Three-to-Seven Phase Matrix Converter Supplied Seven-Phase Three-Motor Drive System

Multi-phase (more than three-phase) converters are required mainly for feeding variable speed multi-phase drive systems. Matrix converter basedseven-phase three-motor drive system is presented for the first time in this paper. Stator windings of seven-phase machines when connected in series or parallel while the rotors may be connected to different loads, are called series-connected or parallel-connected three-motor drive. Appropriate phase transposition is introduced while connecting the series/parallel stator winding to obtain decoupled control of the three machines. This paper proposes simple carrier-based Pulse width modulation (PWM) technique for three-phase to seven-phase matrix converter supplying series/parallel-connected seven-phase AC machine drive system. The developed modulation technique is based on the comparison of high frequency carrier signal with the reference duty ratios. The major aim of the PWM is to generate three independent fundamental frequency components that will subsequently control three series/parallel-connected seven-phase motors. The proposed PWM approach is equally applicable to series-conected and paralleconnected three-motor drive system. The viability of the proposed control techniques is proved using analytical and simulation approach.