Model-driven Design Method For Magnetic Resonance Wireless Charging Coil With High Stability

Magnetic resonance wireless charging utilizes the resonance between the receiving and transmitting coils to improve the charging distance,but its performance is vulnerable to the position of receiving coil and the change of charging load.Therefore,the design of the magnetic resonance wireless charging coil with high stability that is insensitive to the changes of position and load is critical to the practical application of wireless charging technology.Due to the lack of effective modeling methods,the current design of highstability magnetic resonance wireless charging coil usually adopts the trial-and-error method,which results in a lot of time-consuming full-wave simulations during the design process.In order to reduce the number of full-wave simulations in the design process,the following studies on the model-driven design method for magnetic resonance wireless charging coil with high-stability are conducted.Firstly,a design method for multi-antiparallel coils（MAC）based on a hybrid analytical-numerical model is proposed to reduce the number of full-wave simulations in the design process of wireless charging coils that are insensitive to vertical distance.This method takes the optimal mutual inductance between the transmitting and receiving coils as the design goal,and takes the turn numbers of the MAC’s sub-coils as the design variable.The initial design close to the target is obtained from the analytical model of the static mutual inductance,and the initial design is further optimized based on the numerical model to minimize the gap between the realized mutual inductance and the optimal mutual inductance.Furthermore,according to the coupling mechanism of MAC’s transmitting and receiving coils,the abovementioned optimization problem is proved to be a convex optimization problem,which can be solved by the local searching method.Because a good initial solution can be obtained from the analytical model,the proposed method can significantly reduce the number of time-consuming full-wave simulations compared with the commonly used trial-and-error method.Simulation and measured data show that the proposed design method can achieve good design accuracy and high design efficiency.Secondly,in order to expand the design freedom of position-insensitive wireless charging coil,this thesis proposes multi-three-phase coils and its artificial intelligence design method.The multi-three-phase coils take the subcoil layout and current direction as design variables and have a larger space for design and optimization.Besides,the coil can be rapidly optimized by the genetic algorithm after ternary encoding.In order to avoid time-consuming full-wave simulations in the design process,this thesis proposes to use the neural network model based on a prior knowledge to quickly calculate the precise mutual inductance between the transmitting and receiving coils,which further improves the design efficiency.Simulation and measured data show that the proposed method can realize the co-design of position insensitivity for vertical distance and horizontal misalignment,and has good design efficiency and accuracy.Finally,a co-design method for position-insensitive and load-independent wireless charging is proposed.In this thesis,the series-series compensation circuit and SP-S（SP means the series inductor and the parallel capacitor;S means the series capacitor）compensation circuit are used to realize the load-independent wireless charging with constant output current and voltage,respectively,and the position sensitivity problem in the load-independent compensation circuit is pointed out.Furthermore,a design method combining the position-insensitive coil and load-independent compensation circuit is proposed to realize position-insensitive and load-independent wireless charging with high-stability.