Parallel Converter Cell-Based Step-Down Bridgeless PFC Converters With Wide Output for BLDC Motor

Brushless DC (BLDC) motors are typically driven by a voltage source inverter (VSI), which can be fed by an AC-DC step-down power factor correction (PFC) converter for a high power factor (PF). However, the prior-art bridgeless buck PFC converter has poor PF due to the input current dead zones. Thus, this paper proposes a novel step-down bridgeless PFC topology by arranging the buck and buck-boost converter cells in parallel. Due to the parallel configuration, the input current dead zones can be eliminated by the buck-boost operation, resulting in high PF over a wide output voltage range. The operation modes of the proposed topology are introduced, followed by the analysis of the input current and power processing. Integrated magnetic (IM) designs of the inductors, efficiency analysis, and the developed motor drive system control method are presented. Finally, the proposed and the bridgeless buck PFC converters are built and compared, along with a BLDC motor drive system, to verify the feasibility and features of the proposed converter.