Motor device and motor control method

Abstract

To suppress the influence of noise contained in signals used for motor control and achieve higher-precision motor control.SOLUTION: A motor control device has a state estimator that derives an estimated angular velocity value of a motor on the basis of angular velocity information detected from the motor via feedback control, a first speed controller that calculates an angular velocity command value for the motor on the basis of a speed command value, and a second speed controller that calculates a current command value for the motor using the angular velocity command value calculated by the first speed controller and the estimated angular velocity value estimated by the state estimator.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Conventionally, motors are used in a variety of devices, such as machine tools and inspection equipment. The rotational speed of a motor is required to follow a speed command. In reality, speed commands to a motor and detection signals from a detection device that detects the operating state of the motor can contain errors and noise. These can affect the angle and angular velocity of the motor during operation.

[0003] Various motor configurations have been disclosed that take into consideration the effects of such noise, etc. For example, Patent Document 1 discloses a feedforward type configuration in which the rotation angle of the motor is detected by an encoder, the error contained in the detected angle is calculated, and the angle error is corrected before being input to a position / speed controller. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2020-046709 Summary of the Invention [Problem to be solved by the invention]

[0005] To accurately control a motor by tracking the rotational speed according to a speed command, it is necessary to suppress the effects of errors and noise such as those described above. Here, let us consider a feedback-type configuration. For example, the errors described above include multiple periodic sinusoidal errors (linearity errors) corresponding to one rotation of the motor when detecting the angle. If speed control is performed by feeding back an angular velocity signal obtained by differentiating an angle signal without taking such errors into account, noise and vibrations with frequencies proportional to the rotational speed will be generated. Furthermore, as other errors and noise, the speed command used to control the motor may contain high-frequency noise. If the rotational speed is controlled using a speed command containing such noise as is, high-frequency noise and vibrations will be generated. Furthermore, for example, the configuration described in Patent Document 1 has a problem in that tuning is only possible when the motor is moving at a constant speed, which is a condition for calculating the error pattern. It is therefore necessary to achieve more accurate rotation control by suppressing the effects of errors and noise contained in the various signals used in motor control and tracking the rotational speed according to the command.

[0006] In view of the above problems, an object of the present invention is to suppress the influence of noise contained in signals used for motor control and to achieve more accurate motor control. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention has the following configuration: a state estimator that derives an estimated angular velocity value of the motor through feedback control based on angular velocity information detected from the motor; a first speed controller that calculates an angular speed command value for the motor based on the speed command value; a second speed controller that calculates a current command value for the motor using the angular velocity command value calculated by the first speed controller and the angular velocity estimated value estimated by the state estimator; It has.

[0008] Another aspect of the present invention has the following configuration: a motor control device comprising: a first speed controller that calculates an angular speed command value for the motor based on the speed command value; a state estimator that derives an angular velocity estimate for the motor using a value based on an angular error in the output of the motor; a second speed controller that calculates a current command value for the motor using a difference between an angular velocity command value calculated by the first speed controller and an angular velocity estimated value estimated by the state estimator; and a first transfer function of a closed loop system including the first speed controller, the second speed controller, and the state estimator has a characteristic of a first-order low-pass filter; The first transfer function is an adjustable first threshold is set for a frequency domain of the angular velocity; a gain for the speed command value is defined to be reduced in an area where the gain is greater than the first threshold value; a second transfer function of a closed loop system including the second speed controller and the state estimator has characteristics of a first-order low-pass filter and a band-pass filter; The second transfer function is an adjustable second threshold is set for the frequency domain of the angular velocity; The gain for the input value based on the angle error is defined to be reduced with the second threshold as a peak.

[0009] Another aspect of the present invention has the following configuration: A motor control method comprising: an estimation step of deriving an estimated angular velocity value of the motor by feedback control based on angular velocity information detected from the motor; a first calculation step of calculating an angular velocity command value for the motor based on a velocity command value; a second calculation step of calculating a current command value for the motor using the angular velocity command value calculated in the first calculation step and the angular velocity estimated value estimated in the estimation step; It has.

