Continuous and Discontinuous PWM Methods for Symmetrical Six-Phase Induction Motor with Single Isolated Neutral

Among different types of six-phase machines, extensive works have been done on pulse-width modulation (PWM) methods for asymmetrical six-phase machine and symmetrical six-phase machine with 2-isolated neutral connection. However, very limited work has been done on PWM technique for symmetrical six-phase machine with single isolated neutral, i.e. S6-1N though it has higher degree of freedom in post-fault operation. For S6-1N, the presence of zero-sequence plane complicates design of PWM methods. In this paper, the implementations of different PWM schemes for S6-1N machine are discussed. It is shown that zero-sequence injection method can be easily extended for S6-1N machine to yield discontinuous PWM. Using simulation and experiment, the implementation and comparison of continuous and discontinuous PWM methods for S6-1N are demonstrated.