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体内植入器件的Witricity系统设计与实验研究

The Design and Experimental Research of Witricity System Used in Implantable Device

【作者】 赵军

【导师】 徐桂芝;

【作者基本信息】 河北工业大学 , 电气工程, 2013, 博士

【摘要】 作为一个新方法,磁耦合谐振无线能量传输技术受到了国内外研究学者的广泛关注,但是还有很多问题尚未解决,特别是在对体内植入器件进行无线能量传输方面,关注的学者和研究机构相对较少,需要解决的问题还很多。本文主要针对应用于体内植入器件的小型磁耦合谐振无线能量传输系统进行研究,首先利用耦合模理论研究了磁耦合无线能量传输系统的传输规律及最佳工作条件,然后对系统进行建模分析,在仿真分析的基础上设计出适用于体内植入器件的小尺寸谐振器。最后,将小尺寸谐振系统放置于不同的实验环境中进行实验研究,并应用时域有限差分方法计算系统工作时人体的比吸收率,依此判断该方法对体内器件供电的安全性。本文主要研究工作有以下几个方面:1、应用耦合模理论,计算线圈中能量并研究两个线圈在强耦合和弱耦合状态下的能量传输效率、线圈固有频率的改变对能量传输状态的影响以及谐振频率对线圈品质因数的影响,最后研究扰动对工作效率以及损耗效率的影响。2、建立立方体螺旋谐振器及平面螺旋谐振器仿真计算模型,通过改变谐振器各参数,确定各参数对谐振器谐振频率的影响。仿真结果表明线圈线径和介质厚度对线圈谐振频率影响最大,传输效率在谐振点达到最大。在仿真基础上,设计了适用于体内植入器件的小尺寸谐振器,谐振器体积1.35cm3。3、建立了人体头部及胸腔数值仿真模型,对Witricity系统给体内植入器件进行供电时人体头部及胸腔的SAR值进行计算。通过计算得出,应用Witricity系统对体内植入器件进行供电时,人体头部及胸腔的SAR值均低于国际限值标准。4、对立方体螺旋谐振器、平面螺旋谐振器及小尺寸平面螺旋谐振器分别进行了实验分析,通过改变系统两谐振器之间的垂直距离、水平位移以及旋转角度,计算系统传输功率及效率。此外,将系统置于空气、模拟人体组织液及新鲜猪肉这三种不同环境下,进行能量传递,计算系统在不同环境下的传输功率及效率。实验结果表明模拟人体组织液和新鲜猪肉对系统的传输效率影响很小。最后对整流滤波稳压电路进行实验,得到了充电模块所需的电压,验证了整流滤波稳压部分的正确性。本文对磁耦合谐振无线能量传输的传输机理、传输条件进行了研究,还在仿真研究基础上设计出适用于体内植入器件的小型磁耦合谐振无线能量传输系统,并计算了系统工作时对人体的生物安全性,这在国内尚属首次,这也为无线能量传输技术在医学领域发展奠定了基础。

【Abstract】 Nowadays the magnetic coupling resonant wireless power transmission technology hasreceived wide attention as a new theory by the scholars at home and abroad. But manyproblems have not been solved, especially in the aspect of the in vivo implantable devices.In this paper the small size magnetic coupling resonant wireless power transmissionused in implantable devices has been analysed. At first the magnetic coupling transmissionrule of wireless energy transmission system and the best working conditions are studied bycoupled-mode theory. Then the system numerical model is established and the small sizeresonator is designed on the basis of simulation analysis. Finally, the small size resonantsystem is placed in different experiment environments and the finite difference time domainmethod is used to calculate the SAR of human body to judge the safety of the power supplydevice.Main points of this paper are as follows:1. The coil energy transfer efficiency in the condition of strong coupling and weakcoupling using coupled-mode theory, the effects of the change of coil natural frequency onthe energy transfer state and the quality factor is calculated, and the effect of disturbance onthe work efficiency and the loss efficiency is studied.2. The cube spiral resonator and planar spiral resonator simulation model is established.The parameters influence on the resonance frequency of resonators by changing theresonator parameters is determined.The simulation results show that the coil wire diameterand the medium thickness of coil has the greatest effect on the resonant frequency. Thesmall size resonator with the volume of1.35cm3is designed based on the simulation.3. The human head and chest numerical simulation model is established and the SARof head and chest is calculated by FDTD when the implanted device is powered byWitricity system. As the results of the model calculation, the SAR values are lower than theinternational standard limit.4. Experiments are carried out to the cube spiral resonator, planar spiral resonator andsmall size plane spiral resonator respectively. The system transmission power andefficiency is calculated by changing the vertical distance between two resonators,horizontal displacement and rotation Angle. In addition, the system is placed in the air,simulated human body tissue fluid and fresh pork to transfer energy and the transmissionpower and efficiency under the different environment is studied. Experimental results showthat the simulated human body tissue fluid and the fresh pork have little effect on systemII transmission efficiency. Finally the voltage needed for the charging module is got byrectifier filter circuit.In this paper the transmission mechanism and transmission conditions of magneticcoupling resonant wireless power transmission system has been studied, and a small sizemagnetic coupling resonant wireless power transmission system suitable for implantabledevices has been designed based on the simulation.The biological safety to human bodywhen the system is working has been calculated for the first time in our country, and it haslaid a foundation for the wireless energy transmission technology developing in the medicalfield.

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