JPS63144782A - Controller for motor - Google Patents

Abstract

PURPOSE:To obtain excellent speed responding characteristic even if the moment of the inertia of a motor load is changed, by controlling a speed for the model of a motor, and by compensating the speed of the motor to be equal to the speed of the model. CONSTITUTION:A motor 2 is simulated, and a motor simulation means (model) 13 having the same characteristic as that of the motor 2 is set. Torque current It is regulated by a speed controller 11 so that difference between the speed W of the model 13 and a set speed Ws may be zero. Then, the same torque current as that fed to the model 13 is fed also to the motor 2. In the meantime, from a compensator 12, compensating current Ix is fed to the motor 2 through an adder 15 so that the speed Wr of the motor 2 may be made to coincide with the speed W of the model 13. As a result, even if the moment of the inertia of a motor load is changed, excellent speed responding characteristic can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a device for controlling the speed of an electric motor.

B6 Summary of the Invention The first invention of the present invention is a device for controlling the speed of an electric motor, which indirectly controls the speed of the electric motor by controlling the speed of a motor simulating means having characteristics equivalent to that of the electric motor; moreover,
By using a compensator to make the speed of the motor follow the speed of the motor simulating means, it is possible to obtain excellent speed response characteristics even when the moment of inertia of the motor load changes.

Further, a second aspect of the present invention provides the apparatus for controlling the speed of the electric motor, which roughly comprises a moment of inertia estimator and a random noise generator for estimating the moment of inertia of the electric motor, and a motor simulating means. By adjusting the transfer function of the included speed control system according to changes in the moment of inertia, it is possible to obtain excellent speed response characteristics even when the moment of inertia of the motor load changes significantly.

C0 Prior Art FIG. 10 shows a block diagram of a control system when controlling the speed of an electric motor using a conventional electric motor control device. This control system performs feedback control of the motor speed between the control device 200 and the motor 2 under load. The control device 200 has a PI unit 20 as a control element.
1, and its transfer function Gc(S) is expressed by the following equation.

Gc(S) = Kp 10 K soil/S where s
Kp and 1 are control constants. The speed Weld of the electric motor 2 as a controlled variable is fed back to the input of the PI section, and the difference from the speed set value Ws is calculated and input to the PI section 201.e The PI section 201 feeds the torque current Itc to the electric motor 2 as a manipulated variable. The torque of the electric motor is adjusted so that the speed We becomes equal to the set value We. Note that a disturbance T is generally applied to the electric motor 2.

D3 Problems to be solved by the invention In the control system using the conventional electric motor control device described above,
The response characteristic is determined by the control constant Kp and 1. These values are set so that the moment of inertia of the motor load is assumed in advance and desired response characteristics are obtained. The set value is fixed and will not be changed.

Therefore, when the moment of inertia of the motor load changes, the roots of the characteristic equation change, making it impossible to obtain desired response characteristics. Furthermore, if the moment of inertia changes rapidly, the control system may become unstable.

SUMMARY OF THE INVENTION An object of the present invention is to provide a control device for a motor that can solve these problems and always provide desirable speed response characteristics even when the moment of inertia of the motor load changes.

9. Means for Solving the Problems The electric motor control device according to the first aspect of the present invention includes a motor simulating means that simulates an electric motor and has characteristics equivalent to the electric motor, and a motor simulating means that is the same as the electric motor. It has a speed controller that supplies a torque current and adjusts the torque current based on the difference between the speed of the motor simulating means and the set speed so that this difference becomes zero. The compensator also has a compensator that outputs a compensation current to make the speed difference zero based on the speed difference between the motor and the motor simulating means obtained by the subtracter.

This compensation current is added to the torque current by an adder and is supplied to the motor.

In addition to the above, the electric motor control device according to the second aspect of the present invention includes a moment of inertia estimator and a random noise generator for estimating the moment of inertia of the electric motor. Further, the transfer functions of the motor simulating means and the speed controller can be adjusted respectively by the output signals of the moment of inertia estimator.

