| Recent years magnetic resonance coupling wirless power transfer (MCR-WPT) has received more and more attention and research at home and abroad due to possessing many advantages, such as middle transmission distance, non-directional interference, and avoiding the impact from the non-magnetic barrier and so on. Currently study of MCR-WPT has made a lot of positive results on working principle, structural design, coils optimization and transmission characteristics. Transmission efficiency will change when transmission distance or load changes, transmission characteristics of the system will greatly improve if MCR-WPT system can maintain the state of impedance matching. Therefore, this article aims to design a new approach for MCR-WPT system that a is simple, low-loss impedance matching method to optimize the transmission performance of the system. The main contents are as follows:Modeling and theoretical analysis of MCR-WPT system are carried on. The transmission characteristics of two and four-coil transmission structure that are currently widely used are analyzed, and the compensation capacitor expressions of SS or SSSS are relatively simple and have not been effected by mutual inductance between the coils by comparing four kinds of topology of the two transmission structures. It is found that the two coil transfer structure has a greater advantage in study of impedance matching technology. Coil parameters of transmission system are analyzed in detail, and open-loop frequency power of MCR-WPT system is designed. The paper also builds an experimental platform to study the impact of the duty cycle of the driving pulse signal on transmission characteristics.The circuit model of MCR-WPT system based on impedance matching is build, and the isolated and non-isolated two kinds of ways are analyzed. For non-separable two coil impedance matching method, this paper proposes a method based on capacitor array, and a simulation model is set up to implement a corresponding switching of capacitor array by binary conversion. Simulation results verify that the capacitor array can accordingly change switching when transmission distances change. However, this policy must set the lookup table, and the process has some weaknesses due to heavy workload and the huge volume of capacitor array, also its additional losses are relatively large.In order to achieve the simple control, the paper designs a new approach for impedance matching based on DC-DC converter. The step-down transformer is embedded between load and receiving coil to achieve impedance matching, which is easy to control and has two control degrees of freedom. Different control strategies are proposed for fixed load mode and changeful load mode, and the simulation models have verified the validity of the method of impedance matching. This control method is relatively simple, and the transmission efficiency of system can be effectively optimized. |
PDF Full Text Request