Bridgeless Buck-Boost PFC Rectifier using Switched Capacitor Configuration

Bridgeless power factor correction (PFC) rectifiers based on boost topology are used widely since it provides high input power factor (p.f.) and has high efficiency. However, there is requirement of lower output DC voltage than the input AC voltage in certain applications. This is obtained by using a DC/DC converter after the PFC rectifier. Due to this power is processed twice, this raises the number of components and lowers efficiency. Therefore, a bridgeless buck-boost PFC rectifier using switched-capacitor configuration is presented in this paper. The gain of the presented converter is half of the conventional boost PFC rectifier. The operating principle of the converter is discussed, and steady-state analysis is done to determine the voltage gain and design equations for L-C components. The state-space analysis is performed to obtain the small-signal model to derive the relevant transfer functions required for controller design. An inner current loop and an outer voltage loop is designed to control the input current and load voltage of the converter respectively. The simulation for 1 kW converter is performed and results are presented along with the controller design and converter modeling. This converter can be utilized in applications like battery charging, server power supply, speed control of low-power drives, etc.