Motor control device and motor control method

Abstract

This motor control device is connected to a power converter for converting power from direct current power to alternating current power, and controls the driving of a motor that is driven using the alternating current power. The motor control device comprises: a carrier wave generator that generates a carrier wave; a carrier wave frequency adjuster that adjusts the frequency of the carrier wave; and a gate signal generator that uses the carrier wave to pulse width modulate a voltage command according to a torque command, and generates a gate signal for controlling the operation of the power converter. The carrier wave frequency adjuster adjusts the frequency of the carrier wave in accordance with the torque command and a rotational speed of the motor such that the phase of pulsed torque caused by command current generated by the pulse width modulation using the carrier wave overlaps, within a prescribed phase difference, the phase of pulsed torque caused by the interlinkage flux of the motor.

Description

[Technical Field]

[0001] The present invention relates to a motor control device and a motor control method. [Background technology]

[0002] A motor is composed of magnetic flux linkages such as magnets embedded in the rotor and coils wound around the stator. Therefore, torque pulsation occurs in the motor depending on the shape of the magnetic flux linkages. Furthermore, motors are driven by inverter circuits, and torque pulsation is also generated by harmonics contained in the current flowing from the inverter circuit to the motor coils due to control by the inverter circuit's pulse width modulation.

[0003] Patent Document 1 discloses a device that adjusts a carrier frequency fc to reduce pulsating torque by changing a voltage phase error Δθv that represents the phase difference between three-phase voltage commands Vu*, Vv*, Vw* and a triangular wave signal Tr based on a torque command T* and a motor rotation speed ωr. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2021-83276 Summary of the Invention [Problem to be solved by the invention]

[0005] The device disclosed in Patent Document 1 has a problem in that the torque of the motor decreases. [Means for solving the problem]

[0006] A motor control device according to the present invention is connected to a power converter that converts DC power to AC power, and controls driving of a motor that is driven using the AC power, and includes a carrier wave generation unit that generates a carrier wave, a carrier wave frequency adjustment unit that adjusts the frequency of the carrier wave, and a gate signal generation unit that pulse-width modulates a voltage command corresponding to a torque command using the carrier wave to generate a gate signal for controlling operation of the power converter, and the torque output from the motor when the motor is driven includes a first pulsating torque generated due to magnetic flux linkage of the motor, ,before and a second pulsating torque generated due to a harmonic component of a current supplied to the motor in response to control of the power converter by the gate signal, and the carrier wave frequency adjusting unit adjusts the frequency of the carrier wave in response to the torque command and the rotation speed of the motor so that the phase of the second pulsating torque overlaps the phase of the first pulsating torque within a predetermined phase difference. The predetermined phase difference is within the range of ±30 degrees. . A motor control method according to the present invention is a motor control method in a motor control device connected to a power converter that converts DC power to AC power and controls driving of a motor that is driven using the AC power, the method comprising the steps of generating a carrier wave, adjusting a frequency of the carrier wave, pulse-width modulating a voltage command corresponding to a torque command using the carrier wave, generating a gate signal for controlling operation of the power converter, and controlling a torque output from the motor by driving the motor to include a first pulsating torque generated due to magnetic flux linkage of the motor and a second pulsating torque generated due to magnetic flux linkage of the motor. ,before a second pulsating torque generated due to harmonic components of a current supplied to the motor in response to control of the power converter by the gate signal, and a phase of the second pulsating torque is adjusted to match a phase of the first pulsating torque in response to the torque command and a rotation speed of the motor. Within ±30 degrees The frequency of the carrier wave is adjusted so that the two signals overlap. [Effects of the Invention]

[0007] According to the present invention, the torque of the motor can be increased as needed. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a system configuration diagram of a motor control device. [Figure 2] FIG. 2 is a diagram illustrating the configuration of an inverter circuit. [Figure 3] 1A and 1B are diagrams illustrating pulsating torque. [Figure 4] FIG. 2 is a block diagram of a carrier frequency adjustment unit. [Figure 5] FIG. 4 is a block diagram of a voltage phase error calculation unit. [Figure 6] FIG. 10 is a diagram showing a torque boost phase difference table according to Example 1. [Figure 7] FIG. 10 is a diagram showing a torque boost phase difference table according to Example 2. [Figure 8] FIG. 10 is a block diagram of a voltage phase error calculation unit in Modification 1. [Figure 9] FIG. 10 is a block diagram of a voltage phase error calculation unit in Modification 2. [Figure 10] FIG. 10 is a diagram showing a torque boost phase difference table according to Example 3. [Figure 11] FIG. 11 is a block diagram of a voltage phase error calculation unit in Modification 3. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The following description and drawings are examples for explaining the present invention, and some omissions and simplifications have been made as appropriate for clarity of explanation. The present invention can be implemented in various other forms. Unless otherwise specified, each component may be singular or plural.

[0010] FIG. 1 is a system configuration diagram of a motor control device 1000. The motor control device 1000 includes an inverter circuit 100 and a control unit 200. The inverter circuit 100 is a power converter that converts DC power into AC power. The inverter circuit 100 is composed of upper and lower arm circuits for three phases. Each arm circuit includes a switching power semiconductor element and a diode. The power semiconductor element performs a switching operation in response to a gate signal G output from the control unit 200. Through the switching operation of the power semiconductor element, the inverter circuit 100 converts DC power supplied from a DC power supply 300 into AC power and outputs three-phase AC current. The DC power supply 300 is, for example, a secondary battery such as a battery. The three-phase AC current output from the inverter circuit 100 is supplied to a motor 400 to drive the motor 400. The motor 400 will be described using an example of a three-phase motor.

