Characteristics of Impulsive Force on Coupler of Wireless Power Transfer

The coupler of wireless power transfer (WPT) system will be affected by electromagnetic force, generating vibration and deformation. It will seriously affect the security and reliability of WPT system. When there are short circuit or load fluctuating, the impulsive force caused by pulse current will increase the effects. This paper analyzes the characteristics of impulsive force on the coupling coils and ferrite, giving the impulsive force expression by Lorentz force density theory. A 2D finite element model for simulation and experimental prototype are built to validate the theoretical analysis. The results show that the pulse current will change the amplitude and harmonic components of electromagnetic force, but the fundamental frequency of the impulsive force keeps constant. The maximum voltage at measuring points is increased about 33% and 25% in transmitter and receiver, respectively.