JPS61138174A - Method for measuring phase difference - Google Patents

Abstract

PURPOSE:To eliminate substantially the influence of noise and to measure an exact phase difference by determining the integrated output of the 2nd wave between pi/2-3pi/2 phase angle of a reference wave. CONSTITUTION:A max. and min. detector 1 is inputted with an AC waveform F1 and outputs a 1 from the max. value (omegat=pi/2) of the waveform F1 up to the min. value (omegat=3pi/2); otherwise the detector outputs a 0. An AC waveform F2 is inputted to an integrator 2 with control, by which the waveform is integrat ed while the control input is the 1. The phase difference is determined from the output of the integrator 2 by using the angle frequency omega and the peak value of the AC waveform F2 in a calculator 3. The need for the detection of the zero cross point is thus eliminated and the phase is determined from the integrated quantity and therefore the measurement of the phase difference strong to the noise is made possible.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention provides three methods for measuring the phase difference between two AC waveforms. It is determined from the time difference between the zero crossing points of the waveform.

However, the zero cross point is easily affected by noise, increasing the error in phase difference measurement.

[Purpose of the invention]

An object of the present invention is to provide a method that can measure phase differences accurately without being affected by noise.

[Summary of the invention] The two current waveforms are F,,F! Let Fl be the reference chiku.

F, ,F, can be expressed by the following equation.

F1=a, 5inQ)tF, = jLt sin (ωt+θ)F between the extremely thick basket (ω1=-) and the minimum value (ωt-Hπ) of Fl.

is integrated to find the m value P.

°゛sinθ=-πP θ=sin-”(-πP) The phase difference θ is obtained as described above.

Note that when θ is small, θ=sin θ may be used.

〔Effect of the invention〕

According to the present invention, it is not necessary to detect zero cross points and the phase is determined from the integral amount, so a phase difference measurement method that is strong against noise can be obtained.

[Embodiments of the invention]

FIG. 1 (= shows an example. Code 1 in the figure is extremely thick.

A worker detector is shown, which inputs Fl and outputs "1" from 1 dog to the minimum, and outputs "O" otherwise. 12 is an integrator with control, input F, and control human power ρ;
1". 3 calculates 5in-' (-5P) from the output P of the integrator using the peak value a2 of the angular frequency ω and F, which are known in advance by the calculator, and calculates the phase difference θ.
seek.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention. 1... Maximum/minimum detector 2... Integrator with control 3... Arithmetic unit. Agent: Patent Attorney Noriyuki Chika (and 1 other person) No. 1
figure

Claims (1)

[Claims] To measure the phase difference between two AC waveforms, there is a circuit that detects that the phase angle of the reference wave is between π/2 and (3/2)π, a circuit that integrates the second wave between them, and a known AC angular frequency. From ω, the known or measured peak value a_2 of the second wave, and the output P of the integrator, θ=sin^-^1[-ω/(2a_2)P
] A phase difference measurement method that measures the phase difference θ by calculating.