JPS593364A - Phase detection circuit - Google Patents

Abstract

PURPOSE:To enable the measurement of a phase difference without hunting by inputting two input pulse trains with an inhibiting circuit to a phase comparator, and annihilating one pulse when the phase difference exceeds a prescribed value. CONSTITUTION:Respective signal waves are inputted with zero cross comparators 5, 6 and inhibition circuits 12, 13 to a phase comparator 14. When an S input signal is first triggered, an output appears only at the SO output terminals, and when an R input terminal is first triggered, the opposite state takes place. The output of the comparator 14 closes switches 15, 16 respectively which input a DC voltage B to the phase noninverted terminal and phase inverted terminal of an operational amplifier 17. The output of the amplifier 17 is inputted with a low-pass filter 18 to a meter 21. On the other hand, when the phase difference exceeds +190 deg. or -190 deg., theta comparators 19, 20 output inhibition signals 19a, 20a to anhibilate one pulse and to make the output display -170 deg. or +170 deg.. The stable display is obtd. even if there is a <=180 deg.+ or -10 deg. fluctuation in the phase difference.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a circuit for detecting a mutual phase difference in a case where the motion of a rotating movable part of an apparatus having a rotating mechanism is out of phase at the same rotational frequency depending on the location.

For example, if the rotation axis of a rotating machine is not axially symmetrical and wobbles, first detect the phase difference between two points on the axis in order to correct the imbalance.

As shown in Figure 1, vibration signals of the rotating machine and tacho pulses (rotational A train of pulses generated each time the shaft rotates once is taken out, and the angle at which the vibration of the bearing portion deviates from this is calculated using the position of the light-reflecting tape on the shaft periphery as a reference. The angle is measured as the phase of the rotational frequency signal. FIG. 2 shows a conventional phase detection circuit. fS is a sine wave signal obtained by extracting a component of the same frequency as the tacho pulse from the output of the imaging detector 1 by the filter 4, and fr is a sine wave signal corresponding to the tacho pulse train. This fs, fr
The phase difference becomes the angular shift. The output of the phase comparator 9 is averaged by a low frequency wave detector 10 and the angle is displayed on a meter 11. When switch 8 is switched to a or b, the display on meter 1-1 is 00 to 3600 and -180° to +180, respectively.
There are two possibilities: °.

The principle of this phase measurement will be explained using signal waveform diagrams shown in FIGS. 3(a) to (+1). This figure illustrates a case where fs advances by 90 degrees with respect to fr (reference wave). f
The signal s passes through the zero cross comparator 5, and when the switch 8 is turned to the a side, a waveform of (d>) is applied to the input terminal S of the phase comparator 9. fr passes through the zero cross comparator 6 and applies the waveform (C) to the input terminal R of the phase comparator 9. Here, the phase comparator 9 operates on the rising edge of the input waveform, sets the output PC center when input to input terminal S, and resets when input to input terminal R, so the output The PC6 has the waveform (e) when the switch 8 is on the a side, and (g) when it is on the b side.
The waveform becomes The output PC○ is smoothed by the low-frequency wave transducer 10, and its output LP6 is indicated to the potash meter 11.

The above explanation has been about a waveform with a 90° phase lead, but the relationship between the phase difference of fS with respect to fr and the output LPO is as shown in Figure 3 (1) when the switch 8 is set to the a side, and as shown in Figure 3 (1) when the switch 8 is set to the b side. Figure (j) is obtained.

This phase detection circuit has the following drawbacks. In actual equipment measurements, even if there is no phase difference due to unbalance of the equipment itself, due to the influence of vibration from other machines or the small tacho frequency component and minute noise superimposed on it, the difference may be 10° or more. fluctuations may occur. In such a case, in the 00 to 360° display, the indication will hunt between the value of 10B and the value of 0 near 0°, making it impossible to read the phase difference. In such a case, -180° to +1
Switch to 80° and read. In cases such as correcting unbalance in rotating machines, measuring instruments are brought to the site to take measurements, so in the dark environment of the site, the instrument scales are difficult to read and measurement errors are likely to occur. If hunting occurs, the operation is troublesome because switching is done at the operator's discretion.

