JPH02246510A - Control circuit with phase variation type tracking filter - Google Patents

Abstract

PURPOSE:To enable phase compensation near a desired frequency without providing any new phase compensating circuit by providing the phase variation type tracking filter which has a phase command input. CONSTITUTION:A displacement signal (x) is inputted to a phase compensator 2. Whose arithmetic result is inputted to a power amplifier 5 to supply a control current to an actuator. When the displacement signal (x) is inputted to the phase variation type tracking filter 4, a signal having a phase advance phi among displacement vibration components is obtained in synchronism with alpha frequency (f). This signal is multiplied by proper magnification a and superposed upon the signal of the phase compensator 2 to vary the characteristics of a control system only in a frequency range matching the frequency command (f). Consequently, the circuit constitution is simplified and the gain of specific frequency and phase characteristics can be adjusted optionally.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a tracking filter for a control circuit system,
In particular, the present invention relates to a variable phase tracking filter suitable for arbitrarily setting gain and phase characteristics in a narrow frequency range.

[Conventional technology]

Conventionally, one of the most common methods for extracting only specific frequency components from a signal is a bandpass filter. However, when this method is introduced into a control circuit, it is possible to extract a specific frequency component, but the phase characteristics in the vicinity are disturbed, making it difficult to apply in practice.Also, when the frequency to be extracted is synchronized with an external signal, A tracking filter shown in FIG. 4 is a method that eliminates these difficult-to-handle drawbacks. The tracking filter 1 has a signal input X and a frequency command input f, and outputs a component xt of the frequency f of the signal X. This principle will be explained below using mathematical formulas. When the input signal X is expanded into a Fourier series, it becomes Equation (1).

x= ao+ ax cos ωt+ ax cos
2 ωt+-+b1 sin (11t+bx sin
2ωt+-(1) where.

ω=2πj, t: time g a p b: Fourier coefficient.

A transformation To of equation (2), which is composed of a trigonometric function matching the frequency command f (angular frequency ω), is applied to equation (1).

Calculating Tax.

When passed through a low-pass filter (LPF) with a sufficiently small cutoff frequency for the 0 frequency f, Xc becomes .Similarly, the signal Xg becomes
- By applying (7), the output X that matches the frequency f
Only z is obtained... (3) If we apply the product formula of trigonometric functions here, as a conventional device using this tracking filter circuit,
For example, there is one listed in Japanese Patent Application Laid-Open No. 52-93853. The method described in this publication will be explained below with reference to FIG.

The first process of the tracking filter 1 is frequency conversion according to (9). Then, in the second processing, the signal is applied to a low-pass filter, and a signal of XZ e '/Z is obtained. Finally, by applying the inverse transformation Tt (10), the output Xi,'it is obtained.

The output signals xfi, 7i are obtained by extracting a component synchronized with one frequency J from the input signal Xty. By superimposing these signals on the signals of each XeV phase compensation circuit 2 and adjusting the second phase compensation circuit 3, it is possible to increase the feedback gain only at a desired frequency or provide a phase lead operation. When such a control circuit is applied to a control device for an electromagnetic bearing, the amplitude of rotor vibration can be reduced.

Another conventional device is the one shown in FIG. 6, which is listed in Japanese Patent Application Laid-Open No. 61-2622-2S. Tracking filter 1 is the same as in Fig. 5, but the extracted Xz and 7i
are added to the original phase compensation circuit 2 so that they cross each other. By doing so, a damping effect can be expected in the rotor system. On the other hand, it has the disadvantage that it cannot be used when spring action (proportional action) is required.

[Problem to be solved by the invention]

The conventional control system described above requires four phase compensation circuits each consisting of a proportional circuit and a differential circuit, which makes the circuit complex and has the disadvantage that fine adjustment is difficult.

An object of the present invention is to provide a variable phase tracking filter that has a simple circuit configuration and can arbitrarily adjust the gain and phase characteristics of a specific frequency.

[Means for Solving Problem 11] The above purpose is achieved by changing the third transformation as shown in the following formula instead of making the transformation that is the third processing of the tracking filter an inverse transformation of the first transformation. be done. That is, let the first conversion Tx and the third conversion be T8.

Use the transformation that becomes .

[Effect]

The third transformation T8 of the phase variable tracking filter is Because it is.

In the case of, Tδ=[0011(ωt+φ) −sin (ωt+φ) (14).

In Case of.

Equations (14) and (16) show that L
When restoring (converting) the output of PF to a specific frequency,
This means that it is restored using a trigonometric function with a phase advance φ.

