream side, and the pinion rack mechanism 5 side is also referred to as the downstream side.

[0021] Steering torque T detected by the torque sensor 10 dctThe steering torque T includes the driver torque based on the operation of the steering wheel 1 by the driver as well as the torque generated by the input (external disturbance, etc.) from the downstream side. dct The command value based on the input from the downstream side is corrected so as to suppress the vibration caused by the input from the downstream side. The suppression method here is not particularly limited, and any method may be used.

[0022] A steering assist motor 20 that assists the steering force applied to the steering wheel 1 is connected to the steering shaft 2 via a reduction gear 3. An EPS-ECU (Electronic Control Unit) 30, which is a controller that controls an electric power steering (EPS) device, is supplied with power from a battery 13 and receives an ignition key signal via an ignition (IGN) key 11.

[0023] The steering assist motor 20 according to this embodiment (hereinafter also simply referred to as the motor 20) is, for example, a three-phase AC motor, and has a permanent magnet field or a wound field. The motor 20 rotates when three-phase AC currents, the phases of which differ by 120°, are supplied to coils (not shown) of each of the u-, v-, and w-phases. A rotation angle sensor 219, which is configured from a resolver, a rotary encoder, or the like, is installed on the shaft of a rotor (not shown) of the motor 20. The rotation angle θ of the motor 20 detected by the rotation angle sensor 219 is output to the EPS-ECU 30. The use of the rotation angle θ detected here will be described later.

[0024] The EPS-ECU 30 detects the steering torque T dct , and the vehicle speed V detected by the vehicle speed sensor 12 h The EPS-ECU 30 calculates a voltage command value as an assist command value based on the steering torque T dct The power (voltage value V ref The steering assist motor 20 controls the voltage value V refBased on this, the reduction gear 3 is operated to perform assist control for the steering wheel 1.

[0025] The EPS-ECU 30 may include, for example, a computer including a processor and peripheral components such as a storage device. The processor may be, for example, a CPU (Central Processing Unit) or an MPU (Micro-Processing Unit). The storage device may include any one of a semiconductor storage device, a magnetic storage device, and an optical storage device. The storage device may include memories such as a register, a cache memory, and a ROM (Read Only Memory) and a RAM (Random Access Memory) used as a main storage device. The functions of the EPS-ECU 30 described below are realized, for example, by the processor of the EPS-ECU 30 executing a computer program stored in the storage device.

[0026] The EPS-ECU 30 may be formed of dedicated hardware for executing each information processing described below. For example, the EPS-ECU 30 may include a functional logic circuit set in a general-purpose semiconductor integrated circuit. For example, the EPS-ECU 30 may include a programmable logic device (PLD) such as a field programmable gate array (FPGA).

[0027] [Vector control function configuration] The motor current that flows through an AC motor contains harmonic components in addition to the fundamental wave component. Torque ripple that occurs due to this harmonic component can be a cause of vibration and noise. In the case of a three-phase AC motor, the main component of torque ripple is the 6nth order component in electrical angle, and it is known that the harmonic component of the winding current that causes this is the (6n±1)th order component. In a dq rotating coordinate system synchronized with the angular velocity ω, which is the fundamental wave component of the motor, this (6n±1)th order component is observed as a 6nth order component (6nω).

[0028] Therefore, appropriately controlling the 6n-th order component (6nω) in the dq rotating coordinate system is equivalent to appropriately controlling the (6n±1)-th order component of the winding current, which makes it possible to reduce the torque ripple. In this embodiment, motor control is performed with an emphasis on the above.

[0029] Fig. 2 is a diagram showing an example of the functional configuration of a control system for vector control of the motor 20 according to this embodiment. The control system shown in Fig. 2 is configured by two-phase feedback vector control. This control system is configured by, for example, the EPS-ECU 30.