[0011] The motor 400 is provided with a position detector 401 that detects a rotational position θ of the motor 400, and the detected rotational position θ is output to the control unit 200. Furthermore, the three-phase AC 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] A motor control device 1000 including an inverter circuit 100 and a control unit 200 is mounted on a vehicle such as an electric vehicle or a hybrid vehicle together with a DC power supply 300 and a motor 400 to drive the vehicle. Note that the following description will be given taking as an example a power running operation in which the vehicle is driven by the motor 400, but the same applies to a regenerative operation in which the motor 400 functions as a generator.

[0013] The control unit 200 calculates a voltage command value according to a torque command T* from a higher-level control device (not shown) by referring to the current values ​​Iu, Iv, and Iw detected by the current detector 402 and the rotational position θ detected by the position detector 401. Then, the control unit 200 outputs a gate signal G generated from the voltage command value and the carrier wave to the inverter circuit 100.

[0014] The control unit 200 includes a current command value generation unit 210, a dq axis conversion unit 220, a UVW coordinate conversion unit 230, a dq coordinate conversion unit 240, a speed calculation unit 250, a gate signal generation unit 260, a carrier frequency adjustment unit 270, and a carrier generation unit 280.

[0015] The current command value generating unit 210 receives the DC voltage value Dv supplied to the inverter circuit 100, the rotation speed ωr of the motor 400, and the torque command T*, and converts the input torque command T* into a d-axis current command value I d *, q-axis current command value I q Convert to *.

[0016] The dq axis conversion unit 220 converts the rotational position θ of the motor 400 and the d axis current value I obtained by the UVW coordinate conversion unit 230. d Based on this, the d-axis current command value I d * is the d-axis voltage command value V d * and outputs it to the dq coordinate transformation unit 240. Furthermore, the dq axis transformation unit 220 converts the rotational position θ and the q axis current value I q Based on this, the q-axis current command value I q * is the q-axis voltage command value V q * and outputs it to the dq coordinate transformation unit 240.

[0017] The UVW coordinate conversion unit 230 converts the current values ​​Iu, Iv, and Iw detected by the current detector 402 into a d-axis current value I d and the q-axis current value I q and outputs it to the dq-axis transformation unit 220. The dq coordinate conversion unit 240 receives the d-axis voltage command value V d * and the q-axis voltage command value V q * and the rotational position θ are input, and the d-axis voltage command value V d * and the q-axis voltage command value V q * is converted into three-phase voltage command values ​​Vu, Vv, and Vw of the UVW phases, and output to the gate signal generating unit 260.

[0018] The speed calculation unit 250 calculates the motor rotation speed ωr, which indicates the rotation speed (number of rotations) of the motor 400, from the change over time of the rotation position θ. The motor rotation speed ωr may be a value expressed as either an angular velocity (rad / s) or a number of rotations (rpm). These values ​​may also be converted into each other and used.

[0019] The gate signal generating unit 260 compares the carrier wave Tr output from the carrier wave generating unit 280 with the voltage command values ​​Vu, Vv, and Vw, and generates a gate signal G consisting of a PWM pulse. In other words, the gate signal generating unit 260 pulse-width modulates the voltage commands Vu, Vv, and Vw corresponding to the torque command T* using the carrier wave Tr, and generates the gate signal G for controlling the operation of the inverter circuit 100.

[0020] The carrier frequency adjuster 270 adjusts the rotation speed (rotor phase angle speed) ωr of the motor 400 and the d-axis voltage command value V d * and the q-axis voltage command value V q The inverter 100 outputs a carrier frequency fc for shifting the phase of the carrier wave used to generate the gate signal G based on the torque command T*, the rotational position θ, the DC voltage value Dv, and the torque command T*.

[0021] The carrier wave generating unit 280 generates a carrier wave Tr having a triangular waveform based on the carrier wave frequency fc and outputs it to the gate signal generating unit 260. The gate signal generating unit 260 compares the carrier wave Tr with the voltage command values ​​Vu, Vv, and Vw, and generates a gate signal G consisting of PWM pulses.

[0022] Although the control unit 200 has been described as being configured with multiple blocks, the control unit 200 may also be configured with a computer equipped with a CPU, memory, etc. In this case, the computer performs processing by executing a program stored in the memory, etc. Furthermore, all or part of the processing of the multiple blocks may be realized by a hard logic circuit. Furthermore, the program may be provided by being stored in a storage medium in advance. Alternatively, the program may be provided via a network line. It may also be provided as a computer-readable computer program product in various forms, such as a data signal.

[0023] FIG. 2 is a diagram showing the configuration of the inverter circuit 100. The voltage between the positive electrode P and the negative electrode N on the input side of the inverter circuit 100 is detected by a voltage detector (not shown), and the detected value is a DC voltage value Dv. A smoothing capacitor 101 is provided between the positive electrode P and the negative electrode N. Furthermore, upper and lower arm circuits 102u, 102v, and 102w for three phases are connected between the positive electrode P and the negative electrode N. Each of the upper and lower arm circuits 102u, 102v, and 102w includes two power semiconductor elements 103 functioning as switching elements for the upper and lower arms, and a diode 104 provided in parallel with each power semiconductor element 103. The power semiconductor elements 103 are, for example, IGBTs. The power semiconductor elements perform switching operations in response to a gate signal G from a gate signal generating unit 260. As a result, the DC voltage value 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.

