Efficiency Optimization for Wireless Dynamic Charging System With Overlapped DD Coil Arrays

Wireless dynamic charging is one of the most promising power supply methods for electric vehicles (EVs), which can reduce battery volume and extend EVs' range. Stable output power and high system efficiency are two of the most important features for practical applications of wireless dynamic charging. For the low-speed application scenarios of dynamic charging, an efficiency optimization method is proposed to improve the system efficiency while regulating the output voltage. Two overlapped DD coils are employed to generate an enhanced magnetic field without dead points. An optimized current control method is proposed to adjust the direction and the ratio of the two transmitter currents as the receiver moves along the track, dynamically. By applying this method, the efficiency of dynamic charging system can be optimized while the output power can be regulated to the desired value at the same time. A 600 W prototype is established to validate the performance of the proposed method. The experimental results show that the system efficiency for dynamic charging reaches 88.3%-90.4% with the proposed method. The maximum efficiency improvement of proposed algorithm is 2.3% compared to that with the same energized currents for both DD coils.