Accurate Fundamental Harmonic Modeling of Inductive Power Transfer Battery Chargers

This article presents a precise fundamental harmonic approximation (FHA) for modeling series-series compensated inductive power transfer (IPT) systems with constant voltage load, e.g., with battery load. In comparison with previous works, not only an FHA model is devised but also the model is modified to reduce the errors of conventional FHA methods. This improvement is done by considering the intrinsic effect of higher order harmonics, which generates a displacement between fundamental current and voltage at the secondary side. Moreover, the precise model can easily derive the frequency responses and Bode plots for IPT systems with constant voltage load, which is the essential step for appropriate modeling and design. In comparison with iterative solutions and time-domain analysis (TDA) tools, the proposed modeling leads to a time-efficient and straightforward formulation with excellent accuracy. The results of the modified FHA, derived by MATLAB codes, are compared with TDA simulations by using PSIM. Finally, the simulation results are verified by a laboratory prototype.