Impedance Analysis of Parity-Time Wireless Power Transfer System using Digital Separate-Oscillation

抄録

A wireless power transfer system has been widely developed for various applications. A parity-time symmetry WPT (PT-WPT) technology is currently attracting attention for ensuring the robustness of the coupling coefficient changes. The system uses self-oscillation, and therefore, the system does not determine the oscillation frequency. This paper proposes a PT-WPT system using asymmetric coils and a digital separate-oscillation controller. The impedance analysis concludes that the operation frequency, power, and efficiency are constant with the coupling coefficient changes and the same as in a coupled mode theory. Further, the analysis derives the phase and amplitude of the voltage and current, especially the output current. A perturbation and observer method is installed to achieve zero phase between the input voltage and current changing operating frequency. The asymmetric coil WPT system and the digital separate-oscillation controller are designed, constructed, and tested to verify the principles of operations. The experimental results are in good agreement with the calculated values. The proposed method controls the stability and unity power factor. The converged time of the proposed system is 15 ms. The output power and efficiency are 202.4 W and 90.75% and these values are constant varying the coupling coefficient.