JPH0695703A - Machine constant estimating method - Google Patents

Abstract

PURPOSE:To estimate the inertia and the damping constant of a plant by estimating a machine constant in accordance with the parameter adjusting algorithm which performs compensation to eliminate an output error by a parameter adjustment rule based on an input torque command, an estimated speed of adaptive output, and the output error as the difference of an actual measured value. CONSTITUTION:A torque command T* and an angular speed omega are taken as the identification input of the plant and the machine constant of an inertia J and a viscosity coefficient D is identified as the identification output by an adaptive identifying algorithm 17. Further, the control performance is improved by the online control using the identified values. An algorithm 18 of the equivalent disturbance observer is used together to perform the robust control following up the machine constant variance. Thus, the machine constant is easily changed to values of parameters adaptive to the operation condition by adaptive identification, and the online control is possible, and the number of degrees of freedom is considerably improve.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of controlling a motor drive system in an industrial application in which, in the case of a plant in which a mechanical constant fluctuates greatly depending on a driving condition or a load condition, the fluctuation of the mechanical constant is estimated and corrected. Is.

[0002]

2. Description of the Related Art It is well known that in many industrial motor drive systems, the mechanical constants of the drive system and load system influence the control performance of the entire system. Not only is it important in the gain of the speed PI loop and the design of the observer, but it is a large factor that determines its control performance and control range.

Of the mechanical constants, inertia is a motor,
In many cases, it is calculated from the shape of the shaft, gear, load, etc., or the value obtained from the system design data is used. The damping constant is often obtained from the characteristic calculation due to the speed change or the value obtained from the design data is used.

However, these parameters are not constant over the entire operating range, but change depending on operating conditions and load conditions. Conventionally, as described above, parameters such as calculated values and design values are kept constant. Further, when the change is taken into consideration, the inertia value is corrected by, for example, correcting by a function of speed, or by measuring the diameter of the winding thick shaft in the winding system. These are possible when the operation method is one pattern, but when a wide range of operations and highly precise control are required, it is not possible to deal flexibly.

[0005]

Therefore, in order to improve the control performance, it is necessary to constantly grasp and correct the variations in these parameters.

If controlled at a constant value irrespective of changes in operating conditions, the influence thereof may deteriorate the control characteristics. For example, if the PI constant is set to a constant value, an overshoot or windup phenomenon occurs when the setting changes. Also, when the equivalent disturbance observer described in detail in the already-applied multifunction control device (Japanese Patent Laid-Open No. 3-25505) is applied, the torque estimated by this observer is the inertia nominal value as shown in the following equation. And there is a difference between the true value and
It shows that the estimated torque appears as a disturbance.

[Equation 1] Where T _{L is the} disturbance torque J is the inertia of the plant J _{N is} the nominal value of the inertia of the plant S is the differential operator ω is the angular velocity T is the time constant of the first-order lag filter.

[Outer 1] Is.

[0007]

In order to solve the above-mentioned problems, the following means may be taken. First, a torque control system as shown in FIG. 3 will be described. The torque command T ^* is given to the actuator 11 having the torque coefficient K _T , and torque is generated, and the sum of the torque and the torque disturbance −T _L is applied to the drive system 12 to generate the angular velocity ω. Expressed by the equation of motion,

## EQU2 ## T ^** _KT - _TL = (JS + D) ^* [omega] where T ^{* is the} torque command _KT ; the torque coefficient D is the viscosity coefficient of the plant.

When the disturbance T _L = 0,

[Equation 3] J · dω / dt + D · ω = T ^* · _KT dω / dt + (D / J) · ω = ( _KT / J) · T ^*

Here, if D / J≡a K _T / J≡b,

## EQU4 ## dω / dt + aω = bT ^* .

It is assumed that the parameters a and b are unknown and adaptive identification is performed to identify them. Since the designer can freely change the adaptive identification input torque command T ^{* in} this case, it is easy to determine the nature of the input signal to the plant that satisfies the identification condition, and the boundedness of the signal to the plant is determined. Is guaranteed. For the output angular velocity ω, the output error (following error or identification error)

[Equation 5] Based on, the parameter adjustment rule can be determined as follows.