71 Effect In the electric motor control device according to the first aspect of the present invention, speed control is performed not on the electric motor but on the electric motor simulating means. That is, the speed controller receives the speed of the motor simulating means as a feedback signal, and adjusts the torque radio wave supplied to the motor simulating means so that the speed of the motor simulating means becomes equal to the set speed.

Since the same torque current is also supplied to the electric motor, the speed of the electric motor is indirectly controlled to the set speed.

Further, by adjusting the compensation current supplied to the motor by the compensator, the motor is controlled so that the speed difference between the motor and the motor simulating means, which occurs due to a change in the moment of inertia of the motor load, becomes zero.

In the electric motor control device according to the second aspect of the present invention, the random noise current generated by the random noise generator is further injected into the torque current and supplied to the electric motor and the electric motor simulating means, and the moment of inertia estimator is used. The moment of inertia of the motor is estimated based on the speed difference between the motor and the motor simulator and the random noise current that occurred at that time. Then, based on the estimation results, the moment of inertia of the motor simulating means and the transfer function of the speed controller are respectively adjusted. As a result, excellent speed transmission characteristics can be obtained even if the moment of inertia of the electric motor changes significantly.

G. Example Next, embodiments of the present invention will be described with reference to the drawings.

Before we get into the explanation, here is a list of the symbols used here.

W8: Set speed W: Model speed Wr: Motor speed TL: Load torque Jr: Motor inertia J: Model inertia moment e: Speed difference Km: ) Luk constant In - Random noise current It: ) Luk current ■ x: Compensation current, to 'p * K'i + '! q, Kr, Ke
+ Ka: Constant τ: Time constant S: Operator Embodiment 1 FIG. 1 shows a block diagram representing an embodiment of the first invention. This control system is constituted by a control device 1 according to the present invention and a loaded electric motor 2, and the control device 1 is further constituted by the following (a) to (e).

(a) Motor simulating means (hereinafter referred to as model) that simulates the motor 2 and has characteristics equivalent to the motor 2 13° (b)
A torque current It is supplied to the model 13 and the electric motor 2, and the speed W of the model 13 is received as a feedback signal, and the torque current I is set so that this speed becomes equal to the set speed W.
Speed controller 11° for adjusting t (c) Speed W of electric motor 2
If the transfer function is not composed of a proportional element and an integral element, the difference between the speed of the motor 2 obtained by the subtractor 14 and the speed of the model 13 is Based on the compensator 12e, the compensator 12e outputs a compensation current for making the speed Wr of the electric motor 2 follow the speed W of the model 13.
The operation of the adder 15e which adds the compensation current outputted by the adder 15e and outputs it to the motor 2 will now be described. In this control system, a speed controller 11 performs speed control on the model 13.

That is, the speed controller 11 receives the speed W of the model 13 as a feedback signal, and adjusts the torque current so that the difference between the speed W of the model 13 and the set speed W8 becomes zero.

The same torque current as that supplied to model 13 is also supplied to motor 2, so if the characteristics of motor 2 and the characteristics of model 13 are the same, the speed Wr of motor 2 is the same as the speed of model 13. W is therefore equal to the set speed Ws. However, if the moment of inertia of the load of the electric motor 2 changes or if there is a difference in parameter settings in the model 13, the characteristics of the electric motor 2 and the characteristics of the model 13 will be different.

The compensator 12 is provided to make the speed Wr of the electric motor 2 match the speed W of the model 13 even if such a mismatch in characteristics occurs. That is, the compensation current output from the compensator 12 is supplied to the motor through the adder 15,
The compensator 12 receives the difference between the speed Wr and the speed W inputted from the subtractor 14, and adjusts this compensation current so that the difference between the speed Wr and the speed W becomes zero.

In this way, in this embodiment, even if the moment of inertia of the motor load changes, it is possible to obtain excellent speed response characteristics.