[0024] The causes of electromagnetic force pulsation in motor 400 depend on the number of flux linkages and current, which depend on the motor magnetic circuit consisting of the stator core, stator coil, rotor core, and rotor magnet of motor 400. Specifically, it is pulsation caused by fundamental wave current corresponding to three-phase voltage commands Vu*, Vv*, and Vw*, i.e., pulsation of each harmonic component of the fundamental wave current whose order is a multiple of six. This pulsation can be divided into pulsation torque, which is a pulsation component generated in the circumferential direction of motor 400, and electromagnetic excitation force, which is a pulsation component generated in the radial direction of motor 400. Hereinafter, this pulsation torque will be referred to as pulsation torque caused by flux linkages.

[0025] Furthermore, another cause of pulsation of electromagnetic force in motor 400 is due to changes in electromagnetic force caused by harmonics contained in the current passed from inverter circuit 100 to the coils of motor 400 due to control by pulse width modulation of inverter circuit 100. Specifically, among the harmonic components of the command current generated by pulse width modulation using a carrier wave, each harmonic component with an order that is a multiple of six generates pulsating torque. Hereinafter, this pulsating torque will be referred to as pulsating torque caused by the command current.

[0026] The carrier frequency adjuster 270 adjusts the carrier frequency fc of the carrier wave Tr as described above. By adjusting the frequency of the carrier wave Tr, the phase of the pulsating torque caused by the command current is changed. In this embodiment, for example, the frequency of the carrier wave Tr is adjusted in accordance with the torque command T* and the rotational speed ωr of the motor 400 so that the pulsating torque caused by the command current is superimposed on the pulsating torque caused by the motor's flux linkage. The overlap between the pulsating torque caused by the command current and the pulsating torque caused by the motor's flux linkage is such that the phase difference between the pulsating torques is within a range of ±30 degrees, for example. This allows the torque of the motor 400 to be increased as needed.

[0027] Figures 3(A) and 3(B) are diagrams showing pulsating torque. The horizontal axis represents time, and the vertical axis represents torque. Figure 3(A) shows the pulsating torque when the phase of the pulsating torque due to the command current is not changed, while Figure 3(B) shows the case when the phase of the pulsating torque due to the command current is changed to match the phase of the pulsating torque due to the interlinkage magnetic flux. Both pulsating torques represent pulsating torque due to 6Nth-order (N is a natural number) harmonic components.

[0028] As shown in Figure 3(A), the pulsating torque ti1 due to the command current is out of phase with the pulsating torque t0 due to the flux linkage. Therefore, a torque t1, which is a combination of these pulsating torques, appears as the pulsating torque of the motor 400. The pulsating torque causes noise and vibration in the motor 400. The average torque of the motor 400 in this case is designated as T1.

[0029] Next, the phase of the pulsating torque ti1 due to the command current is changed to pulsating torque ti2 as shown in FIG. 3B, and this is perfectly matched to the phase of the pulsating torque t0 due to the flux linkage. In this case, torque t2, which is a combination of these pulsating torques, appears as the pulsating torque. The amplitude of torque t2 is greater than the amplitude of torque t1. The average torque T2 of the motor 400 is then greater than the average torque T1. In this embodiment, under circumstances where noise and vibration of the motor 400 are not a concern or where increasing the torque of the motor 400 is a priority, the phase of pulsating torque ti1 due to the command current is changed as appropriate to increase the torque of the motor 400.

[0030] While Fig. 3(B) shows an example in which the phase of the pulsating torque ti1 due to the command current is perfectly matched to the phase of the pulsating torque t0 due to the flux linkage, it is sufficient if the phase difference between the two is within ±30 degrees. By appropriately setting the phase difference within this range, the magnitude of the torque to be boosted can be adjusted.

[0031] 4 is a block diagram of carrier frequency adjuster 270. Carrier frequency adjuster 270 includes synchronous PWM carrier number selector 271, voltage phase calculator 272, modulation factor calculator 273, voltage phase error calculator 274, synchronous carrier frequency calculator 275, and carrier frequency setting unit 276.

[0032] The synchronous PWM carrier number selection unit 271 selects the synchronous PWM carrier number Nc, which represents the number of carrier waves Tr per cycle of the voltage waveform in synchronous PWM control, based on the rotation speed ωr. For example, the synchronous PWM carrier number selection unit 271 selects the synchronous PWM carrier number Nc so that the value of Nc±3 or Nc×2 matches the order (a multiple of 6) of the pulsating torque caused by the flux linkage. Specifically, for example, if the rotation speed ωr is less than a predetermined threshold, Nc=15, and if the rotation speed ωr is equal to or greater than the threshold, Nc=9. This allows the synchronous PWM carrier number Nc, which corresponds to the order of the pulsating torque caused by the flux linkage of the motor 400, to be set to an optimal value depending on the rotation speed ωr.

[0033] The synchronous PWM carrier number selector 271 may select the synchronous PWM carrier number Nc based on not only the rotation speed ωr but also the torque command T*. Also, the selection criteria for the synchronous PWM carrier number Nc may be changed depending on whether the rotation speed ωr increases or decreases, for example, by setting hysteresis.

[0034] The voltage phase calculation unit 272 calculates the voltage phase θv based on the d-axis voltage command Vd*, the q-axis voltage command Vq*, the rotational position θ, the rotational speed ωr, and the carrier frequency fc using the following equations (1) to (4). θv=θ+φv+φdqv+0.5π ···(1) φv=ωr·1.5Tc ···(2) Tc=1 / fc (3) φdqv=atan(Vq / Vd) (4)

[0035] Here, φv represents a calculation delay compensation value for the voltage phase, Tc represents the carrier wave period, and φdqv represents the voltage phase from the d-axis. The calculation delay compensation value φv is a value that compensates for the calculation delay of 1.5 control periods that occurs between when the position detector 401 acquires the rotational position θ and when the control unit 200 outputs a gate signal to the inverter circuit 100. In this embodiment, 0.5π is added to the fourth term on the right side of equation (1). This is a calculation to convert the voltage phase calculated in the first to third terms on the right side of equation (1) into a sine wave, since the voltage phase is a cosine wave.

