Electric motor control method and electric motor control device

Abstract

To provide an electric motor control method and an electric motor control device by which voltage pulsation in a high frequency region can be reduced.SOLUTION: An electric motor control method for drivingly controls a stator winding-equipped electric motor by using a PWM signal, includes calculating a phase voltage command value to the stator winding on the basis of a torque command value, calculating a harmonic voltage command value including at least a (2n+1)-order harmonic wave with respect to the frequency of a basic wave which is set to the phase voltage command value, generating a PWM signal on the basis of a final voltage command value which is obtained by adding a value obtained by multiplying the harmonic voltage command value with a prescribed gain to the phase voltage command value, and determining a gain on the basis of at least one of a modulation rate related to the PWM signal, a carrier frequency of the PWM signal, and the torque command value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for controlling an electric motor and a device for controlling an electric motor. [Background technology]

[0002] Patent Document 1 relates to the control of an electric motor and discloses a method for suppressing voltage pulsation that occurs when a power conversion device that converts the voltage of DC power supplied from a DC power source performs a switching operation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-057207 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the control of the electric motor according to Patent Document 1 is configured to detect the voltage pulsation that occurs and correct the switching operation of the power conversion device based on the detected voltage pulsation, making it difficult to reduce voltage pulsation in high frequency ranges (for example, frequency ranges higher than the carrier frequency).

[0005] An object of the present invention is to provide a method for controlling an electric motor and a device for controlling an electric motor that are capable of reducing voltage pulsation in the high frequency range. [Means for solving the problem]

[0006] A method for controlling an electric motor according to the present invention is a method for controlling the drive of an electric motor including a stator winding using a PWM signal. This control method calculates a phase voltage command value for the stator winding based on a torque command value, calculates a harmonic voltage command value including at least a (2n+1)th-order harmonic with respect to the frequency of a fundamental wave when the phase voltage command value is a fundamental wave, and generates a PWM signal based on a final voltage command value obtained by multiplying the harmonic voltage command value by a predetermined gain and adding the value to the phase voltage command value. The gain is then set based on at least one of a modulation factor associated with the PWM signal, a carrier frequency of the PWM signal, and the torque command value. Furthermore, in drive control, the DC voltage supplied from the DC power supply is converted into an AC voltage and applied to the motor, and the gain is set to a value such that the maximum value of the final voltage command value does not exceed the DC voltage. . [Effects of the Invention]

[0007] According to the present invention, when DC voltage is converted to AC voltage by PWM control to supply power to an electric motor, harmonics in the PWM signal, particularly ripple components at twice the carrier frequency that appear prominently at a specific modulation rate, can be reduced, so that the amplitude of the ripple components superimposed on the DC voltage can be suppressed without detecting the ripple components, thereby making it possible to reduce voltage ripple in the high frequency range. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing an example of the basic configuration of a motor control device according to this embodiment. [Figure 2] FIG. 2 is a block diagram of the gain calculation unit of this embodiment. [Figure 3] FIG. 3 is a diagram showing a gain region in a coordinate space in which the vertical axis represents the gain and the horizontal axis represents the modulation factor, and in which the final three-phase voltage command value is equal to or less than the battery voltage, with the first characteristic curve representing the relationship between the gain and the modulation factor when the final three-phase voltage command value matches the battery voltage as the boundary. [Figure 4]FIG. 4 is a diagram showing, in a coordinate space with the vertical axis representing the gain and the horizontal axis representing the modulation factor, a gain region where the final three-phase voltage command value is equal to or less than the battery voltage, with the first characteristic curve representing the relationship between the gain and the modulation factor when the final three-phase voltage command value matches the battery voltage as the boundary, and a gain region where the DC voltage ripple is equal to or less than the allowable maximum amplitude, with the second characteristic curve representing the relationship between the gain and the modulation factor when the DC voltage ripple matches the allowable maximum amplitude at a predetermined carrier frequency as the boundary, overlapping with each other. [Figure 5] FIG. 5 is a diagram showing the relationship between the amplitude of a DC voltage ripple pulsating at a frequency twice the carrier frequency and the modulation factor. [Figure 6] FIG. 6 is a diagram in which a third characteristic curve is added to show the relationship between the gain and the modulation factor when the torque command value in FIG. 4 is set to the maximum torque, the carrier frequency is set to a low carrier frequency, and the DC voltage ripple coincides with the allowable maximum amplitude. [Figure 7] FIG. 7 is a diagram showing that the third characteristic curve shifts in the direction in which the gain increases in response to switching the torque command value in FIG. 6 from the maximum torque to a torque lower than the maximum torque. [Figure 8] FIG. 8 is a diagram showing how the third characteristic curve in FIG. 6 changes so that the sharpness of the curve shape centered on the minimum value decreases in response to switching the carrier frequency from a low carrier frequency to a high carrier frequency. [Figure 9] FIG. 9 is a diagram showing a control flow of the motor control device of this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0010] [Basic configuration of the control device] FIG. 1 is a diagram showing an example of the basic configuration of a motor control device according to this embodiment.

[0011] The control device (control method) for an electric motor (motor 109) in this embodiment controls the motor 109 of an electric vehicle. Electric vehicles include not only electric vehicles using the motor 109 as a driving force, but also hybrid vehicles and fuel cell vehicles.

[0012] The motor 109 shown in Fig. 1 has a stator and a rotor. There are no restrictions on the type of rotor of the motor 109, and it is possible to use rotors such as permanent magnet rotors, wound rotors, and cage rotors. Although Fig. 1 shows the number of phases of the stator winding as three, this embodiment is applicable to electric motors having multi-phase stator windings of three or more phases.

[0013] The control device of this embodiment includes a torque control unit 101, a coordinate converter 102 (dq axis → UVW phase converter), a third harmonic voltage calculation unit 103, a gain calculation unit 104, an adder 113, a PWM converter 105, an inverter 106, a voltage detector 107, a current detector 108, a rotor position sensor 110, a rotation speed calculation unit 111, a coordinate converter 112 (UVW phase → dq axis converter), etc.

[0014] The torque control unit 101 (phase voltage calculation means) receives a torque command value T * , rotation speed detection value N, battery voltage detection value V dc , d-axis current i d , q-axis current i q is input. Here, the torque command value T * is calculated based on the accelerator opening, etc.

[0015] The torque control unit 101 calculates the d-axis current command value i based on the input information. d * , q-axis current command value i q * and then calculate the d-axis current command value i d * , q-axis current command value i q * The d-axis voltage command value v is calculated by performing current vector control calculation using the d * , q-axis voltage command value v q* is calculated and output.

