Motor control device, motor control method, and motor system

Abstract

To suppress amplification of noise mixed into a signal even when using a control signal using a transfer function by an N-th order function.SOLUTION: A motor control device that controls a three-phase motor on the basis of a current command value includes derivation means that derives a control signal on the basis of the current command value, calculation means that calculates a future predicted value for the control signal by extrapolation based on an N-th order function, correction means that corrects the predicted value by multiplying it by an inverse characteristic of a gain characteristic based on the N-th order function, and control means that controls the three-phase motor using the predicted value corrected by the correction means.SELECTED DRAWING: Figure 5

Description

[Technical field]

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

[0002] Conventionally, permanent magnet type synchronous motors are used in various devices such as electric power steering devices, railway vibration prevention actuators, etc. Such motors are supplied with power from a power source that can control the frequency, voltage, current, phase, etc., and their operation is controlled.

[0003] In general, a signal for controlling a motor may have a delay due to A / D conversion (analog-digital conversion), control signal calculation processing, etc. For example, Patent Document 1 discloses a configuration for suppressing and controlling a delay in a brushless motor provided in an electric power steering device, in which a future value of an electrical angle is predicted by extrapolating based on a linear function or a quadratic function, and a future duty command value is calculated based on the predicted value. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Re-tabled publication No. 2019-083015 Summary of the Invention [Problem to be solved by the invention]

[0005] For example, when a control signal is corrected using extrapolation based on a linear function or a quadratic function, the gain characteristic increases on the high frequency side, and if noise is mixed in the control signal, this is amplified. As a result of the noise being amplified on the high frequency side, unintended sounds and vibrations are generated. It is necessary to suppress the amplification of noise mixed in the control signal on the high frequency side.

[0006] In view of the above problems, an object of the present invention is to suppress the amplification of noise mixed into a control signal even when a motor is controlled using a control signal obtained by extrapolation based on an Nth-order function. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention has the following configuration. That is, a motor control device that controls a three-phase motor based on a current command value, A derivation means for deriving a control signal based on the current command value; A calculation means for calculating a future predicted value for the control signal by extrapolation based on an N-th order function; a correction means for performing a correction by multiplying the predicted value by an inverse characteristic of a gain characteristic based on the N-th order function; a control means for controlling the three-phase motor using the predicted value corrected by the correction means; A motor control device comprising:

[0008] Another aspect of the present invention has the following configuration. That is, a motor control method for controlling a three-phase motor based on a current command value, comprising the steps of: a derivation step of deriving a control signal based on the current command value; A calculation step of calculating a future predicted value for the control signal by extrapolation based on an N-th order function; a correction step of correcting the predicted value by multiplying the predicted value by an inverse characteristic of a gain characteristic based on the N-th order function; a control step of controlling the three-phase motor using the predicted value corrected in the correction step; The motor control method comprises:

[0009] Another aspect of the present invention has the following configuration. That is, a motor system comprising: A motor control device; a three-phase motor controlled by the motor control device; Equipped with The motor control device includes: A derivation means for deriving a control signal based on a current command value; A calculation means for calculating a future predicted value for the control signal by extrapolation based on an N-th order function; a correction means for performing a correction by multiplying the predicted value by an inverse characteristic of a gain characteristic based on the N-th order function; a control means for controlling the three-phase motor using the predicted value corrected by the correction means; A motor system comprising: Effect of the Invention

[0010] According to the present invention, even when a motor is controlled using a control signal obtained by extrapolation based on an Nth-order function, it is possible to suppress the amplification of noise mixed into the control signal. [Brief description of the drawings]

[0011] [Figure 1] FIG. 11 is a graph illustrating prediction of a control signal by extrapolation using a linear function. [Diagram 2] FIG. 11 is a graph illustrating prediction of a control signal by extrapolation using a quadratic function. [Diagram 3] 1 is a graph illustrating gain and phase characteristics in a conventional method. [Figure 4] 1 is a schematic diagram showing an example of the configuration of a motor system according to an embodiment of the present invention. [Diagram 5] FIG. 4 is a diagram showing an example of a functional configuration based on a linear function according to the embodiment; [Figure 6] FIG. 4 is a diagram showing an example of a functional configuration based on a quadratic function according to the embodiment. [Figure 7] 5 is a graph illustrating gain characteristics and phase characteristics based on a linear function according to the embodiment. [Figure 8] 5 is a graph illustrating gain characteristics and phase characteristics based on a quadratic function according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, the embodiment for carrying out the present invention will be described with reference to the drawings. Note that the embodiment described below is one embodiment for explaining the present invention, and is not intended to be interpreted as limiting the present invention, and all configurations described in each embodiment are not necessarily essential configurations for solving the problems of the present invention. In addition, in each drawing, the same components are given the same reference numbers to indicate their correspondence.