[0011]

[Equation 6] When the parameter adjustment rule is determined as the above equation so as to guarantee the asymptotic stable convergence of the output error, the output error equation is given in the differential form as the following equation.

[0012]

[Equation 7] That is, it is clear from the definition that the mechanical constants J and D can be estimated if the unknown parameters a and b can be estimated.

In many motor drive systems, the mechanical constants of the drive system and the load system influence the control performance of the entire system. Means to detect the torque command and motor speed that are input / output information of the plant when only a part of the state variables can be observed as output when the plant parameters such as mechanical constants always change depending on operating conditions and are unknown. The above-mentioned parameters are identified by the output of
A means of an adaptive identification mechanism is provided to estimate the mechanical constant.

As the nominal value of the plant parameter handled by the equivalent disturbance observer, a value close to the true value newly estimated by the above-described identification may be used.
The present invention proposes a method for estimating the nominal value of the mechanical constant of the equivalent disturbance observer by identifying adaptive control in this way. In addition, it proposes a method of performing control while constantly updating and correcting during operation by performing this estimation method online.

As described above, even if the mechanical constant changes momentarily depending on the operating conditions, the adaptive control system that is robust against the parameter change can be constructed by identifying the parameter that follows it. Furthermore, when there is a load disturbance, a previously proposed "multifunctional control device" (see Japanese Patent Laid-Open No. 3-25505, etc.)
The effect can be eliminated by canceling the disturbance and making it robust against the disturbance T _L by using the equivalent disturbance observer described in (1).

[0016]

FIG. 3 is a diagram showing the torque control system of the motor drive system, which is rewritten as FIG. When the identification model is added to this FIG. 4, FIG. 5 is obtained. Here, the block 13 surrounded by a dotted line shows the same plant as the plant of FIG. 4, and the block 14 surrounded by a dotted line is the same.
Is an adaptive identification block. Estimated value of angular velocity in FIG.

[Outside 2] Flow path 16 instead of flow path 15 (shown by the dotted line)
The detected value ω can be obtained via When FIG. 5 is changed to the flow path 16 and this figure is rewritten, FIG. 1, which is a mechanical constant identification block diagram of the present invention, is obtained. Here, 1 is a block that represents a plant, 2 and 3 are blocks that make the nominal values of the plant parameters a and b variable, 4 is an integrator, and 6 and 7 are adders / subtractors. The coefficient k of the multiplier 5 is a coefficient for adjusting the convergence speed of the angular velocity error.

Next, FIG. 2 is obtained from the above equation of the parameter adjustment rule. Here, 8 and 8 ′ are multipliers, 9 and 10 are multipliers for parameter adjustment gain, 4 ′ and 4 ″ are integrators, and the angular velocity ω, the identification error ε, and the torque command T that is the adaptive identification input. ^{From *}

[Outside 3] Corresponds to the output of this adjustment rule, so that the identification error ε becomes 0

[Outside 4] And the parameters of the plant are identified, that is, estimated, a and b. As described above, the parameter adjustment rule acts to eventually perform the operation of estimating the mechanical constants J and D.

[0018]

FIG. 6 shows a block diagram of an embodiment to which the method for estimating a mechanical constant according to the present invention is applied. An equivalent disturbance observer surrounded by a dotted line portion 18 in the figure is applied to the speed control system of the motor drive system. Block 19 in the equivalent disturbance observer block is the observer filter, and the estimated value of the inertia of the plant, which is the internal variable of this observer.

[Outside 5] In order to estimate, the adaptive identification mechanism block indicated by the part 17 surrounded by the dotted line is provided. The adaptive identification mechanism block 17 of this embodiment is similar to the block diagram of the adaptive identification rule of FIG. 2 derived from the above-mentioned parameter adjustment rule.