In addition, in this embodiment, the compensator 12 is not limited to having a transfer function consisting of a proportional element and an integral element as described above, but may include, for example, a differential element depending on the required control characteristics. It can be a thing etc.

Embodiment 2 FIG. 2 shows a block diagram representing an embodiment of the second invention. This control system is constituted by a control device 100 according to the invention and a loaded electric motor 2. The control device 100 adds a moment of inertia estimator 16 and a random noise generator 17 to the controller fitl shown in FIG.
and an adder 18 are added. Also,
The transfer functions of the speed controller 111 and the model 113 can both be adjusted by signals from the moment of inertia estimator 16.

Next, an overview of the operation will be explained. Random noise generator 1
The random noise current generated by 7 is injected into the torque current supplied to the electric motor 2 by the adder 18 . At this time, if the moment of inertia of the electric motor 2 is different from the moment of inertia of the model 113, a difference occurs between the speed Wr of the electric motor and the speed W of the model. Subtractor 14 outputs this difference to moment of inertia estimator 16. The moment of inertia estimator 16 uses this speed difference and the random noise generator 17
The moment of inertia of the electric motor 2 is estimated based on the random noise current. Based on the estimation results, the moment of inertia of the model 113 is adjusted to match that of the electric motor 2. The moment of inertia estimator 16 simultaneously adjusts the transfer function of the speed controller 111 to
A change in the transfer function of the control system due to a change in the moment of inertia of the model 113 is corrected. As a result, the same speed response characteristics as before changing the moment of inertia can be obtained.

In this way, in this embodiment, it is possible to obtain excellent speed response characteristics even when the moment of inertia of the electric motor changes significantly.

FIG. 3 is a plot diagram showing this embodiment in more detail, and shows each component in FIG. 2 broken down into its constituent transmission elements. The formula written in each block represents a transfer function. This example will be explained in more detail using this figure.

As shown in FIG.
1, 302, and a subtraction element 3 that calculates 1 between the set speed Ws and the model speed W as a feedback signal.
03 and an addition element 304. The electric motor 2 is composed of transmission elements 305 and 307 and an addition element 306. The model 113 correspondingly consists of transfer elements 309, 310. The compensator 12 includes a transfer element 308 , and the moment of inertia estimator 16 includes a transfer element 311 and a multiplication element 312 .

First, speed control for the model 113 will be explained.

In order to facilitate understanding, FIG. 4 shows a block diagram in which only the parts related to speed control of the model 113 in FIG. 3 are extracted. The speed W of the model 113, which is the output of this control system, is expressed by the following equation.

(Kq+J) −S −S+Kp @S+Ki However, Kp = KmK'p, It = K', iKm
, K,q = KmlK'q.

S-operator. In equation (1), when the moment of inertia (Jr) of the model changes and it becomes necessary to change the moment of inertia J of the model, the transfer function can be kept unchanged by adjusting Kq.

Specifically, 'q' of the transmission element 302 is adjusted.

Next, the estimation of the moment of inertia (Jr) of the electric motor by the moment of inertia estimator 16 will be explained. In the block diagram shown in FIG. 5, for the sake of clarity, parts related to making the electric motor 2 follow the model 113 are extracted from FIG. 3. In this figure, the output of the subtractor 14,
That is, the difference between the motor speed Wr and the model speed W, that is, the speed difference e, is expressed by the following equation.

J Jr Jr Here, if we calculate the product of e and In (random noise current injected into the torque current It) and obtain the average by integrating, the second term in equation (2) is ,'I'L
and It are usually zero because they have no relation to each other (because the average of random noise is zero). on the other hand(
) will not be zero because In will be squared. In other words, the term related to the load torque Tt becomes zero, and only the term related to the difference between the moment of inertia (Jr) of the motor and the moment of inertia J of the model remains.

Therefore, if the moment of inertia J of the model is changed as shown in equation (3), the average value of e becomes zero, and the moment of inertia of the electric motor can be estimated.

Jn=Jn-t(1+y)...
...(3) However, Jn-x is the moment of inertia of the previous model, and Jn is the moment of inertia of the next model.

