Design considerations for a moving field inductive power transfer system

Roadway powered electric vehicles with minimum onboard stored energy can offer a solution for the limited cruising range problem of electrical vehicles. This work provides a design study of a moving field inductive power transfer (MFIPT) system based on stationary primary coils linearly arranged along one or several tracks of a roadway and a secondary coil in each vehicle. Due to the unavoidable large spacing between primary and secondary coils, these coils are only loosely coupled. The resulting leakage inductances have to be compensated by capacitors. To minimize power loss only the primary coils under the vehicles are activated. In the MFIPT system the primary coils are operated as a switched resonant converter. When switching from one primary coil to the subsequent primary coil on the track in order to follow the moving vehicle the electric and magnetic energies stored in the coils and capacitors are passed on to the subsequent coils and capacitors in order to avoid loss of the stored energy.