阅读说明：本技术 电动机控制装置 (Motor control device ) 是由 桥本章太郎 森田有纪 于 2019-06-25 设计创作，主要内容包括：提供电动机控制装置,在进行电动机的无速度传感器控制的电动机控制装置中提高实际速度相对于速度指令值的追随性。电动机控制装置具备：旋转速度估计部,基于电动机的电流信息和1次频率信息估计电动机的旋转速度；速度控制系统,基于估计出的旋转速度估计值进行电动机的速度控制；接近开关,在电动机的旋转体的一部分接近时输出接通信号,在电动机的旋转体的一部分不接近时输出断开信号；旋转速度计算部,基于从接近开关输出的接通信号和断开信号计算电动机的旋转速度；速度指令校正部,对速度指令值进行校正,使得速度指令值与计算出的旋转速度计算值的偏差变小,速度控制系统基于校正后的速度指令值和旋转速度估计值进行电动机的速度控制。(Provided is a motor control device which performs a speed sensorless control of a motor and which improves the following performance of an actual speed with respect to a speed command value. The motor control device is provided with: a rotational speed estimating unit that estimates a rotational speed of the motor based on the current information and the 1 st frequency information of the motor; a speed control system for performing speed control of the motor based on the estimated rotational speed; a proximity switch that outputs an on signal when a part of the rotating body of the motor approaches and outputs an off signal when a part of the rotating body of the motor does not approach; a rotational speed calculation unit that calculates a rotational speed of the motor based on an on signal and an off signal output from the proximity switch; and a speed command correction unit that corrects the speed command value so that a deviation between the speed command value and the calculated rotation speed calculated value becomes small, and the speed control system performs speed control of the motor based on the corrected speed command value and rotation speed estimated value.)

1. A motor control device for performing a speed sensorless control of a motor, the motor control device comprising:

a rotational speed estimating unit that estimates a rotational speed of the motor based on current information and 1-order frequency information of the motor;

a speed control system that performs speed control of the motor based on a rotational speed estimation value estimated by the rotational speed estimation unit;

a proximity switch that outputs an on signal when a part of a rotating body of the motor approaches and outputs an off signal when a part of a rotating body of the motor does not approach;

a rotational speed calculation unit that calculates a rotational speed of the motor based on an on signal and an off signal output from the proximity switch; and

a speed command correction unit that corrects a speed command value so that a deviation between the speed command value and the rotation speed calculation value calculated by the rotation speed calculation unit is small,

wherein the speed control system performs speed control of the motor based on the speed command value corrected by the speed command correction unit and the rotation speed estimation value.

2. The motor control device according to claim 1,

the speed command correction unit includes:

a subtractor that obtains a deviation between the speed command value and the rotation speed calculation value calculated by the rotation speed calculation unit;

a calculation unit that generates a correction value of the speed command value based on the deviation obtained by the subtractor; and

and an adder for adding the correction value generated by the arithmetic unit to the speed command value to obtain a corrected speed command value.

3. The motor control device according to claim 2,

the arithmetic unit is constituted by an integral term.

Technical Field

The present invention relates to a motor control device for performing a speed sensorless control of a motor.

Background

As a motor control device for controlling the driving of a motor such as an induction motor or a synchronous motor, there are a motor control device implemented using a speed sensor such as a rotary encoder or a resolver and a motor control device performing so-called speed sensorless control without using such a speed sensor. Patent documents 1 and 2 describe a motor control device that performs a speed sensorless control of a motor.

For example, a motor control device described in patent document 2 estimates a 1-time frequency (japanese: 1 time cycle) and a slip frequency (japanese: す べ り cycle) of a motor from an actual current value (current FB value) of the motor, estimates a rotation speed of the motor by subtracting a slip frequency estimation value from the 1-time frequency estimation value, and performs drive control on the motor based on the rotation speed estimation value.

