Multiple Parameter Estimation Based on Bifurcation Phenomena in Inductive Power Transfer

This paper presents a novel estimation method for obtaining primary and secondary self-inductances and the mutual inductance for inductive power transfer (IPT), based only on measuring the input current amplitude. The input current frequency response characterizes the IPT system, if the IPT system is operated in deep bifurcation, which can be achieved by shorting the load. The frequencies of two peaks emerging in deep bifurcation are used to find the coupling coefficient. The frequency of the minimum between the peaks matches the secondary resonance frequency. The relative ratio of the peak values depends on the ratio of primary and secondary resonance frequencies and coupling coefficient. Thus, the resonance frequencies and coupling can be estimated based on measured frequencies and values of local extrema. Assuming known and constant compensation capacities, values of self-inductances and mutual inductance can be estimated from these parameters. The presented method is experimentally validated for an IPT system under the secondary coil displacement.