Analytical method for mutual inductance and optimum frequency calculation in a series-series compensated inductive power transfer system

摘要

The switching frequency of inductive power transfer (IPT) is sensitive to the air gap between the primary and secondary coils. The mutual inductance might change significantly for different air gaps, resulting in a shift for the switching frequency. The mutual inductance is usually acquired through experimental measurement, finite element analysis, or frequency tracking control. In this paper, Neumann's formula is simplified to compute the mutual inductance of two coils. A frequency-gap model is presented to offer a simple way to calculate the unity-gain frequency for a symmetrical series-series (SS) IPT. Finite element simulation and experiment were conducted to verify the model. The experimental results show that the unity-gain frequency can be output within an average computational time of 9.8ms, and the gain fluctuates from 0.95 to 1.05 when the air gap changes from 7.5cm to 25cm.