Efficiency analysis of a 7.7 kW inductive wireless power transfer system with parallel displacement

This paper provides an efficiency model of a 7.7 kW inductive wireless charging system based on the variations in transmitting and receiving coil alignment. The design and selection of electrical and geometrical parameters for the proposed model have been outlined. The 490 mm diameter magnetic couplers were simulated at an air gap of 165 mm. The system achieved 97% coupler-coupler efficiency under ideal conditions and zero misalignment. The performance of proposed couplers were investigated for 45 mm, 90 mm, 180 mm and 250 mm horizontal displacement in 3D finite element analysis. This model operates at a switching frequency of 85 kHz and employs a single capacitor series-parallel resonant compensation to minimize the VA rating of the supply and to maximize the power transfer capability. The prototype follows the SAE J2954 specification for a level 2 wireless power transfer system.