Research On Small Phase Angle Measurement Technique

Phase angle measurement as an important signal detection technology hasbeen widely used in various fields of science research and engineeringapplications. On the basis of research on conventional phase measurementmethod and circuit, this paper studied the problem of low measuring accuracyand poor anti-interference near zero phase especially. Small phase anglemeasurement difficulty is especially large, using traditional methods to measuresmall phase angle is inaccurate, and can not even be measured. So, this paperstudied the optimization of small phase angle measurement, designed relatedmeasuring circuit.This paper determined the overall scheme of the small phase anglemeasurement system and analyzed the various errors of zero-crossing comparisonand pulse count method. In order to improve the accuracy and anti-interferencecapacity of phase angle measurement, this paper put forward optimizationscheme.In the analog circuit, the mixing method was used. The higher frequencymeasured signal become to low frequency signal that is easy to measure. Thismethod reduced the quantization error which produced because the too highsignal frequency.In the digital circuit, in order to reduce the quantization error whichproduced because of too low frequency of pulse counting clock, the pulse countclock frequency is increased to400MHz by the FPGA PLL And this paperdesigned the responding digital circuit to measure the period and phase angle oftwo measured signal.In order to solve the zero jitter problem when two measured signal be innoisy environment, this paper will use capture statistical method to reduce themeasurement error produced by the zero jitter. The Matlab simulation of events capture and statistics method be made, the simulation results show that thescheme can significantly improve the accuracy of small phase angle measurement.The simulation measurement absolute error of phase angle of0.1degree is0.003degree. So the scheme has good promotional value.