A Soft-Switching Bridgeless Buck-Boost Power Factor Correction Converter With Simple Auxiliary Circuit and Low Input Current THD

In this article, a new bridgeless (BL) buck-boost power factor correction (PFC) converter using pulsewidth modulation (PWM) control is presented. The introduced structure operates in a discontinuous conduction mode (DCM) to achieve the sinusoidal form of the input current inherently. The proposed converter utilizes a simple zero-voltage-transition (ZVT) circuit in which the auxiliary switch is turned on and off under zero current switching (ZCS) condition, and the main switches turn on and off under zero-voltage switching (ZVS). Moreover, all diodes are turned off under ZCS conditions, and the reverse recovery problem is solved. By reducing the number of semiconductor elements in the current flow path, conduction loss is minimized. Also, the proposed structure utilizes only one magnetic element. The above-mentioned advantages along with a low total harmonic distortion (THD) and high efficiency are the main benefits of the proposed structure compared to previous topologies. In addition, unlike the BL-buck converter, the input current dead angle is omitted without adding any extra components. Finally, a 500 W–100 kHz prototype at 90-265-Vrms input and 96-V output is implemented to verify the theoretical analysis and it illustrates the efficiency of 97.35% and the input current THD is about 2.7% at 220-Vrms input voltage.