Wavelet Denoising for Electric Drives

Signal identification is a common problem in electric drive applications. This paper proposes the use of wavelet transforms to extract and identify specific frequency components. Initially, current measurements from a constant voltage/hertz application are filtered using various wavelets and the results compared with conventional filtering methods. A pseudoadaptive denoising method is then proposed based on wavelets which adjust the level of decomposition depending on the rotor speed. Finally, wavelets are used in a high frequency injection speed estimation scheme and shown to be superior to conventional methods in such cases, where the useful information may be at higher frequency and have imprecise frequency components. Experimental and simulated results verify these statements.