SUMMARY OF THE INVENTION It is an object of the present invention to eliminate the above-mentioned drawbacks and to provide a phase detection circuit which provides a single digital display of ±180° without hunting.

The phase detection circuit according to the present invention includes two inhibit circuits that pass or block two human-powered pulse trains of the same frequency; and an output corresponding to the input terminal to which the pulse was input first among the pulse trains output from each inhibit circuit. A phase comparator having two output terminals that produce a pulse train with a width corresponding to the phase difference between two human-powered pulses only on the side; one output of the phase comparator is passed through, and the other output is passed through. an operational amplifier that outputs a pulse train of positive or negative polarity with a width corresponding to the phase difference between the two pulse trains; a low-pass filter that averages the output of the operational amplifier; The output of the filter is compared with a reference voltage value corresponding to a predetermined phase difference set as positive and negative, and a signal is sent to the inhibit circuit so that one pulse is not output from the inhibit circuit on the matching side. Send 2
It is characterized by being equipped with two comparators and measuring the phase difference between two human-powered pulse trains without hunting.

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 4 is a block diagram of a phase detection circuit according to the present invention.

FIG. 5 (- to ω) is a signal waveform diagram showing waveforms at various parts. This figure exemplifies the case where <fB, which is the same as in FIG. 3, advances by 90° with respect to fr (reference wave). Each signal wave is applied to the zero cross comparators 5 and 6, and the output P1+P20 waveforms at the output end become (cJ, (dJ) respectively.If the inhibit signals 19a and 20a are not input to the inhibit circuit 12.13, Considering that, P
it The waveform of P2 is applied to each input terminal S, H of the phase comparator 14.
are added to each.

This phase comparator 14 is provided with an SG output terminal corresponding to the S input terminal and an R5 output terminal corresponding to the R input terminal.
When the S input terminal is first triggered (in this figure, the rising edge of the input rectangular wave is the trigger), an output appears only at the Sb output terminal, and no signal appears at the RO output terminal.

The opposite is true when the R input terminal is first triggered.

Still, the output of the output terminal of the phase comparator 14 becomes "1" at the rising edge of the signal applied to its corresponding input terminal, and in this state, when a signal is applied to the other input terminal, the output becomes "0" at the rising edge. "become.

Therefore, when the S input terminal is triggered first, the output of the 86 output terminal is (eJ), and the output of the RO output terminal is "0".
becomes. If the R input terminal is first connected to l-IJ, the R
The output of the Sb output terminal becomes 0".The output of each output terminal SO and RO of the phase comparator 14 closes the switches 15 and 16, respectively, and the operational amplifier 170 has a phase non-inverting terminal and a phase inverting terminal. A DC voltage with an amplitude of B is input to the terminal.The output of the operational amplifier 17 is averaged by the low-pass filter 18, and the low-pass p-wave filter 18 is applied to the phase difference of f8+fr.
The custom-made output LPO is shown in Figure 5 (gJ.This output L
PO is indicated by a digital voltmeter 21. Therefore, in the example, when the S input terminal is triggered first, +90
°, -270° when the R input terminal is triggered first
will be displayed. Signal force fs for a 90° advance waveform
, +90° or -270 depending on when fr is input.
Although it is displayed as °, the angle display is the same.

This measurement method also has the drawback that hunting occurs when the S input terminal is triggered first and the phase varies around 360°. Same for R input terminal <-360
Hunting occurs at °. It is necessary to eliminate this drawback and limit the maximum indication range of the instrument to around +180° so that a general-purpose, inexpensive 31/2 digit (±1.999) digital voltmeter can be used.

