A novel averaged-model-based control of a SEPIC power factor corrector using the input/output feedback linearization technique

In this paper, a new multiple-loops nonlinear control scheme, based on the input/output feedback linearization method, is proposed for a DC-to-DC Single Ended Primary Inductance Converter (SEPIC). 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. Based on the averaged model of the converter, a Pulse-Width-Modulated (PWM) control algorithm is developed in order to ensure a unity power factor at the AC-source side and a regulated voltage at the DC-load side. In order to verify the performance of the proposed control scheme, numerical simulations are carried out on a switching-functions-based model of the converter, which is implemented using Matiab/Simulink. The proposed model of the converter Is valid in the Continuous Current Mode (CCM) and the Discontinuous Current Mode (DCM). The control system Is tested under both rated and disturbed operating conditions. The system performance is evaluated in terms of source current Total Harmonic Distortion (THD), input power factor, DC voltage regulation and robustness toward a load disturbance.