Such a motor control device has advantages such as low cost and small size because it does not include a speed sensor. Further, since no wiring for the speed sensor is required, the waterproof property of the motor can be improved.

Disclosure of Invention

Problems to be solved by the invention

However, the actual speed may deviate significantly from the estimated rotational speed. This is likely to occur particularly at the time of high load, at the time of rotation in a low speed range, at the time of sudden load change (at the time of sudden transient change), or at the time of sudden speed change (at the time of sudden transient change, for example, at the time of acceleration or deceleration).

The motor control device that performs the speed sensorless control performs control such that the rotation speed estimation value follows the speed command value. However, when the actual speed deviates from the rotation speed estimation value (particularly, when the load is high, when the rotation is in a low speed range, when the load suddenly changes, or when the speed suddenly changes), the actual speed greatly deviates from the speed command value although the rotation speed estimation value follows the speed command value. Therefore, a deviation occurs between the actual speed and the speed command value.

The present invention aims to provide a motor control device for performing a speed sensorless control of a motor, wherein the following performance of an actual speed with respect to a speed command value is improved.

Means for solving the problems

(1) A motor control device (for example, a motor control device 1 described below) according to the present invention is a motor control device that performs speed sensorless control of a motor (for example, an induction motor 3 described below), and includes: a rotation speed estimating unit (for example, a rotation speed estimating unit 30 described later) that estimates a rotation speed of the motor based on current information and 1-order frequency information of the motor; a speed control system (for example, a speed control system 10 described later) that controls the speed of the motor based on the rotational speed estimated value estimated by the rotational speed estimating unit; a proximity switch (for example, a proximity switch 31 described later) that outputs an on signal when a part of the rotating body of the motor approaches and outputs an off signal when a part of the rotating body of the motor does not approach; a rotation speed calculation unit (for example, a rotation speed calculation unit 32 described later) that calculates a rotation speed of the motor based on an on signal and an off signal output from the proximity switch; and a speed command correction unit (for example, a speed command correction unit 34 described later) that corrects the speed command value so that a deviation between the speed command value and the rotation speed calculation value calculated by the rotation speed calculation unit is reduced, wherein the speed control system performs speed control of the motor based on the speed command value corrected by the speed command correction unit and the rotation speed estimation value.

(2) In the motor control device according to (1), the speed command correction unit may include: a subtractor (for example, a subtractor 341 described later) that obtains a deviation between the speed command value and the rotation speed calculation value calculated by the rotation speed calculation unit; an arithmetic unit (for example, an arithmetic unit 342 described later) that generates a correction value of the velocity command value based on the deviation obtained by the subtractor; and an adder (for example, an adder 343 described later) that adds the correction value generated by the arithmetic section to the velocity command value to obtain a corrected velocity command value.

(3) In the motor control device according to (2), the arithmetic unit may be configured by an integral term.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is possible to provide a motor control device that improves the following ability of an actual speed with respect to a speed command value in a motor control device that performs a speed sensorless control of a motor.

Drawings

Fig. 1 is a diagram showing a configuration of a motor control device according to the present embodiment.

Fig. 2 is a diagram for explaining an example of the proximity switch.

Fig. 3 is a diagram showing an example of the configuration of a speed command correction unit in the motor control device shown in fig. 1.

Fig. 4 is a diagram showing an equivalent model of the motor control device shown in fig. 1, and is a diagram showing a simple equivalent model using a transfer function.

Fig. 5 is a diagram showing another example of the configuration of the speed command correction unit in the motor control device shown in fig. 1.

Fig. 6 is a diagram for explaining an example of the arrangement of the proximity switch.

Description of the reference numerals

1: a motor control device; 2: numerical Control (CNC); 3: an induction motor (electric motor); 3 s: a shaft (rotating body); 10: a speed control system; 11. 20: a subtraction operator; 12: a speed controller; 14: a current controller; 16: a frequency control unit for 1 time; 18: a slip frequency calculation unit; 22: a 2-3 phase conversion section; 30: a rotational speed estimation unit; 31: a proximity switch; 32: a rotational speed calculation unit; 34: a speed command correction unit; 341: a subtraction operator; 342: a calculation unit; 343: an adder.

