KR20010076854A - Gain control apparatus of proportional and integral controller - Google Patents

Abstract

PURPOSE: A gain adjusting device of a proportional integral controller is provided, which adjusts a proportional gain and integral gain according to a gear transmission ratio and speed control mode to stabilize a motor control system. CONSTITUTION: A gain adjusting device of a proportional integral controller includes an error detector(31) for receiving a speed instruction value and speed output value to detect a speed error value, a proportional integral controller(32) for multiplying the speed error value by a proportional gain and integral gain and amplifying the multiplied value, and a torque constant controller(33) for multiplying the output value of the proportional integral controller by a torque constant to output a torque instruction value. The gain adjusting device further has an adder(34) for adding up the torque instruction value and a load torque estimation value to apply the added value to a motor, and a full order speed observer(36) for estimating a speed of the motor and the load torque, applies the estimated speed output value to the error detector and supplies the load torque estimation value to the adder. The device also has an inertial moment estimator(37) for estimating inertial moment of the motor, and a gain controller(38) for controlling the proportional gain and integral gain according to a gear transmission ratio between the motor and a load driven by the motor or speed control mode of the motor.

Description

Gain control apparatus of proportional integral controller

The present invention relates to a gain adjusting device of the proportional integral controller, and more particularly, to a gain adjusting device of the proportional integral controller to adjust the gain according to the gear shift ratio and the speed control mode of the motor.

In general, industrial robots and machine tools employ advanced electric control technology to improve the performance of equipment.In the electric control technology control system, a proportional controller and an integral controller are combined. The control torque is calculated from the target value by using a PI controller to control the driving of the motor on the load side, and has a feedback path comparing the target value to the actual output value.

Referring to FIG. 1, when the speed command value ω ^* is applied to control the motor 25, the motor 25 is driven toward this speed. The actual speed data ω is fed back to the error detector 21 by a full order speed observer 26 that estimates the speed and load torque of the motor 25. It is subtracted from (ω ^* ) to produce a speed error value (ω _e ). The velocity error value ω _e is multiplied by the proportional gain and the integral gain by the proportional integral controller 22 and multiplied by the torque constant K _T in the torque constant controller 23 to multiply the torque command value T _m . Is transformed into the adder 24. The adder 24 is fed back with an estimated load torque value T _L estimated by the full-dimensional speed observer 26. The load torque estimation value T _L is added by the adder 24 to the torque command value T _m and then input to the motor 25. Then, the inertia moment estimation value Ja estimated by the inertia moment estimator 27 feeds back to the proportional integral controller 22, and the proportional integral controller 22 transmits an inertia moment with respect to the input velocity error value ω _e . The speed control of the motor is achieved through a feedback control that amplifies and outputs the proportional gain and the integral gain having a functional relationship with the estimated value Ja.

As described above, the abnormal condition in the motor speed control using the proportional integral controller 22 is the ratio of the actual speed ω of the motor to the speed command value ω ^* 1, and the speed of the motor ω and the estimated load torque ( T _L ) is to be 0 (see Equation 1 and 2).

_{^{ω / ω * = K T ·}} G (s) / {Js + K · G (s)} = 1 ......................... ... (Eq. 1)

ω / T _L = 1 / {Js + K · G (s)} = 0 ............... (Eq. 2)

Where G (s) is the transfer function of the proportional integral controller, K _T is the torque constant, J is the equivalent moment of inertia acting on the motor shaft, and s is the differential.

In general, the transfer function G (s) of the proportional integration controller 22 is expressed by the following equation (3).

G (s) = Kp + Ki / s ... (Equation 3)

Where Kp is proportional gain and Ki is integral gain.

Substituting Equation 3 into Equation 1 results in Equation 4.

