Research of three-phase four-leg rectifier

The three-phase four-leg rectifier can be obtained by adding a bridge into the traditional three-phase three-leg rectifier. The cycle by cycle switch average model (CCA) based on three-phase four-leg rectifier is presented in the paper, and the model shows the rectifier can de decoupled to three single phase full bridge rectifiers. The SPWM (Sinusoidal Pulse Width Modulation) and SAPWM (Saddle Pulse Width Modulation) control strategy of rectifier are analyzed respectively. Compared with the SPWM control strategy, the SAPWM control strategy is benefit to lower output DC voltage and reduce the voltage level of switches. The three-phase four-leg rectifier has rigid adaptability to the power system whether it is three-phase balanced or unbalanced. Experimental results based on a 5-kW three-phase four-leg rectifier prototype verified that the rectifier achieves excellent performance.