Single-stage three-phase power-factor-correction circuit using three isolated single-phase SEPIC converters operating in CCM

A single-stage three-phase power-factor-correction circuit is developed using three isolated single-phase SEPIC-based power-factor-correction circuits operating in continuous-current mode. This approach is found to be attractive for low to medium power applications and when stringent THD and EMI specifications have to be met, such as power supplies for avionics systems. Use of isolated single-phase circuits also avoids the problems associated with the interaction among three phases. Detailed design criteria for the power and control stages of the single-phase SEPIC power-factor-correction circuit are presented. Issues specific to the three-phase implementation, such as current sharing at the input, are discussed. Simulation and experimental results corresponding to a 500 W three-phase prototype switching at 100 kHz are reported.