Space vector PWM algorithm for a three-level asymmetrical six-phase motor drive

A space-vector pulse-width modulation (SVPWM) algorithm for a three-level asymmetrical six-phase drive based on vector-space decomposition approach is presented in this study. A modification in zero-plane of the transformation matrix is proposed in order to meet the requirement that the realisation of sinusoidal output phase voltages can be obtained through the chosen output leg voltage space vectors. Furthermore, a method of choosing the switching sequences based on all possible one-level transitions of the leg voltages, i.e. a permutation method, is introduced. The algorithm is then validated experimentally and obtained results show that the developed method successfully achieves the desired fundamental phase voltage, though low-order harmonics are present due to uncompensated inverter dead time. Finally, the performance of the proposed SVPWM algorithm is compared with several carrier-based PWM algorithms including in-phase disposition with 'double min-max injection'. This is a little-known type of injection, which is verified to obtain identical performance as the presented multilevel algorithm.