JP2850531B2 - Servo compensator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a servo compensator suitable for use in a servomotor control system.

[Conventional technology]

FIG. 3 shows a speed control system of the servo motor.
ω _i is a speed command, 1 is a servo compensator (proportional-integral compensator,
Hereinafter referred to PI compensators), 2 proportional element of the proportional gain K _P, the integral element of the integration constant K ₁ 3, 4 the servo amplifier, 5
Is a servo motor (DC motor or brushless motor), 6 is a pulse encoder, 7 is a speed detector, ω _f is speed feedback, and 8 is a motor load. U ₁ is the output of the integral element 3, U _P denotes the output of the proportional element 2.

[Problems to be solved by the invention]

When the speed control of the servo motor 5 is performed,
A ripple occurs in the output torque of the PI compensator, and in response to the ripple, the output U of the PI compensator serving as a current command pulsates, and a speed jitter occurs in the motor speed v as shown in FIG.
There is a problem that the speed control characteristics are deteriorated.

The present invention has been made to solve this problem.
It is an object of the present invention to provide a servo compensator capable of reducing a speed jitter by canceling a torque ripple component.

[Means for solving the problem]

In order to achieve the above object, the present invention provides, in a servo compensator having an integral element and a proportional element, one or a plurality of sine wave generating elements for generating a sine wave having the same frequency as a DC or torque ripple component of a brushless servomotor. Are respectively inserted in parallel with the integration element, the torque ripple component is obtained by measuring the output torque of the servomotor, and the frequency has the same amplitude in an inverted phase with respect to the torque ripple component. Configuration.

The transmission coefficient of the integral element is K ₁ / S, the sine wave S _n from the sine wave generation element _{(K n ω n) / (} S 2
+ Ω _n ² ) is preferred. Where ω _n = n
ω _m , ω _m = rotational angular frequency of servo motor, n = 1,2,
・ ・

[Action]

In a DC or brushless servomotor, a torque ripple component corresponding to the number of commutators or poles is generated. Therefore, the output torque waveform is analyzed to determine the amplitude and high-frequency component of the torque ripple component, and a sine wave generating element having the same amplitude in reverse phase to this torque ripple component is inserted in parallel with the integral element as a compensation element. Then, the torque ripple component is canceled without performing a complicated operation.

〔Example〕

 Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, reference numeral 10 denotes a servo compensator, which includes a PI compensator 1 and a sine wave generating element inserted in parallel with the PI compensator 1.
_{S 1, S 2, S 3} , consists · · · S _n, the compensation output respectively occur _{U 1, U 2, U 3} , ···· U n is the adding unit 11 in the PI compensator 1
Is added to the output Ui of the integral element 3 and the output Up of the proportional element 2. Other configurations are the same as those in FIG. In addition, However, ω ₁ = ω _m , ω ₂ = 2ω _m , ω ₃ = 3ω _m ,..., Ω _n = nω _m , ω _m = rotational angular frequency of the servo motor ω ₁ , _{ω 2, ω 3, ··· ω} n is a frequency equal to the frequency component of Torukuribburu components of the servo motor 5 is a value obtained by measuring the output torque τ of the servo motor 5, the compensation output U ₁ , U _2, U _3, the · · · U _n in opposite phase to the torque ripple having the corresponding frequency components, are to have the same amplitude.

The operation of this embodiment will be described with reference to the waveform time chart of FIG. In FIG. 2, (a) shows the output torque τ of the servo motor, (b) shows the output of the adder 11 which becomes a current command, (c) shows the speed of the servo motor, v shows the speed when ripple compensation is performed, and v ′ Is the speed without compensation,
(D) shows the output of the sine wave generator S _1, shows (e) is the output Ui of the integral element 3, respectively.

The torque ripple component of the servo motor 5 is a torque ripple component Δτ ₁ with one cycle of the servo motor 5 as one cycle.
If it is, since the sine wave generating element S ₁ is omega _{1 =} omega _m should be connected in parallel to the PI compensator 1, the servo motor 5 is operated, the second FIG sine wave generating element S ₁ generating a compensation signal U ₁ of a sine wave shown in (d). The compensation signal U ₁ has the same amplitude U _PP as the amplitude of the torque ripple component Δτ ₁ and is a signal whose phase is inverted by 180 °. Integral element 3 of PI compensator 1
Since the output torque average value U _O of the output torque tau, compensation signal U ₁ to the torque average value U _O is added, the added value
So that the speed control of the servo motor 5 is performed by the current command U for U _P is added. Since the compensation signal U ₁ have the same amplitude in opposite phase to the torque ripple component .DELTA..tau ₁ as described above, as evident from comparison of FIG. 2 (a) and (b), the torque ripple component .DELTA..tau ₁ is As a result, the speed of the servo motor 5 becomes a speed v without jitter as shown in FIG. 2 (c).

A plurality of frequency components torque ripple component of the servo motor _{5 ω 1, ω 2, ω} 3, when consisting of · · · omega _n is
As shown, sine wave generating elements corresponding to each frequency component
S ₁ , S ₂ , S ₃ ,... _Sn are provided.

〔The invention's effect〕

As described above, the present invention measures the compensator output generated based on the deviation between the command and the feedback amount, measures the torque ripple component from the output torque of a DC or brushless servomotor, and inverts this torque ripple component. Compensation with a sine wave generating element that outputs a frequency with the same amplitude in phase eliminates the need for complicated calculations, cancels the torque ripple component, and reduces the torque ripple of the servo motor. The occurrence of speed jitter due to torque ripple can be prevented, and the control characteristics can be improved with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a waveform time chart showing the operation of the above embodiment, FIG. 3 is a block diagram showing a conventional speed control device, and FIG. FIG. 4 is a waveform chart for explaining a problem of the control device. 1 PI compensator, 2 Proportional amplifier, 3 Integrator, 4 Servo amplifier, 5 Servo motor, 6 Pulse encoder, 7 Speed detector, 10 Control compensator , S ₁ , S ₂ , S ₃ ,... S _n .

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) G05D 3/00-3/12 305 G05B 11/36

Claims (2)

(57) [Claims] 1. A servo compensator having an integral element and a proportional element, wherein one or a plurality of sine wave generating elements for generating a sine wave having the same frequency as the torque ripple component of a DC or brushless servomotor are provided in each of the integral elements. Inserted in parallel, the torque ripple component is obtained by measuring the output torque of the servomotor, and that the sine wave has the same amplitude in reverse phase with respect to the torque ripple component. Characterized servo compensator. 2. A transmission coefficient of the integral element is K ₁ / S, the sine wave S _n from the sine wave generation element (K _n ω _n) /
^2. The servo compensator according to claim 1, wherein (S ² + ω _n ² ). Here, ω _n = nω _m , ω _m = rotational angular frequency of the servo motor, and n = 1, 2,.