Motor control device, motor control method, steering system, and vehicle drive system

Abstract

A motor control device of the present application includes an inverter circuit that drives a motor, and a control section that generates a current command value based on a torque command for the motor, controls the inverter circuit by outputting a PWM pulse to the inverter circuit based on the current command value, sets a phase shift amount of the carrier of the PWM pulse, estimates a fluctuation torque corresponding to the phase shift amount, and corrects the current command value based on the fluctuation torque.

Description

Technical Field

[0001] This invention relates to a motor control device, a motor control method, a steering system, and a vehicle drive system. Background Technology

[0002] A motor consists of a magnetic circuit, including magnets embedded in the rotor and coils wound on the stator. Therefore, the motor generates torque pulsations depending on the shape of the magnetic circuit. Furthermore, the motor is driven by an inverter circuit, and harmonics in the current flowing from the inverter circuit to the motor's coils, due to the inverter circuit's control, also contribute to torque pulsations. It is considered that the pulsations caused by the motor's magnetic circuit can be eliminated by shifting the phase of the carrier wave used in generating the PWM signal used to control the inverter circuit, thereby mitigating the pulsations caused by the inverter circuit's control.

[0003] Patent Document 1 discloses a motor drive control device comprising: a switching unit that converts a DC voltage into a quasi-AC voltage with arbitrary frequency and voltage amplitude; a motor that is driven by the output of the switching unit; and a phase adjustment unit that adjusts the phase of the changing component of the current generated by connecting the switching unit and the motor, wherein the phase adjustment unit adjusts the phase of the changing component of the current in a manner that reduces the inherent torque non-uniformity based on the rotational phase of the motor. Existing technical documents Patent documents

[0004] Patent Document 1: Japanese Patent Application Publication No. 2007-215369 Summary of the Invention The problem the invention aims to solve

[0005] By shifting the phase of the carrier wave, motor pulsation can be reduced, but the motor torque will decrease. Technical means to solve the problem

[0006] The motor control device of the present invention includes: an inverter circuit that drives a motor; and a control unit that generates a current command value based on a torque command for the motor, outputs a PWM pulse to the inverter circuit based on the current command value to control the inverter circuit, the control unit sets a phase shift of the carrier wave of the PWM pulse, infers a variable torque corresponding to the phase shift, and corrects the current command value based on the variable torque. The motor control method of the present invention is a motor control method that generates a current command value based on a torque command for the motor, and outputs a PWM pulse to the inverter circuit based on the current command value to control the inverter circuit. In this method, the phase shift of the carrier wave of the PWM pulse is set, the variable torque corresponding to the phase shift is inferred, and the current command value is corrected based on the variable torque. The effects of the invention

[0007] According to the present invention, motor pulsation can be reduced, and the reduction in motor torque can be suppressed. Attached Figure Description

[0008] Figure 1 This is a system configuration diagram that includes a motor control device. Figure 2 This is a circuit diagram of an inverter circuit. Figure 3 This is a block diagram of the carrier current command control unit. Figure 4 (A) and (B) are examples illustrating the relationship between torque command and current command values. Figure 5 (A) and (B) are examples illustrating the relationship between torque command and current command values. Figure 6 (A) and (B) are examples of carrier waves and PWM pulses. Figure 7 This is a circuit diagram of a boost converter. Figure 8 This is a system configuration diagram of the steering system. Detailed Implementation

[0009] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The following description and drawings are examples for illustrating the present invention, and omissions and simplifications have been made as appropriate to make the description clearer. The present invention can also be implemented in various other forms. Unless otherwise specified, the constituent elements may be singular or plural.

[0010] Figure 1 This is a system configuration diagram including a motor control device 1000. The motor control device 1000 includes an inverter circuit 100 and a control unit 200. DC power is supplied to the inverter circuit 100 from a DC power supply 300 or the like. The inverter circuit 100 consists of three-phase upper and lower arm circuits. Each arm circuit includes a power semiconductor element for switching and a diode. The power semiconductor element switches according to a PWM pulse G output from the control unit 200. The inverter circuit 100 converts the DC power supplied from the DC power supply 300 into AC power through the switching operation of the power semiconductor element, outputting a three-phase AC current. The three-phase AC current output from the inverter circuit 100 is supplied to the motor 400 to drive the motor 400. The motor 400 will be described using a three-phase motor as an example.