[Outside 6] The identification error .epsilon. Similar to the adaptive identification block in FIG. 2, the input has three values of angular velocity ω, identification deviation ε, and torque command T ^* . Of the adaptive identification inputs, the angular velocity ω is the detected value, and the identification deviation ε is from the definition,

[Equation 8] Is. Also, the estimated value

[Outside 7] Is a value calculated in the adaptive identification mechanism of FIG. 6, and the identification deviation ε is also a value calculated in the adaptive identification mechanism. Furthermore, identification output

[Outside 8] The torque generation coefficient K _T of the control power actuator, which is known as

[Equation 9] Estimated value of plant inertia by substituting D / J≡a K _T / J≡b

[Outside 9] Is obtained.

As described in detail above, the input of the adaptive identification mechanism block 17 surrounded by the dotted line in FIG. 6 is the angular velocity ω, the torque command T ^* and the identification deviation ε, and the output is the estimated value of the inertia of the plant.

[Outside 10] Is.

Estimated inertia of the plant identified here

[Outside 11] Is an estimate of the plant inertia, which is the mechanical constant of the observer in block 18.

[Outside 12] The observer should be activated by substituting into. With the above configuration, the estimated value that follows the fluctuations of the inertia J of the plant and the viscosity coefficient D of the plant, which are the mechanical constants of the actual plant, can be obtained by the estimation method by the adaptive identification mechanism of the present invention. Therefore, a robust control system can be built in an actual plant.

[0021]

The adaptive identification mechanism as described above estimates the mechanical constants of the plant from the parameter adjustment algorithm that compensates so as to eliminate the output error from the parameter adjustment rule based on the output error. Even if the mechanical constant parameter of the plant fluctuates due to changes, the value that fluctuated is estimated and the parameter related to the mechanical constant of the controller of the equivalent disturbance observer is instantaneously updated as the nominal value. It becomes possible to control with mechanical constants.

For example, it is possible to significantly improve the robustness and stability with respect to parameter fluctuations in setting fluctuations and additional fluctuations as compared with the conventional method. Also, the amount of overshoot is greatly reduced, and the amount of impact drop can be made extremely small. Further, the torque ripple and the speed ripple caused by the parameter variation during the constant control as in the prior art are significantly suppressed. It can also be expected to reduce noise.

According to the present invention, the mechanical constant can be easily changed to the value of the parameter adapted to the operating condition by the adaptive identification, and the online control is possible, so that the degree of freedom is remarkably improved.

[Brief description of drawings]

FIG. 1 is a block diagram of a method for estimating a plant mechanical constant using an adaptive identification mechanism, which is shown in order to facilitate understanding of a technical idea of the present invention.

FIG. 2 is an estimated value of a and b in FIG.

[Outside 13] FIG. 3 is a block diagram of an adaptive identification rule part for identifying and outputting

FIG. 3 is a block diagram of a basic torque control system of a motor drive system.

FIG. 4 is a block diagram obtained by equivalent conversion of FIG.

5 is a block diagram in which an adaptive identification mechanism model surrounded by a dotted line portion 14 is added to FIG.

FIG. 6 is a block diagram of an embodiment of the present invention in a speed control system of a tribe system.

[Explanation of symbols]

1 Block that represents a plant 2,3 Block that makes the nominal values of the parameters a and b of the plant variable 4,4 ', 4 "Integrator 5 Multiplier 6,7 Adder / subtractor 8,8' Integrator 9,10 are parameters Multiplier for adjustment gain 11 Drive motor 12 Drive system 13 Block representing a plant 14 Adaptive identification block 15, 16 Flow path 17 Adaptive identification mechanism block 18 Equivalent disturbance observer 19 Observer filter

Claims (3)

[Claims] 1. A parameter based on an input torque command and an output error which is a difference between an estimated speed of an adaptive output and an actual speed in order to estimate a mechanical constant which is an unknown parameter of a plant. From the adjustment rule, by the parameter adjustment algorithm that compensates to eliminate the output error,
A method for estimating a mechanical constant, which comprises estimating the mechanical constant. 2. A method for estimating a mechanical constant, characterized in that the estimating method according to claim 1 is used together with an equivalent disturbance observer to estimate the mechanical constant. 3. An estimation method according to claim 1 and an estimation method according to claim 2 are sequentially performed during operation of a plant, and a parameter relating to a mechanical constant of a controller is updated. Estimation method.