| With the rapid increase of mobile electronic devices,people has more and more demands for chargers in their daily life.Compared with the traditional wired charging method,the wireless charging method has higher safety,stronger flexibility and versatility,thereby has broad development prospects and important research value,and has been becoming a research hotspot in academia and industry.However,most of the wireless chargers currently on the market generally have problems such as low integration,high cost,complex design,and insufficient data communication,etc.To deal with these problems,this thesis aims to design and implement a high-integrated low-cost Qi wireless charging with stable and reliable charging performance based on a new current ASK demodulation method.The main work includes the following five aspects.⑴ First,this thesis designs an overall scheme of the wireless charging transmitter circuit based on the Qi standard.To this purpose,this thesis summarises a series of functional requirements of the Qi wireless charging transmitter circuit,then analyzes how to choose the best circuit architecture as the basis of the overall transmitter circuit architecture,and finally combines the functional requirements to design the high-integrated transmitter circuit architecture.⑵ Second,this thesis designs power supply circuit and digital-to-analog converter(DAC)based on the System-on-Chip(SoC)architecture.To this end,this thesis designs PSM buck converter suitable for wireless charging SoC with simple structure and low cost,by taking advantage of low static power consumption and simple design of the PSM modulation,and then combines with the Qi standard to derive the fixed frequency voltage regulation accuracy in Apple’s wireless fast charging scheme,thereby designing a current steering DAC circuit with controllable current direction and low cost.Finally,this thesis designs an IDAC fixed-frequency voltage regulation solution that meets the requirements of wireless fast charging and has good regulation linearity based on the DAC.⑶ Third,this thesis designs an ASK demodulation circuit based on the SoC architecture.For this objective,this thesis both design the voltage ASK demodulation circuit and current ASK demodulation circuit based on the envelope demodulation method to enhance the data communication reliability of the wireless charging transmitter.Among them,in view of the shortcomings of the voltage ASK demodulation circuit and the traditional current ASK demodulation circuit,this thesis designs a new current ASK demodulation circuit based on the SoC architecture considering the SoC chip package and the complexity of the peripheral circuit design,then simulates and analyzes its key performance indicators.Finally this thesis proved the feasibility of the designed ASK demodulation circuit through actual measurement data analysis.⑷ Fourth,this thesis designs an inverter circuit based on the SoC architecture.For this goal,this thesis designs the voltage-type full-bridge inverter circuit schematic diagram suitable for the single-coil wireless charging transmitter,then simulates and selects important circuit components based on the Qi standard and system requirements,and finally conduct experiments against the temperature rise problem of field-effect transistor and the potential impact of different driving resistances on the transmission efficiency of the system,and improve the inverter circuit design scheme according to the experimental results.⑸ Fifth,this thesis designs and realizes the printed circuit board(PCB)of the wireless charging transmitter based on the above circuits,and then conduct five system tests including the power supply voltage,the wireless fast charging,the dynamic load change,the charging compatibility,and the transmitter power comparison test.A series of test results show that the system has the performance of miniaturization,low cost,reliable data communication,and has the feature of wireless fast charging for Apple mobile phones,which is in line with expectations. |
