Z-Source inverters for asymmetrical six-phase drives with reduced switching losses

Recently, multiphase drive systems have been proposed for special applications where high reliability is required. Asymmetrical Six-Phase Induction Machine (ASPIM) is one of the most important particular multiphase machines due to many distinctive features. The two-level six-phase Voltage Source Inverter (VSI) is commonly used to supply the ASPIM. However, it has the main conceptual shortcoming of voltage gain limitations. Z-Source Inverter (ZSI) is developed in this paper to overcome the voltage gains shortcomings of standard VSIs. Carrier-based PWM schemes with simple and maximum boost control methods are utilized here to control the shoot-through duration of the ZSI, which is used to supply ASPIM. In addition, new carrier-based modulator to reduce the inverter switching losses is proposed in this paper. This strategy can be extended to other types of impedance network-based six-phase VSI. The operating principles, theoretical analysis and comparative study of the presented PWM schemes are introduced. The feasibility of the proposed PWM schemes and the performance of the drive system are confirmed by the simulation results which show good agreement with the analysis.