Sequential Mutual-Inductance Identification Method for Wireless Power Transfer Systems of Electric Vehicles

In a multitransmitter static wireless power transfer (WPT) system for electric vehicles (EVs), the transmitter-to-receiver mutual-inductance value is required to assign current to each transmitter. This article proposes a sequential mutual-inductance identification method (SMIM) that identifies the transmitter-receiver mutual-inductance transmitter by transmitter in sequence. The proposed method simplifies the multitransmitter system into a single-transmitter system through the current blocking principle. The identification only requires measuring the magnitude of dc-bus voltage and transmitter rms currents where no receiver-side sensor is needed. The mutual inductance can be obtained through simple calculations with low computation requirements. It is demonstrated that the SMIM robustness against transmitter self-inductance deviation is greatly enhanced by introducing a two-point identification technique. High SMIM accuracy is achieved by optimizing test conditions over the entire viable charging zone of the WPT system. The experimental results demonstrate a maximum 3.11% error in identified mutual inductance, provided coupling coefficient exceeds 0.02.