A Detuned LCC-LCC Compensation Topology with Coupling Variation Resisting for EV Wireless Charger

The characteristics of the inductive power transfer system are sensitive to the parameters such as switching frequency, coupling coefficient, and component values of the resonant tank. The parameter sensitivity of dual-sided LCC compensated topology is investigated according to the fundamental harmonic approximation method. It is found that the variations of the parallel compensated capacitors have the greatest impact on the output power. Aiming at alleviating the power drops caused by the coupling variation, a detuned method realized by varying the parallel compensated capacitance for the LCC-LCC topology is proposed. Analytical expressions have been derived in aiding the design of modified value of capacitance ensuring primary zero voltage switching operation. Thus, the detuned parameter combinations, which delivers rated power even with the worst coupling, are obtained. The Steady waveforms simulated in LTspice validates the feasibility of the proposed method. Finally, a 6.6kw prototype has been built to verify the validity of the proposed topology, which can achieve 6.1kw in the worst coupling condition.