[0011] The motor 400 is equipped with a magnetic pole position detector 401 that detects the magnetic pole position θ of the rotor of the motor 400, and the detected magnetic pole position θ of the rotor is output to the control unit 200. In addition, the three-phase alternating current between the inverter circuit 100 and the motor 400 is detected by a current detector 402, and the detected current values ​​Iu, Iv, and Iw of each phase are output to the control unit 200.

[0012] The motor control device 1000, which includes an inverter circuit 100 and a control unit 200, is installed in a vehicle such as an electric vehicle or a hybrid vehicle, for example, along with a DC power supply 300 and a motor 400, to drive the vehicle. Furthermore, in the following description, the traction of the vehicle driven by the motor 400 will be used as an example, but the same applies to regeneration, where the motor 400 functions as a generator.

[0013] The control unit 200 calculates the current command value and voltage command value corresponding to the torque command τ* from the upper control device (not shown) based on the current values ​​Iu, Iv, and Iw detected by the current detector 402 and the rotor magnetic pole position θ detected by the magnetic pole position detector 401. Then, a PWM pulse G generated using the voltage command value and the carrier wave is output to the inverter circuit 100 to drive the power semiconductor elements of the inverter circuit 100. The control unit 200 sets the phase shift of the carrier wave C of the PWM pulse G, infers the variable torque corresponding to the phase shift, and corrects the current command value based on the variable torque, as detailed below.

[0014] The control unit 200 includes a current command value generation unit 210, a dq axis transformation unit 220, a UVW coordinate transformation unit 230, a dq coordinate transformation unit 240, a PWM pulse generation unit 250, and a carrier-current command control unit 260.

[0015] The current command value generation unit 210 converts the input torque command τ* into the d-axis current command value I. d * q-axis current command value I q *. The carrier current command control unit 260, described later, inputs the corrected d-axis current command value I into the current command value generation unit 210. d '*、q-axis current command value I q In the case of '*, the corrected d-axis current command value I will be used. d '*、q-axis current command value I q *As the d-axis current command value I d * q-axis current command value I q * Output.

[0016] The dq-axis transformation unit 220 calculates the d-axis current value I based on the rotor's magnetic pole position θ and the value obtained from the UVW coordinate transformation unit 230. dSet the d-axis current command value i d *Converted to d-axis voltage command value V d * and output to the dq coordinate transformation unit 240. Furthermore, the dq-axis transformation unit 220 calculates the q-axis current value I based on the rotor's magnetic pole position θ and the value obtained from the UVW coordinate transformation unit 230. q Set the q-axis current command value I q *Converted to q-axis voltage command value V q * and output to the dq coordinate transformation unit 240.

[0017] The UVW coordinate transformation unit 230 references the rotor's magnetic pole position θ, transforming the current values ​​Iu, Iv, and Iw detected by the current detector 402 into the d-axis current value I. d and q-axis current value I q And output to the dq axis transformation unit 220. The dq coordinate transformation unit 240 transforms the d-axis voltage command value V d * and q-axis voltage command value V q * The voltage command values ​​Vu, Vv, and Vw for the three phases UVW are converted and output to the PWM pulse generation unit 250.

[0018] The PWM pulse generation unit 250 generates a PWM pulse G based on the carrier C of the triangular wave output from the carrier and current command control unit 260 and the voltage command values ​​Vu, Vv, and Vw. The generated PWM pulse G drives the power semiconductor elements of the inverter circuit 100, which is composed of upper and lower arm circuits of three phases.