[0016] Carrier frequency f carr is the final three-phase voltage command value (v u0 * ,v v0 * ,v w0 * ) to generate the PWM signal, the final three-phase voltage command value (v u0 * ,v v0 * ,v w0 * ) is the frequency of the carrier wave that compares with the carrier frequency f carr is the operating condition, for example, the rotation speed detection value N and / or the torque command value T * (or the d-axis current i corresponding to the torque generated by the motor 109) d , q-axis current i q For example, the faster the motor 109 is rotated, the fewer the number of control operations per rotation. carr needs to be increased.

[0017] The modulation factor m is the d-axis voltage command value v d * , q-axis voltage command value v q * , battery voltage detection value V dc is calculated using the following formula (1).

number

[0018] The coordinate converter 102 (phase voltage calculation means) calculates the d-axis voltage command value v d * , and the q-axis voltage command value v q * Based on the detected electrical angle θ of the motor 109, the three-phase voltage command value (v u * , v v * , v w *) (phase voltage command value) and output it. Note that the modulation factor m is converted into the three-phase voltage command value (v u * , v v * , v w * ) to the maximum value of the carrier wave for generating the PWM signal. u0 * ,v v0 * ,v w0 * ) may be calculated as a ratio of the maximum value of

number

[0019] The third harmonic voltage calculation unit 103 (harmonic calculation means) calculates the three-phase voltage command value (v u * ,v v * ,v w * ) and the detected electrical angle θ of the motor 109, a harmonic voltage command value v0 is output for the purpose of improving the voltage utilization rate. u * ,v v * ,v w * ) is added with the harmonic voltage command value v0 to obtain the sinusoidal three-phase voltage command value (v u * ,v v * ,v w * ) can improve the voltage utilization rate.

[0020] Here, the harmonic voltage command value v0 is intended to improve the voltage utilization rate in a rotating machine equipped with a (2n+1)-phase stator winding having a neutral point, and includes at least the (2n+1)th order harmonics. The harmonic voltage command value v0 can be expressed, for example, as in the following equations (3) and (4), but is not limited to these equations.

number

[0021]

number

[0022] The gain calculation unit 104 (gain output means) calculates the harmonic voltage command value v0 based on the modulation factor m and the carrier frequency f carr , torque command value T * (or the d-axis current i corresponding to the torque generated by the motor 109) d , q-axis current i q ) the correction value v0 multiplied by the gain k set according to * (=k·v0) The setting of the gain k by the gain calculation unit 104 will be described later.

[0023] The adder 113 (final voltage calculation unit) calculates the three-phase voltage command value (v u * ,v v* ,v w * ) each with a value v0 * The final three-phase voltage command value (v u0 * ,v v0 * ,v w0 * ) (final voltage command value) is generated and output.

[0024] The PWM converter 105 (PWM signal conversion means) converts the final three-phase voltage command value (v u0 * ,v v0 * ,v w0 * ), carrier frequency f carr , battery voltage detection value V dc Based on this, a PWM signal (D uu , D ul , D vu , D vl , D wu , D wl ) is output.

[0025] The inverter 106 drives the power element by the PWM signal and converts the battery voltage (DC voltage) output from the battery 114 into a three-phase PWM voltage (v u , v v , v w ) and applied to the motor 109 (stator winding).

[0026] A smoothing capacitor 115 is disposed between the inverter 106 and the battery 114, and smoothes (reduces) the pulsating component generated by the inverter 106 and superimposed on the DC voltage.

[0027] The voltage detector 107 detects the battery voltage V dc (the voltage applied across the smoothing capacitor 115).

[0028] The current detector 108 detects at least two phases of the three phases of the current flowing through the rotor i u, i v Detect.

[0029] The coordinate converter 112 converts the current i detected by the current detector 108 into u , i v Using the detected electrical angle θ, the d-axis current i d and q-axis current i q Calculate.

number

[0030] The rotor position sensor 110 detects the electrical angle θ.

[0031] The rotation speed calculation unit 111 calculates and outputs a rotation speed detection value N from the amount of change in the electrical angle detection value θ over a predetermined period of time.

[0032] [Gain calculation unit 104] 2 is a block diagram of the gain calculation unit 104 of this embodiment. The gain calculation unit 104 includes a gain setting unit 104a (gain setting means) that sets a gain k for correcting the harmonic voltage command value v0 (amplitude).

[0033] Three-phase voltage command value (v u * ,v v * ,v w * ) to the harmonic voltage command value v0 * The technique of improving the voltage utilization rate by adding is a well-known technique, but is useful for improving the output of the motor 109.

[0034] However, when the modulation factor m is near a specific value, the carrier frequency f carr However, there is a problem in that the pulsating component at a frequency twice as high as the normal voltage (hereinafter, the pulsating component in the DC voltage applied to smoothing capacitor 115 is referred to as "DC voltage ripple") increases.

[0035] For example, when the modulation rate m is around 50%, the PWM signal of the U phase (D uu , D ul ), V-phase PWM signal (D vu , D vl ), W-phase PWM signal (D wu , D wl ) change in one cycle, with the duty ratio pulsating around 25%, the duty ratio changing linearly from 25% to 75%, the duty ratio pulsating around 75%, and the duty ratio changing linearly from 75% to 25%.

[0036] For example, the U-phase PWM signal (D uu , D ul ) is pulsating at a duty ratio of around 75%, the V-phase PWM signal (D vu , D vl ) changes its duty ratio linearly from 25% to 75%, and the W-phase PWM signal (D uu , D ul ) but the duty ratio is pulsating at around 25%.

[0037] At this time, the PWM signal (D uu ) rising timing, PWM signal (D wl ) falls, PWM signal (D wl ) rising timing, PWM signal (D uu ) occur at equal intervals. As a result, on the smoothing capacitor 115 side, the carrier frequency f carr A strong DC voltage ripple (triangular wave) with twice the frequency is generated.

[0038] Incidentally, when driving an electric motor (rotating machine) such as motor 109, it is common to connect capacitance means such as smoothing capacitor 115 in parallel to a DC bus, which is the input of a power converter such as inverter 106. This configuration suppresses DC voltage pulsation that occurs due to, for example, load fluctuations of other devices connected to the DC bus or switching of the power converter, thereby enabling good torque or current control and suppressing heat generation in the capacitance means and power supply devices such as batteries.

