Long Range And Low Power Wireless Power Transmission Technology Research

In recent years, as the development of technology and the improvement ofpeople’s living standards, mobile phones, wearable devices, human implantabledevices and wireless sensor networks are widely used and present annual growthtrend. The main features of these devices are lower power levels, high energyconsumption and smaller size. Therefore, the energy supplement is always thebottleneck of the further development of those devices. Most of the traditionalcharging methodes still use wire, although the efficiency is high, the inherentdisadvantage may be much more obvious, such as the charger interface is notuniform, potential security risks，inconvenient to carry and so on. As a result, anovel charging method should be proposed to solve the problem, magnetic couplingresonates wireless power transmission technology presents a solution. Comparedwith other wireless power transmission technologies, this method has the advantageof long transmission distance, high power levels and high efficiency which is t hemost suitable method for everyday life.The basic theory is magnetic coupling resonates technology and the main studyis long-distance, large transmitter to small receiver in the form of asymmetric coilstructures, multi-load connecting mode and low power system which is intend tosolve the energy supplement problem of the portable devices, thus promoting thefurther development of those devices.Firstly, the basic principles of the system are analyzed and researched.Through the mutual coupling circuit theory, the two coils structure is analyzed.Then obtain the main factors that affect the transmission power and efficiency ofthe system. Therefore, the structure’s defect that it is not suitable for long distancepower transmission is obtained. In order to overcome this defect, the three coilstructure which has an enhance coil is presented and optimized, with the enhancecoil, the value of the current, the intensity and the spatial distribution of themagnetic field can be enhanced. Meanwhile, analyze the receivers’ multi-loadconnectin mode and it’s suitable application, then present diffrerent load resistanceshould have the corresponding load mode.Then the efficient power output of thesystem and the long distance power transmission in the form of asymmetric coilstructures can be guaranteed.The system experimental platform is built based on the above three coilstructure, the main study is that the rationality of the system’s transmitter, thereceivers’ multi-load connecting mode and the load change characteristics, the characteristics of the transmission direction, the influnce of the multi-receivers tothe system’s performance, the spatial distribution of the magnetic field and the softswitch condition. From the experiment, it’s proved that the proposed design of thetransimitter can ensure the system’s high performance; different load resistanceshould choose the corresponding load connecting mode and with multi receiverscan improve the transmission power and efficiency effectively which is justconsistent with the requirements of practical application.The specific parameter index of the final system prototype: within thehorizontal transmission distance of40cm, a2W white LED light,1.5W red LEDlight and1.5W smart phone can be wirelessly charged with the efficiency of20%;within the vertical transmission distance of50cm, a3W white LED light,2W redLED light and1.5W smart phone can be wirelessly charged with the efficiency of26%.