Monolithic Systems Using Standard Three-Leg Inverter Supplying Independently Two Motors

This paper presents two series-connected motor-drive-system topologies. These configurations have been designed for applications in which it is necessary to control two motors independently by using a standard three-leg inverter. The systems will be referred to as monolithic systems, since the three-leg inverter and both machines have been considered as a part of the same product. The monolithic systems are seen as a potentially viable industrial solution for applications requiring one high-power (three-phase) machine and one low-power (single-phase) machine. Furthermore, this paper presents the following: 1) relevant characteristics of the systems; 2) pulsewidth-modulation techniques; 3) control strategies; 4) voltage and current analyses; 5) unconventional induction-machine design to improve the performance of the monolithic system; and 6) simulated and experimental results.