ω / ω ^* = [K _T · K _T · Kps + Ki] / [Js ² + Kps + K _T · K _T · Ki] ................ (Equation 4 )

When _{here, K T · Kp = K '} P, K T · Ki = K'i la,

ω / ω ^* = [K ' _P · s / J + K'i / J] / [s ² + K' _P / J · s + K'i / J] ........ (Equation 5 )

If we assume K ' _P = Jω _c and K'i = JBω _c

ω / ω ^* = [ω _c · s + Bω _c ] / [s ² + ω _c · s + Bω _c ] .............. (Equation 6)

Where B is the friction coefficient of the motor and ω _c is the gain constant

If ω _{c ''} B in (6), the secondary system is approximated as the primary system.

ω / ω ^* = ω _c / s + ω _c ................... (Equation 7)

That is, as shown in (7), when the ratio of the motor speed ω and the speed command value ω ^* is approximated to the primary system, the controller has a relatively stable characteristic.

However, since the moment of inertia (J) applied by an industrial robot or machine tool is variable depending on the gear shift ratio and load inertia between the motor and the load side, it is controlled by setting the gain of the proportional integral controller constant. It becomes a factor of system instability.

In addition, the machine tool performs the operation according to the speed control mode (Normal Mode, Servo Mode, Orientation Mode) with different control purposes. Therefore, if the speed control is performed with fixed gain without considering the speed control mode, the optimum performance of the system Since it is impossible to satisfy, it is required to set the gain of the proportional integral controller separately for each speed control mode and to vary the gain according to the given gear shift ratio and the speed control mode.

The present invention is to solve the above problems, the object of the present invention is to adjust the proportional gain and the integral gain in accordance with the gear transmission ratio and the speed control mode to be robust to disturbance and to promote the stability of the motor control system It is to provide a gain adjusting device of the integral controller.

1 is a control block diagram of a gain adjusting device of a proportional integral controller according to the prior art;

2 is a control block diagram of a gain adjusting device of a proportional integral controller according to the present invention;

3 is a view for explaining a gain constant according to the present invention.

Explanation of symbols on the main parts of the drawings

31: error detector 32: proportional integral controller

33: torque constant 34: adder

35: motor 36: full-dimensional speed observer

37: moment of inertia estimator 38: gain adjustment unit

The gain adjusting apparatus of the proportional integral controller according to the present invention includes a control system for controlling the speed of a motor, the error detector receiving a speed command value and a speed output value and detecting a speed error value; A proportional integral controller for multiplying the speed error value by multiplying the proportional gain and the integral gain; A torque constant controller for outputting a torque command value by multiplying the torque constant by the output value of the proportional integral controller; An adder for adding the torque command value and the load torque estimate to the motor; An all-dimensional speed observer for estimating the speed and load torque of the motor, applying the estimated speed output value to the error detector and applying the estimated load torque estimate to an adder; An inertia moment estimator for estimating the inertia moment of the motor; And a gain adjusting unit that adjusts the proportional gain and the integral gain according to the gear shift ratio between the motor and the load side driven by the motor or the speed control mode of the motor.

According to the present invention, the gain adjusting unit adjusts the magnitude of the proportional gain and the integral gain by changing the estimated moment of inertia according to the gear shift ratio, and if the given gear shift ratio among the plurality of proportional gains and integral gains set according to the gear shift ratio is large, the proportion is increased. It is characterized by adjusting the size of the gain and the integral gain relatively small.

Further, according to the present invention, the gain adjusting unit adjusts the magnitude of the proportional gain and the integral gain by changing the gain constant to suit the characteristics of the speed control mode of the motor. The gain adjusting unit is set to a servo mode that follows the speed command value by feeding back a normal mode and a speed output value for performing a general operation, and an orientation mode which focuses on the position control of the motor. When the servo mode is set without changing the integral gain, the gain is decreased by the amount set for the integral gain, and when set in the orientation mode, the proportional gain is increased by the set size and the integral gain is decreased by the set size.

Hereinafter, with reference to the accompanying drawings a preferred embodiment of the present invention will be described in detail.

Prior to the operation of the present invention, the gear shift ratio G _R will be described.

The gear shift ratio G _R may be expressed as a ratio between the motor shaft speed ω _M and the load shaft speed ω _L.

