Cross coupling effects of poly-phase bi-directional inductive power transfer systems used for EV charging

Bi-directional inductive power transfer (BD-IPT) systems are preferable for applications such as Electric Vehicles (EVs) and wireless integration of EVs with the utility grid (V2G). In particular, poly-phase BD-IPT systems are used in high power applications and for rapid charging of EVs but their performance is severely compromised by the cross-coupling effects between phases and the misalignment of charging pads or coils. This paper therefore presents a generalized mathematical model to investigate the cross-coupling effects caused by pad-misalignments and corresponding impacts on the power flow of ploy-phase BD-IPT systems used for EV charging. Using the proposed model, the charging behavior of an EV, based on a 3-phase BD-IPT system, is investigated under different operating conditions, analyzing the sensitivity of power flow and direction to cross coupling. Results are presented in comparison to simulations to demonstrate the accuracy of the proposed mathematical model and as well as to show that the changes in power flow and direction can be somewhat compensated for by the individual control of phases.