ABSTRACT In wireless charging system, limited by the coupling effect between the loads and the change of the equivalent impedance of the battery, it becomes difficult to provide efficient and stable energy supply for multiple load devices. In this paper, a multi-load constant current charging technology for wireless charging system is proposed, which combines the primary side control and the secondary side control to achieve quick charge for multiple load batteries at the same time. The system reduces the influence of interference factors by designing the primary side control module and the transmission structure, to ensure sufficient and stable transmission of energy. And utilising the secondary side control module to charge the battery with constant current, which increases the charging speed, and reduces the impact of battery impedance changes on the system’s transmission state. It is verified by experiments that when charging four 1.2 V Ni-MH batteries, the receiver at different positions within the coverage of the transmitting coil can achieve 100mA constant current charging for the battery and the output voltage fluctuation range of each receiver is within 0.2 V, and the working efficiency of the system can reach 70%.

中文翻译：

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无线充电系统多负载恒流充电技术

摘要 在无线充电系统中，受负载之间的耦合效应和电池等效阻抗变化的限制，为多个负载设备提供高效稳定的能源供应变得困难。本文提出了一种用于无线充电系统的多负载恒流充电技术，该技术将一次侧控制和二次侧控制相结合，实现同时对多个负载电池进行快速充电。系统通过设计一次侧控制模块和传输结构，减少干扰因素的影响，保证能量的充分稳定传输。并利用二次侧控制模块对电池进行恒流充电，提高充电速度，并减少电池阻抗变化对系统传输状态的影响。经实验验证，在给四节1.2V镍氢电池充电时，发射线圈覆盖范围内不同位置的接收器可实现对电池100mA恒流充电，每个接收器的输出电压波动范围在0.2V以内，系统工作效率可达70%。