JP2008029189A - Speed control device of motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a speed control device suitable for variable speed control of a motor. <P>SOLUTION: A speed control device 10 comprises a speed instruction generating means 11, an adder 12, a speed control means 13, a current control means 14, an inertia estimating means 15, an inertia setting means 16, a switching means 17, and a constant setting means 18. If acceleration or deceleration drive operation of a motor 1 for estimating the inertia moment of the object to be driven and the motor is possible, the operation is executed to derive an inertia moment estimated value (J<SP>#</SP>). Based on the inertia moment estimated value (J<SP>#</SP>), a proportional gain K<SB>P</SB>of the speed control means 13 is set through the switching means 17 and the constant setting means 18. If the drive operation is not possible, a proportional gain K<SB>P</SB>of the speed control means 13 is set through the switching means 17 and the constant setting means 18 based on the inertia moment manual set value (J<SP>#</SP>). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a speed control device for an electric motor.

As an automatic adjustment method of a control constant in a speed control means constituting a speed control device that performs variable speed control of an electric motor, for example, a method described in Patent Document 1 below is known. This applies a disturbance signal to the output of the speed control means to change the speed of the motor, and the sum of the moment of inertia of the motor and its driven object from the motor speed and motor current at this time. And the control constant of the speed control means is automatically set based on the estimated value.
JP-A-1-218389

  In the above-described conventional electric motor and the method for estimating the moment of inertia of the driven object, it is necessary to rotate the electric motor via the speed control device and to inject a disturbance signal inside the speed control device. However, depending on the operating conditions of the drive target, it is not possible to inject a disturbance signal into the speed control device because the motor cannot be rotated, so that the control constant of the speed control means constituting the speed control device There is a problem that cannot be set.

  The subject of this invention is providing the speed control apparatus of the electric motor which solved the above-mentioned problem.

A first invention is a speed control device that performs variable speed control of an electric motor using speed control means capable of changing at least a control constant.
Inertia estimating means for estimating the sum of the inertia moments of the electric motor and its driven object and outputting this as an inertia moment estimated value; and inertia setting means for manually setting the inertia moment and outputting this as an inertia moment manually set value Switching means for switching and outputting either the inertia moment estimated value or the inertia moment manual setting value, and constant setting means for setting the control constant of the speed control means based on the output value of the switching means It is characterized by.

According to a second aspect of the present invention, there is provided the motor speed control device according to the first aspect of the present invention.
When the motor is accelerated or decelerated by the speed control means, the inertia estimation means is based on the torque command value output by the speed control means and the speed detection value or speed estimation value of the motor. It is characterized in that an estimated moment of inertia value is derived.

Further, a third aspect of the present invention is the speed control device for an electric motor according to the first or second aspect,
The speed control means is formed by a proportional calculator or a proportional-integral calculator, and the constant setting means sets a proportional gain of any of the calculators based on a value proportional to an output value of the switching means. Features.

  According to the present invention, when the motor can be accelerated or decelerated for estimating the moment of inertia of the motor and its driven object, this operation is performed to estimate the moment of inertia. If the operation is impossible, the control constant of the speed control unit is set based on the inertia moment manual setting value manually set in the inertia setting unit. be able to.

FIG. 1 is a circuit configuration diagram of an electric motor speed control apparatus according to a first embodiment of the present invention. In this figure, 1 is an electric motor such as an induction motor, and 2 is a primary voltage command value (v ₁ ^* described later) ^. ), A power converter such as a PWM (Pulse Wide Modulation) inverter that supplies the AC voltage to the motor 1, 3 is an AC power source for the power converter 2, and 4 is a primary current of the motor 2. A current detector 5 that is detected as a detection value (i ₁ ) is connected to the output shaft of the motor 1, and a speed detector 10 that detects the speed of the motor as a speed detection value (ω _r ), and 10 is a speed control device.

