A Single-Stage Charger for LEV Based on Quadratic Buck-Boost AC-DC Converter Topology

A single-stage AC-DC converter, which uses a quadratic buck-boost voltage gain, for LEVs’ (Light Electric Vehicles) battery charging is presented in this work. Unlike conventional BCs (Battery Chargers), which employ transformer (low or high frequency) based approaches to charge low voltages LEVs’ batteries, the presented charger utilizes transformerless single-stage power architecture. In order to realize desired charging of LEVs and to maintain proper transformerless voltage gain, the presented quadratic buck-boost AC-DC converter ensures high step-down gain characteristics between AC mains and low voltage battery packs. Besides realizing desired battery charging profile, the presented single-stage BC ensures high PQ (Power Quality) indices (low input current distortions and unity power factor operation) at the supply side. Notably, the presented quadratic buck-boost AC-DC converter exhibits an intrinsic power factor correction (PFC) feature at the AC input mains under discontinuous inductor current mode (DICM) operation, thereby, incurring minimum complexities during the control implementation, which further reduces the cost of the charger. The DICM operation facilitates negligible switch turn-on and diode reverse recovery losses, and therefore, ensures an improved conversion efficiency of the BC. Even if, the presented AC-DC converter employs two switching devices, the simultaneous switching of both switches shrinks the cost and complexity of driving circuitry even further. Finally, a comprehensive operational analysis, component selection criteria, and modelling of the presented quadratic buck-boost AC-DC converter-based LEVs BC are carried out and its performance is validated through a test bench set-up in a laboratory environment. Relevant results are presented to validate the efficacy of the presented quadratic buck-boost AC-DC converter for LEVs charging applications.