Design and simulation of a matrix converter-fed scalar controlled synchronous motor drive

Matrix converter is an ac/ac converter without a dc link. It acts much the same way as a cycloconverter, but with better harmonic profile, large range of output frequency and controllable input displacement factor. A synchronous motor is used in many industrial applications such as cement kilns, mine winders, etc. Although synchronous motors are mostly used for high power applications, the matrix converter can also be used to drive a permanent magnet synchronous motor with suitable modification for medium power applications. The present paper proposes a scalar control scheme for a wound field synchronous motor fed from a matrix converter. The scheme is based on steady state phasor diagram of the synchronous motor, and results in unity motor displacement power factor during operation. A suitable PI controller for closed-loop speed control is designed. Subsequently, a modified V/f scheme which ensures unity power factor (UPF) at high speeds is proposed. The simulation results for the proposed control scheme are verified.