Design of Misalignment Tolerant Control for an Inductive Charger with V2G Possibilities

Since the power transfer efficiency in inductive power transfer (IPT) systems is directly related to the coupling of the transformer, coil misalignment can drastically decrease the efficiency. In this paper a misalignment tolerant control scheme is proposed which tracks the maximum power transfer efficiency point under misalignment. It does this by matching the impedance of the load with respect to the transformer based on an online coupling factor estimation, as well as tracking the resonance of the system. The control scheme is implemented on a series-series compensated system and designed such that it can be operated bidirectionally in the future, however this is not in the scope of this paper. The proposed control results in an overall efficiency improvement of 5% and 23% under 0 and 8 cm misalignment, respectively, compared to a constant rectifier output voltage of 48V.