电磁超声脉冲发生器的研究

发布时间：2019-01-06 19:01

【摘要】：电磁超声脉冲发生器是利用电磁感应机理实现高功率超声脉冲输出装置,由于其本身有具有非接触、无需耦合介质、分辨率高等诸多优点,在医疗、工业清洗、工业无损检测、水下声纳等领域获得广泛应用。如在无创肾结石和胆结石医疗应用中,采用脉冲磁场作用于球形曲面箔片的球形汇聚声脉冲波发生器,人们已经在这种超声脉冲发生器中获得最高压力值和可靠性系数。但是,在控制这种电磁声脉冲发生器的声脉冲持续时间时遇到困难,因为其激励线圈匝数固定,所以脉冲时间仅能通过改变放电回路中的电容来实现,不能很好满足实际应用要求,同时还有转换效率低的缺陷。国内有关电磁超声脉冲发生器的性能还与国际先进产品间具有较大差距,因此深入研究电磁超声脉冲发生器具有十分重要的实际应用价值。针对这一现状,本文抓住电磁学和超声波这两个学科的结合,结合多物理场相关理论。在分析现有的电磁超声脉冲发生器的基础上,从结构设计和原理分析出发,设计出成本低,结构简单,输出功率高,具有不同持续时间连续声脉冲的电磁超声脉冲发生器。本文主要安排如下:1.本文第一部分从课题的研究背景出发,分析国内外有关课题的研究现状,从而引出课题研究的意义和必要性,阐述本文主要的研究工作。2.本课题的研究属于交叉学科,涉及到多个学科主要包括电磁学和超声学,所以这一部分从电磁学和超声学的角度介绍相关的理论指导。3.这一部分主要是整个系统的硬件电路的设计,主要有三个部分:储能电容充电电路,激励线圈放电电路和脉冲选择控制电路。对充放电系统中激励线圈结构进行设计,使其有多个输出端,从而产生两个或多个间隔可控的具有不同持续时间的连续声脉冲电路系统。并通过检测脉冲电流来做验证。4.本文这一部分用COMSOL Multiphysics对换能器进行建模仿真,分析了换能器振动箔片的振动原理。并结合箔片的电磁激励响应、振幅响应,得出箔片位移和线圈激励电流关系曲线,讨论了振动箔片形变与机械功率和能量转换效率的关系,提出了箔片形变最佳点的概念。本文的设计可以有效的改善现有声脉冲发生器单一不灵活、转换效率低的缺点,对于超声在医疗设备、声空化等领域的发展提供了理论和实践意义。
[Abstract]:Electromagnetic ultrasonic pulse generator is a high power ultrasonic pulse output device based on electromagnetic induction mechanism. Because of its advantages of non-contact, no coupling medium, high resolution and so on, electromagnetic ultrasonic pulse generator is widely used in medical treatment, industrial cleaning, industrial nondestructive testing, etc. Underwater sonar and other fields have been widely used. For example, in the medical application of non-invasive renal calculi and gallstones, a spherical convergent acoustic pulse generator with pulsed magnetic field acting on the spherical curved foil has been used to obtain the highest pressure and reliability coefficient in this ultrasonic pulse generator. However, it is difficult to control the duration of the electromagnetic acoustic pulse generator. Because the number of coil turns is fixed, the pulse time can only be achieved by changing the capacitance in the discharge loop. It can not meet the practical application requirements well, but also has the defect of low conversion efficiency. The performance of electromagnetic ultrasonic pulse generator in China still has a big gap with the international advanced products, so it has very important practical application value to study electromagnetic ultrasonic pulse generator in depth. In view of this situation, this paper focuses on the combination of electromagnetics and ultrasonic, combined with the theory of multiple physical fields. Based on the analysis of the existing electromagnetic ultrasonic pulse generator, the electromagnetic ultrasonic pulse generator with low cost, simple structure, high output power and different duration continuous acoustic pulse is designed from the structure design and principle analysis. The main arrangement of this paper is as follows: 1. The first part of this paper is based on the background of the research, analyzes the current situation of the research at home and abroad, leads to the significance and necessity of the research, and expounds the main research work of this paper. 2. The research of this subject belongs to the interdisciplinary subject, involving many subjects, mainly including electromagnetism and ultrasound, so this part introduces the relevant theoretical guidance from the point of view of electromagnetism and ultrasound. 3. This part is mainly the design of the hardware circuit of the whole system. There are three main parts: the charge circuit of energy storage capacitor, the discharge circuit of exciting coil and the pulse selection control circuit. The structure of excitation coil in charge-discharge system is designed so that it has multiple output terminals, so as to produce two or more continuous acoustic pulse circuits with controlled intervals and different durations. And by detecting the pulse current to do the verification. 4. In this part, COMSOL Multiphysics is used to model and simulate the transducer, and the vibration principle of the vibration foil of the transducer is analyzed. Combining the electromagnetic excitation response and amplitude response of the foil, the relation curve between the foil displacement and the coil excitation current is obtained, the relationship between the vibration foil deformation and the mechanical power and energy conversion efficiency is discussed, and the concept of the optimal point of the foil deformation is put forward. The design of this paper can effectively improve the shortcomings of single inflexibility and low conversion efficiency of the existing acoustic pulse generator, which provides theoretical and practical significance for the development of ultrasonic in medical equipment, acoustic cavitation and other fields.
【学位授予单位】：杭州电子科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN782

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