Robust Wireless EV Charging: Misalignment Sensing and Auto Aligning System Using Magnetic Sensors and Maximum Power Point Tracking

The optimal power transfer efficiency (PTE) in wireless power transfer systems for electrical vehicle charging primarily depends on the charging coupler’s physical alignment. However, misalignment is inevitable, especially lateral misalignment is common with wireless EV charging. This article introduces a simple strategy to address lateral misalignments using three giant magneto resistance (GMR) sensors. The primary coil’s magnetic field induces a current in the secondary coil due to mutual induction between them, which modulates the primary coil’s magnetic field distribution, GMR sensors placed on the transmitter pad continuously sense these changes and accomplish the maximum power point tracking. In addition, an algorithm determines the direction and magnitude of the transmitter coil’s displacement using an automatic coil alignment system (ACAS) made with mechanical setup, gears, and stepper motors (SMs). The GMR sensors produce identical output only when the coils are perfectly aligned. A prototype was built and tested, demonstrating that the driving system can align the transmitter coil accurately based on the misalignment factors provided by the algorithm and GMR sensor outputs. This new system maintains a constant efficiency of 91.3% even with 45% misalignment without modifications to the vehicle’s charging system.