Small-signal averaged model and carrier-based linear control of a SEPIC-type Power Factor Correction circuit

In this paper, the small-signal averaged model of a DC-to-DC single ended primary inductance converter (SEPIC), used in single-phase power factor correction (PFC) applications, is derived. 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. Based on the proposed model, a carrier-based Pulse-Width-Modulation (PWM) linear control system is developed in order to ensure a unity power factor at the rectifier AC-side and a regulated voltage across the DC load. Both current and voltage regulators are PI-type. The performance of the proposed control scheme is tested through simulations. The system performance is evaluated in terms of source current Total Harmonic Distortion (THD), input power factor and DC-voltage regulation.