[0013] <First embodiment> A first embodiment of the present invention will be described below. A motor control device according to an embodiment of the present invention is applicable to various permanent magnet type synchronous motors, more specifically, to systems equipped with three-phase synchronous motors. Examples of such systems include, but are not limited to, electric power steering devices and railway vibration prevention actuators.

[0014] [Characteristics of predicted values ​​based on N-th order functions] Prediction of future values ​​of signals related to motor control will be described with reference to Figures 1 and 2. As described above, in motor control, signal delays occur due to A / D conversion and control signal arithmetic processing within the device. In order to suppress this delay, future values ​​of signals are predicted based on current and past values ​​by extrapolation using N-th order functions such as linear functions and quadratic functions. By performing control based on this predicted value, it becomes possible to suppress the effects of delay.

[0015] In this embodiment, as an example, a configuration using extrapolation based on a linear function and extrapolation based on a quadratic function will be described. In this specification, the calculation of extrapolation based on a linear function may also be referred to as FOH (First Order Hold) calculation. Also, the calculation of extrapolation based on a quadratic function may also be referred to as SOH (Second Order Hold) calculation.

[0016] FIG. 1 is a graph diagram for explaining prediction of a signal value by extrapolation using a linear function. In FIG. 1, the horizontal axis indicates sample time [k], and the vertical axis indicates signal value y[k]. Here, the signal value at the present time is y[0], and the signal value one sample time in the past is y[-1]. The sample time indicates a time interval (control period) and is predefined. k=0 indicates the present time, k=-1 indicates one sample time in the past, and k=1 / 2 indicates 1 / 2 sample time in the future. Here, an example is shown in which a signal value in the future for 1 / 2 sample time is predicted.

[0017] A prediction equation (transfer function) based on a linear function for predicting a signal value is expressed by the following equation (1).

[0018]

number

[0019] As shown in Figure 1, for example, when deriving a predicted value of a signal at a sample time of k=1 / 2, it is derived using the signal value y[0] at k=0 and the signal value y[-1] at k=-1. Substituting past values ​​into equation (1), it is expressed as the following equations (2) and (3).

[0020]

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[0021] Furthermore, when formulas (2) and (3) are expanded with respect to the coefficients a and b, they are expressed as formulas (4) and (5) below.

[0022]

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[0023] Then, substituting equations (4) and (5) into equation (1), we obtain the following equation (6).

[0024]

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[0025] FIG. 2 is a graph diagram for explaining signal prediction by extrapolation using a quadratic function. In FIG. 2, the horizontal axis indicates sample time [k], and the vertical axis indicates signal value y[k]. Here, the signal value at the current time is y[0], the past signal value for one sample time is y[-1], and the past signal value for two sample times is y[-2]. k=0 represents the current time, k=-1 represents the past for one sample time, k=-2 represents the past for two sample times, and k=1 / 2 represents the future for 1 / 2 sample time. Here, an example is shown in which a signal value for 1 / 2 sample time in the future is predicted.

[0026] A prediction equation (transfer function) based on a quadratic function for predicting a signal value is expressed by the following equation (7).

[0027]

number

[0028] 2, for example, when deriving a predicted value of a signal at a sample time of k=1 / 2, it is derived using the signal value y[0] at k=0, the signal value y[-1] at k=-1, and the signal value y[-2] at k=-2. Substituting past values ​​into equation (7), the following equations (8) to (10) are obtained.

[0029]

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[0030] Furthermore, when formulas (8) to (10) are expanded with respect to the coefficients a, b, and c, they are expressed as the following formulas (11) to (13).

[0031]

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[0032] Then, by substituting the formulas (11) to (13) into the formula (7), the following formula (14) is obtained.

