Research On Impedance Adjustment For Energy-Encrypted Wireless Power Transfer Systems

The wireless power transmission via magnetic resonance coupling has been gradually becoming a new type of power supply in recent years,with the development of science and technology.The multi-objective magnetically resonant coupling wireless power transmission technology has been proposed,which can contactlessly supply energy to multiple electrical devices simultaneously,to solve the drawbacks of conventional wireless charging "one to one" mode,in which the power transmission time is long and the electrical equipment needs to wait.In such a way,it can significantly improve the efficiency of wireless power transmission,having a broad application prospects.However,at the same time,due to the non-restrictiveness of the multi-objective wireless power transmission technology for the power-consuming equipment,in order to ensure the safety of contactless energy transmission,this paper studies the energy encryption strategy of multi-objective wireless power transmission systems based on the principle of magnetic coupling resonance,which includes the following three aspects:1.Based on the principle of magnetically resonant coupling wireless power transmission,the relationship between the operating frequency of the system and the transmission coil and compensation capacitance when the system reaches a resonant state is obtained,by analyzing the circuit model of a multi-objective wireless power transmission systems.The influence of frequency sensitivity on wireless energy transmission performance is obtained,by analyzing the frequency characteristics of existing magnetically resonant coupling wireless power transmission technologies.Accordingly,the capacitive compensation network of the wireless power transmission systems can be designed to match the inductance of the transmission coil,and then controlling the transmitting power by adjusting the impedance of the systems,to achieve energy encryption for the multi-objective wireless power transmission systems.2.Aiming at the technical requirements of impedance adjustment under energy encryption strategy,a multi-level impedance-regulating for multi-objective wireless charging system energy encryption strategy based on a variable topology capacitor matrix is proposed in this paper,to implement energy encryption for the multi-objective wireless power transmission systems.By analyzing the circuit diagram of the proposed capacitor matrix,the topology transformation method of the capacitor matrix is obtained,as well as the principle of impedance adjustment of the proposed variable topology capacitor matrix is deduced theoretically.In addition,based on numerical simulation and prototype test results,the feasibility of the proposed multi-level capacitor matrix for impedance adjustment is verified,which provides the necessary technical basis for energy encryption of multi-objective wireless power transmission systems.3.In order to address the provided limited capacitance value when implementing energy encryption for multi-objective wireless power transmission systems using variable topology capacitor matrix,a step-less impedance-regulating energy encryption strategy based on virtual capacitor is proposed.Firstly,the working mechanism of the virtual capacitor is analyzed based on the equivalent circuit,and a hybrid impedance adjustment mechanism using the capacitor array and the virtual capacitor is proposed.In addition,a numerical simulation and prototype test and test platform is designed.Simulation and experimental results both show that the step-less impedance adjustment strategy based on virtual capacitor can more accurately compensate the wireless energy transmission system,ensuring the resonant state under the active regulation of the operating frequency,thus realizing energy encryption of multi-objective wireless power transmission systems.In summary,for the energy-safe transmission problem of multi-objective wireless power transmission systems,a multi-level impedance adjustment based on variable topology capacitor matrix and a step-less impedance adjustment mechanism based on virtual capacitor are proposed.Through combination of theoretical derivation,numerical simulation analysis and prototype test,it is verified that the two proposed impedance adjustment mechanisms can effectively implement energy encryption for multi-objective wireless power transmission systems.