[0019] The carrier-current command control unit 260 receives inputs including the DC voltage Dv from the DC power supply 300 or the boost circuit described later, the rotational speed (rotor phase angular velocity) ω of the motor 400, and the torque command τ* from the upper control device. The carrier-current command control unit 260 shifts the phase of the carrier C used in generating the PWM signal for controlling the inverter circuit 100, thereby eliminating pulsations caused by the magnetic circuit of the motor 400 due to the control of the inverter circuit 100. While shifting the phase of the carrier C reduces the pulsations of the motor 400, it also reduces the torque of the motor 400. Therefore, the carrier-current command control unit 260 infers the variable torque corresponding to the phase shift of the shifted carrier C and corrects the current command value based on the variable torque. The generated carrier C is output to the PWM pulse generation unit 250, and the corrected d-axis current command value I... d '*、q-axis current command value I q * Output to current command value generation unit 210.

[0020] Alternatively, the control unit 200 can be configured as a computer equipped with a CPU, memory, etc. In this case, the computer performs processing by executing programs stored in the memory, etc. Furthermore, all or part of the processing can be implemented using hardware logic circuits. Moreover, the program can be pre-stored in a storage medium for provision. Alternatively, the program can be provided via a network connection. It can also be provided in the form of a computer-readable computer program product in various forms, such as data signals.

[0021] Figure 2 This is a circuit diagram of inverter circuit 100. A DC voltage Dv is supplied to the inverter circuit 100 from a DC power supply 300, etc. A smoothing capacitor 101 is provided between the positive terminal P and the negative terminal N. Furthermore, three-phase upper and lower arm circuits 102u, 102v, and 102w are connected between the positive terminal P and the negative terminal N. Each upper and lower arm circuit 102u, 102v, and 102w has two power semiconductor elements 103 that function as switching elements for the upper and lower arms, and a diode 104 connected in parallel with each power semiconductor element 103. The power semiconductor elements 103 are, for example, IGBTs. The power semiconductor elements switch according to the PWM pulse G from the PWM pulse generation unit 250. As a result, the DC voltage Dv is converted into a three-phase AC current, which is output from the upper and lower arm circuits 102u, 102v, and 102w to the windings of each phase of the motor 400 via the AC output lines 105 of each phase.

[0022] Figure 3 This is a block diagram of the carrier current command control unit 260. The carrier and current command control unit 260 includes a carrier frequency selection unit 261, a phase shift setting unit 262, a carrier generation unit 263, a variable torque inference unit 264, and a current command value correction unit 265.

[0023] The rotational speed ω [rpm] and torque command τ* of motor 400 are input to carrier frequency selection unit 261, which outputs carrier frequency fc and the number of synchronization pulses Ps of PWM pulse G. The rotational speed ω, carrier frequency fc, and number of synchronization pulses Ps of motor 400 are related by the following equation (1). Ps=fc / f1=fc / (ω / 60*Pp) · · · (1) Here, f1 is the fundamental frequency of motor 400, and Pp is the number of pole pairs of motor 400. If any two of the motor speed ω, carrier frequency fc, and synchronization pulse number Ps are selected, the other can be calculated according to equation (1). In this example, the speed ω and carrier frequency fc are selected, and the synchronization pulse number Ps is calculated according to equation (1).

[0024] Regarding the carrier frequency fc, many factors must be considered when selecting it, such as the heat generated by the motor 400 and inverter circuit 100, and the computing power of the control unit 200. The upper limit of the carrier frequency is determined by considering these factors, and the carrier frequency fc and the number of synchronization pulses Ps of the PWM pulse G per cycle of the electrical angle are selected in a way that does not exceed the upper limit of the carrier frequency at the current motor 400 speed ω. The carrier frequency fc is basically determined based on the motor 400 speed ω, but in cases where the responsiveness to torque is improved, or in order to suppress the temperature rise of the motor 400 and inverter circuit 100, the carrier frequency fc is appropriately changed using the motor 400 speed ω and the torque command value τ*.