Further, y is expressed by y=L (Y), and Y is expressed by equation (4).

In the formula, the Laplace transform L represents the Laplace inverse transform.

In addition, in order to prevent the transfer function of the speed control system from changing, the constant 'q of the transfer element 302 is changed as shown in equation (5).

K'qn = K'qn-x - Jn-1IIy
..."・(5) However, K'qn-1 is the value of '+1' in the previous value 1.'qn represents the next value of leopard. To help understanding, Figure 6 shows the formula (3) , the calculation of Jn by equation (4) is illustrated in a block diagram.Noise multiplication unit 6
01, the product of the speed difference e and the random noise current In is calculated, and the results are averaged by the first-order delay element 602 (corresponding to equation (4)). Then, in block 603, the moment of inertia Jn is obtained (corresponding to equation (3)) e Returning to FIG. Calculate the product with In and convert the result to 1
The transfer element 311, which is the next lag element, outputs the signal y on average. This is input to the transmission elements 310 and 302, and the moment of inertia J of the model 113 and the constant supply of the transmission element 302 are adjusted.

FIG. 7 shows simulation results for showing the performance of this embodiment, and FIGS. 8 and 9 show simulation results for a conventional control system for comparison. In both figures, curves 7a and 8a+9a represent the speed of the electric motor 2, curve 7c represents the speed of the model 113, and curves 7b, 8b, and 9b represent the output torque of the electric motor 2. Then, at time t1, the load torque is changed, and at time t2, the moment of inertia of the electric motor is changed from 0.00467 to 0.0343686 (
(approximately 7.3 times), and the set speed is changed from 0.5 to 0.75 at time t3. Note that the curve 7a representing the speed of the electric motor and the curve 7c representing the speed of the model match and cannot be distinguished except around time tl. Further, in FIG. 8, the moment of inertia is not changed.

First, let's focus on the change in speed when the set speed is changed. In the conventional control system, as shown in FIG. 8, when the moment of inertia is not changed (i.e., moment of inertia of model/moment of inertia of electric motor) = 1), time t3
It responds well even when the set speed is changed.

However, as shown in Figure 9, when the moment of inertia is changed (moment of inertia of the model/moment of inertia of the electric motor) = 0.13588), the responsiveness to changes in the set speed is extremely degraded. . In contrast, in this embodiment, even if the moment of inertia is changed, the moment of inertia of the model is adjusted (moment of inertia of the model/moment of inertia of the electric motor = 0.971251), and as shown in FIG. Good speed response characteristics similar to those shown in FIG. 8 are obtained with respect to changes in the set speed.

Next, we will focus on the speed change when the load torque is changed. Comparing FIG. 7 and FIG. 8 (or FIG. 9), in FIG. 8 showing the conventional control system, when the load torque changes at time t1, the speed of the electric motor changes significantly. However, in FIG. 7, this change has become significantly smaller, and the responsiveness has been greatly improved.

In this embodiment, the compensator 12 is not limited to having a transfer function consisting of a proportional element and an integral element as shown in FIG. It may include a differential element, etc.

(2) Detailed Description of the Invention As described above, the electric motor control device of the present invention performs speed control on a model of the electric motor, and further compensates so that the speed of the electric motor becomes equal to the speed of the model. Therefore, even if the moment of inertia of the motor load changes, excellent speed response characteristics can be obtained throughout the design.

Furthermore, since the speed of the model is checked and the speed of the model is controlled, even if the model parameters differ from the actual values, the automatic control system operates as designed. Since the compensator for making the motor follow the model includes an integral element, the steady-state deviation of the motor speed becomes zero.

Furthermore, since feedback control is performed on the model, the control system is more stable than when the actual speed is fed back.

The compensation current 1x shown in FIG. 1 indicates the load torque, and the torque current It indicates the acceleration/deceleration torque. Therefore, the limit values of the load torque, acceleration/deceleration torque, and motor torque that is the sum of these can be set separately, which facilitates design.

