A Three-Phase Hybrid Multilevel Inverter With Enhanced Pulse-Width Modulation Strategy
Mohamad Fathi Mohamad Elias, Nasrudin Abd Rahim, Nur Farhana Rosli
Abstract
This article presents a three-phase hybrid multilevel inverter (MLI) with enhanced pulsewidth modulation (PWM) strategy. The proposed hybrid MLI is developed based on the series connection of half-bridge and full-bridge for its level generation together with the T-type inverter for its polarity generation. The level and polarity generation circuits operate at high and fundamental frequencies respectively. An enhanced PWM strategy has been proposed to reduce the computational complexity and solve the high-frequency switching transitions issue in the existing hybrid MLI modulation method. The proposed MLI can produce 11 levels of line output voltage with reduced dc sources requirement. The detailed analyses which have been performed include the circuit configuration, operating principles and modeling, PWM signals generation, output voltage characteristics, dynamic response, harmonics content, power loss analysis and voltage stress of power switches. The results obtained from simulation and experiments verified the operating principle and functionality of the proposed hybrid MLI.