磁耦合谐振式无线电能传输系统传输特性研究

Research on transmission characteristics of magnetically coupled resonant wireless power transfer system

针对磁耦合谐振式无线电能传输(MCR-WPT)系统中线圈参数和负载电阻改变对系统传输性能造成的影响,利用两线圈结构的MCR-WPT等效电路模型,推导了系统输出功率和效率表达式,分析了线圈互感、负载电阻与系统输出功率和传输效率的关系,以及线圈线径、匝数与互感的关系;借助COMSOL有限元仿真软件建立线圈三维模型,并搭建多组两线圈MCR-WPT实验系统对理论分析结果进行了验证.研究结果表明:通过增大收发线圈线径和匝数,可以提高系统输出功率和传输效率,但与线圈线径相比,线圈匝数对传输效率的影响更为明显,而且随着匝数的增加,系统会在更远的传输距离处取得输出功率最大值;随着负载电阻不断增大,系统输出功率和传输效率都呈现先增加后减小的趋势,证明了系统的输出功率和传输效率均存在最大值,但系统输出功率和传输效率达到最大值时的最佳负载不同,即不存在可使输出功率和传输效率同时取最大值的最优负载电阻.

In view of the influence of coil parameters and load resistance changes on transmission performance of magnetically coupled resonant wireless power transfer( MCR-WPT) system, output power and efficiency of the system are derived using equivalent circuit model of two coil structure MCR-WPT system. The relationship between coil mutual inductance, load resistance and system output power and transmission efficiency, as well as the relationship between coil wire diameter, coil turns and mutual inductance are analyzed. Three-dimensional coil model is established using finite element simulation software COMSOL, and multiple sets of two-coil MCR-WPT experimental systems are built to verify the theoretical analysis results. Research results show that by increasing coil wire diameter and turns, the output power and transmission efficiency of the system can be improved, but the influence of turns on transmission efficiency is more obvious than that of coil wire diameter, and the transmission distance increases when the maximum output power is obtained as the turns increases;as the load resistance continues to increase, the system output power and transmission efficiency both increase first and then decrease,proving that output power and transmission efficiency both have maximum value, but the optimal load is different when the system output power and transmission efficiency reach the maximum value, that is, there is no optimal load resistance that can maximize the output power and transmission efficiency at the same time.