[0036] The modulation factor calculation unit 273 calculates the modulation factor H based on the d-axis voltage command Vd*, the q-axis voltage command Vq*, and the DC voltage value Dv according to the following equation (5). Note that the modulation factor H represents the voltage amplitude ratio between the DC power supplied from the DC power supply 300 to the inverter circuit 100 and the AC power output from the inverter circuit 100 to the motor 400. H=√(Vd^2+Vq^2) / (Dv / 2) ···(5)

[0037] Voltage phase error calculation unit 274 calculates a voltage phase error Δθv based on the synchronized PWM carrier number Nc selected by synchronized PWM carrier number selection unit 271, the voltage phase θv calculated by voltage phase calculation unit 272, the modulation factor H calculated by modulation factor calculation unit 273, the rotation speed ωr, and the torque command T*. The voltage phase error Δθv represents the phase difference between three-phase voltage commands Vu*, Vv*, Vw*, which are voltage commands for inverter circuit 100, and a carrier wave Tr used for pulse width modulation. By voltage phase error calculation unit 274 calculating the voltage phase error Δθv at each predetermined calculation period, carrier frequency adjustment unit 270 can adjust the frequency of carrier wave Tr so as to change the phase difference between the voltage command for inverter circuit 100 and carrier wave Tr used for pulse width modulation.

[0038] The synchronous carrier frequency calculation unit 275 calculates the synchronous carrier frequency fcs based on the voltage phase error Δθv calculated by the voltage phase error calculation unit 274, the rotation speed ωr, and the synchronous PWM carrier number Nc selected by the synchronous PWM carrier number selection unit 271, according to the following equation (6). fcs=ωr·Nc·(1+Δθv·K) / (2π)···(6)

[0039] The synchronous carrier frequency calculation unit 275 can calculate the synchronous carrier frequency fcs based on equation (6) by, for example, PLL (Phase Locked Loop) control. Note that in equation (6), the gain K may be a constant value or may be variable depending on conditions.

[0040] The carrier frequency setting unit 276 selects either the synchronous carrier frequency fcs calculated by the synchronous carrier frequency calculation unit 275 or the asynchronous carrier frequency fcns based on the rotation speed ωr, and outputs the selected frequency as the carrier frequency fc. The asynchronous carrier frequency fcns is a constant value set in advance in the carrier frequency setting unit 276. Note that a plurality of asynchronous carrier frequencies fcns may be prepared in advance, and one of these may be selected according to the rotation speed ωr. For example, the carrier frequency setting unit 276 may select the asynchronous carrier frequency fcns and output it as the carrier frequency fc so that the value of the asynchronous carrier frequency fcns increases as the value of the rotation speed ωr increases.

[0041] 5 is a block diagram of the voltage phase error calculation unit 274. The voltage phase error calculation unit 274 includes a reference voltage phase calculation unit 2741, an adder 2742, a subtracter 2743, a torque boost phase difference table 2744a, and a phase difference converter 2745.

[0042] The reference voltage phase calculation unit 2741 calculates a reference voltage phase θvb for fixing the phase of the carrier wave Tr in synchronous PWM control based on the synchronous PWM carrier number Nc and the voltage phase θv. Specifically, the reference voltage phase calculation unit 2741 calculates the reference voltage phase θvb based on the voltage phase θv and the synchronous PWM carrier number Nc in accordance with the following equations (7) and (8). θvb=int(θv / θs)·θs+0.5θs ···(7) θs=2π / Nc (8)

[0043] Here, θs represents the variation width of the voltage phase θv per carrier wave, and int represents the rounding down operation. By calculating the reference voltage phase θvb by the reference voltage phase calculation unit 2741, the period of the carrier wave Tr relative to the voltage phase θv and the period of the pulsating torque due to the interlinkage magnetic flux can be made to match each other.

[0044] The torque boost phase difference table 2744a is a table that indicates the phase difference for superimposing the pulsating torque due to the command current on the pulsating torque due to the flux linkage of the motor 400. Here, the phase difference means the phase difference with respect to the reference voltage phase θvb. This table is set for each of a plurality of values ​​of the rotation speed ωr, the torque command T*, and the modulation factor H. The voltage phase error calculation unit 274 refers to these tables based on the rotation speed ωr, the torque command T*, and the modulation factor H to identify the phase difference for boosting the torque.

[0045] For example, by simulation or actual measurement, phase difference data with respect to the reference voltage phase θvb for superimposing the pulsating torque due to the command current on the pulsating torque due to the flux linkage of the motor 400 is acquired in advance for each rotational speed ωr, torque command T*, and modulation factor H. The torque boost phase difference table 2744a is set based on the previously acquired phase difference data. The reason why the torque boost phase difference table 2744a is set for each modulation factor H is to compensate for the fact that the dominant order of the pulsating torque caused by the harmonic current changes depending on the modulation factor H. Note that the phase difference output based on this torque boost phase difference table 2744a may be either the current phase difference θi or the voltage phase difference. In this embodiment, the phase difference output from the torque boost phase difference table 2744a is the current phase difference θi, and the current phase difference θi is converted to a voltage phase difference in the subsequent phase difference conversion unit 2745.

[0046] The phase difference converter 2745 converts the current phase difference θi into a voltage phase difference by adding 0.5π to the current phase difference θi input from the torque boost phase difference table 2744a. The reason for adding 0.5π here is that harmonic currents are less susceptible to the influence of resistance, and therefore the differential value (0.5π lead) of the harmonic currents flowing mainly through the inductance component of the motor 400 affects the voltage of the motor 400.

