Practical Design of a SEPIC Power Factor Corrector with DC-Voltage Regulation

In this paper, practical considerations concerning the design and implementation of a single ended primary inductance converter (SEPIC) pre-regulator are addressed. Compared to conventional buck or boost converters, this topology allows a low current ripple at the input for a relatively low level of the DC-bus voltage. Consequently, the high frequency filter needed at the AC- side of a buck converter is avoided, and the high voltage stresses applied on the switches are significantly reduced with respect to the boost converter. The converter is integrated as a power factor correction circuit at the DC-end of a single-phase diode bridge. A pulse-width-modulated (PWM) control scheme is developed and applied to 1 kW laboratory prototype of the converter in order to ensure a unity power factor at the AC-source side and a regulated voltage at the DC-load side. The experimental setup is tested under both rated and disturbed operating conditions. The system performance is evaluated in terms of source current total harmonic distortion (THD), voltage regulation, robustness and dynamic time response to a set point offset.