[0010] Another aspect of the present invention has the following configuration: A motor control method comprising: a first calculation step of calculating an angular velocity command value for the motor based on the velocity command value in a first velocity controller; an estimation step in a state estimator for deriving an angular velocity estimate of the motor using a value based on an angular error in the output of the motor; a second calculation step in a second speed controller for calculating a current command value for the motor using a difference between the angular velocity command value calculated in the first calculation step and the angular velocity estimated value estimated in the estimation step; and a first transfer function of a closed loop system including the first speed controller, the second speed controller, and the state estimator has a characteristic of a first-order low-pass filter; The first transfer function is an adjustable first threshold is set for a frequency domain of the angular velocity; a gain for the speed command value is defined to be reduced in an area where the gain is greater than the first threshold value; a second transfer function of a closed loop system including the second speed controller and the state estimator has characteristics of a first-order low-pass filter and a band-pass filter; The second transfer function is an adjustable second threshold is set for the frequency domain of the angular velocity; The gain for the input value based on the angle error is defined to be reduced with the second threshold as a peak. [Effects of the Invention]

[0011] The present invention makes it possible to suppress the effects of errors and noise contained in signals used for motor control, thereby achieving more accurate motor control. [Brief explanation of the drawings]

[0012] [Figure 1]FIG. 2 is a conceptual diagram showing an example of a control system for a motor according to an embodiment of the present invention. [Figure 2] FIG. 4 is a graph illustrating a transfer characteristic according to an embodiment of the present invention. [Figure 3] FIG. 4 is a graph illustrating a transfer characteristic according to an embodiment of the present invention. [Figure 4] FIG. 4 is a graph illustrating a transfer characteristic according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings, etc. 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 of the configurations described in each embodiment are not necessarily essential configurations for solving the problems of the present invention.

[0014] First Embodiment A first embodiment of the present invention will be described below. A motor control device according to one embodiment of the present invention may be applicable to motors to which the control described below can be applied, such as linear motors and servo motors. Examples of motor systems in which a motor is installed include, but are not limited to, machine tools, inspection equipment, semiconductor manufacturing equipment, XY stages, and linear feed systems using ball screws. Furthermore, as a detection device for detecting the angle of the motor, a resolver or other angle sensor may be used in addition to an encoder.

[0015] [Control system] 1 is a conceptual diagram showing an example configuration of a motor device 100 including a motor control system according to this embodiment. The motor device 100 according to this embodiment may be configured to include a program, controller, driver, motor, and encoder (not shown). The controller may be configured, for example, with a processing unit such as a CPU (Central Processing Unit) that can read and execute programs, and a storage unit for storing programs.

[0016] The motor device 100 includes a speed control system including a speed controller 101, a subtractor 102, and a speed controller 103. The speed control system is realized, for example, by a controller (not shown) for controlling a motor (not shown). The motor device 100 also includes a current control system 104. The current control system 104 is realized, for example, by a driver (not shown). The motor device 100 also includes, as a motor structural system, a torque conversion system 105, a mechanical characteristics system 106, and an integration system 107. The torque conversion system 105, the mechanical characteristics system 106, and the integration system 107 depend on the characteristics of the motor. The motor device 100 also includes, as a feedback system, an adder 108 and a state estimator 109.

[0017] In the motor device 100, a speed command value ω corresponding to a target speed is ref is input to the speed controller 101. ref is determined by a program (not shown) and is input at a predetermined timing as the program is executed. ref The angular velocity command value is calculated using a predetermined calculation formula, the details of which will be described later.

[0018] The subtractor 102 derives a speed deviation e by subtracting the angular velocity estimated value ω^ estimated by the state estimator 109 from the angular velocity command value calculated by the speed controller 101, and inputs the speed deviation e to the speed controller 103. In other words, the subtractor 102 receives feedback of the angular velocity estimated value ω^ at the current time, and derives the difference between the angular velocity command value and the current angular velocity.

[0019] The speed controller 103 calculates a current command value I ref The details of the calculation formula will be described later. The calculated current command value I ref is input to the current control system 104.

[0020] The current control system 104 controls the current command value I ref Based on this, the q-axis current iq The current control system 104 controls the current of a power supply (not shown).

[0021] In the torque conversion system 105, the q-axis current i q and torque constant K T A torque τ is output based on the torque τ. Furthermore, in the mechanical characteristic system 106, an angular velocity ω is output based on the mechanical characteristics of the torque τ. Furthermore, an angle θ' corresponding to the angular velocity ω is output. The angle θ' by this motor structural system is transmitted to an optional drive unit (not shown), which operates the drive unit. The drive unit may differ depending on the configuration of the system to which the motor device 100 is applied.

