An Improved One-Dimensional Space Vector Modulation for Three-Phase Five-Level Cascaded H-Bridge Inverters

This paper proposes an improved one-dimensional space vector modulation (ODSVM) strategy for a three-phase five-level cascaded H-bridge (CHB) inverter. In the improved ODSVM, the voltage vectors with a common-mode voltage (CMV) of ±2V
dc
/3 are replaced by their redundant vectors, and high-frequency switching events are implemented in a rotating manner. As a result, CMV attenuation and optimal line-to-line voltage harmonic spectrum are achieved for the five-level CHB inverter, surpassing the traditional phase-shifted pulse width modulation (PS-PWM) method and the traditional ODSVM scheme. Additionally, power balance among power semiconductor devices and power loss reduction are achieved, leading to efficiency improvement. Furthermore, the improved ODSVM eliminates the need for dead-time. Finally, the effectiveness of the improved ODSVM is validated through simulation and experimental results. Compared to the traditional PS-PWM method and the traditional ODSVM strategy, the improved ODSVM scheme restricts CMV to the range of V
dc
/3 without sacrificing the harmonic spectrum of the line-to-line voltage. Moreover, the improved modulation method reduces power loss by approximately 30% and the line-to-line voltage total harmonic distortion (THD) by approximately 33%. Notably, the THD of the load current using the improved ODSVM is minimally affected by dead-time presence.