Research And Development Of Low Power Wireless Charging System For Portable Electronic Device

In recent years,consumers have been plagued by the battery life of electronic products when they are enjoying the pleasures and conveniences which are provided by various portable electronic devices such as smartphone,tablet PC.The innovation of battery charging method is a possible way to solve the battery life of electronic products before the battery technology of miniaturization and high-capacity achieves an effective innovation.It is an entirely new battery charging method that applying Wireless Power Transmission(WPT)technology to portable electronic devices which is called low power wireless charging technology.Because of the power transmission between power transmitter and power receiver does not use wires but air as the transmission medium,wireless charging technology not only avoids the traditional wired charging mode’s disadvantages of cluttered wires and data lines,inconvenient and low safety of plugging,but also makes good use of fragmented time,and has an advantage ── put down charging,take up stopping in any time.But the Wireless Charging System(WCS)used to portable electronic devices now still has the problems of high costs,bad uniformity and mechanical strength of coupling structure,a low power WCS was designed in this thesis which reduced the system cost and optimized the coupling mechanism while providing a solution to the battery life problem of portable electronic devices.This thesis took widely used smart phone as an application object,designed a low power WCS which is based on the WPT technology,the main work and achievements are summed up as follows: Firstly,on the basis of comparison between traditional transformer with iron core and Inductive Coupled WCS,the basic working principle and framework of WCS were introduced;the basic structures of power transmitter and power receiver and the functions of every structure module were analyzed.Secondly,according to the requirements of WCS’s structures,functions and costs,the High Frequency Inverter circuit and Resonance Compensation Mode were established through analyzing and comparing three High Frequency Inverter circuits and two Resonance Compensation Modes;the detection circuits of voltage,current and temperature were designed;the design of main circuit was accomplished;the control of system was presented which contains the activities and power control process of four control stages;the selection of control chip was completed.Thirdly,in consideration of WCS’s costs and volume,the WCS’s communications between power transmitter and power receiver was solved,which doesn’t need add extra communication modules;the signal modulation circuits were designed;the encoding scheme contains Bit encoding scheme,Byte encoding scheme and Packet structure and the relevant communications and control protocols were defined.Lastly,the design process of WCS’s coupling structure was presented by simulation of coupling structure and then a phone’s PCB coupling structure was designed according to the process.