[0039] However, since an increase in the size of the capacitance means leads to an increase in the size of the device, there is a demand for a power device that can suppress pulsation of the DC voltage.

[0040] In the prior art (Patent Document 1, etc.), the pulsation component superimposed on the DC voltage applied to the capacitance means is detected, and the load angle of the motor is increased in accordance with the increase in the instantaneous value of the pulsation component, thereby suppressing the pulsation.

[0041] However, in the conventional technology, the pulsating component superimposed on the DC voltage applied to the capacitance means is detected, and therefore there is a problem in that the pulsating component superimposed on the DC voltage applied to the capacitance means cannot be suppressed at frequencies higher than the detection speed.

[0042] Furthermore, in the conventional technology, the motor is driven by PWM control, and the load angle of the motor is increased in response to the pulsating component superimposed on the detected DC voltage applied to the capacitance means. This causes a problem in that the pulsating component superimposed on the DC voltage applied to the capacitance means cannot be suppressed at frequencies higher than the carrier frequency of the PWM signal.

[0043] On the other hand, in this embodiment, the pulsation width when the PWM signal pulsates around the specific duty ratio can be changed by the gain k by which the harmonic voltage command value v0 is multiplied. By increasing the pulsation width, the proportion of time that the PWM signal stays around the specific duty ratio can be reduced, thereby suppressing a decrease in the voltage utilization rate and increasing the carrier frequency f carrIt is possible to reduce the amplitude of DC voltage ripple at twice the frequency of the

[0044] Therefore, in this embodiment, the modulation factor m and the carrier frequency f carr , torque command value T * By setting the gain k according to at least one of the following, the carrier frequency f carr Therefore, the DC voltage ripple at twice the frequency of the DC voltage applied to the smoothing capacitor 115 can be reduced.

[0045] [Gain k setting range] Figure 3 shows the final three-phase voltage command value (v u0 * ,v v0 * ,v w0 * ) is the battery voltage (battery voltage detection value V dc ) and the final three-phase voltage command value (v u0 * ,v v0 * ,v w0 * ) is the battery voltage (battery voltage detection value V dc ) or less.

[0046] Next, the final three-phase voltage command value (v u0 * ,v v0 * ,v w0 * ) is the battery voltage (battery voltage detection value V dc ) will be explained.

[0047] When the absolute value of the gain k is increased, the correction value v0 * The following shows the case where the gain k is increased negatively, but the same applies when it is increased positively. Correction value v0* As a result, the final three-phase voltage command value (v u0 * ,v v0 * ,v w0 * ) increases and exceeds the range that can be output with the battery voltage.

[0048] Final three-phase voltage command value (v u0 * ,v v0 * ,v w0 * ) exceeds the range that can be output by the battery voltage, the three-phase voltage command value (v u * ,v v * ,v w * ) voltage cannot be applied to the motor 109, resulting in insufficient torque. Furthermore, if the voltage cannot be applied to the motor 109 according to the command value, the pulsation component in the DC voltage of the smoothing capacitor 115 cannot be reduced as intended. Therefore, the gain k is set to the final three-phase voltage command value (v u0 * ,v v0 * ,v w0 * ) is limited to a value that does not exceed the range that can be output with the battery voltage.

[0049] The first characteristic curve 201 shown in FIG. 3 is a graph showing the final three-phase voltage command value (v u0 * ,v v0 * ,v w0 * ) is the maximum value of the battery voltage (battery voltage detection value V dc ), and the curve shows that the gain k increases monotonically (the absolute value decreases) as the modulation factor m increases.

[0050] In Fig. 3, the final three-phase voltage command value (v u0 * ,v v0 * ,v w0* ) can be placed at any position on the first characteristic curve 201 or in the area (the area indicated by hatching) to the left of the first characteristic curve 201. As shown in FIG. 3, the settable range of the gain k becomes more limited as the modulation factor m increases.

[0051] Figure 4 shows the final three-phase voltage command value (v u0 * ,v v0 * ,v w0 * ) is the battery voltage (battery voltage detection value V dc ) and the final three-phase voltage command value (v u0 * ,v v0 * ,v w0 * ) is the battery voltage (battery voltage detection value V dc ) and the region of gain k where the carrier frequency f carr 2A is a diagram showing an overlapping region of the gain k region where the DC voltage ripple is equal to or less than the allowable maximum amplitude, with the second characteristic curve 202A (second characteristic curve 202B) showing the relationship between the gain k and the modulation factor m when the DC voltage ripple coincides with the allowable maximum amplitude as the boundary.

[0052] Here, the carrier frequency f carr In general, the equivalent series resistance of the smoothing capacitor 115 is set to a range of the carrier frequency f carr Therefore, when the same amount of DC voltage ripple energy occurs, the loss on the low frequency side increases, and the rated voltage differs for each frequency.

[0053] Furthermore, for example, when a threshold value of the DC voltage ripple for each frequency is set in advance in order to prevent malfunction or failure of a device that shares a battery power source with this embodiment, the threshold value of the DC voltage ripple differs for each frequency. In other words, the threshold value (maximum allowable amplitude) that the DC voltage ripple must not exceed differs for each frequency.

[0054] Also, the carrier frequency f carr Since the frequency distribution of the DC voltage ripple changes depending on the carrier frequency, the limit range of the gain k differs for each carrier frequency. Therefore, the threshold (maximum allowable amplitude) that the DC voltage ripple must not exceed differs for each frequency. Therefore, in this embodiment, the carrier frequency f is set so that the DC voltage ripple threshold for each frequency set in advance is not exceeded. carr The gain k is limited according to

[0055] The second characteristic curve 202A (second characteristic curve 202B) shown in FIG. 4 is a characteristic curve obtained by dividing the set carrier frequency f carr The second characteristic curve 202A (second characteristic curve 202B) shows the relationship between the gain k and the modulation factor m corresponding to the gain k when the gain k coincides with the maximum allowable amplitude of the DC voltage ripple. The second characteristic curve 202A (second characteristic curve 202B) shows a curve in which the gain k increases monotonically as the modulation factor m increases.

[0056] In Fig. 4, the final three-phase voltage command value (v u0 * ,v v0 * ,v w0 * The characteristic point (k, m) indicating the gain k and modulation factor m when generating the first characteristic curve 201 is in the region to the left of the second characteristic curve 202A (second characteristic curve 202B). The settable gain k can be set in the region to the left of the first characteristic curve 201 and the region (indicated by hatching) to the left of the second characteristic curve 202A (second characteristic curve 202B).