The speed control device 10 includes the following means or elements 11 to 18. That is, the speed command generation means 11 generates a speed command value (ω _r ^* ), and the addition calculator 12 detects the speed command value (ω _r ^* ) and the speed detection value (ω _r ) detected by the speed detector 5. The speed control means 13 performs an adjustment calculation to make this deviation zero, and outputs the calculation result to the electric motor 1 as a torque command value (τ ^* ). The current control means 14 derives a primary current command value (i ₁ ^* ) to the electric motor 1 based on the torque command value (τ ^* ), and the primary current command value (i ₁ ^* ) and the current detector 4 The adjustment calculation is performed so that the deviation from the detected primary current detection value (i ₁ ) becomes zero, and the calculation result is output to the power converter 2 as the primary voltage command value (v ₁ ^* ).

Based on the speed detection value (ω _r ) and the torque command value (τ ^* ), the inertia estimation means 15 estimates the sum of the inertia moments of the motor 1 and its driven object, and this is used as the inertia moment estimation value (J ^# ). The inertia setting means 16 outputs the inertia moment manually, and outputs this as a moment of inertia manual setting value (J ^* ). The switching means 17 switches and selects either the inertia moment estimated value (J ^# ) or the inertia moment manual set value (J ^* ) and outputs it as the inertia moment set value (J ^** ). The constant setting means 18 sets the control constant of the speed control means 13 based on the inertia moment setting value (J ^** ). Since each component in the circuit diagram shown in FIG. 1 is formed by a well-known technique, detailed description thereof is omitted.

FIG. 2 is a circuit configuration diagram showing an example of the inertia estimation means 15 shown in FIG. 1. The inertia estimation means 15 includes a differentiation means 15a for differentiating the speed detection value (ω _r ) of the motor 1; A multiplier 15b, an addition calculator 15c, and an integrating means 15d are provided.

A method for deriving the estimated moment of inertia value (J ^# ) in the inertia estimation unit 15 will be described below.

A speed command value (ω _r ^* ) is generated from the speed command generating means 11 as shown in FIG.
Under the condition that the acceleration torque of the electric motor 1 is sufficiently larger than the load torque, the acceleration / deceleration torque (τ _acc ) of the electric motor 1 is expressed by the following equation (1).

τ _acc = J · {d (ω _r ) / dt} (1)
Here, J is the moment of inertia and ω _r is the speed detection value of the electric motor 1.

When accelerating / decelerating the motor 1 under no-load conditions, τ _acc = τ ^* , so that as shown in FIG. 2, the torque command value (τ ^* ) and J ^# · {d (ω _r ) / Dt} is input to the integrating means 15d and its output is J ^# , the moment of inertia can be estimated by the circuit configuration shown in FIG.

That is, if the estimated moment of inertia value is J ^# , this can be obtained from an arithmetic expression such as the following expression (2).
^{J # = ∫ (τ * -J} # · dω r / dt) dt ... (2)

In the constant setting means 18 shown in FIG. 1, when the speed control means 13 is formed by a proportional calculator or a proportional-integral calculator based on the inertia moment setting value (J ^** ) selected and output by the switching means 17, The proportional gain K _P of any arithmetic unit is set to a value obtained by the following equation (3).

K _P = K ・ J ^** (3)
Here, K is a conversion coefficient. If the speed control means 13 is a proportional-integral calculator, an integration time may be further set.

That is, according to the motor control device 10 shown in FIG. 1, in order to estimate the moment of inertia of the motor 1 and the device to be driven, a test for driving the device to be driven by the motor as a test is accelerated or decelerated. If the operation can be executed is determined inertia moment estimation value (J ^#) to perform this test operation, on the basis of the calculated inertia moment estimation value (J ^#), and a switching unit 17 and the constant setting unit 18 The proportional gain K _P of the speed control means 13 is set via If the test operation for estimating the inertia moment cannot be performed, the inertia moment manual setting value (J ^* ) is manually set in the inertia setting means 16, and the inertia moment manual setting value ( J ^* ), the proportional gain K _P of the speed control means 13 is set via the switching means 17 and the constant setting means 18.

  In the manual setting, the total moment of inertia including the load is calculated and set with reference to the motor shaft. Further, when the manually set value is greatly deviated from the actual moment of inertia, there arises a problem that the set constant of the speed control means 13 output from the constant setting means 18 becomes inappropriate.