This operation is performed by comparators 19 and 20. and inhibit circuits 12 and 13. FIG. 6 shows waveforms at various parts to explain this operation. +1 for this
The case where the angle is kept within 90° will be explained. When the S input terminal is triggered first, the phase difference between fs and fr is +190°
When the output LPO of the low-frequency P wave generator 18 becomes +190
Generates a voltage corresponding to °. The 100 comparator 19 is a voltage comparator, and this voltage is set at +■θ, and when the output LPO of the low-pass p wave generator 18 exceeds this voltage, an inhibit signal 19a is outputted to the output side.

When receiving the inhibit signal 19a, the inhibit circuit 12 does not conduct the output P1 of the fs zero cross comparator 5 to the S input terminal of the phase comparator 14. , (as shown by the - dotted line, one pulse disappears. Therefore, the phase comparator 1
4, the R input terminal is triggered first, so the low-pass filter output LPO moves toward a stable point of -170°, and the output display becomes -170°. Similarly, -■θ of 10 comparator 20
If the voltage corresponding to -190° is set and the R input terminal is triggered first, the phase difference will be 11
When the angle reaches 90°, it is detected by the comparator 20, and the inhibit circuit 13 performs the same operation as above, and the output display is +170.
° will be displayed. Therefore, even if the phase difference varies by less than 10 degrees by 180 degrees, a stable display is provided. If the fluctuation is larger than this, θ may be made larger, for example, +195°. Note that the waveform curve (-) shows the time lapse from the start of measurement until the indication becomes stable. If the inhibit circuit 12 is not considered, the waveform curve (-) indicates the -190° indication. Even if it pans, it will return to a constant value of +190° after some time.With this circuit that activates the inhibit circuit 12, by inhibiting only one pulse, it will quickly reverse to the stable point of -170°. This has the advantage of shortening the stabilization time when the frequency is high.

In the explanations so far, the fs and fr (D waveforms have been assumed to be sine waves, but since the phase comparators 9 and 14 operate at the rising edge of the input wave, one or both of fs and fr may be pulse trains. It's okay even if it is.

As detailed above, according to the present invention, hunting occurs in measurement instructions even when the phase difference fluctuates around 0° and around ±180°, and accurate instructions can be given quickly and clearly using a general-purpose digital display instrument. A phase (angle) detector is obtained that provides an indication.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of the part that picks up two signals from two points on the rotary movable part of the rotating mechanism, Figure 2 is a configuration diagram of a conventional phase detection circuit, and Figures 3 (a) to (h) are the Operation waveform diagrams of each part in the figure, (i) to (j) are diagrams showing the relationship between the phase difference and the low-frequency offshore transducer output, and FIG. 4 is a diagram showing one embodiment of the present invention.
Figure 5 (~ ~ information) is an operation waveform diagram of each part in Figure 4, (g+
) is a diagram showing the relationship between the phase difference and the low-pass filter output, and FIG. 6 is a diagram for explaining the operation of the inhibit circuit. 12.13...Inhibit circuit! 14...
Comparator 15.16...Switch circuit. 17...Operation amplifier. 18...Low frequency p-wave device. 19.20...θ comparator. 21...Digital voltmeter. Patent applicant Akihiko Sato, patent attorney representing Anritsu Electric Co., Ltd.

Claims (1)

[Claims] Passing or blocking two human-powered pulse trains of the same frequency 2
inhibit circuits; Two outputs that generate a pulse train with a width corresponding to the phase difference between the two human-powered pulses only on the output side corresponding to the input side where the first pulse was input among the pulse trains output from each inhibit circuit. a phase comparator having a terminal; one output of the phase comparator is passed through as is, and the other output is passed through with its polarity reversed;
an operational amplifier that outputs a pulse train of positive or negative polarity with a width corresponding to the phase difference of the human-powered pulse train; a low frequency filter that averages the output of the operational amplifier; and a positive output of the low frequency filter. two comparators that compare negative reference voltage values corresponding to predetermined phase differences and send signals to the inhibit circuit so that one pulse is not output from the inhibit circuit on the matching side; , a phase detection circuit that measures the phase difference between two human-powered pulse trains without hunting.