[0030] In the control system, first, the torque command value T rq * is input to the current command value calculation unit 201 and the n-th current command value calculation unit 202. rq The symbol "*" may be input from, for example, another control unit (not shown) included in the EPS-ECU 30. In the following description, the symbol "*" indicates a command value. The current command value calculation unit 201 calculates the torque generated by the motor 20 and the torque command value T based on the angular velocity ω of the motor 20 input from the angular velocity calculation unit 221. rq *The current command value i of the zeroth component on the d-axis and q-axis is set to match d0 *, i q0 * Calculate the current command value i d0 , i q0 For example, a predetermined proportional constant is set to the torque command value T rq It is calculated by multiplying with *.

[0031] The d-axis and q-axis are axes in a dq rotating coordinate system. The d-axis indicates the direction of the magnetic flux of a rotor (not shown) of the motor 20. The q-axis indicates a direction perpendicular to the d-axis. The current command value i d0 The current command value i* of the q-axis component calculated by the current command value calculation unit 201 is output to the adder 203. q0 The * is output to the adder 205 .

[0032] The n-th current command value calculation unit 202 calculates the n-th current command value based on the rotation angle θ and the torque command value T rq *Based on this, the current command value i of the 6nth order component (6nω) on the d-axis and q-axis dn *, i qn * Calculate the current command value i dn *, i qn * is, for example, the rotation angle θ and the torque command value T rq * is input, and the current command value i dn *, i qn The n-th current command value calculation unit 202 may calculate the d-axis current command value i dn The n-th current command value calculation unit 202 outputs the q-axis current command value i qn The * is output to the adder 205 .

[0033] The adder 203 receives the current command value i d0 * and the current command value i from the n-th current command value calculation unit 202 dn * is added to obtain the current command value i d The adder 205 calculates the current command value i* from the current command value calculation unit 201 and outputs it to the subtractor 204. q0 * and the current command value i from the n-th current command value calculation unit 202 qn * is added to obtain the current command value i q * is calculated and output to the subtractor 204.

[0034] The subtractor 204 subtracts the current command value i d *, the current value i output from the three-phase / two-phase conversion unit 220 d Subtract the deviation Δi d * to the PI control unit 207 and the correction value calculation unit 208. The subtractor 206 outputs the current command value i q *, the current value i output from the three-phase / two-phase conversion unit 220 q Subtract the deviation Δi q * to the PI control unit 210 and the correction value calculation unit 211.

[0035] The PI control unit 207 calculates the deviation Δi d For *, a voltage command value is calculated using the transfer function shown in the following equation (1). Then, the PI control unit 207 outputs the calculated voltage command value to the adder 209.

[0036]

number

[0037] The correction value calculation unit 208 calculates the actual current value i d In order to make the deviation Δi d The correction value calculation unit 208 calculates a correction value for the voltage command value based on the angular velocity ω of the motor 20 input from the angular velocity calculation unit 221, and outputs the correction value to the adder 209. In this embodiment, the correction value calculation unit 208 calculates the correction value using a transfer function shown in the following equation (2). In equation (2), s is added to the denominator polynomial of the transfer function to correspond to the 6n-th order component. 2 +(6nω) 2 In addition, the transfer function shown in equation (2) is derived from a cosine function.

[0038]

number

[0039] The adder 209 adds the voltage command value from the PI control unit 207 and the correction value from the correction value calculation unit 208 to obtain a voltage command value v d * and outputs it to the two-phase / three-phase conversion unit 213.

[0040] The PI control unit 210 calculates the deviation Δi q For *, the PI control unit 210 calculates a voltage command value using the transfer function shown in the above equation (1) in the same manner as the PI control unit 207. Then, the PI control unit 210 outputs the calculated voltage command value to the adder 212.

[0041] The correction value calculation unit 211 calculates the actual current value i q In order to make the deviation Δi q * and the angular velocity ω of the motor 20 input from the angular velocity calculation unit 221, the correction value calculation unit 211 calculates a correction value for the voltage command value and outputs the correction value to the adder 212. In this embodiment, similar to the correction value calculation unit 208, the correction value calculation unit 211 calculates the correction value by using the transfer function shown in the above formula (2).

[0042] The adder 212 adds the voltage command value from the PI control unit 210 and the correction value from the correction value calculation unit 211 to obtain a voltage command value v q * and outputs it to the two-phase / three-phase conversion unit 213.

