No distortion digital differential filtering method

Abstract

This invention provides a nondistorted digital filter method including setting a sampling frequency for sampling signals and difference step computing differences, which samples signals with the sample frequency, deducts a sample point signal value spaced in a difference step from each sample point signal value to recover the phase with the difference computed signal values, in which, the rario of the sample frequency and the signal frequency is the integral times of 6 and the difference step is the unit sample frequency of the number of the integral times, and amplitude after difference computation is unchanged and the phase change angle of the computed signal is pi / 3=60deg., a special angle.

Description

technical field [0001] The invention relates to a digital differential filtering method, in particular to a distortion-free digital differential filtering method for eliminating DC components. Background technique [0002] Usually, in addition to the normal AC power, there are various harmonic noises and DC component noises in the sinusoidal AC current. These noises will affect the use and normal operation of the equipment, so find a way to eliminate them. [0003] The common way to eliminate the DC component is to use a digital filter: first sample the sinusoidal AC current, use the digital filter to perform digital filtering on the sampled data, and then restore the processed data to a sinusoidal AC current that has eliminated the DC component. In a microprocessor system, a digital filter is represented as a piece of code or algorithm. The algorithm must have the following two characteristics: fast and sensitive. If the response is slow and the actuator cannot act in ti...

AI Technical Summary

Problems solved by technology

[0019] Since the amplitude of the current signal after the differential calculation becomes about 1 / 2 of the original signal, there is a certain distortion, which will also reduce the sensitivity of the device

At the same time, the phase change angle of the filtered signal is 5π / 12=75°, and it is not very convenient to look up the table when restoring the phase.

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