Detailed Description

Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding portions are denoted by the same reference numerals.

Fig. 1 is a diagram showing a configuration of a motor control device according to the present embodiment. A motor control apparatus 1 shown in fig. 1 controls driving of an induction motor 3 in accordance with a speed command based on a machining program supplied from a numerical controller (CNC) 2.

The induction motor 3 drives, for example, a spindle (rotary shaft) of a machine tool that performs cutting. The induction motor 3 is a so-called speed sensorless motor having no speed sensor such as a rotary encoder.

The motor control device 1 is a motor control device that performs so-called speed sensorless control without using a speed sensor such as a rotary encoder. The motor control device 1 performs vector control of the induction motor 3.

The motor control device 1 includes a subtractor 11, a speed controller 12, a current controller 14, a 1-time frequency control unit 16, a slip frequency calculation unit 18, a subtractor 20, and a 2-phase-3-phase conversion unit 22. The subtractor 11, the speed controller 12, the current controller 14, and the 2-phase-3-phase converter 22 constitute a speed control system 10. The slip frequency calculation unit 18 and the subtractor 20 constitute a rotation speed estimation unit 30. The motor control device 1 further includes a proximity switch 31, a rotational speed calculation unit 32, and a speed command correction unit 34.

The subtractor 11 obtains a speed deviation between a speed command value (after correction) obtained by correcting the speed command value supplied from the numerical controller 2 by a speed command correction unit 34 described later and a rotation speed estimation value (speed FB) estimated by a rotation speed estimation unit 30 described later. The speed controller 12 generates a current command value (torque command value) by performing PI (proportional integral) control, for example, on the speed deviation obtained by the subtractor 11.

The current controller 14 generates a voltage command value based on a current command value (torque command value) generated by the speed controller 12 and an actual current value (drive current value, current FB value) of the induction motor 3 detected by a current detector (not shown). The current controller 14 performs vector control, for example. Specifically, the current controller 14 generates a d-phase current command value (field current command value) and a q-phase current command value (torque current command value) based on the current command value (torque command value). The current controller 14 generates a d-phase voltage command value based on the difference between the d-phase current command value and the d-phase actual current value obtained by the UVW3 phase actual current value converted by the 2-phase-3-phase converter 22. The current controller 14 generates a q-phase voltage command value based on the difference between the q-phase current command value and the q-phase actual current value obtained by the UVW3 phase actual current value converted by the 2-phase-3-phase converter 22.

The 1-time frequency control unit 16 generates a 1-time frequency command value based on the current command value (torque command value) generated by the speed controller 12. The 1 st frequency refers to the frequency of the power supply voltage applied to the motor. Various methods are known as a method of calculating the 1-time frequency command value. For example, the actual current value (for example, q-phase actual current value) may be used, or a current deviation between the current command value (for example, q-phase current command value) and the actual current value (for example, q-phase actual current value) may be used instead of the current command value.

The slip frequency calculation unit 18 calculates a slip frequency estimation value based on a current command value (torque command value) generated by the speed controller 12. Specifically, the slip frequency calculation unit 18 calculates an optimum slip frequency in the slip frequency control type vector control based on the d-phase current command value and the q-phase current command value, and uses the calculated slip frequency as a current slip frequency estimated value.

For example, by a 2-degree inductance L based on the mutual inductance M in the induction motor 3₂2 times resistance value R₂2-time d-phase magnetic flux value

And 1 q phase current value i_1qTo obtain an estimated slip frequency value ω_S[rad/s]。

[ numerical formula 1]

In this case, the d-phase current value i is adjusted by a factor of 1 based on the mutual inductance M and the time of stabilization _1d2 times of d-phase magnetic flux value

[ numerical formula 2]

φ_2d＝Mi_1d。

Thus, the slip frequency estimation value ω at steady state is obtained by the following expression (1)_S。

[ numerical formula 3]

K is commonly referred to as the slip constant.