[0022] An angle error Δθ is added to the angle θ' as feedback from the drive unit. This angle error Δθ is, for example, a detection error of an encoder (not shown). Then, an adder 108 adds the angle θ' due to the motor structural system and the angle error Δθ, and inputs the result to a state estimator 109 as the angle θ.

[0023] The state estimator 109 derives an angular velocity estimated value ω^ based on the angle θ, and performs feedback by passing the value to the subtractor 102. The derivation of the angular velocity estimated value ω^ will be described in detail later.

[0024] As described above, in this embodiment, the angle error and noise for each of the two signals are considered. The first is the speed command value ω ref The second is an angle error Δθ (linearity error) mixed into the detection signal. In this embodiment, the processes of the speed controller 101, the speed controller 103, and the state estimator 109 are defined in response to these errors and noises.

[0025] The transfer characteristics of the motor control according to this embodiment will be described with reference to Figures 2 to 4. First, the parameters relating to the transfer characteristics according to this embodiment are defined as follows. Note that each parameter also corresponds to that shown in each block in Figure 1.

[0026] [constant] ω vref :Speed ​​control bandwidth [rad / s] ω vdis :Angle error suppression band [rad / s] ω c :Current control bandwidth [rad / s] K T :Motor torque constant [Nm / A] J: Motor inertia coefficient [kg m 2 ] D: Viscosity coefficient of the motor [Nm / (rad / s)] g1: Gain 1 of the state estimator g2: Gain 2 of the state estimator θ0: Initial angle ω0: Initial value of angular velocity

[0027] [variable] ω ref :Speed ​​command [rad / s] e: Speed ​​deviation [rad / s] I ref :Current command [A] I q :q-axis current [A] τ: Motor torque [Nm] ω: Angular velocity [rad / s] θ: Angle [rad] Δθ: Angle error [rad] θ^: angle estimate [rad] ω^: Estimated angular velocity [rad]

[0028] In the conceptual diagram of the motor device 100 shown in FIG. 1, the speed command value ω ref The transfer function from the angular error Δθ to the angular velocity ω and the transfer function from the angular error Δθ to the angular velocity ω are derived as follows:

[0029]

number

[0030]

number

[0031]

number

[0032] Equation (2) corresponds to the corner frequency of the BPF (Band Pass Filter). Equation (3) corresponds to the attenuation coefficient of the BPF. Examples of these are shown in Figures 3 and 4.

[0033] In the speed control system shown in Figure 1, the speed command value ω ref The transfer characteristic of the closed loop system from the speed control band ω to the angular velocity ω is a first-order LPF (Low Pass Filter) characteristic (speed controller 101 - subtractor 102 - speed controller 103 - current control system 104 - torque conversion system 105 - mechanical characteristic system 106 - integration system 107 - state estimator 109). In this embodiment, as shown in FIG. vref Set.

[0034] In Figure 2, the vertical axis represents the angular velocity ω and the velocity command value ω ref The horizontal axis shows the gain [dB] for the ratio of the angular velocity [rad / s]. vref ) is the angular velocity command value ω ref is the frequency domain that you want to follow. vref ~) is the frequency range where you do not want the angular velocity to follow the velocity command noise. vref For the above region Rb, the influence of high frequency noise contained in region Rb is suppressed by controlling the gain to be lowered.

[0035] In order to realize the control shown in FIG. 2, the velocity controller 101 derives a target angular velocity command using the following equation (4).

[0036]

number

[0037] On the other hand, in the speed control system shown in Fig. 1, the transfer characteristic of the closed loop system from the angle error Δθ to the angular velocity ω is a first-order LPF characteristic + BPF characteristic (adder 108 - state estimator 109 - subtractor 102 - speed controller 103 - current control system 104 - torque conversion system 105 - mechanical characteristic system 106). In this embodiment, as shown in Figs. 3 and 4, the angle error suppression band ω on the first-order LPF characteristic side is vdis In addition, the angle error suppression band ω d Set.

[0038] 3 and 4, the vertical axis represents the gain [dB] relative to the ratio of the angular velocity ω to the angular error Δθ, and the horizontal axis represents the angular velocity [rad / s]. d ) is the region where the low frequency region is desired to be suppressed when the motor is rotating at a low speed. vdis ~) is the region where you want to suppress the high frequency region when the motor is running at medium to high speeds.

