Design and optimisation of magnetic structures for lumped Inductive Power Transfer systems

A solution which enables safe, efficient and convenient overnight recharging of electric vehicles is needed. Inductive Power Transfer (IPT) is capable of meeting these needs however the main limiting factor is the performance of the magnetic structures (termed power pads) which help transfer the power efficiently. These pads are required to transfer 2-5 kW with a large air gap and have good tolerance to misalignment. They also need to be as light-weight, durable and cost effective as possible. An approach using 3D finite-element analysis modelling is used here to optimise the power pads. This technique is viable since measured and simulated results differ by 10% at most. Power pads have been built which allow 2 kW of power to be transferred over a 200 mm air gap with a tolerance of 130 mm in the horizontal direction. The leakage magnetic flux is also investigated via simulation showing that the designed pads comply with human exposure regulations.