Abstract: In order to optimize the parameters of wireless power transmission system and achieve the maximum efficiency,in this paper, the relationship between efficient and system parameters was soluble by analyzing frequency response of the transmission system equivalent circuit model,and verified the decrease of transmission efficient caused by the frequency bifurcation phenomena at the over coupling condition.The design method of maximum efficient system acquiring the best resonant frequency and coil direction angle based on automatically controlled was presented.The simulation results of Multisim software showed that the transmission efficient could be improved above 43% at the over coupling condition.

Key words: transmission efficiency；automatic control；resonant , frequency；coil direction angle