[0043] The two-phase / three-phase converter 213 converts the two-phase voltage command value (the voltage command value v d *, and the voltage command value v from the adder 212 q *), and the rotation angle θ of the motor 20 from the rotation angle sensor 219 are input, and the two-phase voltage command value is set to a three-phase voltage command value v corresponding to the motor 20 so as to be synchronized with the rotation angle θ. u *, v v *, v w Then, the two-phase / three-phase conversion unit 213 converts the three-phase voltage command value v u *, v v *, v w *Each is output to the PWM control unit 214.

[0044] The PWM control unit 214 converts the three-phase voltage command value v u *, v v *, v w *Based on each of these, the duty ratio of each phase is derived and output to the inverter 215.

[0045] Based on the input from the PWM control unit 214, the inverter 215 converts the power of the AC power source supplied by the battery 13 into a three-phase voltage v u , vv , v w and supplies the converted voltage to the motor 20. In FIG. 1, the voltage output from the EPS-ECU 30 to the motor 20 is a voltage value V ref This is because the three-phase voltage v u , v v , v w Corresponds to.

[0046] Current detection circuits 216, 217, and 218 for detecting current values ​​are provided on the connection lines between the inverter 215 and the motor 20, and three-phase current i u , i v , i w The current detection circuits 216, 217, and 218 output the detected current values ​​to the three-phase / two-phase conversion unit 220. The current detection circuits 216, 217, and 218 may be provided inside the inverter 215.

[0047] The rotation angle sensor 219 detects the rotation angle θ of the motor 20 , and outputs it to the two-phase / three-phase conversion unit 213 , the three-phase / two-phase conversion unit 220 , the angular velocity calculation unit 221 , and the n-th order current command value calculation unit 202 .

[0048] The three-phase / two-phase conversion unit 220 converts three-phase current values ​​(three-phase currents i u , i v , i w The three-phase current values ​​are expressed as two-phase actual current values ​​i d , i q Then, the three-phase / two-phase conversion unit 220 converts the actual current value i d is output to the subtractor 204, and the actual current value i q is output to the subtractor 206.

[0049] The angular velocity calculation unit 221 differentiates the rotation angle θ from the rotation angle sensor 219 to calculate the angular velocity ω of the motor 20 , and outputs it to the current command value calculation unit 201 , the correction value calculation unit 208 , and the correction value calculation unit 211 .

[0050] 3 and 4 are diagrams for explaining the PI control unit 207 and PI control unit 210 shown in FIG. 2, and a feedback control system around the motor 20. In FIG. 3 and FIG. 4, the input is U(s) and the output is Y(s). The model of the PI control unit 207 and the correction value calculation unit 208 (and the PI control unit 210 and the correction value calculation unit 211) is G c The motor model around the motor 20 is the control target G p (s) Control object G p The transfer function of (s) is given by the following equation (3).

[0051]

number

[0052] 3 and 4 show the cases where n=1 and 2. In this embodiment, the above formula (2) used in the correction value calculation unit 208 and the correction value calculation unit 211 is a transfer function derived from a cosine function. The transfer functions may be connected in parallel as shown in FIG. 3. Alternatively, the transfer functions may be connected in series as shown in FIG. 4.

[0053] [Processing flow] 5 is a flowchart of a control process performed by the EPS-ECU 30 according to this embodiment. For the sake of simplicity, the EPS-ECU 30 will be collectively referred to as the processing entity.

[0054] In S501, the EPS-ECU 30 sets the torque command value T rq * Get the torque command value T rq * may be obtained from another portion (not shown) of the EPS-ECU 30, or may be obtained from an ADAS-ECU (not shown) provided in the vehicle (not shown).

[0055] In S502, the EPS-ECU 30 calculates the torque command value T rq *, the zero-order current command value i in the dq rotating coordinate system is calculated based on the angular velocity ω of the motor 20. d0 *, i q0Calculate *.