[0039] Angle error suppression band ω vdis By setting and adjusting the angle error suppression band ω d By setting and adjusting ω, angle errors in the low frequency range can be suppressed. For example, when a motor is used at a low rotation speed, linearity errors occur at low frequencies. d By setting ω high, it is possible to enhance the suppression effect of the target angle error. Also, when the motor is used at medium to high rotation speeds, the linearity error becomes high frequency. vdis By setting it low, it is possible to enhance the effect of suppressing the target angle error.

[0040] In order to realize the control shown in FIGS. 3 and 4, the speed controller 103 derives a target current command value using the following equation (5).

[0041]

number

[0042] [State estimator] The design of the state estimator 109 for the above-mentioned control will be explained below. First, the q-axis current i q The transfer function from to the angle θ (torque conversion system 105 - mechanical characteristic system 106 - integration system 107 - adder 108) can be defined by the following equation (6).

[0043]

number

[0044] By performing an inverse Laplace transform on the above equation (6) and deriving the equation of motion, the following equation (7) is derived.

[0045]

number

[0046] Based on equation (7), the following equation (8) of state is derived.

[0047]

number

[0048] Based on equation (8), the state estimator 109 is defined by the following equation (9): where "^" indicates an estimated value.

[0049]

number

[0050] Furthermore, based on equations (8) and (9), the derivative of the state estimation error is derived as shown in the following equation (10).

[0051]

number

[0052] Furthermore, based on equation (10), the state estimation error is derived as shown in the following equation (11).

[0053]

number

[0054] Based on the above equations, the state estimate can be calculated as shown in the following equation (12).

[0055]

number

[0056] Then, from equation (12), the angular velocity estimated value ω^ is derived as shown in the following equation (13).

[0057]

number

[0058] The state estimator 109 according to this embodiment is implemented based on the above equation (13) as defined by the following equations (14) and (15).

[0059]

number

[0060] Integrating the above equation over time yields the following equation (15).

[0061]

number

[0062] In each block shown in FIG. 1, various controls are performed to obtain a speed command value ω ref and the angle error Δθ contained in the angle detector can be suppressed.

[0063] More specifically, when the motor is used at a low rotation speed, the linearity error included in Δθ has a low frequency. Therefore, when a speed command value corresponding to a low rotation speed is input, ω d and ω vdis This suppression effect can be improved by setting ω high. Also, when the motor is used at medium to high rotation speeds, the linearity error contained in Δθ becomes high frequency. Therefore, when a speed command value corresponding to medium or high rotation speeds is input, ω d and ω vdis The suppression effect can be improved by setting the parameter to a low value. Note that the level of the parameter adjustment here is relative and is not limited to a specific value. Therefore, it may be determined appropriately depending on the configuration of the motor, etc.

[0064] Also, the adjustable parameter ω vref , ω d , ω vdis may be switched stepwise in accordance with the rotation speed of the motor, or may be adjusted seamlessly. For example, as the rotation speed decreases, ω d As the rotation speed increases, ω d and ω vdis may be adjusted to be lower.

[0065] As described above, in the motor control according to this embodiment, the state estimator acquires encoder angle information, taking into account errors contained in the encoder's detection values. Furthermore, because feedforward control results in a one-way signal flow, if parameter correction along the way is insufficient, it becomes difficult to generate a highly accurate speed command. Therefore, the motor control according to this embodiment uses a configuration based on feedback control. Furthermore, by performing feedback control of the angle information in the state estimator, the output accuracy of the state estimator is improved. As a result, it becomes possible to track the speed command with high accuracy.

[0066] As described above, this embodiment makes it possible to suppress the effects of noise and errors contained in signals used for motor control and achieve more accurate motor control. In particular, by seamlessly adjusting parameters according to the angular velocity of the motor, it becomes possible to suppress angle errors over a wide range of rotation speeds. It also becomes possible to suppress noise and vibrations caused by noise and errors.

[0067] <Other embodiments> Furthermore, in the present invention, a program or application for realizing the functions of one or more of the above-described embodiments can be supplied to a system or device via a network or a storage medium, etc., and one or more processors in the computer of the system or device can read and execute the program.

[0068] As such, the present invention is not limited to the above-described embodiments, and the present invention also contemplates the mutual combination of the various components of the embodiments, as well as modifications and applications by those skilled in the art based on the description in the specification and well-known techniques, and these modifications and applications are included in the scope of protection sought.

