English title

In this paper CCM/CVM operation and modeling of the improved Sheppard-Taylor based power factor correction (PFC) rectifier is presented and a predictive control strategy is introduced for this rectifier. Compared with conventional boost or buck–boost PFC’s, this topology allows a better current tracking at the AC side, with a relatively reduced voltage at the DC side. Consequently, the high frequency AC filters required by the buck PFCs are avoided, and the voltage stresses on the boost switches are significantly reduced. Furthermore In predictive control strategy the duty cycle required to achieve unity power factor in a half line period can be calculated in advance. The main advantage of this digital control PFC method is achieving on high dynamics directly depending on the processing speed of micro processor. Simulation results show that an improved Sheppard-Taylor converter controlled by this strategy can achieve sinusoidal current waveform with good dynamic response. Input voltage feed-forward compensation makes the output voltage insensitive to the input voltage variation and guarantees sinusoidal input current even if the input voltage is distorted.