Single‐phase multi‐level AC–DC power conversion interface

This study proposes a single-phase multi-level AC–DC power conversion interface that is composed of a power factor correction stage and a buck power conversion stage. The power factor correction stage is configured using two power factor correctors (PFCs) connected in cascade. Only the power electronic switch in one of the PFCs is switched in high-frequency pulse-width modulation to generate a five-level voltage at the input AC terminals of the power factor correction stage. The input current of the power factor correction stage is controlled to be sinusoidal and in phase with the utility voltage. Accordingly, the voltage stress and switching loss are improved because the change in voltage in each switching operation is reduced. The filter inductance and the electromagnetic interference are also reduced. The buck power conversion stage integrates a buck power converter and a forward power converter that combines the output voltages of the two PFCs in a stable DC voltage that supplies the load. The controllers for the buck power converter and the forward power converter are integrated to simplify the controller for the buck power conversion stage. A hardware prototype is developed to verify the performance of the proposed single-phase AC–DC power conversion interface.