[0057] For example, the carrier frequency f carrWhen a high carrier frequency (e.g., 10 kHz) is set as the characteristic point (k, m), the second characteristic curve 202B is positioned to the right of the first characteristic curve 201. Therefore, when a high carrier frequency is set, the range in which the characteristic point (k, m) can be set is substantially limited with the first characteristic curve 201 as the boundary.

[0058] On the other hand, the carrier frequency f carr When a low carrier frequency (for example, 5 kHz) is set as the gain k, there are portions where the second characteristic curve 202A is located to the left of the first characteristic curve 201 (portion where the gain k is from -6.3 to -3.7) and portions where the second characteristic curve 202A is located to the right (portion where the gain k is lower than -6.3 and portion where the gain k is higher than -3.7). Therefore, when a low carrier frequency is set, in the region where the gain k is lower than -6.3 and higher than -3.7, the region where the characteristic point (k, m) can be set is limited with the second characteristic curve 202A as the boundary, and when the gain k is equal to or higher than -6.3 and equal to or lower than -3.7, the region where the characteristic point (k, m) can be set is limited with the first characteristic curve 201 as the boundary.

[0059] Figure 5 shows the carrier frequency f carr 10 is a diagram showing the relationship between the amplitude of a DC voltage ripple pulsating at twice the frequency of the modulation factor m.

[0060] FIG. 6 shows the torque command value T * is set to the maximum torque and the carrier frequency f carr 10 is a diagram in which a third characteristic curve 203A is added, which shows the relationship between the gain k and the modulation factor m when the carrier frequency is set to a low frequency and the DC voltage ripple coincides with the maximum allowable amplitude.

[0061] FIG. 7 shows the torque command value T * 10 is a diagram showing that the third characteristic curve 203B shifts in the direction in which the gain k increases in response to switching from the maximum torque to a torque lower than the maximum torque.

[0062] As shown in Figure 5, the carrier frequency f carrWhen the carrier frequency is set to a low frequency (for example, 5 kHz), a DC voltage ripple pulsating at twice the frequency of the low carrier frequency (10 kHz) occurs, but the DC current ripple increases or decreases depending on the modulation factor m. In particular, the DC voltage ripple is maximum when the modulation factor m is around 0.5 (characteristic point 204). Also, the torque command value T * Therefore, when the motor 109 is supplied with a predetermined torque command value T * is set, the settable range of the characteristic point (k, m) is the third characteristic curve 203A (torque command value T * is limited to the maximum torque (including when the torque is less than the maximum torque).

[0063] In FIG. 6, the third characteristic curve 203A shows the torque command value T * is set to the maximum torque and the carrier frequency f carr is set to a low carrier frequency and the DC voltage ripple coincides with the maximum allowable amplitude. Third characteristic curve 203A (third characteristic curve 203B in FIG. 7 and third characteristic curve 203C in FIG. 8) corresponds to the curve shown in FIG. 5 turned upside down, and has a curved shape in which the modulation factor m when the DC voltage ripple is maximum and the position where the gain k is lowest is a minimum value, and the direction in which the gain k decreases is convex.

[0064] Here, the third characteristic curve 203A (the third characteristic curve 203B in FIG. 7) does not intersect with the first characteristic curve 201 and the second characteristic curve 202A (the carrier frequency fcarr is the same as that of the third characteristic curve 203A), and is located to the left of the first characteristic curve 201 and the second characteristic curve 202A, that is, within the region where the gain k can be set. * The characteristic point (k, m) where the torque becomes maximum can be set on the third characteristic curve 203A.

[0065] As shown in FIG. 6, when the characteristic point (k, m) (characteristic point 204) is set at the minimum value (modulation factor m is about 0.5) on the third characteristic curve 203A, the carrier frequency fcarr The inventors of the present application have confirmed that the DC voltage ripple, which pulsates at twice the frequency of the inverter, is reduced by approximately 23.6%.

[0066] Torque command value T * When the torque generated by the motor 109 is reduced, the DC voltage ripple is also reduced. Therefore, the gain k can be set to a larger value accordingly.

[0067] FIG. 7 shows the torque command value T * 10 is a diagram showing that the third characteristic curve 203B shifts in the direction in which the gain k increases in response to switching from the maximum torque to a torque lower than the maximum torque.

[0068] As shown in FIG. 7, the third characteristic curve 203B has a torque command value T * As the gain k decreases, the torque command value T * In accordance with this, the highest gain k can be set so that the DC voltage ripple does not exceed the maximum allowable amplitude (threshold voltage of the smoothing capacitor 115).

[0069] Figure 8 shows the carrier frequency f carr 10 is a diagram showing how third characteristic curve 203C changes so that the sharpness of the curve shape centered on the minimum value decreases in response to switching from a low carrier frequency to a high carrier frequency.

[0070] Carrier frequency f carr When the preset carrier frequency f carr The DC voltage ripple threshold (maximum allowable amplitude) also differs for each carrier frequency f carr When m is set to a high carrier frequency (for example, 10 kHz), a DC voltage ripple pulsating at a frequency that is an integer multiple of the high carrier frequency may occur, but the change in the amplitude of the DC voltage ripple due to a change in modulation factor m tends to be small.

[0071] Therefore, as shown in Figure 8, the carrier frequency fcarr The third characteristic curve 203C when the carrier frequency f is set to a high frequency is carr Compared to the third characteristic curve 203A when the carrier frequency is set to a low frequency (for example, 5 kHz), the position of the minimum value hardly changes, but the sharpness of the curve shape centered on the minimum value decreases. In other words, the change in gain k with the change in modulation factor m is deformed to be smaller.

[0072] The third characteristic curve 203C does not intersect with the first characteristic curve 201 and the second characteristic curve 202B (the carrier frequency fcarr is the same as that of the third characteristic curve 203C), and is located to the left of the first characteristic curve 201 and the second characteristic curve 202B, i.e., within the region where the gain k can be set.

[0073] The third characteristic curve 203A shown in FIG. 6, the third characteristic curve 203B shown in FIG. 7, and the third characteristic curve 203C shown in FIG. 8 can be stored as maps, and the modulation factor m, the carrier frequency f carr , torque command value T * (or the d-axis current i corresponding to the torque generated by the motor 109) d ,q-axis current i q ) as an input value, and the gain k can be set by referring to a map. Of course, the third characteristic curve 203A and the like can also be replaced with an equation such as a polynomial.

