Asymmetrical multi-phase voltage methods of autotransformer-based boost rectifier systems with three-phase sinusoidal line currents

Novel multiple boost rectifier systems coupled with an autotransformer having a capacity rating of 20% are presented. The autotransformer in the triple rectifier system synthesizes two three-phase voltage systems with a phase shift angle of 20deg and an amplitude of 1.064 times with respect to the line voltages. These asymmetrical voltage systems make the transformer winding structure simpler. The boost choppers control the DC currents along with the DC output voltage so that the output DC power of each rectifier becomes equal. The quasi-trapezoidal modulation of the DC currents generates sinusoidal resultant input line currents except for switching ripples. The modification of the proposed concept to a quintuple rectifier system and the comparison with a conventional PWM converter are also presented.