[0033]

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[0034] Figure 3 is a Bode plot showing frequency characteristics based on the linear transfer function shown in equation (6) and the quadratic transfer function shown in equation (14). Figure 3(a) shows gain characteristics, with the horizontal axis representing frequency [Hz] and the vertical axis representing amplitude [dB]. Figure 3(b) shows phase characteristics, with the horizontal axis representing frequency [Hz] and the vertical axis representing phase [deg].

[0035] In Fig. 3(a), dotted line 301 indicates the ideal value of the amplitude, which is preferably 0 dB in order to suppress noise and vibrations caused by driving the motor. In contrast, solid line 302 indicates the amplitude based on a linear transfer function, and solid line 303 indicates the amplitude based on a quadratic transfer function. In other words, both the linear and quadratic transfer functions deviate from the ideal value of 0 dB toward the higher frequencies. Therefore, if the control signal contains noise, this noise will be amplified, and unintended noise and vibrations may occur when the motor is driven.

[0036] In Fig. 3(b), dotted line 311 indicates the ideal value of the phase. Solid line 312 indicates the phase due to a linear transfer function, and solid line 313 indicates the phase due to a quadratic transfer function. Referring to Fig. 3(b), both the linear and quadratic transfer functions have phases that deviate from the ideal value as one moves toward the high frequency side, but the quadratic transfer function can provide control that is closer to the ideal value.

[0037] In consideration of the above-mentioned phenomenon of linear or quadratic transfer functions, in this embodiment, a configuration will be described in which the increase in gain is corrected to suppress the effect on control.

[0038] [Circuit configuration] First, an example of the functional configuration of a motor system 10 according to this embodiment will be described with reference to Fig. 4. The motor system 10 includes a motor control device 100 and a three-phase motor 200. Note that only parts related to this embodiment are shown here as examples, and the motor system 10 may further include other parts (for example, sensors, interfaces for signal input, etc.).

[0039] The motor control device 100 controls the drive of a three-phase motor 200. The various functions of the motor control device 100 may be implemented by a processing unit such as a CPU (Central Processing Unit) reading and executing a program stored in a storage unit, or may be implemented by various electronic circuits, or may be implemented by a combination of these.

[0040] In the motor control device 100, a current command value calculation unit 101 calculates a current command value I ref_q , I ref_d The motor control unit 102 calculates the current command value I from the current command value calculation unit 101 and issues a command to the motor control unit 102. The d-axis indicates the direction of the magnetic flux of a rotor (not shown) included in the three-phase motor 200. The q-axis indicates a direction perpendicular to the d-axis. The motor control unit 102 calculates the current command value I from the current command value calculation unit 101 and issues a command to the motor control unit 102. ref_q , I ref_d , and the duty value (D u ,D v ,D w ) and outputs it to the PWM control unit 103. The motor control unit 102 according to this embodiment predicts the control signal by extrapolation using a calculation unit described later with reference to FIGS.

[0041] The PWM control unit 103 receives the duty value (D u ,D v ,D w), performs PWM (Pulse Width Modulation) processing, and outputs a control signal to the inverter circuit 104. The inverter circuit 104 converts the power of an AC power source supplied by a battery (not shown) into a current for each phase based on a control signal from the PWM control unit 103, and outputs the current to the three-phase motor 200. The motor current detection circuit 105 detects the current output by the inverter circuit 104 to the three-phase motor 200, and outputs the detected current value I u ,I v ,I w to the three-phase / two-phase conversion unit 106.

[0042] The three-phase / two-phase conversion unit 106 converts the current value I u ,I v ,I w The motor angle θ e Based on this, the two-phase current values ​​I of the d-axis and q-axis are calculated. d ,I q and outputs the converted signal to the motor control unit 102. The motor angle detection unit 107 detects the motor angle θ based on a signal from a rotation angle sensor (not shown) provided for the three-phase motor 200. e Then, the motor angle detection unit 107 detects the detected motor angle θ e to the motor control unit 102, the three-phase / two-phase conversion unit 106, and the angular velocity calculation unit 108. The angular velocity calculation unit 108 receives the motor angle θ e Based on this, the angular velocity ω and the motor rotation speed N are calculated and output to the motor control unit 102.

[0043] The three-phase motor 200 is, for example, a three-phase brushless motor, and has a permanent magnet field or a winding field. The three-phase motor 200 rotates when three-phase AC currents, the phases of which differ by 120°, are supplied to u-phase, v-phase, and w-phase coils (not shown). A rotation angle sensor (not shown) composed of a resolver, a rotary encoder, or the like is installed on the shaft of the rotor (not shown) of the three-phase motor 200.

