Modes of Operation and Analysis of a Separately Excited Motor Fed by a Three-Phase Converter with a Freewheeling Diode

Low-speed performance of a three-phase fully controlled converter-fed dc separately excited motor drive can be improved by connecting a freewheeling diode. This paper describes the modes of operation and a method of analysis taking these modes of operation into account. Normalized curves are presented which allow the selection of a suitable value of filter inductor to keep the ripple within permissible values.