Method for measuring power factor of variable-frequency power supply

Abstract

The invention presents a method for measuring the power factor of a variable-frequency power supply. After angular frequency tracking becomes stable, the real-time fundamental signal phase is calculated according to the angular frequency convergence value and the state variable, and then, the voltage and current phase difference and the power factor can be obtained. Compared with the prior art, the method of the invention has the advantages as follows: the fundamental frequency of a variable-frequency power supply can be tracked dynamically; the result of power factor measurement is not affected by harmonic; no complex phase locked loop circuit is needed; the requirement on signal stability is not high; and the instantaneous frequency, amplitude and apparent power can be measured simultaneously.

Description

technical field [0001] The invention relates to the field of electric parameter measurement, in particular to a method for measuring the power factor of a variable frequency power supply. Background technique [0002] The electrical parameters of variable frequency power supply include voltage, current effective value, power factor, active power, reactive power, peak voltage, peak current, etc. Among them, power factor is the key point and difficulty in the measurement of variable frequency power supply parameters. Traditional AC electrical measuring instruments are suitable for measuring sine waves and power frequency signals, but cannot accurately measure variable frequency power supplies containing harmonics. At present, the main methods of power factor measurement are: ① zero-crossing method. The zero-crossing method is the most direct method to measure the current and voltage phase difference, but the measurement results are seriously affected by harmonic and non-perio...

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Problems solved by technology

[0003] In order to solve the above problems, the present invention aims to propose a new power factor measurement method based on iteration and with a small amount of calculation, which solves the problem that the measurement results of the above methods are affected by harmonics, complex phase-locked loop circuits must be used, and instantaneous power cannot be measured. It is necessary to predict the fundamental frequency and other issues

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