[0044] (In the case of linear function type) Fig. 5 is a diagram showing an example of the functional configuration of a linear function type first calculation unit 500 provided in the motor control unit 102 shown in Fig. 4. In this embodiment, the first calculation unit 500 is used to correct three-phase duty command values ​​and three-phase current command values. Here, the duty command value will be described as an example.

[0045] The first calculation unit 500 has a holding unit 501 that holds the previous duty command value of the current duty command value, a coefficient unit 502 for the current duty command value, a coefficient unit 503 for the previous duty command value, an adder 504, and a correction calculation unit 505.

[0046] The duty command value generated in the motor control unit 102 is input to the holding unit 501 and the coefficient unit 502 of the first calculation unit 500 of the linear function type. The holding unit 501 outputs the previous duty command value to the coefficient unit 503, and then updates the held value with the current duty command value. The coefficient unit 502 multiplies the current duty command value by a coefficient that is predefined, and outputs the result to the addition unit 504. The coefficient by the coefficient unit 502 corresponds to the coefficient (k+1) shown in the formula (6). The coefficient unit 503 multiplies the duty command value from the holding unit 501 by a coefficient that is predefined, and outputs the result to the addition unit 504. The coefficient by the coefficient unit 503 corresponds to the coefficient (-k) shown in the formula (6). The addition unit 504 adds the value from the coefficient unit 502 and the value from the coefficient unit 503, and outputs the result to the correction calculation unit 505.

[0047] A correction calculation unit 505 derives and outputs a correction duty command value by multiplying the value from the addition unit 504 by a parameter indicating the inverse characteristic of a linear function. The parameter indicating the inverse characteristic will be described below.

[0048] The above equation (6) is expanded as follows using the Laplace operator s and Pade approximation. In order to simplify the expression, the parameters a0, a -1 , A1 is defined and used.

[0049]

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[0050]

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[0051] Based on the above equation (15), the linear function type gain characteristic can be defined as shown in the following equation (16).

[0052]

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[0053] Then, as shown in the following equation (17), the gain characteristic is cancelled by multiplying the inverse of the gain characteristic shown in the above equation (16) by the linear function equation (1).

[0054]

number

[0055] (In the case of quadratic functions) Fig. 6 is a diagram showing an example of the functional configuration of a quadratic function type second calculation unit 600 provided in the motor control unit 102 shown in Fig. 4. In this embodiment, the second calculation unit 600 is used to correct three-phase duty command values ​​and three-phase current command values. Here, the duty command value will be described as an example.

[0056] The second calculation unit 600 has a holding unit 601 that holds the previous duty command value of the current duty command value, a holding unit 602 that holds the duty command value before the previous for the current duty command value, a coefficient unit 603 for the current duty command value, a coefficient unit 604 for the previous duty command value, a coefficient unit 605 for the duty command value before the previous, an adder 606, an adder 607, and a correction calculation unit 608.

[0057] The duty command value generated in the motor control unit 102 is input to a holding unit 601 and a coefficient unit 603 of a quadratic function type second calculation unit 600. The holding unit 601 outputs the previous duty command value to a holding unit 602 and a coefficient unit 604, and then updates the held value with the current duty command value. The holding unit 602 outputs the duty command value before last to a coefficient unit 605, and then updates the held value with the previous duty command value.

[0058] The coefficient unit 603 multiplies the current duty command value by a predetermined coefficient and outputs the result to the adder 606. The coefficient by the coefficient unit 603 is the coefficient ((k 2 +3k+2) / 2). The coefficient unit 604 multiplies the duty command value from the holding unit 601 by a coefficient that is specified in advance, and outputs the result to the adding unit 607. The coefficient by the coefficient unit 604 is the coefficient (-k 2 The coefficient unit 605 multiplies the duty command value from the holding unit 602 by a coefficient that is specified in advance, and outputs the result to the adding unit 607. The coefficient by the coefficient unit 605 corresponds to the coefficient ((k 2 +k) / 2).

[0059] The adder 607 adds the value from the coefficient unit 604 and the value from the coefficient unit 605 , and the adder 606 adds the value from the coefficient unit 603 and the value from the adder unit 607 , and outputs the result to the correction calculation unit 608 .