G _R = ω _L / ω _M ..................... (Equation 8)

Since the output is the same for the motor shaft and the load shaft when the motor is driven,

Be represented by _{Tm · ω M = T L ·} ω L ......................... ( formula 9), and

By modifying (9) and using (8),

Tm = (ω _L / ω _M ) T _L = G _R T _L ... (Eq. 10).

Further, the torque command value T _m and the load torque estimation value T _L can be expressed as follows.

Tm = Jm · (dω _M / dt), T _L = J _L · (dω _L / dt) ... (Eq. 11)

It can be expressed by the following equation using (10), (11) and (8).

= Jm · Tm _(M dω / dt) = G · T _R G _L = _{R L} · J · (dω _L / dt) = G _{R L} ² · J · (dω _M / dt)

... (Eq. 12)

Therefore, the moment of inertia J is defined as follows by the expression (12).

J = J _L + J _M = (1 + 1 / G ² ) J _M ........ (Equation 13)

According to equation (13), the moment of inertia J is inversely proportional to the square of the gear transmission ratio.

This moment of inertia (J) is an equivalent moment acting on the motor shaft by the motor itself and the load.

FIG. 2 is a control block diagram of a gain adjusting device of a proportional integral controller according to the present invention, and a configuration and operation overlapping with those of the related art will be briefly described.

First, when the speed command value ω ^* is applied to control the motor 35, the motor 35 is driven toward this speed. The full-dimensional speed observer 36 estimates the actual speed and the load torque of the motor 35 and applies the estimated speed output value? To the error detector 21 with a negative sign. The error detector 31 subtracts the input speed command value [omega] ^* and the feedback speed output value [omega] applied and generates a speed error value [omega] _e corresponding to the error. This velocity error value ω _e is amplified by the proportional gain Kp and the integral gain Ki in the proportional integral controller 32 and then multiplied by the torque constant K _T in the torque constant controller 33. It is transformed into the torque command value T _m . This torque command value T _m is input to the adder 34. The adder 34 adds the torque command value Tm and the estimated load torque estimate T _L fed back by the full-dimensional speed observer 36 and outputs it to the motor 35. The inertia moment estimator 37 estimates the inertia moment of the motor 35 by using a virtual system by mathematical modeling, and outputs the inertia moment estimation value Ja to the gain adjusting unit 38.

The gain adjusting unit 38 outputs the moment of inertia Ja 'reflecting the gear shift ratio G _R to the proportional integrating controller 32 with respect to the moment of inertia Ja estimated by the moment of inertia estimator 37. The gain constant ω _c 'reflecting the speed control mode is output to the proportional integral controller 32 with respect to the output value ω. In addition, the gain adjusting unit 38 outputs the moment of inertia Ja 'and the gain constant ω _c ' reflecting the gear shift ratio and the speed control mode to the full-dimensional speed observer 36. ) Estimates the speed output value ω and applies it to the error detector 32.

In the proportional integral controller 32, the proportional gain Kp and the integral gain Ki multiplied by the speed error value ω _e have a functional relationship with the moment of inertia J and the gain constant ω _c (Equation 6) And the proportional gain Kp and the integral gain Ki are determined according to the moment of inertia J 'and gain constant ω _c ' input from the gain adjusting unit 38. As shown in FIG. 3, the gain constant ω _c ′ means the bandwidth of the proportional integral controller 32.

Table 1 shows the relationship between the proportional gain Kp and the integral gain Ki by the gear shift ratio G _R. For example, if the gear selection is classified into three types (low, medium, and high) and the gear shift ratio is determined accordingly, the proportional gain Kp and the integral gain Ki may be set differently.

Table 1

Gear shift ratio (G) Proportional gain (Kp) Integral gain (Ki) Low (0.05-0.6) Go Go Medium (0.15-0.8) medium medium High (0.6-2.5) that that

Since the moment of inertia (J) is inversely proportional to the square of the gear shift ratio, as shown in [Table 1], when the gear shift ratio (G _R ) is large, the proportional gain (Kp) and the integral gain (Ki) are relatively small. .

