A Reduced Switch High Step Down Gain Bridgeless Coupled Switched Inductor SEPIC HPF AC-DC Converter for LVEVs Charging Applications

A charger topology using a bridgeless coupled switched inductor configuration is demonstrated in this paper for battery charging of low voltage electric vehicles (LVEVs). In an attempt to obtain wide voltage gain (high step-down gain) between high AC input and low DC output (EVs battery packs), a bridgeless SEPIC topology, with reduced switch and a coupled switched inductor structure is designed, which is able to give good grid side as well as battery side performance. Unlike existing bridgeless configurations, the circulating current through anti-parallel diode of the switch during its non-conduction period is completely eliminated in the presented topology. The coupled switched inductor along with the operation of the inductors in discontinuous inductor current mode (DICM), further helps in decreasing the size of the magnetic components and hence the size of the charger as a whole. In contrary to many of the existing SEPIC high power factor (HPF) AC-DC converter based battery chargers, the topology presented in this work has continuous flow of current both at the input side and output side, thus reducing the need of large filters, as the ripple content is considerably low. The operation of the inductors in DICM, helps in implementing inherent power factor correction, and soft switching for the switches and diodes. Lastly, the design, operating modes, and performance of the charging circuitry are verified through simulation and corresponding results are discussed here for performance verification.