[0025] The number of synchronization pulses Ps is set to a positive integer. More preferably, the number of synchronization pulses Ps is set to a positive integer and an odd number. In this embodiment, synchronous PWM control is performed to control the carrier frequency fc in a manner that is an integer multiple of the frequency of the current flowing to the motor 400. When using asynchronous PWM control to drive the motor 400 to rotate at high speed, the current waveform flowing to the motor 400 does not become a three-phase symmetrical waveform, resulting in electromagnetic force pulsation in the motor 400. With synchronous PWM control, the current waveform flowing to the motor 400 becomes a three-phase symmetrical waveform, so a reduction in electromagnetic force pulsation in the motor 400 can be expected compared to asynchronous PWM control.

[0026] For example, if the upper limit of the carrier frequency fc is 10000Hz and the 8-pole motor rotates at 12000rpm, according to equation (1), the carrier frequency fc with a synchronization pulse number Ps of 15 pulses is fc = Ps * f1 = 15 * 12000 / 60 * (8 / 2) = 12000Hz, which exceeds the upper limit of the carrier frequency fc, so it is not feasible. For example, according to equation (1), the carrier frequency fc with a synchronization pulse number Ps of 9 pulses is fc = 9 * f1 = 9 * 12000 / 60 * (8 / 2) = 7200Hz, which does not exceed the upper limit of the carrier frequency fc, so it is feasible.

[0027] The carrier frequency fc and the number of synchronization pulses Ps of the PWM pulse G are input from the carrier frequency selection unit 261 to the phase shift setting unit 262. Furthermore, the torque command τ* and the DC voltage Dv are input to the phase shift setting unit 262. Using the carrier frequency fc, the number of synchronization pulses Ps, the torque command τ*, and the DC voltage Dv, the relationship between the phase shift fs of the carrier C that minimizes the torque ripple of the motor 400 is determined in advance through simulation or experimentation, and these relationships are stored in the memory within the phase shift setting unit 262 in the form of a graph. The graph can also be stored numerically, and is not limited to a graph. The phase shift setting unit 262 outputs the phase shift fs of the carrier C that minimizes the torque ripple based on the input carrier frequency fc, the number of synchronization pulses Ps, the torque command τ*, and the DC voltage Dv, referring to the graph.

[0028] The pulsation of electromagnetic force generated in motor 400 is due to the change in electromagnetic force generated in the rotor caused by the current flowing from inverter circuit 100 to motor 400. The pulsation of electromagnetic force generated by motor 400 can be roughly divided into a pulsation component generated in the circumferential direction of motor 400, namely torque pulsation, and a pulsation component generated in the radial direction of motor 400, namely electromagnetic excitation force. Phase shift setting unit 262 selects one of the torque pulsation generated in the circumferential direction of motor 400 and the electromagnetic excitation force generated in the radial direction of motor 400, and sets the phase shift fs of carrier C in a manner that reduces the selected torque pulsation or electromagnetic excitation force.

[0029] The carrier generation unit 263 receives a carrier frequency fc selected by the carrier frequency selection unit 261 and a phase shift fs of the carrier C set by the phase shift setting unit 262. Based on the input carrier frequency fc and phase shift fs, it generates a triangular wave carrier C and outputs it to the PWM pulse generation unit 250. Regarding the carrier C, its frequency is the carrier frequency fc, and its phase is shifted by an electrical angle, expressed as the phase shift fs.

[0030] The variable torque estimation unit 264 receives input DC voltage Dv, carrier frequency fc, torque command τ*, motor speed ω, and phase shift fs. Based on these input values, it outputs the variable torque Δτ to the current command value correction unit 265. Using DC voltage Dv, carrier frequency fc, torque command τ*, motor speed ω, and phase shift fs, the relationship between the variable torque Δτ and the reduction in motor torque 400 is pre-determined through simulation or experimentation, and these relationships are stored in the memory within the variable torque estimation unit 264 in the form of a graph. It can also be stored numerically, and is not limited to a graph. The variable torque estimation unit 264 calculates the variable torque Δτ of the motor 400 based on the input DC voltage Dv, carrier frequency fc, torque command τ*, motor speed ω, and phase shift fs, referring to the graph, and outputs it to the current command value correction unit 265. The variable torque Δτ is the amount of torque that has changed compared to the torque of motor 400 under the torque command τ* without shifting the phase of carrier C.

