Implementation of a digital filter for speed noise reduction in drives with electromagnetic resolver

Motor rotation speed is often measured in industrial drives employing an electromagnetic resolver. The sine and cosine signals provided by resolver are, subsequently, processed either by an appropriate circuit (resolver to digital converter) or by the microprocessor-based board controlling the drive. However, the obtained speed signal is rather noisy and a suitable filter must be used to reduce the noise. The paper describes the implementation of a suitable phase locked loop based filter on an industrial drive and analyses the obtained performances compared with those achieved using the previous filter