The Research Of An Ultrasonic Generator Based On The Symmetric Automatic Steady Speed Control Method

As a kind of the simplest MEMS devices, microcantilever was firstly used in SFM and AFM as a tool to measure surface morphology or small force. Recently, microcantilever has also been widely used for chemical and biological detection due to their advantages of reduced size, high sensitivity, fast response and low costs. Microcantilever has two kinds of operational mode: static mode and dynamic mode. The microcantilever with functionalized surface can be used to biological and chemical detection by detecting its static deflection or change of resonant frequency.Based on the comprehensive analysis of researchs in frequency tracking and method of steady speed control of the ultrasonic generator at home and abroad, then point out that the traditional constant-current method for stablizing vibration speed of transducers has a problem that ultrasonic transducer and generator will be overcurrent, Aiming at this problem, according to the mechanical and electronic equivalent circuit of the transducer, this paper analyzes the reason of overcurrent of the traditional constant-current method for steadying speed. And then in order to help solve the problem the paper puts forward a novel method for steadying vibration speed of transducers, namely the asymmetric automatically steadying vibration speed method. This method is also by keeping the current of transducers constant to steady vibration speed of transducers, but different to the traditional constant-current method that frequency tracking first and then adjusting incentive voltage, this method in the process of frequency tracking, simultaneously regulates the incentive voltage of transducers, and sets that the adjusting speed of increasing incentive voltage is far less than the speed of frequency tracking, the adjusting speed of decreasing incentive voltage is much faster than the speed of frequency tracking, in order to avoid or reduce the overcurrent during the adjustment when the load of the transducer changes. That is, through the asymmetric adjusting speed of the transducer incentive voltage to inhibit the flow of the transducer current during the process of steadying the vibration speed of the transducer.Then analyze the traditional constant-current method for steadying speed and the asymmetric automatically steadying vibration speed method proposed by this paper respectively by simulation using Matlab, to verify the superiority of the asymmetric automatically steadying vibration speed method proposed by this paper.Finally an ultrasonic generator based on the method is designed, and is taken as the core of an experimental platform which is built for testing the performance of ultrasonic generator. The performance mainly includes performance of automatic frequency tracking performance and performance of automatically steadying speed.