In recent years, the harmonics and EMI noise sent out from an electric power conversion system are getting a great deal of attenton in electromagnetic enviroment probrems. So, the considerations for mentioned above have been getting important. Therefore, there is need to do a detail frequency analysis such as trasient phenomena at the switching. So, we have proposed the analytic technique using Wavelet-transformer which is possible to chatch a phenomonon from the both sides of the time and the frequency. In this paper, we performed the analysis using Wavelet-transformer against the actual measured date at the switching interval. Then, based on obtained result, we describe the high validity of Wavelet-transformer and the application to the power electronics field.