[0031] The current command value correction unit 265 receives input values ​​such as variable torque Δτ, DC voltage Dv, torque command τ*, and motor speed ω of 400. Based on these input values, it corrects the current command value and displays the corrected d-axis current command value I. d '*、q-axis current command value I q * Output to current command value generation unit 210. The variable torque Δτ, DC voltage Dv, torque command τ*, motor speed ω, and d-axis current command value I are pre-determined through simulation or experimentation. d '*、q-axis current command value I q The relationship between the current command and the current command value is determined and stored in the memory of the current command value correction unit 265 in the form of a graph. It can also be stored in numerical form, and is not limited to a graph. Using this graph, the d-axis current command value I is determined in such a way that the output torque of the motor 400 matches the output torque under the torque command τ* without phase shifting of the carrier wave C. d '*、q-axis current command value I q '*.

[0032] Figure 4 (A) Figure 4 (B) is a diagram showing the relationship between the torque command τ* and the current command value. Figure 4 Figure (A) shows the relationship between the rotational speed ω and output torque of motor 400 and the torque command τa*. The horizontal axis represents the rotational speed ω of motor 400, and the vertical axis represents the output torque. It illustrates the situation where the torque command τa* is in the low range of the motor 400's rotational speed ω. The torque command τa* is within the range M in which motor 400 can operate.

[0033] Figure 4 In (B), the horizontal axis represents the d-axis current command value, and the vertical axis represents the q-axis current command value. Corresponding to the torque command τa*, when the phase of the carrier C is shifted, the current command value A (d-axis current command value Ida*, q-axis current command value Iqa*) is output; when the phase of the carrier C is not shifted, the current command value A' (d-axis current command value Ida*', q-axis current command value Iqa*') is output. When the phase of the carrier C is shifted, the current command value correction unit 265 corrects the amplitude of the vector of the current command value A in the region of low rotational speed ω by transforming it into a vector of the current command value A'.

[0034] Figure 5 (A) Figure 5 (B) is a diagram showing the relationship between the torque command τ* and the current command value. Figure 5 Figure (A) shows the relationship between the motor 400's rotational speed ω and output torque and the torque command τb*. The horizontal axis represents the motor 400's rotational speed ω, and the vertical axis represents the output torque. It illustrates the case where the torque command τb* is in the region where the motor 400's rotational speed ω is high.

[0035] Figure 5 In (B), the horizontal axis represents the d-axis current command value, and the vertical axis represents the q-axis current command value. Corresponding to the torque command τb*, when the phase of the carrier C is shifted, the current command value B (d-axis current command value Idb*, q-axis current command value Iqb*) is output; when the phase of the carrier C is not shifted, the current command value B' (d-axis current command value Idb*', q-axis current command value Iqb*') is output. When the phase of the carrier C is shifted, voltage limitation occurs in the region of high rotational speed ω, so the current command value correction unit 265 corrects the amplitude and phase of the vector of the current command value B by transforming it into a vector of the current command value B'.

[0036] In the region where the motor 400's rotational speed ω is low, the current command value correction unit 265... Figure 4 (A) Figure 4 As shown in (B), the amplitude of the vector of the current command value A is corrected in a way that transforms into a vector of the current command value A'. In the region of high motor speed ω at 400, like... Figure 5 (A) Figure 5 As shown in (B), the amplitude and phase of the vector of the current command value B are corrected in a way that transforms it into a vector of the current command value B'. In other words, the current command value correction unit 265 changes the ratio of the d-axis current command value to the q-axis current command value based on the rotational speed ω of the motor 400.

[0037] When the phase shift of carrier C is shifted to reduce torque ripple, the output torque of motor 400 tends to decrease when the speed ω of motor 400 is high and the torque command τb* is low. In this case, the current command value is also corrected according to the phase shift fs, so the desired torque can be ensured while reducing torque ripple.