Various methods are known as a method for calculating the slip frequency estimation value. For example, instead of the current command value, an actual current value, such as a q-phase actual current value (FB) and a d-phase actual current value (FB), may be used.

The subtractor 20 obtains the estimated rotation speed value of the induction motor 3 by the following expression (2) based on the 1 st order frequency command value from the 1 st order frequency control unit 16 and the slip frequency estimated value obtained by the slip frequency calculation unit 18.

The rotation speed estimation value is 1-time frequency command value — slip frequency estimation value … (2).

In the present embodiment, the slip frequency calculation unit 18 and the subtractor 20 described above function as a rotation speed estimation unit 30. That is, the rotational speed estimation unit 30 estimates the slip frequency based on the current command value (current information) generated by the speed controller 12 and the slip constant (in other words, the motor constant), and estimates the rotational speed of the induction motor 3 based on the slip frequency estimation value and the 1 st order frequency command value from the 1 st order frequency control unit 16.

As described above, the rotation speed estimation unit 30 may use an actual current value (current information) instead of the current command value.

The 2-phase-3-phase converter 22 converts the d-phase voltage command value and the q-phase voltage command value generated by the current controller 14 into voltage command values for the respective UVW phases based on the 1 st frequency command value from the 1 st frequency controller 16, thereby generating voltage command values for driving the induction motor 3.

The proximity switch 31 is provided to the induction motor 3. The proximity switch 31 may be built in the induction motor 3 or may be provided outside the induction motor 3. The proximity switch 31 is, for example, a proximity switch (proximity switch) defined by JIS C8201-5-2 or IEC60947-5-2 and is an inductive proximity switch (inductive proximity switch) or a capacitive proximity switch (capacitive proximity switch) that detects the proximity of a metal and/or a non-metal object. The proximity switch 31 outputs an ON (ON) signal when a part of the shaft (rotating body) of the induction motor 3 is in proximity, and outputs an OFF (OFF) signal when a part of the shaft of the induction motor 3 is not in proximity.

For example, as shown in fig. 2, when two orthogonal diameters x and y of the shaft 3s of the induction motor 3 are different, the proximity switch 31 outputs an on signal (high-level pulse signal) when the long diameter y side is close and outputs an off signal (low-level signal) when the long diameter y side is not close. In the example of fig. 2, the proximity switch 31 outputs a pulse signal twice because the long-diameter y side is close to the proximity switch 31 twice during one rotation of the shaft 3s of the induction motor 3.

In the above description, the proximity switch 31 is attached to the shaft of the induction motor 3, but the method of installing the proximity switch 31 is not limited to this. For example, as shown in fig. 6, the proximity switch 31 may be attached to the main shaft 4 coupled to the shaft of the induction motor 3 via gears 3a and 3b, a timing belt, or the like. In this case, in fig. 2, the shaft 3s (rotating body) of the induction motor 3 may be replaced with the main shaft 4 (rotating body). Thus, the proximity switch 31 outputs an on signal when a part of the main shaft 4 (rotating body) approaches, and outputs an off signal when a part of the main shaft 4 does not approach.

The shape of the shaft of the induction motor 3 or the main shaft 4 (rotating body) is not limited to this. Another example of the shape of the shaft of the induction motor 3 or the main shaft 4 (rotating body) is a gear shape.

The proximity switch 31 is different from a speed sensor such as a rotary encoder used in a speed control system of an induction motor. Hereinafter, differences between the proximity switch and the rotary encoder will be described.

The rotary encoder has an A-phase output and a B-phase output. Therefore, by using the rotary encoder, in addition to the rotational speed, the rotational position and the rotational direction can be detected. And the rotational speed and the rotational position can be detected with high accuracy and at high speed.

