A hybrid bi-directional IPT system with improved spatial tolerance

Bi-directional inductive power transfer (BD-IPT) systems are suitable for applications such as V2G where a bi-directional wireless interface between the electric vehicle (EV) and the utility grid has a number of advantages over a wired link. However, physical misalignment between the magnetic couplers of BD-IPT systems used in EVs are unavoidable and introduces variations in self-inductance, leakage inductance and mutual inductance. These variations invariably detune the compensation circuits, thus significantly increasing losses and affecting the power throughput. This paper proposes a hybrid BD-IPT system, which combines a parallel tuned inductor-capacitor-inductor (LCL) network and a series tuned capacitor-inductor (CL) compensation network to provide a constant power transfer over a wide range of spatial displacements. A mathematical is developed to investigate the behavior and the sensitivity to variation in parameters of the proposed hybrid BD-IPT system. The validity of the mathematical model has been verified using simulated results of a 3.3 kW hybrid BD-IPT system. Both theoretical and simulated results are presented to show that a constant power throughput and an improved efficiency can be achieved over a wide range of horizontal and vertical displacements.