Research And Measurement On Power Factor Of Variable Frequency Power Supply

The modern power electronics technology has entered a stage of rapid development, at the same time, the electrical equipment for power requirements are expecting higher and higher, and the frequency conversion power is outstanding because of its high effic iency and low loss, which has been widely used in all walks. Ho wever, as a power electronic device, the output electrical signal waveforms of frequency conversion power will inevitably produce distortion that will be a certain security risk for the electrical equipment. Therefore, it should not be ignored to detect the performance of frequency conversion power, what is more, as an important indicator of performance parameters, the power factor has essential significant for the measurement and research.This paper summarizes the study of application in frequency conversion power at home and abroad, and it makes the output signal frequency power regarded as a non-sinusoidal signal, therefore, overall design scheme has been proposed for the characteristics of output signal. In order to achieve more complex control and signal processing algorithms, it uses DSP and CPLD hardware core.Firstly, this paper is analyzing the processing method of non-sinusoidal signals in harmonic analys is, and focusing on compare the differences between the Fourier transform and wavelet transform, besides, it determined a more appropriate harmonic wavelet transform wave treatment due to the characteristics of output frequency for a wide range and fast speed, meanwhile, it analyzed the wavelet transform in detail and proposed power factor measurement algorithms based on wavelet transform. In order to filter out interference higher harmonics and accurate extraction of the fundamental parameters, a FIR digital filter is designed based on Hanning window and the accuracy of the algorithm is verified by Matlab simulation.On the basis of theoretical analysis and practical conditions, the paper uses a Butterworth filter the signal preliminary processing and 16-bit AD7606 digital to analog conversion, and then puts data to the dual-port RAM cache, and finally completes data calculation and processing by a high-speed digital processor TMS320F28335 DSP, the entire system of sequential logic control and sampling c lock provided by the CPLD. After each module system hardware and software design all are completed, a small motor running system is built for the actual operation based on the existing laboratory equipment, moreover, an comparative analysis with Henghe WT230 has been done, in addition, the experiment result preliminarily verified the feasibility and accuracy of measurement system, finally, an analysis of error sources and improved strategies has been done.