[0069] As described above, the present specification discloses the following: (1) A state estimator (e.g., 109) that derives an estimated angular velocity value (e.g., ω̂) of the motor through feedback control based on angular velocity information (e.g., θ) detected from the motor; Speed ​​command value (e.g., ω ref a first speed controller (e.g., 101) that calculates an angular velocity command value for the motor based on the A current command value (e.g., I ref a second speed controller (e.g., 103) that calculates A motor control device having the same. This configuration makes it possible to suppress the influence of angle errors and noise contained in the signals used for motor control, and to make the rotation speed follow the angle command.

[0070] (2) Speed ​​command value (e.g., ω ref a first speed controller (e.g., 101) that calculates an angular velocity command value for the motor based on the a state estimator (e.g., 109) that derives an angular velocity estimate (e.g., ω̂) of the motor using a value (e.g., θ) based on an angular error (e.g., Δθ) at the output of the motor; A current command value (e.g., I ref a second speed controller (e.g., 103) that calculates and a first transfer function of a closed loop system including the first speed controller, the second speed controller, and the state estimator has a characteristic of a first-order low-pass filter; The first transfer function is For the frequency domain of the angular velocity, an adjustable first threshold (e.g., ω vref ) is set, The area larger than the first threshold (e.g., R b ) is defined to decrease a gain for the speed command value, a second transfer function of a closed loop system including the second speed controller and the state estimator has characteristics of a first-order low-pass filter and a band-pass filter; The second transfer function is For the frequency domain of the angular velocity, an adjustable second threshold (e.g., ω d ) is set, The motor control device is defined so as to reduce a gain for an input value based on the angle error, with the second threshold being the peak. This configuration makes it possible to suppress the effects of angle errors and noise contained in the signals used for motor control, thereby achieving more accurate motor control.

[0071] (3) The second transfer function further comprises: For the frequency domain of the angular velocity, an adjustable third threshold (e.g., ω vdis ) is set, The motor control device according to (2), wherein the region greater than the third threshold (e.g., Rd) is defined so as to reduce the gain for the speed command value more than the region between the second threshold and the third threshold. This configuration makes it possible to suppress angle errors and noise in higher frequency ranges, thereby making it possible to suppress sounds and vibrations caused by angle errors and noise.

[0072] (4) The motor control device according to (3), wherein the gain in the region smaller than the second threshold and the gain in the region between the second threshold and the third threshold are specified to decrease at the same rate with the second threshold as a peak. This configuration makes it possible to achieve the same suppression effect both before and after the target frequency.

[0073] (5) The motor control device according to any one of (2) to (4), wherein the first threshold value is set based on the speed command value. With this configuration, it is possible to define, in accordance with the speed command value, a frequency range in which the angular velocity is desired to follow the speed command value and a frequency range in which the angular velocity is not desired to follow the speed command value, thereby making it possible to suppress the effects of the desired high-frequency noise.

[0074] (6) The motor control device according to any one of (2) to (5), wherein the second threshold value is set to increase as the rotation speed of the motor according to the speed command value decreases. With this configuration, when the motor is used at low rotation speeds, it is possible to control it so that low-frequency linearity errors are suppressed, and when the motor is used at medium to high rotation speeds, it is possible to control it so that high-frequency linearity errors are suppressed, making it possible to suppress the effects of angle errors and noise according to the rotation speed.

[0075] (7) The motor control device according to (3) or (4), wherein the third threshold value is set to increase as the rotation speed of the motor according to the speed command value decreases. This configuration makes it possible to control the linearity error at higher frequencies so as to suppress it.

[0076] (8) an estimation step of deriving an estimated angular velocity value (e.g., ω̂) of the motor by feedback control based on angular velocity information (e.g., θ) detected from the motor; Speed ​​command value (e.g., ω ref a first calculation step of calculating an angular velocity command value for the motor based on the A current command value (e.g., I ref ) a second calculation step of calculating A motor control method comprising: This configuration makes it possible to suppress the influence of angle errors and noise contained in the signals used for motor control, and to make the rotation speed follow the angle command.