[Table 2] shows the relationship between the proportional gain (Kp) and the integral gain (Ki) adjusted according to the speed control mode of the motor.

Speed control mode Proportional gain (Kp) Integral gain (Ki) Normal mode × × Servo mode × Drastically reduced Orientation Mode A significant increase decrease

The gain adjusting unit 38 receives the first setting signal from the user to determine the gear shift ratio G _R given by the gear selection, and after determining the speed control mode of the motor by receiving the second setting signal, the [Table 1] and According to [Table 2], the moment of inertia Ja and the gain constant ω _c 'for adjusting the proportional gain and the integral gain are output to the proportional integral controller 32. Accordingly, the proportional gain Kp and the integral gain Ki of the proportional integration controller 32 can be expressed as follows.

Kp = Ja '· ω _c ', Ki = 1/10 · (Ja '· ω _c ')

The proportional integral controller 32 amplifies and outputs the speed error value ω _e with the proportional gain Kp and the integral gain Ki reflecting the gear shift ratio G _R and the speed control mode.

As shown in [Table 2], when it is set to normal mode to drive a motor to perform a general operation, it does not adjust proportional gain (Kp) and integral gain (Ki), but feeds back the speed output value (ω). When the servo mode is set to follow the speed command value (ω *), only the integral gain (Ki) is adjusted.In the orientation mode which focuses on the motor position control, the proportional gain (Kp) is increased and the integral gain (Ki) is adjusted. ) To decrease.

The present invention described above can be applied to estimating a DC-link capacitor in a PWM converter and estimating the proportional gain and the integral gain for each control mode in a spindle motor drive.

The present invention as described above can secure the high stability of the motor control system by adjusting the proportional gain and the integral gain of the proportional integral controller, thereby improving the performance of the system. In particular, the present invention can adjust the gain of the proportional controller according to the gear shift ratio and the speed control mode when performing the work using the industrial robot device and the machine tool in response to disturbances inevitably generated due to load fluctuation or voltage fluctuation It is effective to build a robust system.

Claims (5)

In the control system for controlling the speed of the motor, An error detector for detecting a speed error value by receiving a speed command value and a speed output value; A proportional integral controller for multiplying the speed error value by multiplying the proportional gain and the integral gain; A torque constant controller for outputting a torque command value by multiplying the torque constant by the output value of the proportional integral controller; An adder for adding the torque command value and the load torque estimate to the motor; An all-dimensional speed observer for estimating the speed and load torque of the motor, applying the estimated speed output value to the error detector and applying the estimated load torque estimate to an adder; An inertia moment estimator for estimating the inertia moment of the motor; And And a gain adjusting unit for adjusting the proportional gain and the integral gain according to the gear shift ratio between the motor and the load side driven by the motor or the speed control mode of the motor. The method of claim 1, wherein the gain adjusting unit A gain adjusting device of a proportional integral controller, characterized in that for adjusting the magnitude of the proportional gain and the integral gain by changing the estimated moment of inertia according to the gear shift ratio. The method of claim 2, wherein the gain adjusting unit Gain control device of proportional integral controller, characterized in that the proportion of the proportional gain and the integral gain is relatively small if the given gear shift ratio of the plurality of proportional gain and integral gain set according to the gear shift ratio is large. The method of claim 1, wherein the gain adjusting unit A gain adjusting device of a proportional integral controller, characterized in that to adjust the magnitude of the proportional gain and the integral gain by changing the gain constant to suit the characteristics of the speed control mode of the motor. The method of claim 4, wherein the gain adjusting unit It is set to the normal mode for performing general work, the servo mode following the speed command value by feeding back the speed output value, and the orientation mode focusing on the position control of the motor. If it is set to normal mode, it does not change proportional gain and integral gain. If it is set to servo mode, it decreases by the amount set for integral gain.If it is set to orientation mode, proportional gain increases by the set size and integral gain decreases by the set size. Gain adjusting device of the proportional integral controller, characterized in that.