| In order to adapt to special working environment with high temperature,high pressure,radioactivity or toxicity,a large of modern equipments use the hermitical metal structure,in which sensors and microcontrollers are installed to monitor the internal conditions.To ensure that the sensors and microcontrollers work well,wireless power transmission technology need to be adopted.At present,the most commonly used wireless power transmission technology is based on electromagnetic induction methods,but due to the influence of metal electromagnetic shielding effect,the wireless power transmission scheme based on electromagnetic waves is not highly feasible.The method of transmitting energy through a elastic wall by acoustic waves using piezoelectric transducers can effectively overcome this obstacle and transfer energy through metal wall.In this paper,based on the two-port network model of the ultrasonic coupling wireless power transmission system,the impedance matching technology of the system is studied,and the simulation analysis of system is realized using electro-acoustic analogy method.Meanwhile,the research and analysis of impedance matching technology of system is realized using the test platform.The main contents of this thesis are as follows:(1)The working principle and components of system are outlined,and the equivalent two-port network model is established according to the input and output parameters of the system.Two important concepts of power gain are defined: port power gain and transmission power gain.With the concept of power wave,the whole system comprised of the power source and the load is described,which providess the theory basis of impedance matching scheme.(2)With the concept of power wave,the two-port network model of the system is described,and then the dual conjugate impedance matching conditions are given.Compared with the lumped element matching network and the transmission line matching network,impedance matching network of the actual system is designed according to the advantages and disadvantages of two methods.(3)Based on electro-acoustic analogy method,the equivalent circuit model of the system is established,and then the model is simulated using Mulitisim10.0.When the hickness of the metal wall and the load impedance change respectively,variation of power gain before or after the joining of matching network is given and the feasibility of impedance matching method is verified.(4)Using the testing platform of the ultrasonic coupling wireless power transmission system through the metal wall,the impedance matching technology is studied.When the load impedance changes,the impedance matching performance is verified using the proposed matching network,variation of power gain before and after the joining of matching network are given.Meanwhile,the testing results and simulation results are compared. |
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