The Study Of Electromegnatic Shock Wave Generator

The shock wave is the pressure rapidly changing product,withshort-term, high-speed and high-pressure three characteristics. Due to thecharacteristics of its occurrence way, the shock wave has strong tensile andcompressive stresses and it can easily penetrate any elastic medium, theshock wave has been widely used in all aspects of life.For some of the problems of the shock wave sound pattern, such as anexplosion shock wave energy source is not easy to control; piezoelectricshock wave source power is difficult to improve due to the restrictions of thepiezoelectric material withstand conditions; electrohydraulic shock wavesource electrodes require frequent replacement; The energy of existingelectromagnetic shock wave source is small, and it is also easy toshort-circuit. This paper presents a new kind of electromagnetic shock wavegenerator which is based on the mature electromagnetic induction principleand the excellent characteristics of the shock wave. Seven aspects arestudied in this paper,covering theory, design and experimental study:(1)Two transducers which consist of Static magnetic field weredesigned in this paper: transducer A and transducer B. Except that the structural design were different between the two transducers, the thicknessof transducer A vibrating plate is0.2mm,with the transducer B0.16mm.The two types of transducers were formed by the vibration system, amagnetic circuit, supporting portion, and the fixed portion. The vibrationsystem mainly consists the vibration coil and the vibrating plate. Thequality of the vibration coil was controled so that the quality of the vibrationsystem was mainly a quality of the vibrating plate. The vibration coil in theexternal magnetic field coil was put through AC and then operated bymagnetic force.The vibration coil with magnetic force can promote thevibrating plate and then a shock wave was produced with enough power.(2) Since the transducer vibrating plate is a thin metal plate, thevibration theory model of the transducer vibration system was found basedon the Vibration Equation (Young’s modulus becomes equivalentE12) andthe relationship between overtones frequency and baseband of a thin aroundembedded circular plate.(3) Excitation source was designed for transducer A and B, theexcitation source comprises a power management control circuit, theswitching circuit, the boost circuit, the charging circuit and the LCoscillating circuit. And in accordance with the principles of the circuitdebugging,the designed excitation source was debugged.(4) In theory, when the excitation frequency is the same with thevibration system fundamental frequency (f1) or coincide with the Pan-frequency fn,the largest vibration amplitude and intensity of thevibration system can beobtained, and the mechanical and electricalconversion efficiency is the highest. The overtone of the vibration system isvery important. It’s very difficult to obtain the positive frequency of thetransducer by theoretical or numerical methods,the calculated basebandvalue of the vibration plate as reference, the actual fundamental frequency ofthe transducer vibration system value was obtained by measurement method.Based on the measured fundamental frequency and vibration systemvibration model, Electromechanical coupling was established between thetransducer and the excitation source with resonant principle,and thefrequency of the LC oscillator circuit, the used inductance L and the usedcapacitance C values were obtained.(5) Appropriate detection means should be selected, respectively, on thetransducer A,and B transducer excitation current detection; detection onthe vibration plate impact vibration signal; detection on the impact acousticsignal of transducer B simply. Shown as the detection result, the excitationcurrent strength is high enough to guarantee the high-power drive capability;the transducer B is more suit to the vibration modle of the vibration system.The sound pressure generated is considerable tested by level meter totransducer B.(6) Prior to the test on a small resistor in the excitation source, only thepositive pulse was detected, a negative pulse was not detected, perhaps because the drive capability of IGBT was not enough.Therefore anumber of attempts were made to the excitation source so that Sasser-shapedcan be detected. Four methods were tried to improve the driving capability ofthe excitation source and excitation signal were also detected. The newcircuit of the excitation signal was improved.(7) Based on the idea of reducing costs, air core inductors transducerswithout applied magnetic field were made, and then the excitation signal wasdetected and the intensity of vibration of the vibrating plate was obserbedafter the simple matching."mover" and "stator inductance coil involved inthe LC oscillator circuit in the air-core inductors transducer,which resulted inthe problems such as inductor series and parallel, the same name as the endof the string and synonym end of the string. The results showed that thevibration intensity was weaker than the intensity with magnetic field; thedifference is not obvious between the use of the same name as the end ofthe string and the synonym end of the string; the shock current strength inthe flat wire is stronger than the strength in the round wire.In this paper, the principle of electromagnetic shock wave generator isreliable, and,it’s easy to design and use it, design method is feasible byexpetiment results. The generator will have a high biological value afterin-depth study, which can be considered for use in physical therapy andproviding high sound pressure environment, there is a good applicationprospect.