[0056] In S503, the EPS-ECU 30 calculates the torque command value T rq *, the n-th current command value i for reducing the torque ripple is calculated based on the rotation angle θ of the motor 20. dn *, i qn Calculate *.

[0057] In S504, the EPS-ECU 30 calculates the zero-order current command value i d0 * and the n-th current command value i on the d axis calculated in S503 dn * and the current command value I d Similarly, the EPS-ECU 30 calculates the zero-order current command value i q0 * and the n-th order current command value i on the q axis calculated in S503 qn * and the current command value i q Calculate *.

[0058] In S505, the EPS-ECU 30 calculates the current command value i d *, i q * and the actual current value of motor 20 i d , i q Deviation Δi d *, Δi q Calculate *.

[0059] In S506, the EPS-ECU 30 calculates the deviation Δi d *, Δi q * is used to calculate a voltage command value by PI control. In the PI control here, the transfer function shown in the above-mentioned formula (1) may be used.

[0060] In S507, the EPS-ECU 30 calculates the deviation Δi d *, Δi qA correction value for the voltage command value is calculated using the input voltage Vcc* and the angular velocity ω of the motor 20. Here, the transfer function shown in the above-mentioned formula (2) may be used.

[0061] In S508, the EPS-ECU 30 corrects the voltage command value of the d-axis component calculated in S506 with the correction value of the d-axis component calculated in S507, thereby obtaining the voltage command value v d Similarly, the EPS-ECU 30 corrects the voltage command value of the q-axis component calculated in S506 with the correction value of the q-axis component calculated in S507, thereby calculating the voltage command value v q Calculate *.

[0062] In S509, the EPS-ECU 30 calculates the voltage command value v d *, v q * is a three-phase voltage command value v for controlling the motor 20 based on the rotation angle θ of the motor 20. u *, v v *, v w Convert to *.

[0063] In S510, the EPS-ECU 30 calculates the voltage command value v obtained in S509. u *, v v *, v w * is used to derive the duty of each phase by the PWM control unit 214, and based on this, the three-phase voltage v u , v v , v w to control the motor 20. Then, this process flow is terminated. This process flow is repeatedly executed while the motor 20 is being controlled.

[0064] As described above, the present embodiment makes it possible to appropriately reduce the torque ripple generated in the electric motor while reducing the number of functional units in the device. In particular, since the number of functional units related to feedback can be reduced compared to the conventional configuration, the responsiveness of the entire device can be improved.

[0065] [Variations] In the above example, the formula (2) is used as the transfer function used in the correction value calculation unit 208 and the correction value calculation unit 211. However, this is not limited to this, and other transfer functions may be used.

[0066] The transfer function shown in the above formula (2) is a transfer function derived from a cosine function. Instead of this, a transfer function shown in the following formula (4) derived from a sine function may be used. In formula (4), as in formula (2), s is added to the denominator polynomial of the transfer function to accommodate the 6n-th order component. 2 +(6nω) 2 Includes.

[0067]

number

[0068] Fig. 6 is a diagram for explaining the control system around the PI control unit 207, the PI control unit 210, and the motor 20 shown in Fig. 2. The difference from Fig. 3 is that the above formula (4) is used in the correction value calculation unit 208 and the correction value calculation unit 211. Here, a configuration example in which transfer functions are connected in parallel is shown.

[0069] <Other embodiments> Although an electric power steering device has been described as an example of an application of a synchronous motor using the control according to the present invention, the configuration of the electric power steering device is not limited to the configuration shown in Fig. 1. For example, the electric power steering device may be configured with a Steer-By-Wire (SBW) mechanism in which the steering wheel 1 side and the pinion rack mechanism 5 side are mechanically separated.

[0070] In addition, the present invention can also be realized by supplying a program or application for realizing the functions of one or more of the above-mentioned embodiments to a system or device via a network or a storage medium, etc., and having one or more processors in a computer of the system or device read and execute the program.

[0071] As such, the present invention is not limited to the above-described embodiments, and the present invention also contemplates mutual combinations of the various components of the embodiments, as well as modifications and applications by those skilled in the art based on the descriptions in the specification and well-known technologies, and these are included in the scope of protection sought.