Also, the moment of inertia of the model) J and the torque constant Km
Even if the value is slightly distorted, it is possible to obtain a response close to the designed value.

Furthermore, in a control device that has a means for estimating the moment of inertia of the motor, even if the moment of inertia of the motor load changes, it is estimated and the parameters of the model and speed controller are adjusted, so the moment of inertia of the motor increases. Excellent speed response characteristics can be obtained even when the speed changes. Moreover, as shown in the simulation, even if the load torque suddenly changes, the speed fluctuation is very small.

[Brief explanation of the drawing]

1 is a block diagram showing an embodiment of the first invention; FIG. 2 is a block diagram showing an embodiment of the second invention; FIG. 3 is a block diagram showing the embodiment in more detail; Fig. 5 is a block diagram showing a part of the same embodiment, Fig. 6 is a block diagram to facilitate understanding of the theoretical explanation of the same embodiment, and Fig. 7 shows simulation results of the same embodiment. 8 and 9 are waveform diagrams showing simulation results of a conventional device. FIG. 10 is a block diagram showing a conventional device. 1.100...Control device 11, 111...Speed controller 12...Compensator 13, 113...Model 14...Subtractor 15.18 e0 adder 16 ... Φ ... moment of inertia estimator 17
......Random noise generator 301, 3
02, 305, 307-311...Fist transmission element 30
3...Subtraction element 304.306...Addition element

Claims (6)

[Claims] (1) In a device for controlling the speed of an electric motor, a motor simulating means having characteristics equivalent to the characteristics of the electric motor is provided, and the speed of the motor simulating means is received as a feedback signal, and the speed of the electric motor simulating means is made equal to the set speed. a speed control means for adjusting the torque current supplied to the electric motor simulating means and simultaneously supplying the torque current to the electric motor; and a subtracting means for determining a speed difference between the electric motor and the electric motor simulating means and outputting a speed difference signal representing the speed difference. and a compensation means for outputting a compensation current for supplying the motor to the motor based on the speed difference signal from the subtraction means to make the speed difference between the motor and the motor simulating means zero, Add current,
1. A control device for an electric motor, comprising: addition means for supplying a signal to the electric motor. (2) The electric motor control device according to claim 1, wherein the transfer function of the compensation means has a proportional element and an integral element. (3) The electric motor control device according to claim 1, further comprising a differential element of the transfer function of the compensation means. (4) In a device for controlling the speed of an electric motor, a motor simulating means having characteristics equivalent to the characteristics of the electric motor is provided, and the speed of the motor simulating means is received as a feedback signal, and the speed of the electric motor simulating means is made equal to the set speed. a speed control means for adjusting the torque current supplied to the electric motor simulating means and simultaneously supplying the torque current to the electric motor; and a subtracting means for determining a speed difference between the electric motor and the electric motor simulating means and outputting a speed difference signal representing the speed difference. and a compensation means for outputting a compensation current for supplying the motor to the motor based on the speed difference signal from the subtraction means to make the speed difference between the motor and the motor simulating means zero, Add current,
Adding means for supplying to the electric motor; Noise generating means for generating a random noise current; Another adding means for adding the random noise current generated by the noise generating means to the torque current; and the random noise current and the speed. a multiplication means for calculating a product with a difference signal; and an averaging means for averaging the multiplication results of the multiplication means and outputting a control signal for adjusting the moment of inertia of the motor simulating means and the control constant of the speed control means. The motor simulating means has means for adjusting the moment of inertia of the motor simulating means according to the control signal outputted by the averaging means, and the speed controlling means adjusts the moment of inertia of the electric motor simulating means according to the control signal outputted from the averaging means. A control device for an electric motor, comprising means for adjusting a control constant of a control means. (5) The electric motor control device according to claim 4, wherein the transfer function of the compensation means has a proportional element and an integral element. (6) The electric motor control device according to claim 4, wherein the transfer function of the compensation means has a differential element.