[0060] A correction calculation unit 608 derives and outputs a correction duty command value by multiplying the value from the addition unit 606 by a parameter indicating the inverse characteristic of the quadratic function. The parameter indicating the inverse characteristic will be described below.

[0061] Regarding the above equation (14), we use the Laplace operator s and the Pade approximation to expand it as follows. In order to express the equation simply, we use the parameters a0, a -1 ,a -2 , A1, A2 are defined and used.

[0062]

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[0063]

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[0064] Based on the above equation (17), the quadratic function type gain characteristic can be defined as shown in the following equation (18).

[0065]

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[0066] Then, as shown in the following equation (19), the gain characteristic is cancelled by multiplying the inverse of the gain characteristic shown in the above equation (18) by equation (7) based on a quadratic function.

[0067]

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[0068] [Characteristics after correction] 7 and 8 are Bode plots for explaining gain characteristics and phase characteristics before and after the correction according to this embodiment.

[0069] (In the case of linear function type) FIG. 7 is a Bode plot of a linear transfer function. FIG. 7(a) shows the gain characteristic before correction, with the horizontal axis being frequency [Hz] and the vertical axis being amplitude [dB]. FIG. 7(b) shows the phase characteristic before correction, with the horizontal axis being frequency [Hz] and the vertical axis being phase [deg]. FIG. 7(c) shows the gain characteristic after correction, with the horizontal axis being frequency [Hz] and the vertical axis being amplitude [dB]. FIG. 7(d) shows the phase characteristic after correction, with the horizontal axis being frequency [Hz] and the vertical axis being phase [deg].

[0070] Comparing FIG. 7(a) with FIG. 7(c) in terms of gain characteristics, after correction, the amplitude is suppressed to the ideal value of 0 dB in all frequency bands. In other words, even if noise is mixed into the control signal, the amplification of the noise can be suppressed. Comparing FIG. 7(b) with FIG. 7(d) in terms of phase characteristics, there is no effect of the correction process according to this embodiment. In other words, it is possible to correct the signal without affecting the phase characteristics.

[0071] (Quadratic function type) FIG. 8 is a Bode plot of a transfer function based on a quadratic function. FIG. 8(a) shows the gain characteristic before correction, with the horizontal axis being frequency [Hz] and the vertical axis being amplitude [dB]. FIG. 8(b) shows the phase characteristic before correction, with the horizontal axis being frequency [Hz] and the vertical axis being phase [deg]. FIG. 8(c) shows the gain characteristic after correction, with the horizontal axis being frequency [Hz] and the vertical axis being amplitude [dB]. FIG. 8(d) shows the phase characteristic after correction, with the horizontal axis being frequency [Hz] and the vertical axis being phase [deg].

[0072] Comparing FIG. 8(a) with FIG. 8(c) in terms of gain characteristics, it is seen that after correction, the amplitude is suppressed to the ideal value of 0 dB in all frequency bands. In other words, even if noise is mixed into the control signal, it is possible to suppress the amplification of the noise. Comparing FIG. 8(b) with FIG. 8(d) in terms of phase characteristics, it is seen that there is no effect of the correction process according to this embodiment. In other words, it is possible to correct the signal without affecting the phase characteristics.

[0073] As described above, the method of this embodiment makes it possible to suppress the increase in gain that occurs on the high frequency side and suppress the amplification of noise mixed into the control signal, even when controlling a motor using a control signal obtained by extrapolation based on an Nth-order function such as a linear function or a quadratic function.

[0074] <Other embodiments> In the above embodiment, an example using a linear function and a quadratic function has been shown. However, the present invention is not limited to these, and an N-th order (N≧3) function may be used. Such functions can also be applied to motor control by deriving the inverse characteristic of the gain characteristic in a similar manner.

[0075] In addition, the present invention can also be realized by supplying a program or application for realizing the functions of one or more of the above-mentioned embodiments to a system or device via a network or a storage medium, etc., and having one or more processors in a computer of the system or device read and execute the program.

[0076] As such, the present invention is not limited to the above-described embodiments, and the present invention also contemplates mutual combinations of the various components of the embodiments, as well as modifications and applications by those skilled in the art based on the descriptions in the specification and well-known technologies, and these are included in the scope of protection sought.

