Input inductor current for unity power factor operation

Abstract

A fixed frequency, fixed duty cycle boost converter with continuous input inductor current for unity power factor operation is introduced in this paper. The proposed boost converter has the same "voltage follower" (unity power factor) property as the conventional boost converter operating with discontinuous inductor current mode, but with continuous input inductor current. Thus, the proposed topology has much lower input harmonics and much better EMI performance than the conventional boost converter. By using the coupled inductor technique, the input inductor current ripple can be even dumped into another winding. Ripple free input inductor current is thus achieved. Therefore, the high frequency harmonic distortion can be avoided. The low frequency input current waveform distortion is analyzed. Simulation results are presented and compared with the conventional boost converter operating in discontinuous conduction mode. Compared to the well known Cuk and Sepic converters, the proposed boost topology has the advantages of lower switch voltage stress, lower switch current stress and lower voltage stress on capacitor C/sub s/. The theoretical prediction is verified experimentally.