A Simple PWM scheme for a four-level dual-inverter fed open-end winding five-phase motor drive

摘要

A simple PWM scheme for a four-level dual-inverter fed open-end winding (OeW) five-phase motor drive is discussed in this paper. The proposed PWM scheme adapts the decomposition PWM scheme of dual-inverter fed five-phase drive with equal DC-link voltage. The modulation strategy operates at three different modes according to modulation index (M). When modulation index, M > 0.35, inverter 1 operates at fundamental frequency while inverter 2 operates in PWM mode. When M ≤ 0.35 only inverter 2 operates in PWM mode while inverter 1 is locked at zero switching state (11111 or 00000). The proposed PWM schemes is verified using Matlab/simulink. The results show that the quality of the output voltages improves in comparison with the voltage output of three-level inverter for all modulation indices. The inverter performance is also improved compared to the previous four-level PWM scheme (URS PWM) especialy for M > 0.35 while for M ≤ 0.35, the performance is exactly the same as the four-level URS PWM scheme. One drawback of the proposed PWM scheme is that an additional circuit is required to reduce the DC-link voltage of inverter 1 at the particular speed ranges of 0.35 < M ≤ 0.7.