| Capsule endoscopy has been put into clinical use,and it is mainly powered by lithium batteries and other micro batteries.it has a short power supply period and is a potential threat to human health.Therefore it is can not meet the requirements on long time examination.Wireless power transmission technology is an effective way to provide continuous energy supply for capsule endoscopy,and has received extensive attention.Based on the previous research of our group,the wireless power transmission system of capsule endoscopy is improved and optimized.A test platform for wireless power transmission system with one-dimensional and three-dimensional receiving coils is built.Theoretical analysis and experimental research are carried out to verify the correctness and feasibility of the optimized parameters and schemes.The detailed work accomplished in the dissertation is as follows.Based on the application conditions of capsule endoscopy,the application circuit of the receiving end of the wireless power transmission system is designed,and the feasibility of the application circuit is verified by simulation and experimental analysis.The calculation formulas of output power and transmission efficiency under different resonance compensation models are analyzed.The performances of different resonant compensation models are analyzed,the effects of different factors on the output power and transmission efficiency are analyzed.The magnetic induction intensity and magnetic field uniformity of the transmitting coil with different cross-section shapes are analyzed and studied,and the shape of the circular coils is selected.The calculating formulas of the magnetic induction intensity of different types of transmitting coils on the axis plane are obtained by using approximate method.The magnetic induction intensity and magnetic field uniformity of different types of transmitting coil are analyzed with Matlab,and the improved Helmholtz coil is selected as the transmitting coil of the system.The COMSOL software is used to simulate the current density and specific absorption rate in the simplified human abdominal model.Taking the efficiency product as the objective function in the optimization model,the resonance frequency and coil parameters are taken as the optimization variables,and the temperature rise condition and electromagnetic safety are taken as constraints.The parameters of the one-dimensional receiving coil and the three-dimensional receiving coil wireless power transmission are optimized.In the process of three-dimensional receiving coil optimization,the three-dimensional receiving coil application circuit after rectification and parallel connection is selected considering the actual application conditions.The optimized parameters of one-dimensional receiving coil and three-dimensional receiving coil are simulated and experimentally verified.According to the requirement of capsule endoscope,the receiving side of the wireless power transmission system is miniaturized,and the miniaturized camera module,the signal transmitting module and rectifier filter voltage regulator module are analyzed and integrated.The experimental analysis of the integrated capsule endoscope is carried out to verify the correctness of the optimization scheme.A full-bridge inverting circuit with single chip computer as the control core is designed,which solves the problems of large volume and difficult frequency adjustment of WL3866 signal generator,the effect of the circuit is verified by simulation and experiment. |
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