Research On Wireless Charging On Transmission Power Converter Based On Rezence Standard

Wireless charging technology is concerned widely because of its convenience and application to various complex environments.Rezence standard is based on magnetic coupling resonance system(RWPT),this standard transmission power is larger than the other low power standards,there is no limit to the number and location of the receiving unit.And it satisfied the urgent need of wireless charging market for portable electronic products like mobile phones,computers,etc.This paper focused on the design of RWPT power transmitting terminal unit(PTU)based on Rezence standard,and generate 6.78 MHz AC power supply and load matching,in view of these problems,we had done the following work.Firstly,the coupling circuit model between the transmitter coil and the receiver coil of RWPT was established,and the mathematical analysis was done.We have concluded the main impact factors of system’s efficiency and power through the above research,at the same time,doing the simulation experiment with the resonant topology SS and SP.Experiments show that Q value of the coil and the coupling factor have a great influence on transmission characteristics,and suitable for this system’s resonance model is obtained.Then,we studied the theory and simulation analysis of the class-D and class-E amplifiers,and realized the soft switch of class-E and class-D amplifier at 1MHz frequency.Comparison of both efficiency and circuit characteristics,the class-D and class-E amplifier have a high efficiency when working under the fixed frequency,fixed input voltage.But once the load changes,the transmission power and efficiency will be affected greatly.In order to solve this problem,a class-D full-bridge inverter is proposed.In addition,the structure of class-D inverter is optimized,and the variable load and variable input voltage are realized.Meanwhile,the dead zone time can be controlled dynamically,which reduced the large switching loss.Finally,this paper chosed the eGaN(?)FET as the class-D full-bridge inverter’switch tube to build the WPT system’s PTU,and the rectifier circuit as the receiver terminal unit.And set up the experimental platform based on Rezence standard.When the transmission distance is 25mm,the maximum efficiency is 81%.This experiment showed that by using the optimization of class D full bridge inverter and dynamically control dead-time method,the system also had high transmission efficiency and power in variable conditions(changing by input voltage,load).