| Wireless charging technology is a power transmission technology that excites the free-space energy field as a transmission medium.Due to the unique advantages of no physical electrical connection,safety,and portability,it provides a perfect solution to the problems of frequent plugging in power,mismatched data cables,mismatched chargers,and aging of smart phones.And this technology has become the main research and development direction of smart portable device charging solutions.This paper is mainly based on the magnetic coupling resonance technology.In order to solve the problem of the equivalent power supply and the optimal distance of the coil transmission of the bilateral resonance network in the wireless charging system of the mobile phone,the circuit theory and the electromagnetic field theory are used for research.The main research contents are:First,an equivalent circuit model of a magnetically coupled resonant mobile phone wireless charging system is established based on circuit theory,and the functions of each module of the system are introduced.Based on the theoretical modeling and analysis of four basic resonant networks and bilateral LCC resonant networks,the effects of load and frequency on output power and system transmission efficiency are compared and analyzed.A bilateral LCC resonant network equivalent to a constant current source is selected,and Optimize and increase the control constants,design a bilateral LCC power adjustable constant voltage and constant current wireless charging scheme,establish a mathematical model of each component parameter and a parameter selection scheme.Simulation verification was performed through the Multisim circuit simulation platform.Secondly,the basic model of the system coil is established based on the electromagnetic field theory,and the self-inductance and mutual inductance of the coil are calculated by the overall turn method.Relying on the HFSS(High Frequency Structure Simulator)three-dimensional electromagnetic field simulation platform to establish a three-dimensional model of the coil of the system and simulation calculations,the coil model is optimized by analyzing the magnetic field strength and its distribution in the space electromagnetic field,the relationship between the coil distance and the magnetic field strength,and mutual inductance.Based on the analysis results,the actual coil is wound.Then,based on the results of theoretical analysis,the software and hardware of the system are designed.The Cadence EDA design platform is used to design the hardware circuit schematic diagram of the transmitter,receiver and control module of the system,and the selection of the main components of the circuit is given.The software controller uses the STM32 chip,and details the overall software design flow and the segmented charging program control scheme.Finally,based on the results of the above design analysis,a system test platform is built.The test results show that the optimal transmission distance of the system is 5cm,the maximum transmission efficiency of the system is 82.55%,and the standby power consumption of the system is 45.1mW.The system realizes the functions of wireless energy transmission,equipment search and matching,and segmented charging. |