[0072] As described above, the present specification discloses the following: (1) A torque command value (e.g., T rq The first two-phase current command value (e.g., i d0 *,i q0 *) (e.g., 201); A second two-phase current command value (for example, i dn *,i qn *), and Based on the rotation angle of the synchronous motor, the three-phase current value (for example, i u ,i v ,i w ) into two-phase current values ​​(e.g., i d ,i q ) a first conversion means (e.g., 220) for converting A two-phase current command value obtained by superimposing the first two-phase current command value and the second two-phase current command value (for example, i d *,i q *) and the difference between the two-phase current values ​​converted by the first conversion means (for example, Δi d *,Δi q *) to obtain the first two-phase voltage command value (for example, v d *,v q *) (e.g., 207 to 211) for deriving; The first two-phase voltage command value is converted into a three-phase voltage command value (for example, v u *,v v *,v w *) to a second conversion means (e.g., 213); supplying means (e.g., 214, 215) for supplying a three-phase voltage to the synchronous motor based on the three-phase voltage command value; Equipped with The derivation means is PI control is performed using the difference to calculate a second two-phase voltage command value (e.g., 207, 210); Calculating a correction value for the second two-phase voltage command value based on the difference and the rotation angle of the synchronous motor (e.g., 208, 211); The motor control device derives the first two-phase voltage command value by correcting the second two-phase voltage command value with the correction value (for example, 209, 212). According to this configuration, it is possible to appropriately reduce the torque ripple generated in the AC motor while suppressing the number of functional parts in the device.

[0073] (2) The motor control device according to (1), wherein the derivation means calculates the correction value using a transfer function based on a sine function. According to this configuration, the sixth-order component of the actual two-phase current of the synchronous motor is reflected in the current command value without delay using a sine function, thereby making it possible to appropriately reduce the torque ripple.

[0074] (3) The motor control device according to (1), wherein the derivation means calculates the correction value using a transfer function based on a cosine function. According to this configuration, the sixth-order component of the actual two-phase current of the synchronous motor is reflected in the current command value without delay using a cosine function, thereby making it possible to appropriately reduce the torque ripple.

[0075] (4) The transfer function is expressed as {s 2 +(6nω) 2}. The motor control device according to (2) or (3). According to this configuration, the sixth-order component of the actual two-phase current of the synchronous motor can be focused on and reflected in the current command value.

[0076] (5) The motor control device according to any one of (1) to (4), wherein the correction value corresponds to a 6n-th order component of the two-phase current value converted by the first conversion means. According to this configuration, it is possible to derive a current command value by focusing on the sixth-order component of the actual two-phase current of the synchronous motor, which is a cause of torque ripple.

[0077] (6) a first calculation step of calculating first two-phase current command values ​​corresponding to a torque command value of the synchronous motor based on an angular velocity of the synchronous motor; a second calculation step of calculating a second two-phase current command value corresponding to a 6n-th order component in a dq rotating coordinate system based on the torque command value and a rotation angle of the synchronous motor; a first conversion step of converting a three-phase current value supplied to the synchronous motor into a two-phase current value based on a rotation angle of the synchronous motor; a derivation step of deriving a first two-phase voltage command value by using a difference between a two-phase current command value obtained by superimposing the first two-phase current command value and the second two-phase current command value and the two-phase current value converted in the first conversion step; a second conversion step of converting the two-phase voltage command values ​​derived in the derivation step into three-phase voltage command values; a supply step of supplying a three-phase voltage to the synchronous motor based on the three-phase voltage command value; having In the deriving step, PI control is performed using the difference to calculate a second two-phase voltage command value; calculating a correction value for the second two-phase voltage command value based on the difference and a rotation angle of the synchronous motor; a correction value for correcting the second two-phase voltage command value, thereby deriving the first two-phase voltage command value. According to this configuration, it is possible to appropriately reduce the torque ripple generated in the AC motor while suppressing the number of functional parts in the device.

