Space-Vector Based Excitation of a Bipolar Transmitter for Wireless Power Transfer Applications

A space-vector (SV) based excitation method for wireless power transfer systems with a bipolar transmitter is introduced in this article. Unlike traditional bipolar excitation techniques that rely on fixed transmitter current distributions, this SV approach provides an elegant analytical method of redistributing a greater magnitude of current to the transmitter coil, which is closer to a misaligned receiver. This method is shown to require a smaller transmitter current vector magnitude for a required output power compared to all other bipolar coil excitation schemes over a broad range of receiver misalignments, thereby reducing conduction losses within the system. Additionally, the gradual redistribution of transmitter current as a function of receiver misalignment achieved by the SV method causes it to be less influenced by errors in receiver position sensing compared to conventional methods. Experimental results shows that the proposed method in conjunction with single coil operation at extreme misalignments was able to achieve a coil efficiency profile with minimal variation due to misalignment (93.2% at perfect alignment to 92.7% at a misalignment of 20 cm, for 2 kW power transfer into a 200 V battery load.)