[0074] In the overmodulation region (region where the modulation factor m is higher than 1), the final three-phase voltage command value (v u0 * ,v v0 * ,v w0 * ) is the battery voltage (battery voltage detection value V dc ), which exceeds the range that can be output by the final three-phase voltage command value (v u0 * ,v v0* ,v w0 * ) is the battery voltage (battery voltage detection value V dc ), by setting the gain k to 1 in a range exceeding the range of

[0075] [Control Flow] 9 is a diagram showing the control flow of the motor control device of this embodiment. The flow of the motor control device (control method) of this embodiment will be described. The control device (control method) of this embodiment includes a program for executing the processes of steps S301 to S311 below.

[0076] In step S301, the current detector 108 detects the current i u , current i v The rotor position sensor 110 detects the rotor electrical angle detection value θ.

[0077] In step S302, the coordinate converter 112 calculates the current i u , current i v , current i w (i w =-i u -i v ) based on the above equation (5), the d-axis current i d , q-axis current i q Furthermore, the rotation speed calculation unit 111 calculates the rotation speed detection value N based on the electrical angle detection value θ.

[0078] In step S303, the torque control unit 101 calculates the torque command value T * , d-axis current i d , q-axis current i q , rotation speed detection value N, battery voltage detection value V dc Based on this, the d-axis voltage command value v is calculated through current vector control. d * and q-axis voltage command value v q * Furthermore, the torque control unit 101 calculates the carrier frequency fcarr and calculate the modulation factor m based on the above equation (1) etc.

[0079] In step S304, the coordinate converter 102 calculates the d-axis voltage command value v based on the above equation (2). d * and q-axis voltage command value v q * By performing coordinate transformation to u * ,v v * ,v w * )

[0080] In step S305, the third harmonic voltage calculation unit 103 calculates the three-phase voltage command value (v u * ,v v * ,v w * ), and based on the detected electrical angle θ of the motor 109, a harmonic voltage command value v0 is generated based on, for example, the above equations (3) and (4).

[0081] In step S306, the gain calculation unit 104 calculates the carrier frequency f carr , torque command value T * , modulation factor m is input.

[0082] In step S307, the gain calculation unit 104 (gain setting unit 104a) determines whether or not overmodulation is occurring, that is, whether or not the modulation factor m is higher than 1. If YES, the process proceeds to step S308, and if NO, the process proceeds to step S309.

[0083] In step S308, the gain calculation unit 104 (gain setting unit 104a) calculates the carrier frequency f carr and torque command value T * Regardless of the gain k, set it to 1, multiply the harmonic voltage command value v0 by the gain k, and obtain the correction value v0 * Calculate.

[0084] In step S309, the gain calculation unit 104 (gain setting unit 104a) refers to the map and calculates the carrier frequency f carr , torque command value T * , the value of the gain k corresponding to the modulation factor m is set.

[0085] In step S311, the gain calculation unit 104 (gain setting unit 104a) multiplies the harmonic voltage command value v0 by the gain k to obtain the correction value v0 * Calculate.

[0086] In step S312, the adder 113 calculates the three-phase voltage command value (v u * ,v v * ,v w * ) and correction value v0 * and the final three-phase voltage command value (v u0 * ,v v0 * ,v w0 * ), and the PWM converter 105 calculates the final three-phase voltage command value (v u0 * ,v v0 * ,v w0 * ) based on the PWM signal (D uu , D ul , D vu , D vl , D wu , D wl ) is calculated.

[0087] [Effects of this embodiment] According to the control method for the electric motor (motor 109) of this embodiment, the electric motor (motor 109) including the stator winding is driven and controlled by a PWM signal, and a torque command value T * Based on the phase voltage command value (three-phase voltage command value (v u * ,v v * ,v w *)) and calculates the phase voltage command value (three-phase voltage command value (v u * ,v v * ,v w * )) is used as the fundamental wave, a harmonic voltage command value v0 including at least the (2n+1)th order harmonics for the frequency of the fundamental wave is calculated, and the harmonic voltage command value v0 is multiplied by a predetermined gain k (correction value v0*) and the phase voltage command value (three-phase voltage command value (v u * ,v v * ,v w * The final voltage command value (final three-phase voltage command value (v u0 * ,v v0 * ,v w0 * )) to generate a PWM signal based on the modulation factor m associated with the PWM signal, and the carrier frequency f of the PWM signal. carr , torque command value T * The gain k is set based on at least one of the above.

[0088] When DC voltage is converted to AC voltage by PWM control using the above method to supply power to an electric motor, harmonics, especially carrier frequency f that appears prominently at a specific modulation factor m, are generated in the PWM signal. carr Since the pulsation component having a frequency twice as high as the DC voltage can be reduced, the amplitude of the pulsation component superimposed on the DC voltage can be suppressed without detecting the pulsation component, thereby making it possible to reduce voltage pulsation in the high frequency range.

[0089] In this embodiment, in drive control, a DC voltage supplied from a DC power supply (battery 114) is converted into an AC voltage and applied to an electric motor (motor 109), and the gain k is set to a final voltage command value (final three-phase voltage command value (v u0 * ,v v0 * ,v w0 * )) is the DC voltage (battery voltage detection value V dc) to a value not exceeding

[0090] As a result, the final voltage command value (final three-phase voltage command value (v u0 * ,v v0 * ,v w0 * )) can realize a desired voltage command value, so that the pulsating component in the DC voltage applied to smoothing capacitor 115 can be reduced as intended.

[0091] In this embodiment, in drive control, a DC voltage supplied from a DC power supply (battery 114) is converted into an AC voltage and applied to an electric motor (motor 109), and when the DC voltage is converted into an AC voltage, a pulsating component superimposed on the DC voltage is smoothed by a smoothing capacitor 115. In this case, the gain k is set to a value corresponding to the final voltage command value (final three-phase voltage command value (v u0 * ,v v0 * ,v w0 * )) is the DC voltage (battery voltage detection value V dc ) and the carrier frequency f carr The carrier frequency f is set so as not to exceed the maximum allowable amplitude of the pulsating component set corresponding to carr Set accordingly.

[0092] By the above method, the carrier frequency f carr It is possible to adjust the amount of reduction in the pulsating component superimposed on the DC voltage applied to smoothing capacitor 115 for each time.

