Frequency bifurcation in a series-series compensated fractional-order inductive power transfer system

This paper reveals and analyzes the frequency bifurcation phenomena in the fractional-order inductive power transfer (FOIPT) system with series-series compensation topology. Using fractional calculus theory and electric circuit theory, the circuit model of the series-series compensated FOIPT system is first proposed, then taking the case of a single variable fractional order as an example, three frequency analytical solutions of frequency bifurcation equation are solved by using Taylor expansion method. By analyzing the three bifurcation frequencies solved, it can be found that the frequency bifurcation phenomenon can be effectively eliminated by controlling the fractional order, and the boundary of critical distance and critical load is reduced, thereby expanding the working range of the conventional inductive power transfer (IPT) system. Furthermore, the output power and transfer efficiency at the three bifurcation frequencies are analyzed, it can be observed that the output power and transfer efficiency at the high bifurcation frequency and low bifurcation frequency are close and basically keep constant against the variation of transfer distance, and the output power is obviously higher than that at the intrinsic frequency. In addition, the output power at the three bifurcation frequencies can be significantly improved by adjusting the fractional order. Finally, the experimental prototype of FOIPT is built, and the experimental results verify the validity of theoretical analysis.