[0038] Figure 6 (A) Figure 6 (B) is a diagram showing the carrier C and PWM pulse G. Figure 6 (A) shows a carrier C with a synchronization pulse count Ps of 9 pulses per cycle for the electrical angle. The phase of carrier C is shifted by an electrical angle degree, expressed as a phase shift fs. The phase shift fs is the value at which torque ripple reaches its minimum. Figure 6 In (A), the dashed line represents the d-axis current command value I after correction by the current command value correction unit 265. d '*、q-axis current command value I q The voltage command value Vu for the U phase is represented by '*'. Additionally, the uncorrected d-axis current command value I is represented by a solid line. d * q-axis current command value I q The voltage command value Vu for phase U is shown in the diagram. Only phase U is shown; the voltage command values ​​for phase V and phase W are omitted. With the electrical angle cycle set to 360 degrees, the voltage command values ​​for phases U, V, and W are offset by 120 degrees from each other.

[0039] Figure 6 (A) shows the carrier C after its phase has been shifted and the voltage command value Vu. When the voltage command value Vu before the phase shift of the carrier C is used for current control after the phase shift of the carrier C has been shifted, the pulsation of the motor 400 can be reduced, but the torque of the motor 400 is reduced.

[0040] The carrier-current command control unit 260 infers the variable torque Δτ corresponding to the phase shift fs of the carrier C, and corrects the current command value to the d-axis current command value I based on the variable torque Δτ. d '*、q-axis current command value I q *. Corrected d-axis current command value I d '*、q-axis current command value I q The current command value is input to the current command value generation unit 210, which then converts the input modified d-axis current command value I... d '*、q-axis current command value I q *Output. Then, in the dq-axis conversion unit 220, it is converted into the d-axis voltage command value V. d * q-axis voltage command value V q* and is transformed into a voltage command value in the dq coordinate transformation unit 240. As a result, the amplitude of the voltage command value Vu' is increased in a manner consistent with the output torque under the torque command τ* without shifting the phase of the carrier C. Figure 6 The voltage command value Vu' of (A) indicates this state. This example demonstrates a reference... Figure 4 This is an example where the amplitude of the vector of the current command value A is corrected in a way that transforms into a vector of the current command value A', while the phase remains unchanged.

[0041] like Figure 6 As shown in (B), the PWM pulse generation unit 250 compares the voltage command value Vu' with the carrier wave C to generate a PWM pulse G. Since the amplitude of the voltage command value Vu' is larger than that of the voltage command value Vu, the pulse width of the PWM pulse G also increases. With the help of the inverter circuit 100 driven by this PWM pulse G, the alternating current flowing to the motor 400 also increases, thereby increasing the output torque of the motor 400. This reduces the pulsation of the motor 400 and suppresses the decrease in the torque of the motor 400.

[0042] Furthermore, when the amplitude of the carrier wave C is set to Eb and the amplitude of the voltage command values ​​V (Vu', Vv', Vw') is set to Es, the voltage amplitude ratio M is expressed as Es / Eb. The amplitude Eb of the carrier wave C is consistent with the upper limit of the DC voltage Dv. The amplitude Es of the voltage command value V is determined by the corrected current command value A'. The current command value correction unit 265 sets the corrected current command value A' in such a way that the amplitude Es of the voltage command value V does not exceed the amplitude Eb of the carrier wave C, that is, the corrected current command value A' is set to an appropriate value that the PWM pulse G can drive the power semiconductor elements 103 of the upper and lower arm circuits of the inverter circuit 100. In other words, the current command value correction unit 265 sets the current command value A' based on the voltage amplitude ratio M of the amplitude of the DC voltage Dv input to the inverter circuit 100 and the amplitude of the output voltage command value V.

[0043] Figure 7 This is a circuit diagram of the boost circuit 310. The boost circuit 310 is located between the DC power supply 300 and the inverter circuit 100 to boost the DC voltage of the DC power supply 300 and supply DC power to the inverter circuit 100. In addition, the boost circuit 310 is provided as appropriate, taking into account factors such as the modulation rate M, and is not mandatory.

[0044] The boost circuit 310 connects the switching elements 311 and 312 in series, and the DC power supply 300 is connected to the intermediate connection point of the series-connected switching elements 311 and 312 via the reactor 313. In addition, the capacitor 314 is connected in parallel with the DC power supply 300.