[0093] In this embodiment, in drive control, a DC voltage supplied from a DC power supply (battery 114) is converted into an AC voltage and applied to an electric motor (motor 109), and a pulsating component superimposed on the DC voltage when the DC voltage is converted into an AC voltage is smoothed by a smoothing capacitor 115. In this case, a torque command value T *is set to the maximum torque that can be applied by the electric motor (motor 109), and the pulsating component has a carrier frequency f carr When the amplitude of the pulsating component has a maximum value at a specific modulation factor m, the gain k is set to the final voltage command value (final three-phase voltage command value (v u0 * ,v v0 * ,v w0 * )) is the DC voltage (battery voltage detection value V dc ) and the carrier frequency f carr The amplitude is set so as not to exceed the threshold voltage (maximum allowable amplitude) of the smoothing capacitor 115 set corresponding to the modulation factor m, and so as not to exceed the maximum allowable amplitude of the pulsating component set at a specific modulation factor m.

[0094] By the above method, the DC voltage applied to the smoothing capacitor 115 has a carrier frequency f carr At the operating point where the amplitude of the pulsating component of the frequency twice as high as the reference frequency is maximized, the pulsating component can be reduced most effectively.

[0095] In this embodiment, the gain k is set to 1 when the modulation factor m exceeds a predetermined value (for example, 1).

[0096] By using the above method to set the gain k to 1 in the overmodulation region, it is no longer necessary to switch logic between the overmodulation region, where the present invention cannot be applied, and the normal region, where the present invention can be applied.

[0097] In this embodiment, the DC voltage supplied from the DC power supply (battery 114) is converted into an AC voltage by drive control and applied to the electric motor (motor 9). In a coordinate space with the gain k as the first axis and the modulation factor m as the second axis, the final voltage command value (final three-phase voltage command value (v u0 * ,v v0 * ,v w0 * )) and DC voltage (battery voltage detection value V dc) coincides with the gain k and the modulation factor m, and the final voltage command value (final three-phase voltage command value (v u0 * ,v v0 * ,v w0 * When the gain k and modulation factor m used in calculating the gain k) are expressed as characteristic points on the coordinate space, the gain k for the characteristic point is set at a position where its value is equal to or greater than the point on the first characteristic curve 201 where the gain k is the same as that of the characteristic point, and the modulation factor m for the characteristic point is set at a position where its value is equal to or less than the point on the first characteristic curve 201 where the gain k is the same as that of the characteristic point.

[0098] As a result, the final voltage command value (final three-phase voltage command value (v u0 * ,v v0 * ,v w0 * )) can realize a desired voltage command value, so that the pulsating component in the DC voltage applied to smoothing capacitor 115 can be reduced as intended.

[0099] In this embodiment, in drive control, a DC voltage supplied from a DC power supply (battery 114) is converted into an AC voltage and applied to an electric motor (motor 109), and a pulsating component superimposed on the DC voltage when the DC voltage is converted into an AC voltage is smoothed by a smoothing capacitor 115. In this case, in a coordinate space with a gain k as the first axis and a modulation factor m as the second axis, a final voltage command value (final three-phase voltage command value (v u0 * ,v v0 * ,v w0 * )) and DC voltage (battery voltage detection value V dc ) coincides with the first characteristic curve 201, which shows the relationship between the gain k and the modulation factor m, and the relationship between the amplitude of the ripple component (DC voltage ripple) and the carrier frequency f carrand a second characteristic curve 202A (202B) showing the relationship between the gain k and the modulation factor m when the amplitude of the pulsating component coincides with the maximum allowable amplitude of the pulsating component set corresponding to the final voltage command value (final three-phase voltage command value (v u0 * ,v v0 * ,v w0 * When the gain k and modulation factor m used in calculating the gain k) are expressed as characteristic points on the coordinate space, the gain k for the characteristic point is set so that it is located at a position equal to or greater than the point on the first characteristic curve 201 and the point on the second characteristic curve 202A (202B) that has the same modulation factor m as the characteristic point, and the modulation factor m for the characteristic point is set at a position equal to or less than the point on the first characteristic curve 201 and the point on the second characteristic curve 202A (202B) that has the same gain k as the characteristic point.

[0100] By the above method, the carrier frequency f carr It is possible to adjust the amount of reduction in the pulsating component superimposed on the DC voltage applied to smoothing capacitor 115 for each time.

[0101] In this embodiment, in the coordinate space, the amplitude of the pulsating component (DC voltage ripple) is * The third characteristic curve 203A (203B, 203C) shows the relationship between the gain k and the modulation factor m when the gain k coincides with the maximum allowable amplitude of the ripple component (DC voltage ripple) set based on the above, and the gain k on the third characteristic curve 203A (203B, 203C) is placed at a position equal to or greater than the point on the first characteristic curve 201 and the point on the second characteristic curve 202A (202B) at which the modulation factor m is the same as the modulation factor m on the third characteristic curve 203A (203B, 203C) related to the gain k. When the third characteristic curve 203A (203B, 203C) is expressed so that the modulation factor m on the third characteristic curve 203A (203B, 203C) is located at a position equal to or lower than the point on the first characteristic curve 201 and the point on the second characteristic curve 202A (202B) that has the same gain k as the gain k on the third characteristic curve 203A (203B, 203C) associated with the modulation factor m, the gain k is set so that the characteristic point is located on the third characteristic curve 203A (203B, 203C).

[0102] By the above method, the torque command value T * Even if the value of is set to a high value, the pulsating component can be reduced.

[0103] In this embodiment, when the pulsating component includes a frequency twice the carrier frequency fcarr and the amplitude of the pulsating component has a maximum value at a specific modulation factor m, the third characteristic curve 203A (203B, 203C) has a minimum value at a specific modulation factor m, the torque command value T * is set to the maximum torque that can be applied by the electric motor (motor 9).

[0104] By the above method, the DC voltage applied to the smoothing capacitor 115 has a carrier frequency f carr The pulsating component can be reduced most at the operating point (characteristic point in the coordinate space) where the amplitude of the pulsating component with a frequency twice as high as the reference frequency is maximized.