[0078] (7) A motor control device according to any one of (1) to (5), a synchronous motor controlled by the motor control device; An electric power steering device comprising: According to this configuration, it is possible to appropriately reduce torque ripple generated in an AC motor mounted in an electric power steering device while suppressing the number of functional units in the motor control device. [Explanation of symbols]

[0079] 1 Steering wheel 2 Steering shaft 3 Reduction gear 4a, 4b Universal joint 5. Pinion rack mechanism 6a,6b Tie rod 7a, 7b Hub unit 8L,8R steering wheels 9 Torsion bar 10 Torque Sensor 11 Ignition (ING) key 12 Vehicle speed sensor 13 Battery 14 Steering angle sensor 20 Steering assist motor (motor) 30 EPS(Electric Power Steering)-ECU(Electronic Control Unit)) 201 Current command value calculation unit 202 nth-order current command value calculation unit 203,205,209,212 Adder 204,206 Subtractor 207,210 PI control unit 208,211 Correction value calculation unit 213 2-phase / 3-phase conversion unit 214 PWM control unit 215 Inverter 216,217,218 Current detection circuit 219 Rotational Angle Sensor 220 3-phase / 2-phase converter 221 Angular velocity calculation section

Claims

1. a first calculation means for calculating a first two-phase current command value corresponding to a torque command value of the synchronous motor based on an angular velocity of the synchronous motor; a second calculation means for calculating a second two-phase current command value corresponding to a 6n-th order component in a dq rotating coordinate system based on the torque command value and a rotation angle of the synchronous motor; a first conversion means for converting a three-phase current value supplied to the synchronous motor into a two-phase current value based on a rotation angle of the synchronous motor; a derivation means for deriving a first two-phase voltage command value by using a difference between a two-phase current command value obtained by superimposing the first two-phase current command value and the second two-phase current command value and the two-phase current value converted by the first conversion means; a second conversion means for converting the first two-phase voltage command value into a three-phase voltage command value; a supply means for supplying a three-phase voltage to the synchronous motor based on the three-phase voltage command value; Equipped with The derivation means is performing PI control using the difference to calculate a second two-phase voltage command value; calculating a correction value for the second two-phase voltage command value based on the difference and the angular velocity of the synchronous motor; a correction value for correcting the second two-phase voltage command value, thereby deriving the first two-phase voltage command value.

2. 2. The motor control device according to claim 1, wherein the deriving means calculates the correction value using a transfer function based on a sine function.

3. 2. The motor control device according to claim 1, wherein the deriving means calculates the correction value by using a transfer function based on a cosine function.

4. The transfer function is expressed as follows: ２ +(6nω) ２ 4. The motor control device according to claim 2, further comprising:

5. 5. The motor control device according to claim 1, wherein the correction value corresponds to a 6n-th order component of the two-phase current value converted by the first conversion means.

6. a first calculation step of calculating a first two-phase current command value corresponding to a torque command value of the synchronous motor based on an angular velocity of the synchronous motor; a second calculation step of calculating a second two-phase current command value corresponding to a 6n-th order component in a dq rotating coordinate system based on the torque command value and a rotation angle of the synchronous motor; a first conversion step of converting a three-phase current value supplied to the synchronous motor into a two-phase current value based on a rotation angle of the synchronous motor; a derivation step of deriving a first two-phase voltage command value by using a difference between a two-phase current command value obtained by superimposing the first two-phase current command value and the second two-phase current command value and the two-phase current value converted in the first conversion step; a second conversion step of converting the first two-phase voltage command value into a three-phase voltage command value; a supply step of supplying a three-phase voltage to the synchronous motor based on the three-phase voltage command value, In the deriving step, performing PI control using the difference to calculate a second two-phase voltage command value; calculating a correction value for the second two-phase voltage command value based on the difference and the angular velocity of the synchronous motor; a correction value for correcting the second two-phase voltage command value, thereby deriving the first two-phase voltage command value.

7. A motor control device according to any one of claims 1 to 5, a synchronous motor controlled by the motor control device; An electric power steering device comprising:

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