Research On Dynamic Maching Of The Ultrasonic Transducer

Ultrasound transducer systems are widely used in industrial production, such as electronic packaging industry and ultrasonic processing industry. Generally, high power ultrasonic equipment must have a matching circuit, but most of the current matching circuit using static matching circuit, which is studied in the system without any load. In fact, in the process of the transducer, the change of the parameters of the transducer is influenced by the temperature change, load change and the tool wear and it will lead to the failure of static matching. The problem of reactive power generation, vibration amplitude reduction will be caused. Obviously, the static matching is not suitable for long-term operation of high power equipement. So the whole work is aimed to dynamically match the ultrasonic system to adapt to the change of the parameters of the transducer.The impedance model is established based on the equivalent circuit method. The matching circuit is studied by using the series inductance to offset the capacitive characteristics of the transducer. Mathematical models of the various parts of the ultrasound transducer system are established and the simulation model is built by MATLAB/Simulink. The relationship between the equivalent parameters of transducer and matching parameters is achieved and the law is verified by simulation. It is deduced that the change of dynamic resistance parameters of the transducer has a great influence on the value of the matching parameters. Based on the law and the effect of the matching parameters on the phase difference, the feasibility of dynamic matching circuit is proposed.The design of dynamic matching scheme is based on the number of adjustable inductors. The dynamic matching circuit is built based on the STM32 platform and the matching inductance value is calculated according to the matching parameters and the variation of the parameters of the transducer. Transducer impedance was obtained by on-line detection method. The phase difference of the control signal is measured by zero crossing comparison method with high accuracy. Information processing and relay switch matching inductors are controlled by ARM. Real time dynamic matching of ultrasonic system is realized by continuous detection.The fuzzy adaptive PID controller is adopted to control the frequency of the ultrasonic system in the dynamic matching, and the accuracy of the system is improved. Based on MATLAB fuzzy toolbox and Simulink simulation platform, a Simulink simulation model is built based on the dynamic matching frequency tracking control algorithm. The simulation analysis of the frequency tracking speed of the system when the system switches between different inductors can reach 0.2 ms, and the dynamic matching effect of the system is improved.Based on the hardware platform and the simulation analysis of the controller, the switch of different inductance of the ultrasonic system is tested, and the analysis is carried out in the condition of no-load and load. The experimental results show that the phase difference of the dynamic matching circuit can be maintained at 0?and the dynamic matching of the ultrasonic system can be met.