Accurate and Fast Load Estimation Under Detuned Operation of IPT Systems

This paper introduces an accurate and easy-to-implement algorithm for estimating the mutual inductance and load for inductive power transfer (IPT) systems. The algorithm employs a modified fundamental harmonic analysis (MFHA) and takes into account models of the battery and output filter. Using this algorithm, mutual inductance, output power, and the instantaneous voltage of the battery are predicted with less than 5% error. The formulations are presented for a series–series IPT system and generalized for non-symmetric conditions, meaning when the primary and secondary sides have different resonant frequencies. The proposed estimation method has been verified by different sensitivity analyses and simulations, using MATLAB and PSIM simulators. To validate the proposed algorithm, a laboratory prototype with operating frequencies of 82 to 85 kHz and maximum output power of 200 W was implemented and the accuracy of the estimations has been verified under different output power and operating frequencies for both symmetrical and non-symmetrical conditions.