Research on Transmission Performance of Wireless Power Transfer System Under System Mistuning

For wireless power transfer system, the transmission performance is determined by its compensation network part. Normally, specific resonant conditions are needed for network parameters to achieve expected transmission performance. However, parameters detuning caused by aging components, coils misalignment or non-purely resistive impedance is unavoidable. Therefore, in this paper, the coupled mode model of the compensation network part is established to reveal the operation mechanism of reactive power minimization first, then the inverter part is taken as an adjustable negative resistor by following the inherent frequency characteristics of whole network. According to the theoretical analysis results, a primary frequency tracking strategy without wireless communication or any parameter identification guarantees the input zero phase angle realization under parameters detuning. In addition, secondary output can be realized by adopting the traditional phase shift control in the inverter part or adding a DC-DC converter, which is decoupled with proposed frequency tracking strategy. Finally, an experimental prototype is built to verify the feasibility of the proposed system. Experimental results show that input zero phase angle can be maintained when system mistuning happens.