On the other hand, the proximity switch outputs very few 1-phase pulses compared to the output pulses of the rotary encoder, and typically, the proximity switch outputs 1-phase pulses once to twice for every rotation of the motor. Therefore, the use of the proximity switch enables detection of the rotational speed, but fails to detect the rotational position and the rotational direction.

In addition, when the rotational speed is calculated from the pulse output of the proximity switch, since the number of pulses is counted in a predetermined sampling period, speed conversion is performed, and then averaging (smoothing) is performed, it takes time to detect the rotational speed. Further, the detection resolution of the rotation speed determined by the sampling period and the averaging time is low. As described above, since the response and resolution of the rotation speed calculated from the output pulse of the proximity switch are low, the proximity switch cannot be used in a speed control system as in the case of using a rotary encoder.

In the present embodiment, the detection of the rotational speed of the induction motor is performed as follows using a proximity switch instead of using a speed sensor such as a rotary encoder.

The rotational speed calculation unit 32 calculates the rotational speed of the induction motor 3 based on the on signal and the off signal output from the proximity switch 31. For example, the rotation speed calculation unit 32 counts the number of pulses of the on signal from the proximity switch 31 at a predetermined sampling period, converts the counted number of pulses into a speed, and averages (smoothes) the converted speed with a filter to obtain the rotation speed of the induction motor 3.

When the proximity switch 31 outputs the pulse signal n times while the shaft 3s of the induction motor 3 rotates once, the number of pulses generated during the sampling period Fs is speed-converted by the following equation.

Speed (min)^-1)＝1/Fs×60/n。

The speed command correction unit 34 generates a speed command value (after correction) obtained by correcting the speed command value from the numerical controller 2, based on the rotation speed calculation value calculated by the rotation speed calculation unit 32. Specifically, the speed command correction unit 34 corrects the speed command value so that the deviation between the speed command value and the calculated rotation speed value becomes small. The speed command correction unit 34 inputs the corrected speed command value (after correction) to the speed control system 10.

Fig. 3 is a diagram showing the configuration of the speed command correction unit 34 according to the present embodiment. The velocity command correction unit 34 shown in fig. 3 includes a subtraction unit 341, an arithmetic unit 342, and an addition unit 343. The subtractor 341 obtains a speed deviation between the speed command value (before correction) from the numerical controller 2 and the rotation speed calculation value calculated by the rotation speed calculation unit 32. The arithmetic unit 342 includes an integral term of the transfer function K/s (K is a correction gain). The arithmetic unit 342 performs I (integral) control on the speed deviation obtained by the subtractor 341, and generates a correction value of the speed command value. The adder 343 adds the correction value generated by the arithmetic section 342 to the speed command value (before correction) from the numerical controller 2 to obtain the speed command value (after correction).

The subtractor 11, the speed controller 12, the current controller 14, the 1 st order frequency control unit 16, the slip frequency calculation unit 18, the subtractor 20, the 2-phase-3-phase conversion unit 22, the rotational speed estimation unit 30, the rotational speed calculation unit 32, and the speed command correction unit 34 in the motor control device 1 are configured by an arithmetic Processor such as a DSP (Digital Signal Processor) or an FPGA (Field Programmable Gate Array). The various functions of the motor control device 1 are realized by executing predetermined software (programs, applications) stored in a storage unit, for example. The various functions of the motor control device 1 may be realized by cooperation of hardware and software, or may be realized by only hardware (electronic circuit).

Next, the operation of the motor control device 1 of the present embodiment will be described.