[0077] (9) In the first speed controller (e.g., 101), a speed command value (e.g., ω ref a first calculation step of calculating an angular velocity command value for the motor based on the an estimation step in a state estimator (e.g., 109) of deriving an angular velocity estimate (e.g., ω̂) of the motor using a value (e.g., θ) based on an angular error (e.g., Δθ) at the output of the motor; In a second speed controller (for example, 102), a current command value (for example, I ref ) a second calculation step of calculating and a first transfer function of a closed loop system including the first speed controller, the second speed controller, and the state estimator has a characteristic of a first-order low-pass filter; The first transfer function is For the frequency domain of the angular velocity, an adjustable first threshold (e.g., ω vref ) is set, The area larger than the first threshold (e.g., R b ) is defined to decrease a gain for the speed command value, a second transfer function of a closed loop system including the second speed controller and the state estimator has characteristics of a first-order low-pass filter and a band-pass filter; The second transfer function is For the frequency domain of the angular velocity, an adjustable second threshold (e.g., ω d ) is set, A motor control method in which a gain for an input value based on the angle error is reduced with the second threshold as a peak. This configuration makes it possible to suppress the effects of angle errors and noise contained in the signals used for motor control, thereby achieving more accurate motor control. [Explanation of symbols]

[0078] 100...Motor device 101...Speed ​​controller 102...Subtractor 103...Speed ​​controller 104...Current control system 105...Torque conversion system 106...Mechanical properties 107...Integral system 108...adder 109...State estimator

Claims

1. a state estimator that derives an estimated angular velocity value of the motor through feedback control based on angular velocity information detected from the motor; a first speed controller that calculates an angular speed command value for the motor based on the speed command value; a second speed controller that calculates a current command value for the motor using the angular velocity command value calculated by the first speed controller and the angular velocity estimated value estimated by the state estimator; A motor control device having the same.

2. a first speed controller that calculates an angular speed command value for the motor based on the speed command value; a state estimator that derives an angular velocity estimate for the motor using a value based on an angular error in the output of the motor; a second speed controller that calculates a current command value for the motor using a difference between an angular velocity command value calculated by the first speed controller and an angular velocity estimated value estimated by the state estimator; and a first transfer function of a closed loop system including the first speed controller, the second speed controller, and the state estimator has a characteristic of a first-order low-pass filter; The first transfer function is an adjustable first threshold is set for a frequency domain of the angular velocity; a gain for the speed command value is defined to be reduced in an area where the gain is greater than the first threshold value; a second transfer function of a closed loop system including the second speed controller and the state estimator has characteristics of a first-order low-pass filter and a band-pass filter; The second transfer function is an adjustable second threshold is set for the frequency domain of the angular velocity; The motor control device is defined so as to reduce a gain for an input value based on the angle error, with the second threshold value being the peak.

3. The second transfer function further comprises: an adjustable third threshold value greater than the second threshold value is set for a frequency domain of the angular velocity; The motor control device according to claim 2 , wherein the region greater than the third threshold value is defined so as to reduce a gain for the speed command value more than in the region between the second threshold value and the third threshold value.

4. 4. The motor control device according to claim 3, wherein a gain in a region smaller than the second threshold and a gain in a region between the second threshold and the third threshold are defined so as to decrease at the same rate from a peak at the second threshold.

5. The motor control device according to claim 2 , wherein the first threshold value is set based on the speed command value.

6. The motor control device according to claim 2 , wherein the second threshold value is set to increase as the rotation speed of the motor according to the speed command value decreases.

7. The motor control device according to claim 3 , wherein the third threshold value is set to increase as the rotation speed of the motor according to the speed command value decreases.

8. an estimation step of deriving an estimated angular velocity value of the motor by feedback control based on angular velocity information detected from the motor; a first calculation step of calculating an angular velocity command value for the motor based on a velocity command value; a second calculation step of calculating a current command value for the motor using the angular velocity command value calculated in the first calculation step and the angular velocity estimated value estimated in the estimation step; A motor control method comprising:

9. a first calculation step of calculating an angular velocity command value for the motor based on the velocity command value in a first velocity controller; an estimation step in a state estimator for deriving an angular velocity estimate of the motor using a value based on an angular error in the output of the motor; a second calculation step in a second speed controller for calculating a current command value for the motor using a difference between the angular velocity command value calculated in the first calculation step and the angular velocity estimated value estimated in the estimation step; and a first transfer function of a closed loop system including the first speed controller, the second speed controller, and the state estimator has a characteristic of a first-order low-pass filter; The first transfer function is an adjustable first threshold is set for a frequency domain of the angular velocity; a gain for the speed command value is defined to be reduced in an area where the gain is greater than the first threshold value; a second transfer function of a closed loop system including the second speed controller and the state estimator has characteristics of a first-order low-pass filter and a band-pass filter; The second transfer function is an adjustable second threshold is set for the frequency domain of the angular velocity; A motor control method in which a gain for an input value based on the angle error is reduced with the second threshold as a peak.

Images