Efficiency and electromagnetic interference analysis of wireless power transfer for high voltage gate driver application

Wireless power transfer (WPT) holds great potential to achieve strong galvanic isolation, compact size, and low parasitic capacitance in the power supply of gate driver. In this paper, a wireless power supply is designed and analyzed for high voltage gate driver application. The performance of the power supply in terms of power delivery, parasitic capacitance, and driver output is explored in the functional test. Meanwhile, electromagnetic interference (EMI) is investigated in both frequency and space distribution based on measurement and simulation. The experimental results demonstrate that the prototype successfully delivers power for gate driver board with an 80 mm air gap while the maximum transfer efficiency is kept around 90%. The parasitic capacitance brought by the air gap is only 1.72 pF, which significantly increases common mode impedance. Radiated EMI affects the frequency span around the resonant frequency, and its distribution regularity in space is clearly displayed by field curves in horizontal axis and vertical axis.