Resonance Converter for Inductive Charging of Electric Vehicles; Modeling and Design

Nowadays, electric vehicles have gained more attention due to environmental issues. In this regard, charging the batteries of electric vehicles is one of the main challenges. Because of recent advancements in power electronics, inductive power transfer (IPT) chargers are rapidly developing due to some advantages compared to conventional plug-in chargers, such as no cable required and higher reliability. This new solution allows the building of low-cost and intelligent energy transfer systems. IPT chargers have a transmitter coil on the ground and a receiver coil on the vehicle. Due to the air gap, the magnetic coupling between the primary and secondary is weak. In this paper, the structure of a typical bidirectional charger based on a resonant converter is developed by a weak magnetic coupling. Finally, the obtained model and the performed computational analyzes are confirmed by simulation on a 6.6 kW battery charging converter in the Simulink Matlab. It is shown that by changing the electromagnetic coupling in the range of 0.1 to 0.9, if the resonance frequency is kept constant with a variable resonance capacitor, the battery charging voltage remains almost constant in the range of 440 V to 450 V.