JPH07322664A - Controller for electric motor - Google Patents

Abstract

PURPOSE:To provide a controller for electric motor Mich can attain fast response speed and stable control over the whole range of rotational speed at the time of controlling the rotating position and rotational speed of an electric motor. CONSTITUTION:This controller 20 is provided with the first addition operating device 21, a position gain operating device 21, the first gain regulating device 23, the second addition operating device 24, a speed gain operating device 25, a torque control means 9, a speed operating device 3, and a position operating device 4. By the detecting signals of a pulse encoder 2 mechanically-connected with an electric motor 1, the rotating position and the rotational speed of the electric motor 1 are controlled, and the first gain regulating device 23 decreases the gain of the position gain operating device 21 and the speed gain operating device 25 in the low rotational speed range of the electric motor 1, and increases gain in the medium and high rotational speed ranges.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a controller for controlling the rotational position and rotational speed of an electric motor used as a drive source for various industrial machines.

[0002]

2. Description of the Related Art FIG. 6 shows a block diagram of a conventional motor control device. In FIG. 6, the pulse encoder 2 is mechanically coupled to the electric motor 1, and the rotational speed detection value of the electric motor 1 is detected by the speed calculator 3 from the output pulse frequency of the pulse encoder 2. Further, the rotational position detection value of the electric motor 1 is calculated by integrating the output pulses of the pulse encoder 2 by the position calculator 4. The difference between the rotation position command value set from the outside and the rotation position detection value is obtained by the adder 5, and the output of the adder 5 is multiplied by a desired constant by the position gain calculator 6 to obtain a rotation speed command value. Output. The difference between the rotation speed command value and the rotation speed detection value is obtained by the adder 7,
The speed gain calculator 8 multiplies the output of the adder 7 by a desired constant and outputs the result as a torque command value. In accordance with the torque command value of the speed gain calculator 8, the torque control means 9 including a current regulator and a power converter controls the torque generated by the electric motor 1.

The control unit 10 controls the electric motor 1 as described above.
The torque control loop by the torque control means 9 and the rotation speed control loop by the adder 7, the speed gain calculator 8, and the speed calculator 3 are configured as a minor loop, and the adder 5, the position gain calculator 6, and the position calculation are performed. And a rotary position control loop with the device 4. Further, when the pulse encoder 2 is used to detect the rotation speed of the electric motor 1 in the control device 10, there is a problem in principle that the rotation speed of the electric motor 1 cannot be detected in the vicinity of zero speed. In order to solve the problem, as a method for detecting the rotation speed of the electric motor 1 by the pulse encoder 2, for example, the rotation speed of the electric motor 1 is low and higher than that disclosed in Japanese Patent Laid-Open No. 3-48162. The speed calculator 3 employs a method of switching the rotation speed detection method depending on the speed (hereinafter, referred to as medium / high speed).

[0004]

In the above-mentioned conventional control device, the response speed is fast when the rotation speed of the electric motor is medium or high, and the rotation speed can be controlled with high accuracy, but the above-mentioned control is performed even when the rotation speed is low. In order to increase the response speed of the rotation speed control loop, the gain of the speed gain calculator is set to the same gain as the above-mentioned middle / high speed, so that the rotation speed control with low accuracy must be performed. There was a problem.

In addition, the pulse encoder uses ± of output pulses.
Since the rotational position cannot be detected during one pulse, the rotational position control deviation of the rotational position control loop is within ± 1 pulse.
The rotational position control loop described above may cause a vibration phenomenon, and the vibration phenomenon due to the detection roughness of the pulse encoder is likely to occur when the electric motor is stopped and at a low speed. In order to suppress this vibration phenomenon, in the conventional control device, the gains of the position gain calculator and the speed gain calculator have to be reduced, and therefore, the control device has a slow response speed in the entire range of the rotation speed of the electric motor. There was a problem of becoming.

An object of the present invention is to solve the above problems,
An object of the present invention is to provide a control device for an electric motor, which does not impair the response speed and performs stable control.

[0007]

