Small-Signal Averaged Model and Carrier-Based Linear Control of a Sheppard-Taylor PFC

In this paper, the small-signal averaged model of a Sheppard-Taylor DC-DC converter, used in single-phase Power Factor Correction (PFC) applications, is derived. Compared to conventional buck, boost or buck-boost PFCs, this topology allows a better current tracking at the AC side, with a relatively reduced voltage at the DC side. Based on this 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 at the rectifier DC-side. 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.