JPH04319715A - Controller for suppressing axially torsional vibration - Google Patents

Abstract

PURPOSE:To simplify the constitution of an observer, to shorten an adjusting time and to obtain an axially torsional vibration suppressing effect by providing this controller with a transmission function part for controlling the speed of a motor based upon a torque command. CONSTITUTION:A deviation detecting part 11 obtains a deviation between the speed command of a motor and its speed. The output value of a dumping determining amplifier 26 is supplied to the minus input terminal of a 1st subtracting part 13 is amplified by a 2nd control amplifier 14 and used for executing the feedback compensation of a torque command. The output of the amplifier 14 is added to a load torque estimation value outputted from an approximate load torque estimation observer part 17 by an adding part 15 to execute the feed-forward compensation of the load torque estimation value to the torque command. The load torque estimation value outputted from the observer part 17 and the output of a high speed spindle torque estimation part 22 are supplied to a 2nd subtraction part 15 to obtain a load torque value from the output of the subtraction part 25. The obtained load torque value is inputted to the amplifier 26.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to speed control of an electric motor, and more particularly to a torsional vibration suppression control device of a two-inertia system in which an electric motor and a load are connected by an elastic shaft.

0002

[Prior Art] When an electric motor and a load are connected by a shaft with low rigidity in an elevator, a steel rolling mill, a robot arm, etc., shaft torsional vibration occurs, making it difficult to speed up the response of the speed control system. The problem is that it disappears. Shaft torsional vibration is influenced by the ratio of the moment of inertia of the motor to the load, and becomes more vibratory especially when the moment of inertia of the load is smaller than that of the motor. It has been revealed that the conventionally proposed method using a shaft torque estimation observer has a small shaft torsional vibration suppression effect when the moment of inertia of the load is smaller than that of the electric motor. (References: Proceedings of the 1985 National Conference on Electrical Engineering 604 and Theory of Electrical Engineering D.1
Volume 10, No. 4. 1990)

0003

[Problem to be Solved by the Invention] In order to solve the above conventional problems, a compensation method using state feedback using modern control theory has been proposed, but this method also measures shaft torque τS and load speed ωL. It is often difficult to Therefore, observers are used. The configuration of this observer also includes all state quantities (motor speed τM, shaft torque τ
There are a number of methods ranging from a method of estimating S, disturbance torque τL, and load speed ωL) using an observer and providing state feedback to a method of estimating the shaft torque as the minimum state quantity using an observer. However, when the configuration of this observer becomes complicated, the number of adjustment points increases, and new problems arise that require time for adjustment.

The present invention was made in view of the above circumstances, and it simplifies the configuration of the observer, reduces the number of adjustment points, and shortens the time required for adjustment. It is an object of the present invention to provide a shaft torsional vibration suppression control device that can obtain shaft torsional vibration suppression effects even when the load acceleration is larger or smaller, and also by performing load acceleration control.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the present invention inputs the torque command of the electric motor and the speed of the electric motor, and sets the sum of the mechanical time constants of the electric motor and the load as a model mechanical time constant. and an approximate load torque estimation observer section that estimates the load torque using a minimum dimension observer or a full dimension observer and obtains the load torque estimated value as an output, and subtracts the torque command of the electric motor and the value obtained by differentiating the speed of the electric motor. , a high-speed shaft torque estimating section that obtains a high-speed shaft torque estimated value as an output, and subtracting the estimated value from this high-speed shaft torque estimating section and the load torque estimated value from the approximate load torque estimation observer section; A subtraction unit that obtains a value equivalent to the acceleration, an amplifier for damping determination into which the obtained value equivalent to the load acceleration is input to the output of the subtraction unit, and a deviation output between the speed command and the speed of the electric motor is supplied. a first control amplifier; a second control amplifier to which a deviation output between the output of the first control amplifier and the output of the damping determining amplifier is supplied and performs feedback compensation on the torque command;
The output of the second control amplifier and the estimated value output from the approximate load torque estimation observer section are supplied, and an adding section that adds both outputs to perform feedforward compensation to the torque command of the electric motor; The present invention is characterized in that it is provided with a transfer function unit which is supplied with a torque command for the electric motor outputted from the motor and controls the speed of the electric motor based on the torque command.

[0006]

[Operation] A value corresponding to the load acceleration is obtained by subtracting the load torque estimate obtained from the approximate load torque estimation observer section and the high-speed shaft torque estimate obtained from the high-speed shaft torque estimation section. This value is input to an amplifier for damping determination and amplified, and the output from the amplifier is used to perform feedback approximate load acceleration control on the motor torque command. At the same time, feedforward compensation is performed by adding the estimated load torque value to the motor torque command.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 11 denotes a deviation detection unit that obtains the deviation between the motor speed command ωM* and the motor speed ωM. is supplied to the plus input terminal of the subtraction unit 13. An output value from an amplifier 26 for determining damping, which will be described later, is supplied to the minus input terminal of the first subtractor 13, and an output value from the amplifier 26 for determining damping is supplied to the plus input terminal from the output of the first control amplifier 12. 26 output values are subtracted. This subtracted value is amplified by the second control amplifier 14 to perform feedback compensation on the torque command of the electric motor.

