SU1700493A1 - Method of measurement of phase error of phase inverter - Google Patents

Abstract

The invention relates to a measurement technique, in particular to methods for measuring phases, and can be used to measure the phase error of phase shifters. The aim of the invention is to improve the accuracy and reliability of measurements. A device for implementing the method includes a pulse generator 1, a frequency divider 2, a sinusoidal shaper 3, a 4 position meter, a phase shifter 5, a shaper 6 pulses with discretely adjustable phase shift, a shaper 7 pulses, RS-flip-flop 8, a band-pass filter 9, a shaper 10 average value and voltage meter 11. With this method of measurement, the phase error is determined as the difference between the readings of the scale of the meter 4 and the angle code set by the shaper 6 pulses with a discrete-controlled phase shift. 3 il. (L С vi о о fcb Ю С

Description

The invention relates to a measurement technique, in particular, to methods for measuring a phase difference, and can be used to measure the phase error of phase shifters.

The aim of the invention is to increase the reliability of the measurement.

FIG. 1 shows a diagram of the device that implements the proposed method; in fig. 2a is a diagram of the trigger operation in case of discrepancy between the counting and phase pulses; b - the same, with a small phase difference; in - the same, with zero phase difference (pulse combination); in fig. 3 - dependence of the level of the selected mean value of the signal and the function on the phase difference between the counting and phase pulses.

In diagrams 2a, the signs are denoted: O.I., - counting pulses, F.I. - phase pulses, T - trigger output signal.

A device that implements the proposed method contains (Fig. 1) a pulse generator 1, a frequency divider 2, a sinusoidal shaper 3, a position meter 4, a phase shifter 5, a shaper 6 of the pulses with a discrete-controlled phase shift, a pulse shaper 7, RS- the trigger 8, the bandpass filter 9, the mean value driver 10 and the voltage meter 11 with the corresponding connections between them.

In the former, a desired angle code is set (specified). Phaser 5, the primary windings of which are excited by the supply voltage through a series-connected generator 1, divider 2 frequencies and shaper 3, produces a voltage on the secondary winding, the phase of which (with some error) is proportional to the angle of rotation of the rotor, and the angle of rotation of the rotor is set by the meter 4 and equals the angle, the code of which is set in the imaging unit 6.

The phase pulse from the output of the imaging unit 6 receives the input S of the RS-flip-flop 8, and the input pulse R from the output of the imaging unit 7 goes to the input R of this trigger. In the diagrams of FIG. 2a, b show the cases when the phase difference between the reference and phase pulses is not equal to the bullet degree, then the output of the RS flip-flop 8 generates pulses with a frequency fo and a duration tu that is proportional to the phase difference, Filter 9 has a flat characteristic with an upper cutoff frequency t0 / 2 and the lower cut-off frequency WK.

The slope steepness of the filter characteristics is calculated so that

so that its transmission coefficients at f f0 / K and f f0m would be close to zero {the value of K must be greater than 10-12; to suppress the frequencies defining the edges of the pulses, it must be m 2).

In this case, with non-coinciding edges of the pulses at the inputs of the trigger 8, the amplitude of the sinusoidal signal at the output of the filter 9 is equal to

Vykh kfo s | n 1l cos2 n f0

JLC |

t,

where o; - pulse duty cycle.

Um is the pulse amplitude;

Kf0 is the filter transmission coefficient at the frequency fo.

At the output of the former 10, the amplitude of the signal measured by the meter 11 varies depending on the phase difference in accordance with FIG. 3

When the pulse fronts coincide at the inputs of the trigger 8, pulse signals of duration T0, 2T0 ... ST0 appear at its output, whereTo 1 / fo is the period of the pulses at the trigger input, while the probability of forming at the output of the trigger 8 signals as zero , and the unit level is 0.5. In this case, the output of the trigger 8 generates pulsed signals with frequencies below that are in the passband of the filter 9, and the probability of forming signals with frequencies f0 / K, where K 10-12, is close to O.

The constant component of the signals from the output of the trigger 8 through the filter 9 does not pass.

Due to the fact that the transmission coefficient of the filter 9 Kf0 / n - Kf0, and also due to the fact that the signals at the output of the trigger 8 with a duty cycle q 2-4 are most probable, the output voltage at the output of the filter 9 corresponds to the expression 2Um ...

to / p

U

out

 Kfo

sin - cos2 Ttio t,

Is l

L

the influence of the sin term is not significant, and the output voltage is mainly determined by the filter coefficient Kf0 / n. The measurement results are shown in FIG. 3, where it is shown that with a zero difference, the output voltage increases abruptly due to the simultaneous influence of two factors: a sharp decrease in the duty cycle and an increase in the filter transmission coefficient due to the formation of frequencies 8 at the output of the trigger that are less than f0

With this method of measurement, the phase error is defined as the difference between the readings of the scale of the block 4 and the angle code specified by the shaper 6 pulses with discrete-controlled phase shift.

Claims (1)

Invention Formula The method of measuring the phase error of the phase shifter, which consists in forming the reference voltage of the frequency shifter f0 from the high-frequency voltage and the same frequency sampling pulses having a discretely adjustable phase shift relative to the reference voltage, form phase pulses shifted relative to the reference voltage from the output voltage of the phase shifter zero phase of the reference voltage on the phase angle, convert the phase angle between the counting and phase pulses into a binary signal, the duration of a single (zero) whose level, proportional to the phase difference between them, characterizes the phase error of the phase shifter, differing in that. that, in order to increase the reliability of measurement, they limit the frequency spectrum of the received binary signal from above to frequency f0 / 2, and from below to f0 / K, where K 1 is extracted from the received signal, the average value of the variable component, measure the amplitude of its maximum and minimum values when changing the magnitude of the mismatch of the reference and phase pulses in the range of 0-360 °, and the moment of combining the reference and phase pulses are recorded when the minimum values of the measured voltage signal appear in the zone with a level exceeding threshold, equal to the amplitude of the smooth maximum of the measured signal. but O.U. Fm S ohm P pp pp 8 yi fm P FIG. 2 I WWT FI.3