[0045] The boost circuit 310 receives commands from the control unit 200, causing the switching elements 311 and 312 to switch, thereby boosting the DC voltage supplied from the DC power supply 300 to the optimal DC voltage Dv for the motor control device 1000. The boosted DC voltage Dv is then supplied to the inverter circuit 100. The inverter circuit 100 operates according to the PWM pulse G output from the control unit 200, performing power conversion from the boosted DC voltage to AC voltage.

[0046] Figure 8 This is a system configuration diagram of the steering system 500. Figure 8 The example shown is an application of the motor control device 1000 of this embodiment to the steering system 500.

[0047] The steering system 500 includes a drive control system 502 comprising a DC power supply 300, a motor control device 1000, and a motor 400. The steering system 500 detects the rotational torque of the steering wheel 503 using a torque sensor 504, and actuates the drive control system 502 based on this torque. This generates an auxiliary torque corresponding to the input of the steering wheel 503, which is output to the steering mechanism 506 via a steering assist mechanism 505, thereby assisting the steering force. As a result, the steering mechanism 506 causes the tires 507 to turn, thereby controlling the vehicle's direction of travel.

[0048] The vehicle's steering system 500 is typically directly connected to the driver via the steering wheel 503, so vibrations and noise caused by the pulsation of the motor 400 are easily transmitted to the driver. By using the motor control device 1000 of this embodiment, the pulsation of the motor 400 can be reduced, and the reduction in the torque of the motor 400 can be suppressed.

[0049] Figure 8 The example shown is an application of the motor control device 1000 of this embodiment to a steering system 500, but it can also be applied to vehicle drive systems such as electric vehicles and hybrid vehicles. In the case of an electric vehicle, the vehicle drive system includes a motor 400 controlled by the motor control device 1000, which drives the vehicle. In the case of a hybrid vehicle, the vehicle drive system includes an internal combustion engine that drives the vehicle and a motor 400 controlled by the motor control device 1000, and the vehicle is driven by the motor 400 and the internal combustion engine. In both cases, the pulsation of the motor 400 can be reduced, and the reduction in the torque of the motor 400 can be suppressed.

[0050] Based on the implementation methods described above, the following effects are achieved. (1) The motor control device 1000 includes: an inverter circuit 100 that drives a motor 400; and a control unit 200 that generates a current command value I based on a torque command τ* to the motor 400. d *、I q *, based on the current command value I d *、I q * The inverter circuit 100 is controlled by outputting a PWM pulse G. The control unit 200 sets the phase shift fs of the carrier C of the PWM pulse G, infers the corresponding change torque Δτ, and corrects the current command value I based on the change torque Δτ. d '*、I q This reduces motor pulsation and suppresses the decrease in motor torque.

[0051] (2) The motor control method is to generate a current command value I based on the torque command τ* of the motor 400. d *、I q *and according to the current command value I d *、I q *A method for controlling the motor of inverter circuit 100 by outputting a PWM pulse G to inverter circuit 100, wherein the phase shift fs of the carrier C of PWM pulse G is set, the corresponding change torque Δτ is inferred, and the current command value I is corrected based on the change torque Δτ. d '*、I q This reduces motor pulsation and suppresses the decrease in motor torque.

[0052] This invention is not limited to the embodiments described above. Other forms conceived within the scope of the technical concept of this invention are also included within the scope of this invention, as long as they do not impair the characteristics of this invention. Furthermore, it may also be configured as a combination of the above embodiments and application examples. Symbol Explanation