[0047] The adder 2742 adds the voltage phase difference calculated by the phase difference converter 2745 to the reference voltage phase θvb calculated by the reference voltage phase calculator 2741, and calculates a corrected reference voltage phase θvbbost that aligns the phase of the pulsating torque due to the command current with the phase of the pulsating torque due to the linkage magnetic flux.

[0048] The subtractor 2743 subtracts the corrected reference voltage phase θvbbost from the voltage phase θv to calculate the voltage phase error Δθv.

[0049] The voltage phase error calculation unit 274 calculates the voltage phase error Δθv as described above. As a result, it is possible to determine the voltage phase error Δθv based on the rotational speed ωr, the torque command T*, and the modulation factor H so that the phase of the pulsating torque due to the command current matches the phase of the pulsating torque due to the flux linkage. As a result, it is possible to set the carrier frequency fc by changing the phase difference between the voltage command for the inverter 3 and the carrier wave Tr used for pulse width modulation so that the pulsating torque due to the command current is superimposed on the pulsating torque due to the flux linkage.

[0050] 6 is a diagram showing the torque boost phase difference table 2744a according to Example 1. The horizontal axis represents the rotation speed ωr of the motor 400, and the vertical axis represents the torque command T*. In Fig. 6, torque boost conditions for applying boost to the torque of the motor 400 are stored according to the rotation speed ωr and torque command T* of the motor 400. Specifically, when the relationship between the rotation speed ωr and the torque command T* becomes as shown by the solid line p in Fig. 6, the torque of the motor 400 is boosted as shown by the dotted line q in Fig. 6. The torque Ts indicated by the arrow is the amount of torque that is boosted.

[0051] The solid line p represents the maximum torque command T* of the motor 400, and as the rotation speed ωr increases, the maximum torque command T* gradually decreases. In the low-speed rotation range r where the rotation speed ωr is 0 or slow, the dotted line q overlaps with the solid line p. That is, in this low-speed rotation range r, the torque of the motor 400 is not increased. This is because, when the rotation speed ωr is 0 or slow, there is a high possibility that the motor 400 will vibrate or resonate with the vehicle when the motor 400 is used as a drive source for the vehicle. Note that in FIG. 6, when the torque command T* is a negative value, this indicates that the motor 400 is in regeneration mode.

[0052] The torque enhancement phase difference table 2744a stores the relationship between the rotation speed ωr and torque command T* and the current phase difference θi obtained by simulation, actual measurement, or the like for each modulation factor H. Here, the current phase difference θi is a value such that the enhanced torque becomes torque Ts by superimposing the pulsating torque due to the command current on the pulsating torque due to the flux linkage.

[0053] When the relationship between the rotation speed ωr of the motor 400 and the torque command T* satisfies the torque boost condition for applying the torque boost of the motor 400, the voltage phase error calculation unit 274 outputs a voltage phase error Δθv such that the boosted torque becomes torque Ts by superimposing the pulsating torque due to the command current on the pulsating torque due to the flux linkage. This makes it possible to further boost the maximum torque of the motor 400 compared to the normal maximum torque when the maximum torque command T* is input.

[0054] 7 is a diagram showing a torque boost phase difference table 2744b according to Example 2. The horizontal axis represents the rotation speed ωr of the motor 400, and the vertical axis represents the torque command T*. 7, torque boost conditions for applying the torque boost of the motor 400 are stored according to the rotation speed ωr and torque command T* of the motor 400. Specifically, when the relationship between the rotation speed ωr and the torque command T* falls within the range enclosed by the solid line p shown in FIG. 7 and is within the range excluding ranges r1, r2, and r3, the torque of the motor 400 is boosted.

[0055] Range r1 is a low-speed rotation range where rotation speed ωr is 0 or slow. In this range r1, the torque of motor 400 is not increased. This is because when rotation speed ωr is 0 or slow, there is a high possibility that motor 400 will vibrate or resonate with the vehicle when motor 400 is used as a drive source for the vehicle.

[0056] Range r2 is a range in which, when motor 400 is driven relatively quietly in a steady state, the vibrations and sounds of inverter 100, motor 400 itself, and vibrations and sounds due to resonance with a vehicle using motor 400 as a drive source become noticeable when the torque of motor 400 is increased. Range r3 is a range in which, when the rotation speed of motor 400 increases and the torque of motor 400 is increased, the vibrations of motor 400 and resonance with a vehicle using motor 400 as a drive source become noticeable. Note that these ranges r1, r2, and r3 are merely examples, and the ranges in which the vibrations and sounds become noticeable when the torque of motor 400 is increased can be determined appropriately by obtaining the vibrations and sounds of inverter 100, motor 400, and a vehicle using motor 400 as a drive source through simulations, actual measurements, etc.

[0057] The torque enhancement phase difference table 2744b stores the relationship between the rotation speed ωr and torque command T* and the current phase difference θi obtained by simulation, actual measurement, or the like for each modulation factor H. Here, the current phase difference θi is a value that becomes an enhanced torque by superimposing the pulsating torque due to the command current on the pulsating torque due to the flux linkage.

[0058] When the relationship between the rotational speed ωr of the motor 400 and the torque command T* satisfies the torque enhancement condition for applying the torque enhancement of the motor 400, the voltage phase calculation unit 272 outputs a voltage phase θv that results in the torque being enhanced by superimposing the pulsating torque due to the command current on the pulsating torque due to the interlinkage magnetic flux.

