THREE-PHASE HIGH POWER FACTOR SINGLE-STAGE AC/DC DCM SEPIC CONVERTER WITH BIDIRECTIONAL SWITCHES

This paper proposes a three-phase high power factor AC/DC converter based on SEPIC converter with bidirectional switches. The converter operates in DCM as a voltage follower where the input currents waveforms follow the voltages waveforms without current control loops. This single-stage converter has high reliability, since it employs four active switches and six high frequency diodes for AC/DC conversion with high power factor and high frequency isolation. Regarding the control system, it is composed by a single DC output voltage control loop (such as an output voltage control of a DC-DC converter). The four active switches are command with the same gate signal. Therefore, the PWM modulator is realized with a sawtooth waveform, performing a trailing edge modulation. Simulation results and the assembly of the prototype from a converter with 127 V input voltage, 200 V output voltage, 50 kHz switching frequency and 3000 W output power are also presented.