The output of the second control amplifier 14 is sent to the adder 15.
A load torque estimated value τS, which will be described later, is supplied to a second input terminal thereof. This adder 15 adds the estimated load torque value τS to the torque command to perform feedforward compensation. The torque command τM of the electric motor obtained at the output end of the adder 15 is calculated by the transfer function unit 16 to obtain the speed ωM of the electric motor.

Reference numeral 17 denotes an approximate load torque estimation observer section, and this observer section 17 includes a deviation detection section 18 to which the torque command τM of the electric motor is supplied to the plus input terminal, and a model machine to which the output of this deviation detection section 18 is supplied. a first-order delay element 19 having a time constant Tm; a deviation detection unit 20 to which the output of the delay element 19 is supplied to a plus input terminal and a motor speed ωM to a minus input terminal;
and an observer gain section 21 to which an output of 0 is supplied, and the output of the observer gain section 21 is supplied to the deviation detection section 1.
8 is supplied to the negative input terminal of the adder 1.
5.

Reference numeral 22 denotes a high-speed shaft torque estimating section, and this estimating section 22 includes a differentiating section 23 to which the speed ωM of the electric motor is supplied, an output of this differentiating section 23 is input to a negative input terminal, and a torque command of the electric motor is input to a positive input terminal. Deviation detection unit 24 to which τM is supplied
It consists of The high-speed shaft torque estimated value τS' output from the high-speed shaft torque estimator 22 is passed to the second subtractor 25.
The estimated load torque value τS is supplied to the plus input terminal of the second subtractor 25, the load torque estimated value τS is supplied to the minus input terminal, and the load acceleration (load acceleration torque) torque value (τS
'-τS) is obtained. This load acceleration torque value is amplified by a damping determining amplifier 26 with a gain KPF and is supplied to the minus input terminal of the first subtractor 13.

When the embodiment is configured as described above, the load torque estimated value τS outputted from the approximate load torque estimation observer section 17 is added to the torque command to perform feedforward compensation (torque compensation), and at the same time, the high speed axis The load acceleration torque value of the estimated value τS' of the torque estimation unit 22 and the estimated value τS of the approximate load torque estimation observer unit 17 is fed back to the torque command. By performing such control, it is possible to perform control to suppress shaft torsional vibration.

Next, in order to describe in detail the process of obtaining the embodiment shown in FIG. 1 using mathematical formulas, etc., first, the elements of the rotational motion system will be explained. There are the following three elements of the rotational motion system used in the two-inertia system.

(a) The relationship between the moment of inertia J and T shown in FIG. 4(a) is T=J・dωm/dt, and (b)
The relationship between the torsion element Kθ and T shown in FIG. 4(b) is T=
θ1-θ2/Kθ=Km(θ1-θ2) (However, Km
= 1/Kθ), (c) rotation control Rω and Fig. 4(c)
The relationship with T shown in is T=Rω・d(θ1−θ2)/d
It becomes t.

Next, the equation of motion of the axial torsional vibration system (two-inertia system) will be shown. The following equation of motion is obtained from the two-inertial frame model shown in FIG.

[0015]

[Math 1]

Equation (3) can be expressed as follows.

[0017]

[Math 2]

When a block diagram of the torsional vibration system is drawn using the above equation, it becomes as shown in FIG. Here, τM is the generated torque of the electric motor, τS is the shaft torque, τL is the load torque, ωM
, ωL is the angular velocity of the motor and load, θM, θL is the angular displacement of the motor, TM, TL are the mechanical time constants of the motor (rated torque ⇒ rated rotation speed), TS is the spring time constant of the shaft = 1/Km,
Rm is the viscosity coefficient of the shaft.

Next, the transfer function of the shaft torsional vibration system will be described. From the generated torque τM in the model ignoring the viscosity coefficient Rm (Rm=0), the motor speed (angular velocity) ωM,
Find the transfer functions GMM(S) and GML(S) up to the load speed (angular velocity) ωL. Transfer function G from τM to ωM
The calculation of MM(S) is as shown in equation (5).

[0020]

[Math 3]

[0021] Also, the transfer function GLM from τL to ωM
(S) becomes as shown in equation (6).

[0022]

[Math 4]

Next, the transfer function GML from τM to ωL
When (S) is determined, it becomes as shown in equation (7).

[0024]

[Math 5]

Furthermore, the transfer function GL from τL to ωL
L(S) is expressed as equation (8).

[0026]

[Math 6]

Here, the transfer function Kωn2/ of the second-order lag system is
When compared with the general expression of S2+2ζωn+ωn2, (9
).