With this method, the proportional gain and differential gain can be easily adjusted by arbitrarily setting the phase advance φ. By adding these signals to the signal of the phase compensation circuit,
It is possible to increase the gain or increase the phase lead only at specific frequencies.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. The displacement signal X is input to the phase compensator 2, the calculation result is input to the power amplifier 5, and a control current is passed to an actuator (not shown). Such a method is the basic configuration of a servo control system.

Now, when this detected displacement signal X is input to the variable phase tracking filter 4, a signal is obtained which is synchronized with one frequency f of the displacement vibration components and further has a phase lead φ. This signal is multiplied by an appropriate magnification α and superimposed on the signal of the phase compensator 2. By doing this, the characteristics of the control system are changed only in the frequency range that matches one frequency command f.

Assuming the transformation of the phase variable tracking filter 4,
The output signal Xx of the tracking filter becomes first-order.

xn= a (a 1 cow(ωt + φ)
10 b 1 5in(ωt + φ))...(18
), the frequency synchronized component of the displacement signal is Xz(1”aI Cog ωt+bz sin
Noting that ωt = (19), Xf
indicates that the phase lead is φ and the gain is 0 times greater than that of the original signal. Therefore, the second phase compensator 3 explained in FIG. 5 becomes unnecessary, and an arbitrary phase lead can be set by changing the phase command φ.

FIG. 2 shows an example of the configuration of a variable phase tracking filter. The 0 frequency command f is input to the PLL circuit 6, and according to the phase difference of another input f', vCO in the PLL circuit is used. The signal is input to the primary day byte number N counter 7 which outputs an output Nf', and is 1/Ned and re-input to the PLL circuit. The PLL circuit operates so that f' matches f and is stable. The counter 7 is simultaneously outputting signals (addresses) from 0 to N, and the ROMs 8a and 8 are filled with sine waves.
A signal is generated from b every moment. These signals and input signal X are calculated by multipliers 9a and 9b.

As a result of the calculation, a component matching the frequency command f from the low-pass filters 10a and 10bk- can be the DC output.

On the other hand, in response to the one-phase advance command φ, the address shifter 11 shifts the address of the signal (address) output by the counter 7;
If the sine wave stored in the ROM has one period, the shift amount is φ.The ROM8c, corresponding to this shifted address,
From 8d, a signal whose phase is advanced by φ with respect to 8a and 8b is output. This signal and the output of the filter are multiplied by a multiplier 9c.
, 9d and add the results to achieve the objective.

In another embodiment, a variable phase tracking filter 4 is used in place of the tracking filter shown in FIG. With this configuration, the cross inputs Xg and 7x can be set to any phase angle, making the effect even higher3.
In this figure, the outputs Xztyf of the tracking filters are connected in a crossed manner, but even if they are directly coupled as shown in FIG. 5, the purpose can be achieved by appropriately adjusting one phase and the order φ.

〔Effect of the invention〕

According to the present invention, it is possible to perform phase compensation in the vicinity of a desired frequency without providing a new phase compensation circuit, and a great effect can be expected as a tracking filter for a control system. Further, since one phase advance can be easily realized by shifting the address of l(OM), complication of the circuit can be avoided.

[Brief explanation of drawings]

FIG. 1 shows block I! of an embodiment of the present invention. 2 is a block diagram showing the configuration of the variable phase tracking filter shown in FIG. 1, FIG. 3 is a block diagram showing another embodiment of the two-signal human-powered system, and FIG. A block diagram showing functions, FIG. 5 is a known example in which a conventional tracking filter is used as a control system filter, and FIG. 6 is another conventional example in which a conventional tracking filter is used as a control system filter. DESCRIPTION OF SYMBOLS 1... Tracking filter, 2... First phase compensation circuit, 3... Second phase compensation circuit, 4... Phase variable tracking filter, 5... Power amplifier, 6...
... PLL circuit, 7... Counter, 8... ROM,
9...Multiplier, 10...Low pass filter. Figure 1 Grass 2 ≠ Figure

Claims (1)

[Claims] 1. In a control system comprising a phase compensation circuit and a tracking filter that outputs a signal synchronized with a frequency command, in which the output of the tracking filter is superimposed on the output of the phase compensation circuit, a phase command input 1. A control circuit comprising a variable phase tracking filter having a variable phase tracking filter. 2. A control circuit according to claim 1, characterized in that it is provided with a tracking filter that simultaneously varies the phase of two or more signals. 3. A variable phase tracking filter, characterized in that the phase angles of the sine waves used for the first conversion and the third conversion after the low-pass filter are shifted. 4. In claim 3, a sine wave having a phase difference is generated by shifting the address of the ROM in which the third conversion sine wave is written to the address of the first conversion ROM. A variable phase tracking filter characterized by: