Field-Oriented Control of a Three-Phase Wireless Power Transfer System Transmitter

This paper presents a method of designing a three-phase wireless power transfer (WPT) transmitter analogous to the stator windings of a three-phase, two-pole electrical machine. A method of deriving the required transmitter coil currents based on lateral receiver misalignment is presented, wherein the transmitter currents are decomposed into direct and quadrature axis components. This decomposition simplifies the derivation of the transmitter currents required to minimize copper losses for a wide range of receiver misalignment by reorienting the transmitter magnetic field toward the receiver. Based on the required transmitter current, the required series compensation capacitors and transmitter voltage sources needed for unity power factor operation are calculated. Simulation results are shown for a 3.3-kW system utilizing a receiver-side voltage-doubling rectifier and 300-V battery. Finally, experimental results on a 1-kW prototype are shown, where a coil efficiency of 95.17% at perfect receiver alignment and 90.52% at 20-cm lateral misalignment was measured.