[0028]

[Math 7]

In other words, by approximating the viscosity coefficient Rm to 0, ζ=0, resulting in a permanently oscillating system. Further, its resonance frequency is ωn. Denominator of transfer function

[0030]

[Math. 8]

When the pole is determined, the equation (11) is obtained.

[0032]

[Math. 9]

From equation (11), the pole is on the imaginary axis, so it is an oscillating system.

When the block diagram of the compensation device based on approximate load acceleration estimation shown in FIG. 1 is modified, it becomes as shown in FIG. FIG. 6 is a block diagram that is a further modification of FIG. 5. From FIG. 6, the embodiment of the present invention is equivalently IDP control. Also, since a proportional-integral element shown by PI in FIG. 6 appears due to the observer, the first and second control amplifiers 12,
14 may be composed of only proportional elements.

The object to be controlled in the above-described embodiments may be composed of a stationary Leonardo for controlling a DC machine or an inverter using vector control for controlling an induction motor. Torque finger τM
*In the case of a DC machine, it is the armature-current command, and in the case of vector control of an induction motor, it is the torque component current command.

After a delay in the current control system from the torque command τM*, the actual motor torque command τM becomes the actual motor torque command τM. For this reason, current detection may be performed as shown in FIG. 7, and the detected value may be used for the observer and shaft torque estimation.

Since a motor having a constant output range has field weakening control, if the configuration of the observer etc. is as shown in FIG. 8, it can be used for both constant torque and constant output. In FIG. 8, if a' is made into a PI amplifier, it becomes a complete dimensional observer. Further, if the gain a' of the observer gain unit 21 of the approximate load torque estimation observer unit 17 shown in FIG. 1 is replaced with a PI amplifier, a complete dimensional observer will be obtained.

[0038]

[Effects of the Invention] As described above, according to the present invention,
The following various effects can be obtained.

(1) Approximate load torque estimation The model machine time constant Tm of the observer section is set to the time constant of the electric motor and the load machine, so that the load torque estimate in the absence of shaft torsional vibration is obtained as the observer output. , the configuration can be simplified, (2) the configuration of the high-speed shaft torque estimator can be simplified, (3) load disturbances can be suppressed by adding the load torque estimate to the torque command, (4) high-speed Shaft torsional vibration can be suppressed by feeding back the difference between the estimated shaft torque value and the estimated load torque value and approximately controlling the load acceleration. (5) Even when the ratio of the inertia moment of the motor to the load is large, (6) Because there are few adjustment elements,
The adjustment method is simple.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a model of an axial torsional vibration system.

FIG. 3 is a block diagram of the shaft torsional vibration system.

FIG. 4: (a) An explanatory diagram showing the elements of the rotary motion system used in the moment of inertia, (b) An explanatory diagram showing the elements of the rotary motion system used in the torsion element, (c) Rotary motion used in rotational braking. An explanatory diagram showing the elements of the system.

FIG. 5 is a block diagram showing a modified embodiment of the invention.

FIG. 6 is a block diagram showing a modification of FIG. 5;

FIG. 7 is a block diagram when a current control system is approximated by a first-order lag.

FIG. 8 is a configuration diagram of an observer in an electric motor having a constant output range.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11... Deviation detection part, 12... First control amplifier, 13... First subtraction part, 14... Second control amplifier, 15... Addition part,
16... Transfer function section, 17... Approximate load torque estimation observer section, 22... High speed shaft torque estimation section, 25... Second subtraction section, 26... Amplifier for damping determination.

Claims (1)

[Claims] [Claim 1] The torque command of the electric motor and the speed of the electric motor are input, the sum of the mechanical time constants of the electric motor and the load is set as a model mechanical time constant, and the load torque is estimated using a minimum dimension observer or a full dimension observer. , an approximate load torque estimation observer section that obtains an estimated load torque value as an output; and a high-speed shaft torque estimation section that subtracts a value obtained by differentiating the torque command of the motor and the speed of the motor to obtain a high-speed shaft torque estimation value as an output. and a subtraction unit that subtracts the estimated value from the high-speed shaft torque estimation unit and the load torque estimation value from the approximate load torque estimation observer unit to obtain a value equivalent to the load acceleration as an output; a damping determining amplifier to which a value corresponding to the obtained load acceleration is input; a first control amplifier to which a deviation output between the speed command and the speed of the motor is supplied; and an output of the first control amplifier. a second control amplifier to which a deviation output from the output of the damping determining amplifier is supplied and performs feedback compensation on the torque command; and a second control amplifier that performs feedback compensation on the torque command; An adder is supplied with the estimated value output, and an adder that adds both outputs to provide feedforward compensation to the torque command of the electric motor, and a torque command of the electric motor outputted from this adder. What is claimed is: 1. A shaft torsional vibration suppression control device comprising: a transfer function section that controls speed;