Analysis and design of a three-phase high power factor rectifier based on the SEPIC converter operating in discontinuous conduction mode

The analysis and design of a single-stage three-phase high power factor rectifier, with high-frequency isolation and regulated load voltage are detailed in this paper. The circuit operation is presented, being based on the DC-DC SEPIC converter operating in the discontinuous conduction mode. This operational mode provides to the rectifier a high input power factor feature, with sinusoidal input current, without the use of any current sensors and current control loop. The paper presents the theoretical analysis, design example and experimental results for a 4 kW, 380 V line-to-line input voltage, 400 V output voltage, 0.998 power factor, 40 kHz switching frequency and 4% input current THD laboratory prototype. The rectifier can operate in the step-up or in the step-down modes.