According to a first aspect of the present invention, there is provided an electric motor control device for controlling a rotational position and a rotational speed of the electric motor by an electric motor and a pulse encoder mechanically coupled to the electric motor. A position calculator that integrates the output pulses of the pulse encoder and outputs as a rotation position detection value; a first addition calculator that calculates the difference between the rotation position detection value and a preset rotation position command value; A position gain calculator that multiplies the output of the 1 addition calculator by a preliminarily adjusted multiplier value and outputs the value as a rotation speed command value, and a speed calculator that calculates from the output pulse frequency of the pulse encoder and outputs the rotation speed detection value. And a second addition calculator for calculating the difference between the rotation speed command value and the rotation speed detection value,
A speed gain calculator that multiplies the output of the second addition calculator by a multiplier value that is adjusted in advance and outputs it as a torque command value; torque control means that controls the torque generated by the electric motor according to the torque command value; and the position. Each of the multiplier value of the gain calculator and the multiplier value of the speed gain calculator is set to a small value when the absolute value of the rotation speed detection value is less than a predetermined level, and when the absolute value of the rotation speed detection value is equal to or higher than the level, A first gain adjuster for adjusting the multiplier value to a large value,
Further, in the second invention, the same position arithmetic unit, the first addition arithmetic unit, the position gain arithmetic unit, the speed arithmetic unit, the second addition arithmetic unit, and the speed gain arithmetic unit as those of the first invention are provided. And a torque control means, and further, a differential calculator for differentially calculating the rotational position command value, and a multiplier value of the position gain calculator and a multiplier value of the speed gain calculator, respectively. A second gain adjuster is provided for adjusting the multiplier value to a small value when the absolute value of the output is below a predetermined level, and for adjusting the multiplier value to a large value when the absolute value of the output is above the level.

According to a third aspect of the invention, in a motor control device for controlling the rotational speed of the electric motor by means of the electric motor and a pulse encoder mechanically coupled to the electric motor, a rotation is calculated from the output pulse frequency of the pulse encoder. A speed calculator that outputs a speed detection value, a second addition calculator that calculates the difference between the rotation speed detection value and a preset rotation speed command value, and a second addition calculator that is adjusted in advance to the output A speed gain calculator that multiplies a multiplier value and outputs it as a torque command value, a torque control unit that controls the torque generated by the electric motor according to the torque command value, and a multiplier value of the speed gain calculator that is the rotation speed command. When the absolute value of the value is less than a predetermined level, the multiplier value is set to a small value,
And a third gain adjuster for adjusting the multiplier value to a large value when the level is equal to or higher than the level.

According to a fourth aspect of the invention, the first to third aspects are
In the electric motor controller according to any one of the inventions, the first, second, or third gain adjuster sets the multiplier value to a small value when the absolute value is less than a predetermined level. When the level is equal to or higher than the level, the multiplier value is adjusted to a large value in proportion to the magnitude of the absolute value until the multiplier value reaches a predetermined multiplier value.

Further, in a fifth aspect of the present invention, in the motor control device according to any one of the first to fourth aspects of the present invention, a low range is provided at the output section of the first, second or third gain adjuster. It is characterized by having a pass filter characteristic.

[0011]

According to the present invention, the first, second, or third gain adjuster changes the multiplier value of the position gain calculator or the multiplier value of the speed gain calculator to the rotation speed detection value, the derivative calculator, or the rotation speed command, respectively. When the absolute value of the output of the value is less than a predetermined level, the multiplier value is set to a small value to suppress the vibration phenomenon described above, and when the absolute value is more than the level, the multiplier value is set to a large value to provide a high-speed control operation response. The common action is to obtain.

In the second and third inventions, when the above-mentioned action is performed, if the load machine of the electric motor has a resonance point, a vibration phenomenon may occur in the rotation speed when the electric motor decelerates and stops. The output of the first gain adjuster of the invention of claim 1 may be shaken, and the control system may become unstable. In such a case, the configuration by the differential calculator for differentially calculating the rotational position command value, or the speed command With the configuration based on the value, the output of the second or third gain adjuster can be stabilized and the vibration phenomenon can be suppressed.

In the fourth invention, the first, second or third gain adjuster sets the multiplier value to a small value when the absolute value is less than a predetermined level, and when the absolute value is equal to or higher than the level. Is adjusted to a large value in proportion to the magnitude of the absolute value until the multiplier value reaches a predetermined multiplier value from the small value, thereby suppressing abrupt change of the multiplier value, The control device of the electric motor acts so as to perform control operation with smooth switching.

Further, in the fifth invention, the first
Alternatively, there may be a time delay between the rising and falling of the output operation waveform of the first, second, or third gain controller due to the low-pass filter characteristic provided in the output section of the second or third gain controller. Utilizing this, in particular, the multiplier value immediately after the electric motor is stopped is kept at a large value only during the time delay to act to shorten the convergence time of the control operation to the target value.

