Over current and over voltage protection of permanent magnet brushless dc motor using wavelet analysis

Valluru Hemanth Kumar
2014 IOSR Journal of Electrical and Electronics Engineering  
The objective of this paper is to develop Over Current and Over Voltage Protection of Permanent Magnet Brushless DC Motor (PMBLDCM) using Wavelet Analysis. The Motor's operating point is continuously changing with time and the motor is never operating at a constant speed throughout its operation. A Motor operating in a non-stationary environment has a non-stationary voltage and current signals. Fourier Transform (FT) cannot be used for analysis of non-stationary signals, because FT tells about
more » ... hich frequency components exist in the signal, but gives no time information about these frequency components. Short-Time Fourier Transform (STFT) was developed to solve this problem. STFT used a window function to view a part of non stationary signal as stationary and then perform analysis. However, STFT can have either good time resolution or good frequency resolution, but not both. Wavelet Transform was developed to overcome this resolution problem. Wavelet Analysis uses contracted and expanded versions of a single prototype function called a wavelet. Fine time resolution can be achieved using contracted version of the wavelet and fine frequency resolution can be achieved using expanded version. Daubechies4 wavelet is chosen for this application.
doi:10.9790/1676-09537986 fatcat:v2svlqmfhvhe5eq5auhgbamtey