Improving Misalignment Tolerance by Variation of Self-Inductance for EV-WPT with Small Air Gap

One of the most serious issues that needs to be addressed in electric vehicle wireless power transfer (EV-WPT) is lateral misalignment (LTM). This paper proposes a novel receiver (Rx) topology that improves LTM tolerance by varying the self-inductance of the receiver coil caused by the coupling change due to LTM. In the topology, all Rx coils are connected to the same AC bus line, which passes the output filter via the its compensation networks. This increases the current of the coupled coils and decreases the current of the uncoupled coils without control, which not only improves LTM tolerance but also reduces the system losses. A mathematical model was built to analyze the impedance and compensation network structure of the system, and the coil was designed using finite element simulation on the basis of this mathematical model. The simulated circuit model outputs a power bit of 1kW, and the results show that the maximum offset at rated power is 45mm, which is 52.9% of the size of the pickup end.