[0015]

1 is a block diagram of an electric motor controller according to a first embodiment of the present invention. In FIG. 1, the electric motor 1
The pulse encoder 2 is mechanically coupled to the pulse encoder 2 and the rotational speed detection value of the electric motor 1 is calculated by the speed calculator 3 from the output pulse frequency of the pulse encoder 2. Further, the rotational position detection value of the electric motor 1 is calculated by integrating the output pulses of the pulse encoder 2 by the position calculator 4. The difference between the rotational position command value set from the outside and the rotational position detection value is obtained by the first addition arithmetic unit 21 to obtain the first addition arithmetic unit 21.
Is output to the first gain adjuster 23 by the position gain calculator 22.
The product is multiplied by the multiplication value adjusted in step S4 and output as a rotation speed command value. The difference between the rotation speed command value and the rotation speed detection value is obtained by the second addition calculator 24, and the output of the second addition calculator 24 is multiplied by the speed gain calculator 25 by the first gain adjuster 23. The value is multiplied and output as a torque command value.
According to the torque command value of the output of the speed gain calculator 25,
A torque control unit 9 including a current regulator and a power converter controls the torque generated by the electric motor 1.

The first gain adjuster 2 in the controller 20
As shown in the functional block diagram of FIG. 2, 3 indicates the multiplier value of the position gain calculator 22 and the multiplier value of the speed gain calculator 25 according to the magnitude of the absolute value of the output of the rotation speed detection value. When the absolute value is at a low level (for example, the rotation speed of the electric motor 1 is less than 10 r / min), the multiplier value is set to a small value to suppress the vibration phenomenon described above, and at a high level (for example, the rotation speed of the electric motor 1 is 50 r / min). (min or more), the multiplier value is set to a large value so as to obtain a high-speed response of the control operation. The multiplier value is increased to the high-level multiplier value in proportion to the magnitude of the absolute value, and the control device 20 performs the control operation with smooth switching.

The multiplier value of the position gain calculator 22 and the velocity gain calculator 25 in the first embodiment shown in FIG.
The small value and the large value of the multiplier value are values that are adjusted and determined each time by the load of the electric motor 1 (not shown). By providing the output section of the first gain adjuster 23 shown in the above-described embodiment with the low-pass filter characteristic shown in the functional block diagram of FIG. 3, there is a time delay in the rise and fall of the output operation waveform. By taking advantage of this, particularly, the multiplier value immediately after the motor 1 is stopped is kept to a large value only during the time delay, so that the convergence time of the control operation to the target value is shortened.

FIG. 4 shows a block diagram of a motor control device according to a second embodiment of the present invention. In the following explanation,
Members having the same functions as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted, and members having different functions from those in FIG. 1 will be mainly described. That is, in FIG. 4, the control device 30 includes a differential calculator 31 for differentially calculating the rotational position command value and a second gain adjuster 32, and the second gain adjuster 32 is shown in the functional block diagram of FIG. In the same manner as shown, each of the multiplier value of the position gain calculator 22 and the multiplier value of the velocity gain calculator 25 is
When the absolute value of the output of the differential calculator 31 is at a low level, the multiplier value is set to a small value to suppress the above-mentioned vibration phenomenon, and when it is at a high level, the multiplier value is set to a large value to provide a high-speed control operation response. Therefore, between the low level and the high level, the multiplier value is increased to the value of the high level in proportion to the magnitude of the absolute value so that the control device 30 performs the control operation with smooth switching. ing.

The multiplier value of the position gain calculator 22 and the speed gain calculator 25 in the second embodiment shown in FIG.
The small value and the large value of the multiplier value are values that are adjusted and determined each time by the load of the electric motor 1 (not shown). FIG. 5 shows a block diagram of an electric motor control device according to a third embodiment of the present invention. In FIG.
Unlike the control device 40 shown in FIGS. 1 and 3, the control device 40 is configured to control only the rotation speed of the electric motor 1, and has a third gain adjuster 41.
In the same manner as shown in the functional block diagram of FIG. 2, the multiplier value of the speed gain calculator 25 is set to a small value when the absolute value of the output of the rotation speed command value is at a low level, and The vibration phenomenon is suppressed, and when the level is high, the multiplier value is set to a large value to obtain a high-speed response of the control operation, and between the low level and the high level, the multiplier is proportional to the magnitude of the absolute value. By increasing the numerical value up to the high level value, the control device 40 performs control operation with smooth switching.

The small value and the large value of the multiplier value of the speed gain calculator 25 in the third embodiment shown in FIG. 5 are adjusted each time by the load of the motor 1 not shown. , The value to be determined. In the description of the embodiment shown in FIGS. 4 and 5, the control operation can be similarly improved by the function shown in FIG. 3 whose description is omitted.

[0021]

According to the present invention, when the rotation speed of the electric motor is medium or high, the rotation speed can be controlled with high accuracy, and the gain of the speed gain calculator is reduced when the rotation speed is low. Enables stable rotation speed control. In addition, the gain of the position gain calculator and the speed gain calculator in the rotational position control is increased when the rotation speed of the electric motor is medium or high, and when the rotation speed of the electric motor is low, the gain is decreased to control the rotation position. It is possible to achieve both stability.

