电磁超声激励系统阻抗匹配网络的设计  

Design of Impedance Matching Network for Electromagnetic Ultrasonic Excitation System

作　　者：刘素贞[1] 张严伟[1] 张闯[1] 蔡智超[1] 杨庆新[1,2] 

机构地区：[1]河北工业大学电磁场与电器可靠性省部共建重点实验室,天津300130 [2]天津工业大学电工电能新技术天津市重点实验室,天津300387

出　　处：《电工技术学报》2016年第16期1-6,共6页Transactions of China Electrotechnical Society

基　　金：国家自然科学基金(51307043);河北省自然科学基金(E2016202260);天津市自然科学基金(16JCYBJC19000)资助项目

摘　　要：电磁超声换能器的换能效率低是限制电磁超声技术广泛应用的一个重要因素，如何提高换能器的换能效率一直都是电磁超声领域的研究重点。激励线圈作为激励系统中十分重要的一部分，其激励电流的大小决定试件表面产生电磁力的大小。但是，由于线圈和功率放大器之间存在严重的阻抗失调，使其流过的电流及获得的功率不是很理想。为此，根据电抗元件网络可精确实现调谐和变阻的特性，结合二进制的组合方式，设计了能够匹配多种频率线圈的电抗网络。该网络的接入可实现功率源和负载之间的最大功率传递，提高加载在线圈上的电流，为电磁超声激励提供较大的能量。仿真和实验结果表明：该匹配网络能在0.5～5MHz宽频率范围内有效地提高电源的输出效率，提升电磁加载的信噪比及转换效率，为电磁超声的后续研究奠定基础。The low transduction efficiency of electromagnetic ultrasonic transducer （EMAT） is a principal factor which limits the wide application of electromagnetic ultrasonic technology. Improving the efficiency of EMAT has always been one of the most important issues in the field of electromagnetic ultrasonic. Designing suited excitation coil is a very important part in the system. The amplitude of the exciting current plays a crucial role in the production process of electromagnetic force in the specimen surface. However, due to serious non-matching of impedance between coil and power source, the current and power through the coil are not ideal. Therefore, combined with the binary encoding method, a reactance network based on the characteristics of reactive elements network can accurately realize tuning and transforming the resistance in this paper. The designed mode can match a variety of coils with different frequencies. The coil can reach the maximum power and higher amplitude of current from the power source by using this novel network, which can provide enough power to excite the EMAT. Simulation and experimental results show that the matching network can effectively improve the output efficiency of the power source within the scope of 0.5～5MHz as well as the signal-to-noise ratio and the transduction efficiency of EMAT. The design lays a foundation for follow-up studying on EMAT.

关 键 词：电磁超声 电磁力 调谐 变阻 阻抗匹配 宽频率 

分 类 号：TM133[电气工程—电工理论与新技术]