[0059] Figure 8 is a block diagram of voltage phase error calculation unit 274-1 in Modification 1. It differs from voltage phase error calculation unit 274 shown in Figure 5 in that torque boosting can be applied as needed. The same reference numerals are used to designate the same parts as those in voltage phase error calculation unit 274 shown in Figure 5, and their description will be omitted.

[0060] The voltage phase error calculation unit 274-1 includes a reference voltage phase calculation unit 2741, an adder 2742, a subtracter 2743, a torque boost phase difference table 2744a, a phase difference converter 2745, and a switch 2746.

[0061] When a torque boost command Te is input, the switching unit 2746 switches to output the current phase difference θi from the torque boost phase difference table 2744a to the phase difference conversion unit 2745. When a torque boost command Te is not input, the switching unit 2746 switches to the "0" output side. On the "0" output side, the current phase difference θi from the torque boost phase difference table 2744a is not output to the phase difference conversion unit 2745. The torque boost command Te is output from a vehicle control device (not shown), for example, when a driver of a vehicle using the motor 400 as a drive source depresses the pedal to accelerate the vehicle. In addition, the torque boost command Te can be input as appropriate under circumstances where it is desired to boost the torque of the motor 400.

[0062] In this modified example, an example using the torque boost phase difference table 2744a has been shown, but the torque boost phase difference table 2744b may also be used, or alternatively, a torque boost phase difference table in which the current phase difference θi is defined according to the torque command T* and the rotational speed ωr of the motor 400 may also be used.

[0063] Figure 9 is a block diagram of voltage phase error calculation unit 274-2 in Modification 2. Compared to voltage phase error calculation unit 274-1 shown in Figure 8, it differs in that it enables torque increase in accordance with torque command T* and rotation speed ωr of motor 400 even during torque limiting of motor 400. The same components as those in voltage phase error calculation unit 274-1 shown in Figure 8 are assigned the same reference numerals, and their description will be omitted.

[0064] The voltage phase error calculation unit 274-2 includes a reference voltage phase calculation unit 2741, an adder 2742, a subtracter 2743, a torque boost phase difference table 2744a, a phase difference converter 2745, a switcher 2746, and a torque boost phase difference table 2744c.

[0065] When the torque limiting signal Td is not input, the switching unit 2746 switches to output the current phase difference θi from the torque boost phase difference table 2744a to the phase difference conversion unit 2745. When the torque limiting signal Td is input, the switching unit 2746 switches to output the current phase difference θi from the torque boost phase difference table 2744c to the phase difference conversion unit 2745. The torque limiting signal Td is output from the control unit 200 based on, for example, temperatures from temperature sensors (not shown) provided in the inverter circuit 100, the DC power supply 300 (such as a battery), the motor 400, etc. This torque limiting signal Td is a signal output from the control unit 200 for the purpose of limiting the torque of the motor 400 to suppress temperature rise when the temperatures of the inverter circuit 100, the DC power supply 300 (such as a battery), the motor 400, etc. exceed a threshold value.

[0066] Similar to the torque boost phase difference table 2744a, the torque boost phase difference table 2744c stores the relationship between the rotation speed ωr, torque command T*, and current phase difference θi for each modulation factor H. When the rotation speed ωr and torque command T* are in a relatively low range, the current phase difference θi is output so as to boost the torque. Details of the torque boost phase difference table 2744c will be described later.

[0067] While this modification shows an example in which the torque boost phase difference table 2744a is used, the torque boost phase difference table 2744b may also be used, or a torque boost phase difference table in which the current phase difference θi corresponding to the torque command T* and the rotational speed ωr of the motor 400 is defined may also be used. Also, a configuration may be adopted in which the torque boost phase difference tables 2744a and 2744b are not provided, and only the torque boost phase difference table 2744c is provided. In this case, when the torque limiting signal Td is input, the current phase difference θi from the torque boost phase difference table 2744c is output to the phase difference conversion unit 2745.

[0068] Fig. 10 is a diagram showing a torque boost phase difference table 2744c according to Example 3. It is used in the voltage phase error calculation unit 274-2 in Modification 2 shown in Fig. 9. The horizontal axis represents the rotation speed ωr of the motor 400, and the vertical axis represents the torque command T*.

[0069] In FIG. 10, torque boost conditions for applying torque boost to motor 400 during torque limiting are stored according to the rotational speed ωr of motor 400 and torque command T*. Specifically, when the relationship between rotational speed ωr and torque command T* is within the range surrounded by solid line p' in FIG. 10, torque Ts', indicated by the arrow, is boosted. When rotational speed ωr and torque command T* are on solid line p', for example, the torque is boosted as indicated by dotted line q' in FIG. 10. In the low-speed rotation range r' where rotational speed ωr is 0 or slow, dotted line q' overlaps with solid line p. In other words, when torque command T* is at its maximum in this low-speed rotation range r', the torque of motor 400 is not boosted to avoid vibration of motor 400 and resonance with the vehicle.

[0070] 10, when the torque command T* is a negative value, this indicates that the motor 400 is in regeneration. Furthermore, the solid line p indicates the maximum torque command T* of the motor 400 relative to the rotational speed ωr. The range surrounded by the solid line p' is set inside the solid line p. This indicates that the range surrounded by the solid line p' is a range in which the rotational speed ωr and the torque command T* are relatively low. This is because, in the range surrounded by the solid line p', even if torque is being limited or torque is increased by controlling the current phase difference θi, the influence on the inverter circuit 100, the DC power supply 300 (such as a battery), the motor 400, etc. can be suppressed.

