PWM techniques for an open-end winding fivephase drive with a single DC source supply

Open-end winding drive topologies have been extensively investigated in the last two decades, predominantly in conjunction with three-phase machines. The research conducted so far includes various aspects pertinent to the topology, such as different inverter topologies connected to each side of the stator winding, different ratios of dc-bus voltages, operation with differing switching frequencies of the two inverters, comparison of performance with equivalent single-sided supply topologies, etc. In vast majority of cases supply of inverters at the two sides of the winding is provided from isolated dc sources. This paper investigates for the first time a five-phase open-end winding topology, which is obtained by connecting a two-level five-phase inverter at each side of the stator winding and supplying both inverters from a common dc source. In such configuration it is essential to eliminate the common-mode voltage (CMV) that is inevitably created by usual PWM techniques. Based on established criteria, the switching states that create zero CMV are indentified and plotted, giving a space vector pattern that is characterized with large redundancy of switching states. Suitable space vectors are selected to realize the required voltage reference at the machine terminals with zero CMV. The large number of redundant states enables some freedom in choice of switching states to impress these space vectors. Out of numerous possibilities, two particular switching sequences are chosen for further investigation. Both are simulated and also implemented in an experimental rig, and the results are presented.