[0105] In this embodiment, the torque command value T * The gain k is set so that the third characteristic curve 203A (203B, 203C) shifts in the direction of the first axis of the coordinate space and in the direction in which the gain k increases as the torque command value T * The appropriate gain k can be set based on the change in

[0106] In this embodiment, the pulsating component has a carrier frequency f carr When the amplitude of the pulsating component has a maximum value at a specific modulation factor m, and the third characteristic curve 203A (203B, 203C) has a minimum value at a specific modulation factor m, the carrier frequency f carr The gain k is set so that the sharpness of the curve shape of the third characteristic curve 203A (203B, 203C) centered on the minimum value decreases as the carrier frequency f carr The appropriate gain k can be set based on the change in

[0107] According to the motor control device of this embodiment, the motor (motor 109) including the stator winding is driven and controlled by a PWM signal, and a torque command value T * Based on the phase voltage command value (three-phase voltage command value (v u * , v v * , v w * )) and a phase voltage calculation means (torque control unit 101, coordinate converter 102) for calculating a phase voltage command value (three-phase voltage command value (v u * , v v * , v w * )) as a fundamental wave, a harmonic calculation means (third-order harmonic voltage calculation unit 103) for calculating a harmonic voltage command value v0 including at least a (2n+1)th-order harmonic with respect to the frequency of the fundamental wave, and a value (correction value v0) obtained by multiplying the harmonic voltage command value v0 by a predetermined gain k. * ), and a harmonic output means (gain calculation unit 104) that outputs a phase voltage command value (three-phase voltage command value (v u * , v v * , v w * )) and the output (correction value v0 * ) to obtain the final voltage command value (final three-phase voltage command value (v u0 * ,v v0 * ,v w0 * a final voltage calculation unit (adder 113) that generates a final voltage command value (final three-phase voltage command value (v u0 * ,v v0 * ,v w0 * a PWM signal conversion means (PWM converter 105) for converting the modulation factor m associated with the PWM signal, a carrier frequency f of the PWM signal, and a harmonic output means (gain calculation unit 104 ... carr , torque command value T *The gain setting unit 104a includes a gain setting means for setting the gain k based on at least one of the above.

[0108] With the above configuration, when DC voltage is converted to AC voltage by PWM control and power is supplied to an electric motor, harmonics, particularly carrier frequency f that appears prominently at a specific modulation factor m, are generated in the PWM signal. carr Since the pulsation component having a frequency twice as high as the DC voltage can be reduced, the amplitude of the pulsation component superimposed on the DC voltage can be suppressed without detecting the pulsation component, thereby making it possible to reduce voltage pulsation in the high frequency range.

[0109] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and the technical scope of the present invention is not intended to be limited to the specific configurations of the above embodiments. Furthermore, the above embodiments can be combined as appropriate. [Explanation of symbols]

[0110] 101 torque control unit, 102 coordinate converter, 103 third harmonic voltage calculation unit, gain calculation unit 104, 104a gain setting unit, 105 PWM converter, 109 motor, 113 adder

Claims

1. A method for controlling an electric motor including a stator winding by a PWM signal, comprising: calculating a phase voltage command value for the stator winding based on a torque command value; calculating a harmonic voltage command value including at least a (2n+1)th order harmonic with respect to a frequency of the fundamental wave when the phase voltage command value is a fundamental wave; generating the PWM signal based on a final voltage command value obtained by multiplying the harmonic voltage command value by a predetermined gain and adding the resultant value to the phase voltage command value; setting the gain based on at least one of a modulation factor associated with the PWM signal, a carrier frequency of the PWM signal, and the torque command value; In the drive control, a DC voltage supplied from a DC power supply is converted into an AC voltage and applied to the electric motor, A motor control method for setting the gain to a value that does not cause the maximum value of the final voltage command value to exceed the DC voltage.

2. A method for controlling an electric motor that drives and controls an electric motor including a stator winding using a PWM signal, comprising: calculating a phase voltage command value for the stator winding based on a torque command value; calculating a harmonic voltage command value including at least a (2n+1)th order harmonic with respect to a frequency of the fundamental wave when the phase voltage command value is a fundamental wave; generating the PWM signal based on a final voltage command value obtained by multiplying the harmonic voltage command value by a predetermined gain and adding the resultant value to the phase voltage command value; setting the gain based on at least one of a modulation factor associated with the PWM signal, a carrier frequency of the PWM signal, and the torque command value; In the drive control, a DC voltage supplied from a DC power supply is converted into an AC voltage and applied to the electric motor, and a pulsating component superimposed on the DC voltage when the DC voltage is converted into the AC voltage is smoothed by a smoothing capacitor, a control method for an electric motor, wherein the gain is set in accordance with a carrier frequency so that a maximum value of the final voltage command value does not exceed the DC voltage and so that the maximum allowable amplitude of the pulsating component set corresponding to the carrier frequency is not exceeded.

3. A method for controlling an electric motor that drives and controls an electric motor including a stator winding using a PWM signal, comprising: calculating a phase voltage command value for the stator winding based on a torque command value; calculating a harmonic voltage command value including at least a (2n+1)th order harmonic with respect to a frequency of the fundamental wave when the phase voltage command value is a fundamental wave; generating the PWM signal based on a final voltage command value obtained by multiplying the harmonic voltage command value by a predetermined gain and adding the resultant value to the phase voltage command value; setting the gain based on at least one of a modulation factor associated with the PWM signal, a carrier frequency of the PWM signal, and the torque command value; In the drive control, a DC voltage supplied from a DC power supply is converted into an AC voltage and applied to the electric motor, and a pulsating component superimposed on the DC voltage when the DC voltage is converted into the AC voltage is smoothed by a smoothing capacitor, When the torque command value is set to a maximum torque that can be applied to the electric motor, the pulsating component includes a frequency that is twice the carrier frequency, and the amplitude of the pulsating component has a maximum value at a specific modulation factor, a control method for an electric motor, wherein the gain is set to a value such that the maximum value of the final voltage command value does not exceed the DC voltage, does not exceed a threshold voltage of the smoothing capacitor set corresponding to the carrier frequency, and does not exceed an allowable maximum amplitude of the pulsating component set at the specific modulation factor.

4. A method for controlling an electric motor that drives and controls an electric motor including a stator winding using a PWM signal, comprising: calculating a phase voltage command value for the stator winding based on a torque command value; calculating a harmonic voltage command value including at least a (2n+1)th order harmonic with respect to a frequency of the fundamental wave when the phase voltage command value is a fundamental wave; generating the PWM signal based on a final voltage command value obtained by multiplying the harmonic voltage command value by a predetermined gain and adding the resultant value to the phase voltage command value; setting the gain based on at least one of a modulation factor associated with the PWM signal, a carrier frequency of the PWM signal, and the torque command value; A motor control method in which the gain is set to 1 when the modulation rate exceeds a predetermined value.

