电磁超声脉冲激励系统设计

Design of Electromagnetic Ultrasonic Pulse Excitation System

为了更好地解决电磁超声检测技术换能效率低的问题,在对当前已有的激励系统进行调查研究的基础上,设计了一种新型的电磁超声脉冲激励系统。该系统可以针对不同的检测对象,设定频率、脉冲个数、相邻两组脉冲的间隔时间等参数。在设计中,采用了现场可编程门阵列(FPGA)提供控制信号,采用光电耦合器对前后端系统电气隔离、全桥逆变技术,对输入信号进行直流到交流的变换,并且可以实现较大的功率输出。同时,基于线圈和涡流场的相互耦合作用,设计了由单层完全相同的线圈组成的堆积线圈,完成换能器的阻抗匹配。为了控制处于活跃状态线圈的阻抗值,可根据实际阻抗灵活选择线圈的个数从而实现阻抗匹配,解决了电磁超声换能效率低的问题。试验结果表明,该设计达到了预期的设计目标,为进一步研究电磁超声检测技术提供了参考,具有一定的推广价值。

In order to better solve the problem of low transduction efficiency of electromagnetic ultrasonic detection technology,on the basis of investigation and research on the existing excitation system,a new type of electromagnetic ultrasonic pulse excitation system has been designed.With this system,the parameters such as frequency;number of pulses;and interval between adjacent two groups of pulses can be set for different detection objects.In the design,the field programmable gate array(FPGA)is used to provide control signals,the optocoupler electrically isolates the front and rear end systems,and the full-bridge inverter technology converts the input signal from DC to AC,and achieves large power output.In addition,based on the mutual coupling of the coil and the eddy current field,a stacked coil composed of single layer of identical coils is designed to complete the impedance matching.In order to control the impedance value of the coil in the active state,the number of coils can be flexibly selected according to the actual impedance to achieve impedance matching,thus the problem of low transduction efficiency of electromagnetic ultrasonic transducers is solved.The test results show that the design achieves the expected goals and provides a reference for further research on electromagnetic ultrasonic testing technology,which has certain promotion value.