A modular medium voltage adjustable speed drive system

In this paper a new modular motor-modular inverter (MM-MI) concept for medium voltage adjustable speed drive (MV-ASD) systems is introduced. It is shown that standard medium voltage motor winding connections can be reconnected into several three-phase groups, each powered by a separate three-phase PWM inverter, resulting in a high performance MV-ASD system. The proposed approach is fault tolerant and can continue to operate at reduced power levels, under inverter and/or motor faults. An example 250 HP, 4 pole, 60 Hz, 2300 V/4160 V motor winding connection diagram along with the associated inverter configurations is analyzed. Analysis results are presented on the aspects of faults and motor operation under partial winding excitation