Further, due to the low-pass filter characteristics provided in the output parts of the first to third gain adjusters, the gains of the position gain calculator and the speed gain calculator, especially immediately after the motor is stopped, are delayed by the time delay. It is possible to shorten the convergence time of the control operation to the target value by keeping the value large only during the period.

[Brief description of drawings]

FIG. 1 is a block diagram of a motor control device according to a first embodiment of the present invention.

FIG. 2 is a functional block diagram illustrating the operation of the first gain calculator shown in FIG.

FIG. 3 is a functional block diagram illustrating the operation of the first gain calculator shown in FIG.

FIG. 4 is a block diagram of a motor control device according to a second embodiment of the present invention.

FIG. 5 is a block diagram of an electric motor controller showing a third embodiment of the present invention.

FIG. 6 is a block diagram of a conventional motor control device.

[Explanation of symbols]

1 ... motor, 2 ... pulse encoder, 3 ... speed calculator,
4 ... Position calculator, 5, 7 ... Adder, 6 ... Position gain calculator, 8 ... Speed gain calculator, 9 ... Torque control means, 1
0, 20, 30, 40 ... Control device, 21 ... First addition calculator, 22 ... Position gain calculator, 23 ... First gain adjuster, 24 ... Second addition calculator, 25 ... Velocity gain calculator,
31 ... Differential calculator, 32 ... 2nd gain adjuster, 41 ... 3rd gain adjuster.

Claims (5)

[Claims] 1. A position calculator for integrating output pulses of a pulse encoder mechanically coupled to an electric motor and outputting as a rotational position detection value; and a rotational position detection value and a preset rotational position command value. A first addition calculator for calculating the difference; a position gain calculator for multiplying the output of the first addition calculator by a preliminarily adjusted multiplier value to output as a rotation speed command value; and an output pulse frequency of the pulse encoder. A speed calculator that calculates and outputs a rotation speed detection value; a second addition calculator that calculates the difference between the rotation speed command value and the rotation speed detection value; and a second addition calculator output adjusted in advance. A speed gain calculator that multiplies a multiplier value and outputs it as a torque command value, a torque control unit that controls the generated torque of the electric motor according to the torque command value, and a multiplier value and a multiplier value of the position gain calculator. When the absolute value of the rotation speed detection value is less than a predetermined level, the multiplier value is set to a small value, and when the absolute value of the rotation speed detection value is less than a predetermined level, the multiplier value is set to a large value. An electric motor control device comprising: a first gain adjuster for adjusting. 2. A position calculator for accumulating output pulses of a pulse encoder mechanically coupled to an electric motor and outputting as a rotational position detection value; and a rotational position detection value and a preset rotational position command value. A first addition calculator for calculating the difference; a position gain calculator for multiplying the output of the first addition calculator by a preliminarily adjusted multiplier value to output as a rotation speed command value; and an output pulse frequency of the pulse encoder. A speed calculator that calculates and outputs a rotation speed detection value; a second addition calculator that calculates the difference between the rotation speed command value and the rotation speed detection value; and a second addition calculator output adjusted in advance. A speed gain calculator that multiplies a multiplier value and outputs a torque command value, a torque control unit that controls the torque generated by the electric motor according to the torque command value, and a differential calculation of the rotational position command value. Differentiating calculator, and each of the multiplier value of the position gain calculator and the multiplier value of the velocity gain calculator, the multiplier value is a small value when the absolute value of the output of the derivative calculator is less than a predetermined level. And a second gain adjuster for adjusting the multiplier value to a large value when the level is higher than the level. 3. A speed calculator for calculating the output pulse frequency of a pulse encoder mechanically coupled to an electric motor and outputting the detected value as a rotation speed detection value, the rotation speed detection value and a preset rotation speed command value. And a speed gain calculator that multiplies the output of the second addition calculator by a pre-adjusted multiplier value and outputs it as a torque command value. Torque control means for controlling the generated torque, and a multiplier value of the speed gain calculator, when the absolute value of the rotation speed command value is less than a predetermined level, the multiplier value is a small value, when the level or more Is a third gain adjuster that adjusts the multiplier value to a large value. 4. The motor control device according to claim 1, wherein the first, second, or third gain adjuster controls the absolute value when the absolute value is less than a predetermined level. The multiplier value is adjusted to a small value, and when the level is equal to or higher than the level, the multiplier value is adjusted to a large value in proportion to the magnitude of the absolute value until the multiplier value reaches a predetermined multiplier value. Control device for electric motor. 5. The motor control device according to claim 1, wherein the output portion of the first, second, or third gain adjuster has a low-pass filter characteristic. A control device for an electric motor.