[0071] The torque enhancement phase difference table 2744c stores the relationship between the rotation speed ωr, torque command T*, and current phase difference θi during torque limiting, obtained by simulation, actual measurement, etc., for each modulation factor H. Here, the current phase difference θi is a value at which the enhanced torque becomes torque Ts' by superimposing the pulsating torque due to the command current on the pulsating torque due to the flux linkage.

[0072] When a torque limiting signal Td indicating that torque is being limited is being input, and the relationship between the rotational speed ωr of the motor 400 and the torque command T* satisfies a torque boosting condition for applying torque boosting of the motor 400, the voltage phase error calculation unit 274-2 outputs a voltage phase error Δθv such that the boosted torque becomes torque Ts' by superimposing the pulsating torque due to the command current on the pulsating torque due to the flux linkage. This makes it possible to boost the torque of the motor 400 even during torque limiting.

[0073] Fig. 11 is a block diagram of voltage phase error calculation unit 274-3 in Modification 3. Compared to voltage phase error calculation unit 274-1 shown in Fig. 8, it differs in that it controls torque boost in response to vibrations of motor 400, etc. The same parts as those in voltage phase error calculation unit 274-1 shown in Fig. 8 are given the same reference numerals, and their description will be omitted.

[0074] The voltage phase error calculation unit 274-3 includes a reference voltage phase calculation unit 2741, an adder 2742, a subtracter 2743, a torque boost phase difference table 2744a, a phase difference converter 2745, a vibration detection unit 2747, a vibration gain table 2748, a minimum value selector 2749, a previous value output unit 2750, and a multiplier 2751.

[0075] The vibration detection unit 2747 includes a filter unit 2747-1 and an absolute value output unit 2747-2. The rotation speed ωr of the motor 400 is input to the filter unit 2747-1, which selects and outputs a fluctuation waveform related to vibration from among the fluctuation waveforms of the rotation speed ωr. The absolute value output unit 2747-2 outputs an absolute value corresponding to the amplitude of the fluctuation waveform output from the filter unit 2747-1 as time-series data.

[0076] Gains corresponding to absolute values ​​are set and stored in advance in vibration gain table 2748, and a gain is output according to the absolute value input from absolute value output unit 2747-2. For example, as shown in Fig. 11, vibration gain table 2748 outputs a gain of '1' until the absolute value exceeds a threshold, and once the absolute value exceeds the threshold, outputs a gain that gradually decreases from '1' as the absolute value increases.

[0077] The minimum value selection unit 2749 compares the gain output from the vibration gain table 2748 with the previous gain output from the previous value output unit 2750, and outputs the smaller gain to the multiplication unit 2751. The initial value of the previous value output unit 2750 is '1'. When the gain from the vibration gain table 2748 suddenly changes to a large gain, the previous value output unit 2750 suppresses this.

[0078] As already described with reference to FIG. 6, the torque boost phase difference table 2744a stores the relationship between the rotational speed ωr, torque command T*, and current phase difference θi for each modulation factor H. The multiplier 2751 multiplies the gain selected by the minimum value selector 2749 by the current phase difference θi output from the torque boost phase difference table 2744a, and outputs the current phase difference θi according to the gain. For example, if vibration of the motor 400 is detected due to fluctuations in the rotational speed ωr of the motor 400, the current phase difference θi set in the torque boost phase difference table 2744a is multiplied by a gain that decreases according to the magnitude of the vibration. This reduces the current phase difference θi according to the magnitude of the vibration.

[0079] When the relationship between the rotation speed ωr of the motor 400 and the torque command T* satisfies the torque boost condition for applying the torque boost of the motor 400, the voltage phase error calculation unit 274-3 outputs the voltage phase error Δθv that results in a suppressed torque in accordance with the vibration of the motor 400. This suppresses the torque boost when the vibration of the motor 400 is large, so that the torque can be appropriately boosted while preventing excessive vibration of the motor 400.

[0080] In this modification, the vibration detection unit 2747 detects vibration of the motor based on the rotation speed ωr of the motor 400, but for example, in a vehicle driven by the motor 400, vibration of the vehicle may be detected based on left-right, front-rear, or up-down acceleration of the vehicle detected by an acceleration sensor provided on the vehicle. Also, although the example using the torque boost phase difference table 2744a has been shown, the torque boost phase difference table 2744b may also be used, or alternatively, a torque boost phase difference table in which the current phase difference θi corresponding to the torque command T* and the rotation speed ωr of the motor 400 is defined may also be used.

[0081] According to the embodiment described above, the following effects can be obtained. (1) The motor control device 1000 is connected to a power converter (inverter circuit 100) that converts DC power to AC power, and controls the driving of a motor 400 that is driven using AC power. The motor control device 1000 includes a carrier wave generation unit 280 that generates a carrier wave, a carrier wave frequency adjustment unit 270 that adjusts the frequency of the carrier wave, and a gate signal generation unit 260 that pulse-width modulates a voltage command corresponding to a torque command using the carrier wave to generate a gate signal for controlling the operation of the power converter (inverter circuit 100). The carrier wave frequency adjustment unit 270 adjusts the frequency of the carrier wave in accordance with the torque command and the rotational speed of the motor 400 so that the phase of the pulsating torque caused by the command current generated by pulse-width modulation using the carrier wave overlaps with the phase of the pulsating torque caused by the flux linkage of the motor 400 within a predetermined phase difference. This allows the motor torque to be increased as needed.

