Frequency characteristic of resonance- based wireless energy transfer

For the purpose of practical application of wireless energy transfer, the frequency characteristic is investigated based on an electromagnetic resonance system. Considering the circuit model of electromagnetic coupling theory, different working status of receiver, including the performance of system harmonic oscillation, damped oscillation and forced oscillation is analyzed from the physical standpoint. With the discussion to the forced oscillation status of the receiver, the relation between frequency of external excitation of alternating magnetic field and the power of the transmission system is derivated. Depending on the type of excitation source of power supply device (voltage source or current source), the mathematical expression with frequency and other circuit parameters which can make the transfer system generate the electromagnetic resonance is put forward and point out the power of the load will be maximum when the receiver circuit resonates. This conclusion is verified by the simulation and the experiment results.