[0053] 100…Inverter circuit, 101…Smoothing capacitor, 102u, 102v, 102w…Upper and lower arm circuits, 103…Power semiconductor element, 104…Diode, 105…AC output line, 200…Control unit, 210…Current command value generation unit, 220…dq axis transformation unit, 230…UVW coordinate transformation unit, 240…dq coordinate transformation unit, 250…PWM pulse generation unit, 260…Carrier current command control unit, 261…Carrier frequency selection unit Selection unit, 262… Phase shift setting unit, 263… Carrier generation unit, 264… Variable torque inference unit, 265… Current command value correction unit, 300… DC power supply, 400… Motor, 401… Magnetic pole position detector, 402… Current detector, 1000… Motor control device, Iu, Iv, Iw… Current value, τ*… Torque command, G… PWM pulse, C… Carrier, fc… Carrier frequency, Ps… Number of synchronization pulses, fs… Phase shift, Δτ… Variable torque, I… d *、I d '*…d-axis current command value, I q *、I q *...q-axis current command value, Vu, Vv, Vw...voltage command value, I d …d-axis current value, I q …q-axis current value, θ… magnetic pole position.

Claims

1. A motor control device, characterized in that, have: Inverter circuit, which drives the motor; and The control unit generates a current command value based on the torque command given to the motor, and outputs PWM pulses to the inverter circuit based on the current command value to control the inverter circuit. The control unit sets the phase shift of the carrier of the PWM pulse, infers the variable torque corresponding to the phase shift of the carrier of the PWM pulse, and corrects the current command value based on the variable torque.

2. The motor control device according to claim 1, characterized in that, The control unit includes a carrier frequency selection unit, which selects the carrier frequency of the carrier and the number of synchronization pulses of the PWM pulse per electrical angle cycle. The carrier frequency selection unit sets the number of synchronization pulses to a positive integer.

3. The motor control device according to claim 2, characterized in that, The carrier frequency selection unit sets the number of synchronization pulses to an odd number.

4. The motor control device according to claim 2, characterized in that, The control unit includes a phase shift setting unit, which sets the phase shift amount based on the DC voltage input to the inverter circuit, the number of synchronization pulses, the carrier frequency, and the torque command. The phase shift setting unit selects either the torque pulsation generated in the circumferential direction of the motor or the electromagnetic excitation force generated in the radial direction of the motor, and sets the phase shift in a manner that reduces the selected torque pulsation or electromagnetic excitation force.

5. The motor control device according to claim 4, characterized in that, The control unit includes a variable torque inference unit, which infers the variable torque based on the DC voltage input to the inverter circuit, the carrier frequency, the torque command, the motor speed, and the phase shift.

6. The motor control device according to claim 5, characterized in that, The control unit includes a carrier generation unit, which generates the carrier based on the carrier frequency and the phase shift.

7. The motor control device according to claim 6, characterized in that, The control unit includes a current command value correction unit, which corrects the current command value based on the DC voltage input to the inverter circuit, the speed of the motor, the torque command, and the variable torque.

8. The motor control device according to claim 7, characterized in that, The current command value correction unit changes the ratio of the d-axis current command value to the q-axis current command value according to the rotational speed of the motor.

9. The motor control device according to claim 7, characterized in that, The current command value correction unit sets the current command value based on the voltage amplitude ratio between the amplitude of the DC voltage input to the inverter circuit and the amplitude of the output voltage command value.

10. The motor control device according to claim 1, characterized in that, have: A DC power supply that supplies DC voltage to the inverter circuit; and A boost circuit that boosts the DC voltage of the DC power supply.

11. A steering system, characterized in that, have: The motor control device according to any one of claims 1 to 10; and The motor is controlled by the motor control device. The motor controls the vehicle's steering.

12. A vehicle drive system, characterized in that, have: The motor control device according to any one of claims 1 to 10; and The motor is controlled by the motor control device. The motor controls the drive of the vehicle.

13. A vehicle drive system, characterized in that, have: The motor control device according to any one of claims 1 to 10; Internal combustion engine; and The motor is controlled by the motor control device. The vehicle drive system uses the motor and the internal combustion engine to drive and control the vehicle.

14. A motor control method, comprising generating a current command value based on a torque command for a motor, and controlling the inverter circuit by outputting PWM pulses to an inverter circuit based on the current command value, characterized in that, The phase shift of the carrier wave of the PWM pulse is set, the variable torque corresponding to the phase shift of the carrier wave of the PWM pulse is inferred, and the current command value is corrected according to the variable torque.

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