Three‐phase ripple free DCM boost converter with low THD

Abstract

High total harmonic distortion (THD) and ripple of input current are the two main disadvantages of a single switch discontinuous current mode boost power factor correction (PFC) converter. In this study, THD and input current ripple of conventional DCM boost converter are improved. Reduction of input current THD is achieved by reducing the discharge time of input inductors using magnetic switch concept. Input inductors currents are discharged with a voltage equal to twice of output voltage instead of the output voltage. Also, high input current ripple in discontinuous conduction mode (DCM) operation is solved by using an additional input inductor-capacitor (LC) filter in the conventional converter. This will result in extra weight and volume of the converter. To eliminate the required additional inductors for implementation of the mentioned input LC filter, a ripple cancellation cell using coupled inductors is used and by adjusting mutual inductance in a proper manner, very low input current ripple is achieved. Results from a 400 W prototype converter are presented. Input current THD is below 8% for a wide range of input voltage. Furthermore, the efficiency of the proposed converter is compared with conventional DCM boost PFC converter under the same input current THD. Although the proposed converter applies two switches, the total switching and conduction losses are reduced considerably.