[0082] (2) A motor control method is a motor control method in a motor control device 1000 connected to a power converter (inverter circuit 100) that converts DC power to AC power and controls driving of a motor 400 that is driven using the AC power, the method generating a carrier wave, adjusting the frequency of the carrier wave, and using the carrier wave to pulse-width modulate a voltage command corresponding to a torque command to generate a gate signal for controlling the operation of the power converter (inverter circuit 100), and adjusting the frequency of the carrier wave according to the torque command and the rotational speed of the motor so that the phase of the pulsating torque caused by the command current generated by the pulse-width modulation using the carrier wave overlaps within a predetermined phase difference with the phase of the pulsating torque caused by the flux linkage of the motor 400. This makes it possible to increase the torque of the motor as needed.

[0083] The present invention is not limited to the above-described embodiment, and other forms that can be conceived within the scope of the technical concept of the present invention are also included within the scope of the present invention as long as they do not impair the characteristics of the present invention. Furthermore, a configuration that combines the above-described embodiment with multiple modified examples may be adopted. [Explanation of symbols]

[0084] 100···Inverter circuit, 102u, 102v, 102w···Upper and lower arm circuits, 103···Power semiconductor element, 200···Control unit, 210···Current command value generation unit, 220···dq axis conversion unit, 230···UVW coordinate conversion unit, 240···dq coordinate conversion unit, 250···Speed ​​calculation unit, 260···Gate signal generation unit, 270···Carrier frequency adjustment unit, 280···Carrier generation unit, 271···Synchronous PWM carrier number selection unit, 272···Voltage phase calculation unit, 273···Modulation factor calculation unit, 274, 274-1, 274-2, 274-3···Voltage phase error calculation unit, 275···Synchronous carrier Transmission frequency calculation unit, 276···Carrier frequency setting unit, 300···DC power supply, 400··Motor, 402···Current detector, 1000Motor control device, 2741···Reference voltage phase calculation unit, 2742···Adder unit, 2743···Subtractor unit, 2744a, 2744b, 2744c···Torque enhancement phase difference table, 2745···Phase difference conversion unit, 2746···Switching unit, 2747···Vibration detection unit, 2747-1···Filter unit, 2747-2···Absolute value output unit, 2748···Vibration gain table, 2749···Minimum value selection unit, 2750···Previous value output unit, 2751···Multiplier unit.

Claims

1. A motor control device connected to a power converter that converts DC power into AC power and controls driving of a motor that is driven using the AC power, a carrier wave generating unit that generates a carrier wave; a carrier frequency adjusting unit that adjusts the frequency of the carrier wave; a gate signal generating unit that pulse-width modulates a voltage command corresponding to a torque command using the carrier wave to generate a gate signal for controlling an operation of the power converter, a torque output from the motor when the motor is driven includes a first pulsating torque caused by a flux linkage of the motor, and a second pulsating torque caused by a harmonic component of a current supplied to the motor in response to control of the power converter by the gate signal; the carrier wave frequency adjusting unit adjusts the frequency of the carrier wave in accordance with the torque command and the rotational speed of the motor so that a phase of the second pulsating torque overlaps a phase of the first pulsating torque within a predetermined phase difference; A motor control device in which the predetermined phase difference is within a range of ±30 degrees.

2. 2. The motor control device according to claim 1, The motor control device, wherein the carrier wave frequency adjusting unit adjusts the frequency of the carrier wave when the relationship between the torque command and the rotational speed of the motor satisfies a torque boosting condition.

3. 3. The motor control device according to claim 2, A motor control device, wherein the torque boosting condition is when the torque command indicates a maximum torque command.

4. 4. The motor control device according to claim 3, A motor control device, wherein the torque boosting condition is when the torque command indicates a maximum torque command and the rotational speed of the motor does not include a low-speed range.

5. 3. The motor control device according to claim 2, A motor control device, wherein the torque boosting condition is that the relationship between the torque command and the rotational speed of the motor is within a specified range.

6. The motor control device according to any one of claims 2 to 5, The carrier wave frequency adjustment unit adjusts the frequency of the carrier wave when a torque increase command to increase the torque of the motor is input and the torque increase condition is satisfied.

7. The motor control device according to any one of claims 2 to 5, The carrier wave frequency adjustment unit adjusts the frequency of the carrier wave when a torque limiting signal indicating that torque is being limited is input and the torque increase condition is satisfied.

8. The motor control device according to any one of claims 2 to 5, The carrier wave frequency adjustment unit adjusts the frequency of the carrier wave when vibrations of the motor or a vehicle in which the motor is mounted are detected and when the torque increase condition is satisfied.

9. 9. The motor control device according to claim 8, The carrier wave frequency adjusting unit is a motor control device that adjusts the frequency of the carrier wave according to the magnitude of the vibration of the motor or the vehicle.

10. The motor control device according to any one of claims 2 to 5, The motor control device, wherein the carrier wave frequency adjustment unit adjusts the frequency of the carrier wave when the torque increase condition is satisfied during the regenerative operation of the motor.

11. 6. The motor control device according to claim 1, A motor control device in which the second pulsating torque is generated due to a 6Nth-order (N is a natural number) harmonic component of the current.

12. 1. A motor control method in a motor control device that is connected to a power converter that converts DC power into AC power and controls driving of a motor that is driven using the AC power, comprising: Generate a carrier wave, adjusting the frequency of the carrier wave; pulse-width-modulating a voltage command corresponding to a torque command using the carrier wave to generate a gate signal for controlling an operation of the power converter; a torque output from the motor when the motor is driven includes a first pulsating torque caused by a flux linkage of the motor, and a second pulsating torque caused by a harmonic component of a current supplied to the motor in response to control of the power converter by the gate signal; a motor control method for adjusting the frequency of the carrier wave in accordance with the torque command and the rotational speed of the motor so that the phase of the second pulsating torque overlaps the phase of the first pulsating torque within a range of ±30 degrees.

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