Efficiency Study of Vertical Distance Variations in Wireless Power Transfer for E-Mobility

A Wireless Power Transfer (WPT) system is a safe, convenient and smart charging solution for Electric Vehicle (EV) users. However, a drawback of WPT systems is reduced efficiency in comparison to conventional wired charging due to lower coupling. By increasing the volume of EVs in the market, improving the system efficiency even a few percent, beside of being environmentally suitable, will benefit both consumers and distributors. According to the previous studies, efficiency improvement by decreasing the vertical distance (VD) between transmitter (TX) and receiver (RX) coils, has been one of the aims of the companies and universities. However, in low VD, system performance becomes highly sensitive, due to the magnetic coupling strength. The focus of this paper is to analyze the effects of decreasing the vertical distances to WPT resonance tank efficiency’s. Finally, some of the most significant parameters that affect the system efficiency at low VD such as quality factor and third harmonic interference are analyzed and a mitigating approach is proposed.