5. A method for controlling an electric motor that drives and controls an electric motor including a stator winding using a PWM signal, comprising: calculating a phase voltage command value for the stator winding based on a torque command value; calculating a harmonic voltage command value including at least a (2n+1)th order harmonic with respect to a frequency of the fundamental wave when the phase voltage command value is a fundamental wave; generating the PWM signal based on a final voltage command value obtained by multiplying the harmonic voltage command value by a predetermined gain and adding the resultant value to the phase voltage command value; setting the gain based on at least one of a modulation factor associated with the PWM signal, a carrier frequency of the PWM signal, and the torque command value; In the drive control, a DC voltage supplied from a DC power supply is converted into an AC voltage and applied to the electric motor, A motor control method for setting the gain to a value such that the maximum value of the final voltage command value does not exceed the DC voltage, and for setting the gain to 1 when the modulation factor exceeds a predetermined value.

6. A method for controlling an electric motor that drives and controls an electric motor including a stator winding using a PWM signal, comprising: calculating a phase voltage command value for the stator winding based on a torque command value; calculating a harmonic voltage command value including at least a (2n+1)th order harmonic with respect to a frequency of the fundamental wave when the phase voltage command value is a fundamental wave; generating the PWM signal based on a final voltage command value obtained by multiplying the harmonic voltage command value by a predetermined gain and adding the resultant value to the phase voltage command value; setting the gain based on at least one of a modulation factor associated with the PWM signal, a carrier frequency of the PWM signal, and the torque command value; a first characteristic curve representing the relationship between the gain and the modulation factor when the DC voltage coincides with a maximum value of the final voltage command value in a coordinate space having the gain as a first axis and the modulation factor as a second axis; and the gain and the modulation factor when calculating the final voltage command value are represented as characteristic points on the coordinate space; A method for controlling an electric motor, wherein the gain associated with the characteristic point is set at a position where the value is equal to or greater than a point on the first characteristic curve where the modulation factor is the same as that of the characteristic point, and the gain is set at a position where the value is equal to or less than a point on the first characteristic curve where the modulation factor is the same as that of the characteristic point.

7. A method for controlling an electric motor that drives and controls an electric motor including a stator winding using a PWM signal, comprising: calculating a phase voltage command value for the stator winding based on a torque command value; calculating a harmonic voltage command value including at least a (2n+1)th order harmonic with respect to a frequency of the fundamental wave when the phase voltage command value is a fundamental wave; generating the PWM signal based on a final voltage command value obtained by multiplying the harmonic voltage command value by a predetermined gain and adding the resultant value to the phase voltage command value; setting the gain based on at least one of a modulation factor associated with the PWM signal, a carrier frequency of the PWM signal, and the torque command value; In the drive control, a DC voltage supplied from a DC power supply is converted into an AC voltage and applied to the electric motor, and a pulsating component superimposed on the DC voltage when the DC voltage is converted into the AC voltage is smoothed by a smoothing capacitor, wherein a first characteristic curve is represented in a coordinate space having the gain as a first axis and the modulation factor as a second axis, the first characteristic curve representing the relationship between the gain and the modulation factor when the DC voltage matches a maximum value of the final voltage command value, and a second characteristic curve representing the relationship between the gain and the modulation factor when the amplitude of the pulsating component matches an allowable maximum amplitude of the pulsating component set corresponding to the carrier frequency, and the gain and the modulation factor when calculating the final voltage command value are represented as characteristic points on the coordinate space, A method for controlling an electric motor, wherein the gain associated with the characteristic point is set at a position equal to or greater than a point on the first characteristic curve and a point on the second characteristic curve at which the modulation factor is the same as that of the characteristic point, and the modulation factor associated with the characteristic point is set at a position equal to or less than a point on the first characteristic curve and a point on the second characteristic curve at which the gain is the same as that of the characteristic point.

8. In the coordinate space, a third characteristic curve is represented which shows the relationship between the gain and the modulation factor when the amplitude of the pulsating component coincides with the allowable maximum amplitude of the pulsating component which is set based on the torque command value, and the gain on the third characteristic curve is located at a position equal to or larger than a point on the first characteristic curve and a point on the second characteristic curve at which the modulation factor is the same as the modulation factor on the third characteristic curve relating to the gain, and the modulation factor on the third characteristic curve is located at a position equal to or smaller than a point on the first characteristic curve and a point on the second characteristic curve at which the gain is the same as the gain on the third characteristic curve relating to the modulation factor, 8. The method for controlling an electric motor according to claim 7, wherein the gain is set so that the characteristic point is located on the third characteristic curve.

9. 9. The method for controlling an electric motor according to claim 8, wherein, when the pulsating component includes a frequency that is twice the carrier frequency and the amplitude of the pulsating component has a maximum value at a specific modulation rate, the third characteristic curve has a minimum value at the specific modulation rate, the torque command value is set to a maximum torque that can be applied to the electric motor.

10. 10. The motor control method according to claim 8, wherein the gain is set so that the third characteristic curve shifts in the direction of the first axis of the coordinate space in a direction in which the gain increases as the torque command value decreases.

11. 9. The motor control method according to claim 8, wherein, in a case where the pulsating component includes a frequency twice the carrier frequency and the amplitude of the pulsating component has a maximum value at a specific modulation rate, causing the third characteristic curve to have a minimum value at the specific modulation rate, the gain is set such that the sharpness of a curve shape of the third characteristic curve centered on the minimum value decreases as the carrier frequency increases.

12. A motor control device that drives and controls a motor including a stator winding using a PWM signal, a phase voltage calculation means for calculating a phase voltage command value for the stator winding based on a torque command value; a harmonic calculation means for calculating a harmonic voltage command value including at least a (2n+1)th order harmonic with respect to a frequency of the fundamental wave when the phase voltage command value is a fundamental wave; a harmonic output means for outputting a value obtained by multiplying the harmonic voltage command value by a predetermined gain; a final voltage calculation unit that generates a final voltage command value by adding the phase voltage command value and the output of the harmonic output means; a PWM signal conversion means for converting the final voltage command value into the PWM signal, The harmonic wave output means a gain setting means for setting the gain based on at least one of a modulation factor associated with the PWM signal, a carrier frequency of the PWM signal, and the torque command value; In the drive control, a DC voltage supplied from a DC power supply is converted into an AC voltage and applied to the electric motor, The gain setting means A motor control device that sets the gain to a value that does not cause the maximum value of the final voltage command value to exceed the DC voltage.

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