Enhanced decoupling PWM methods for five-phase open-end winding drives

Open-end winding topology provides a number of supply and control possibilities. The dc-bus voltages can be connected or isolated, of equal or unequal value, the power can be supplied in a balanced or unbalanced manner, and even the operating regime of the two inverters can differ. The open-end topology is also an alternative to multilevel single-sided supply. The focus of the investigation until very recently in this area has been placed on three-phase machines. An increase of the phase number leads to an exponential rise in the available switching states and therefore to a considerable increase in the modulation algorithm complexity. This paper deals with an open-end winding five-phase drive system and investigates the possibility of using one inverter to supply the bulk of the power, while the other inverter works in pulse width modulation (PWM) mode, eliminating unwanted harmonics and contributing to the fundamental. Several possibilities are described. Finally, the open-end supply system is implemented to supply a five-phase induction machine and experimental results are provided.