First, referring to fig. 1, when a speed command value is supplied from the numerical controller 2, the subtractor 11 obtains a speed deviation between the speed command value (after correction) obtained by correcting the speed command value supplied from the numerical controller 2 by the speed command correction unit 34 and the estimated rotation speed value estimated by the rotation speed estimation unit 30, and the speed controller 12 generates a current command value (torque command value) based on the speed deviation. The current controller 14 generates a d-phase voltage command value and a q-phase voltage command value based on the current command value and an actual current value (current FB value) of the induction motor 3 detected by a current detector (not shown). At this time, the 1 st-order frequency control unit 16 generates a 1 st-order frequency command value based on the current command value. The 2-phase-3-phase converter 22 converts the d-phase voltage command value and the q-phase voltage command value generated by the current controller 14 into voltage command values for the respective UVW phases based on the 1 st frequency command value from the 1 st frequency controller 16, and supplies the voltage command values to the induction motor 3.

At this time, in the rotation speed estimation unit 30, the slip frequency calculation unit 18 calculates an optimum slip frequency in the slip frequency control type vector control based on the d-phase current command value and the q-phase current command value, and sets the optimum slip frequency as the current slip frequency estimation value. For example, the slip frequency estimated value ω is obtained by the above expression (1)_S. Then, the subtractor 20 obtains the rotation speed estimated value by the above expression (2) based on the 1 st order frequency command value and the slip frequency estimated value.

Here, the actual speed may be greatly deviated from the estimated rotational speed. This is likely to occur particularly at the time of high load, at the time of rotation in a low speed range, at the time of sudden load change (at the time of sudden transient change), or at the time of sudden speed change (at the time of sudden transient change, for example, at the time of acceleration or deceleration).

The motor control device that performs the speed sensorless control performs control such that the rotation speed estimation value follows the speed command value. However, when the actual speed deviates from the rotation speed estimation value (particularly, when the load is high, when the rotation is in a low speed range, when the load suddenly changes, or when the speed suddenly changes), the actual speed greatly deviates from the speed command value although the rotation speed estimation value follows the speed command value. Therefore, a deviation occurs between the actual speed and the speed command value.

Therefore, in the present embodiment, when the actual speed deviates from the estimated rotational speed value, that is, when the actual speed deviates from the speed command value (particularly, at the time of high load, rotation in a low speed range, load sudden change, or speed sudden change), the speed command value is corrected so that the actual speed approaches the speed command value.

Specifically, the rotational speed calculation unit 32 calculates and detects the rotational speed of the induction motor 3 based on the on signal and the off signal from the proximity switch 31.

Next, the speed command correction unit 34 corrects the speed command value so that the deviation between the speed command value and the rotation speed calculation value (actual speed) calculated by the rotation speed calculation unit 32 is small. More specifically, as shown in fig. 3, the speed command correction unit 34 corrects the speed command value by adding a correction value obtained by integrating a speed deviation between the speed command value and a rotational speed calculation value (actual speed) to the speed command value. Thus, the speed command correction unit 34 increases the speed command value as the rotation speed calculated value (actual speed) decreases. As a result, the actual speed approaches the speed command value.

As described above, according to the motor control device 1 of the present embodiment, the proximity switch 31 and the rotational speed calculation unit 32 detect the actual speed (rotational speed calculated value) of the induction motor 3, and the speed command correction unit 34 corrects the speed command value so that the deviation between the speed command value and the detected actual speed (rotational speed calculated value) of the induction motor 3 is reduced, that is, the actual speed (rotational speed calculated value) of the induction motor 3 approaches the speed command value. Thus, even when the actual speed greatly deviates from the estimated rotational speed value (particularly, at the time of high load, rotation in a low speed range, sudden load change, or sudden speed change), the following ability of the actual speed with respect to the speed command value can be improved.

In addition, as described above, when the speed is detected by the proximity switch 31, the resolution of the proximity switch 31 is low, and therefore, it is necessary to apply a filter having a large time constant to the rotation speed calculation unit 32. When the speed detected by the proximity switch 31 is used as the feedback value of the speed control system 10, the motor control device 1 is likely to become unstable due to the delay of the filter. In contrast, according to the embodiment in which the speed command value is corrected using the speed detected by the proximity switch 31, the stability of the motor control device 1 can be obtained.