[0077] As described above, the present specification discloses the following: (1) A motor control device (e.g., 100) that controls a three-phase motor (e.g., 200) based on a current command value, A derivation means (e.g., 102) for deriving a control signal based on the current command value; A calculation means (e.g., 501, 502, 503, 504) for calculating a future predicted value for the control signal by extrapolation based on an N-th order function; A correction means (e.g., 505) for correcting the predicted value by multiplying the predicted value by an inverse characteristic of a gain characteristic based on the N-th order function; A control means (e.g., 102, 103, 104) for controlling the three-phase motor using the predicted value corrected by the correction means; A motor control device comprising: With this configuration, even when controlling a motor using a control signal extrapolated based on an Nth-order function, it is possible to suppress an increase in gain that occurs on the high frequency side and suppress the amplification of noise mixed into the control signal.

[0078] (2) The motor control device according to (1), wherein the control signal is a three-phase duty command value or a three-phase current command value. According to this configuration, by performing correction on the three-phase duty command values ​​or the three-phase current command values ​​for controlling the three-phase motor, it is possible to suppress amplification of noise in the command values.

[0079] (3) the N-th order function is a linear function, The motor control device according to (1) or (2), wherein the inverse characteristic of the gain characteristic based on the linear function is expressed by the following equation.

[0080]

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[0081] (4) the N-th order function is a quadratic function, The motor control device according to (1) or (2), wherein the inverse characteristic of the gain characteristic based on the quadratic function is expressed by the following equation.

[0082]

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[0083] (5) A motor control method for controlling a three-phase motor (e.g., 200) based on a current command value, comprising: a derivation step of deriving a control signal based on the current command value; A calculation step of calculating a future predicted value for the control signal by extrapolation based on an N-th order function; a correction step of correcting the predicted value by multiplying the predicted value by an inverse characteristic of a gain characteristic based on the N-th order function; a control step of controlling the three-phase motor using the predicted value corrected in the correction step; The motor control method comprises: With this configuration, even when controlling a motor using a control signal extrapolated based on an Nth-order function, it is possible to suppress an increase in gain that occurs on the high frequency side and suppress the amplification of noise mixed into the control signal.

[0084] (6) A motor control device (e.g., 100) according to any one of (1) to (4), A three-phase motor (e.g., 200) controlled by the motor control device; A motor system (e.g., 10) comprising: According to this configuration, in a motor system that controls a motor using a control signal extrapolated based on an Nth-order function, it is possible to suppress an increase in gain that occurs on the high frequency side and suppress the amplification of noise mixed into the control signal. [Explanation of symbols]

[0085] 10. Motor system 100...Motor control device 101...Current command value calculation unit 102...Motor control unit 103...PWM control unit 104...Inverter circuit 105...Motor current detection circuit 106...3-phase / 2-phase conversion section 107...Motor angle detector 108...Angular velocity calculation section 200...Three-phase motor 500…First calculation unit 501,601,602...Holding part 502, 503, 603, 604, 605...Coefficient section 504,606,607…Addition section 505,608…Correction calculation section 600...Second calculation unit

Claims

1. A motor control device that controls a three-phase motor based on a current command value, A derivation means for deriving a control signal based on the current command value; A calculation means for calculating a future predicted value for the control signal by extrapolation based on an N-th order function; a correction means for performing a correction by multiplying the predicted value by an inverse characteristic of a gain characteristic based on the N-th order function; a control means for controlling the three-phase motor using the predicted value corrected by the correction means; A motor control device comprising:

2. The motor control device according to claim 1 , wherein the control signal is a three-phase duty command value or a three-phase current command value.

3. The N-th order function is a linear function, The motor control device according to claim 1 , wherein an inverse characteristic of the gain characteristic based on the linear function is expressed by the following equation (1): [0010]

4. The N-th order function is a quadratic function, The motor control device according to claim 1 , wherein the inverse characteristic of the gain characteristic based on the quadratic function is expressed by the following equation (2). [0025]

5. A motor control method for controlling a three-phase motor based on a current command value, comprising: a derivation step of deriving a control signal based on the current command value; A calculation step of calculating a future predicted value for the control signal by extrapolation based on an N-th order function; a correction step of correcting the predicted value by multiplying the predicted value by an inverse characteristic of a gain characteristic based on the N-th order function; a control step of controlling the three-phase motor using the predicted value corrected in the correction step; The motor control method comprises:

6. A motor control device according to any one of claims 1 to 4, a three-phase motor controlled by the motor control device; A motor system comprising:

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