That means
When the actual load> the manual set value, the response of the speed control means 13 becomes slow,
If the actual load is less than the manual set value, the response of the speed control means 13 is too fast and the vibration tends to occur.
In either case, manual adjustment or the like is required, but the optimal countermeasure can be said to be a future issue.

  FIG. 4 is a circuit diagram of a motor speed control apparatus according to a second embodiment of the present invention. In this figure, components having the same functions as those of the embodiment circuit shown in FIG. The description thereof is omitted here.

  That is, in the circuit configuration shown in FIG. 4, the speed detector 5 is omitted, and the speed controller 20 as the speed controller 20, the addition calculator 12, the speed controller 13, the current controller 14, the inertia estimator 15, In addition to the inertia setting unit 16, the switching unit 17, and the constant setting unit 18, a speed estimation unit 21 is provided.

This speed estimation means 21 is formed by a well-known technique. For example, the back electromotive force of the motor 1 is calculated from the primary voltage command value (v ₁ ^* ) of the motor 1 and the primary current detection value (i ₁ ). Then, the estimated speed value (ω _r ^# ) of the electric motor 1 is derived based on the counter electromotive force.

The mathematical formula for deriving ω _r ^# is, for example, the following formula (4).
ω _r ^# = sgn (E _T ) {(| E _T | / φ ₂ ) −G _em E _M } (4)
Where φ ₂ is a secondary magnetic flux, E _M is an induced voltage of a magnetic flux axis component, E _T is an induced voltage of a component of a torque axis (perpendicular to the magnetic flux axis), and G _em is a transfer function of the adjusting means having E _M as an input Indicates.

Then, assuming that ω ₁ ^* is the primary angular frequency command value and ω _S ^* is the slip frequency command value, the estimated speed value ω _r ^# can be obtained by the following equation (5).
ω _r ^# = ω ₁ ^* −ω _S ^* (5)

Therefore, the inertia estimation means 15 in the circuit configuration shown in FIG. 4 obtains the inertia moment estimated value (J ^# ) based on the torque command value (τ ^* ) and the speed estimated value (ω _r ^# ). Yes.

That is, instead of the detected speed value (ω _r ) of the inertia estimation means 15 shown in FIG. 2, the estimated speed value (ω _r ^# ) is input, and the estimated speed value (ω _r ^# ) and the torque command value (τ ^* Calculate the estimated moment of inertia (J ^# ) from).

1 is a circuit configuration diagram of an electric motor speed control apparatus according to a first embodiment of the present invention. Partial detailed circuit configuration diagram of FIG. Waveform diagram explaining the operation of FIG. FIG. 2 is a circuit configuration diagram of an electric motor speed control apparatus according to a second embodiment of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Electric motor, 2 ... Power converter device, 3 ... AC power supply, 4 ... Current detector, 5 ... Speed detector, 10 ... Speed control device, 11 ... Speed command generation means, 12 ... Addition computing unit, 13 ... Speed control Means, 14 ... current control means, 15 ... inertia estimation means, 16 ... inertia setting means, 17 ... switching means, 18 ... constant setting means, 20 ... speed controller, 21 ... speed estimation means.

Claims (3)

In a speed control device that performs variable speed control of an electric motor using speed control means capable of changing at least a control constant,
An inertia estimation means for estimating the sum of the inertia moments of the electric motor and its drive target, and outputting this as an inertia moment estimation value;
Inertia setting means for manually setting the moment of inertia and outputting this as a moment of inertia manual setting value;
Switching means for switching and outputting either the inertia moment estimated value or the inertia moment manual setting value;
A motor speed control apparatus comprising: constant setting means for setting a control constant of the speed control means based on an output value of the switching means.   When the motor is accelerated or decelerated by the speed control means, the inertia estimation means is based on the torque command value output by the speed control means and the speed detection value or speed estimation value of the motor. 2. The motor speed control apparatus according to claim 1, wherein an estimated moment of inertia value is derived.   The speed control means is formed by a proportional calculator or a proportional-integral calculator, and the constant setting means sets a proportional gain of any of the calculators based on a value proportional to an output value of the switching means. The speed control apparatus for an electric motor according to claim 1, wherein the speed control apparatus is an electric motor.

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