| With the more and more attention being paid on the security testing of electrical equipment's fixing, working and testing, Partial Discharge (PD) experiment is widely used in different situation. As an effective way to successfully catch the tiny defect of insulation, PD experiment can not only be able to have a clear picture of equipments'insulation situation, but also know the potential security hazard, so it is regarded as an important preventive experiment. The PD experiment of transformers is a kind of induction withstand voltage test and because of its extensive application, the requirement of power supply's convenient controlling, energy economization and environment protection comes near. Obviously, the using of variable frequency power supply marches the development trend of power supply miniaturization.This paper presents the design and implementation of a variable frequency power supply based on selected harmonic elimination pulse width modulation (SHEPWM) technology and Walsh transform. To make it clear, this paper gives a detailed introduction of SHEPWM theory and identifies its advantages, and the contract of 3 main different algorithms shows the superiority of Walsh transform. To apply this design in real-time control, Walsh transform converters nonlinear transcendental equations to linear algebraic ones and the detailed algorithm implement progress is also shown in this paper.The simulation of experiment platform and SHEPWM power supply is available, and the simulation result shows this kind of power supply won't cause interference to the detection result. After the simulation, a 2KW SHEPWM power supply and the experiment platform were built up. The analyzing result of detection signal proves interference is under acceptable level. After the error analysis, power supply's controlling algorithm is improved, and as a result, the performance of variable frequency power supply enhances and the interference decreases.
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