Based on the operating principle of the three-phase four-Leg voltage source PWM inverter, voltage feedback dual closed-loop control strategy is researched. This paper achieves a triangle wave injection control strategy for three-phase four-leg inverter by using three phase half-wave rectifier. Voltage feedback dual closed-loop control method for three former legs. The former three phase modulation signals processed by three-phase half-wave rectifier to generate the control signal for the fourth leg. The structure of the system is simple and easy to achieve. By using pure analog devices can avoid restriction of DSP processing ability and increase the switch frequency of the system effectively. It has a fast dynamic response and low harmonic content of output voltage waveform. In addition, triangle wave injection can improve the utilization rate of DC voltage; enhance the capacity of the system with unbalanced load. The simulation results further verify the accuracy and the feasibility of the control strategy.
