带前级DC/DC的无线充电系统建模与分析

Modeling and Analysis of Wireless Charging System with Front Stage DC/DC Control

无线充电过程中需要控制从电网侧流向电池的功率,在现有功率控制方式中,逆变器前附加DC/DC控制具有相对高的传输效率和控制精度,针对带前级DC/DC控制的磁耦合谐振式无线充电系统进行建模与分析。系统中引入解耦电容将DC/DC单元与其后级的逆变-耦合谐振单元解耦,采用状态空间平均法和广义状态空间平均法建立了整个系统的线性化模型。同时在Simulink下搭建系统拓扑模型,并将两种模型得到的状态变量的时域运动轨迹进行了对比,验证了数学模型的准确性。基于所建模型分析了系统稳定性及其控制特性,结果表明,系统是稳定的,并且在传输效率不变的前提下,前级DC/DC控制方式能够很好地实现对输出功率的控制。

In the wireless charging process,it is necessary to control the power flow from the grid side to the battery.In the existing power control mode,the additional DC/DC control in front of the inverter has relatively high transmission efficiency and control accuracy.In this paper,the modeling and analysis of the magnetic coupling resonant wireless charging system with the former DC/DC control were carried out.Decoupling capacitor was introduced to decouple the DC/DC unit and the subsequent inverter coupling resonance unit.The linearization model of the whole system was established by using the state space average method and the generalized state space average method.At the same time,the system topology model was built under Simulink,and the time-domain trajectory of the state variables obtained from the two models was compared to verify the accuracy of the mathematical model.Based on the model,the stability and control characteristics of the system were analyzed.The results show that the system is stable,and the former DC/DC control mode can control the output power well under the premise of constant transmission efficiency.