Here, the configuration of the arithmetic unit 342 in the speed command correction unit 34 will be considered. Fig. 4 is a diagram showing an equivalent model of the motor control device 1 shown in fig. 1, and is a diagram showing a simple equivalent model using a transfer function. In fig. 4, the transfer function of the speed control system 10 is simply set to 1, the motor 3 is represented by a transfer function n (x), and the proximity switch 31 and the rotational speed calculation unit 32 are represented by a transfer function 1/(τ s +1) of a 1-order filter. The arithmetic unit 342 of the velocity command correction unit 34 is represented by a transfer function f(s). The speed command correction unit 34 uses a value obtained by passing the difference between the speed command value and the rotation speed calculation value (actual speed) through the transfer function f(s) as a correction value, and adds the correction value to the speed command value to generate the speed command value (corrected).

The speed command correction unit 34 actually operates to bring the rotational speed calculation value vfb2 after the proximity switch 31 and the rotational speed calculation unit 32 close to the speed command value (before correction) v 0. However, it is preferable that the actual speed vfb1 of the motor 3 before the proximity switch 31 and the rotational speed calculation unit 32 is matched with the speed command value (before correction) v 0. The calculated rotation speed vfb2 changes so as to be delayed from the actual speed vfb1 of the motor 3 by an amount (for example, 1s to 2s) corresponding to the time constant. Therefore, it is conceivable that the transfer function f(s) of the arithmetic unit 342 of the speed command correction unit 34 includes a derivative term for correcting the delay amount.

If only the differential term is present, then a steady deviation exists, so it is considered that the transfer function f(s) also includes the integral term. Also, it may be considered that the transfer function f(s) includes a proportional term.

That is, the arithmetic unit 342 may include a transfer function sK as shown in fig. 5_D(K_DAs differential gain), transfer function K_I/s(K_IIntegral gain), transfer function K_P(K_PProportional gain). Thus, the arithmetic unit 342 can perform PID (proportional, integral, derivative) control.

However, if the arithmetic unit 342 of the speed command correction unit 34 includes the differential term and the proportional term, it is expected that the speed command value (after correction) v1 becomes unstable, and it becomes difficult to perform adjustment. In the present embodiment, the speed command correction unit 34 does not generally need a high response from the viewpoint of performing speed control using the rotation speed estimation value estimated by the rotation speed estimation unit 30 and improving the following ability of the actual speed with respect to the speed command value when the actual speed greatly deviates from the rotation speed estimation value (particularly, at the time of high load, rotation in a low speed range, load sudden change, or speed sudden change).

Therefore, in actual use, it is expected that the arithmetic unit 342 of the speed command correction unit 34 is preferably configured by only an integral term as shown in fig. 3. This makes it possible to obtain the stability of the motor control device 1 by correcting the speed command value relatively slowly by the integral term alone.

While the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various changes and modifications can be made. For example, although the motor control device that controls the induction motor has been described as an example in the above-described embodiment, the present invention is not limited to this, and can be applied to a motor control device that controls various motors. For example, the present invention is also applicable to a motor control device that performs speed sensorless control of a so-called speed sensorless synchronous motor that does not include a speed sensor such as a resolver.

Further, the present invention is characterized by being suitably applied to a motor control device that performs sensorless control of an induction motor, because the deviation of the rotation speed estimated value from the actual speed in the sensorless control of the induction motor is larger than the deviation of the rotation speed estimated value from the actual speed in the sensorless control of the synchronous motor.

In the above-described embodiment, the rotation speed calculation unit 32 obtains the rotation speed calculation value by averaging the speeds converted from the pulse number of the on signal of the proximity switch 31 by a filter, but the present invention is not limited thereto. For example, the rotation speed calculation unit 32 may obtain the rotation speed calculation value by averaging the speeds converted from the number of pulses of the on signal of the proximity switch 31 for a predetermined time period without using a filter.