Enhancement of ultrasonic effect on work medium in technological systems by means of optimizing the electric matching mode

The article is devoted to the problem of increasing the operating effectiveness of ultrasonic technological systems by means of optimizing of electric matching between electronic generator and ultrasonic oscillatory system under the alternating properties of work medium in width ranges during technological processes. Results of studies in providing a new method of automatic control of optimal electric matching between electronic generator and ultrasonic oscillatory system are presented. The proposed method and its practical realization provide effective ultrasonic action on work media even through medium properties varies during technological process. In the introduction it is denoted that operating effectiveness of up-to-date ultrasound technological systems is less than it potentially possible. In the first part it is shown that potential efficiency of electronic generators is 92-97%, potential efficiency of piezoelectric oscillators is 80% and potential efficiency of completed ultrasonic device is about 76%, but efficiency is less in practice. It is evident that low efficiency is incomplete energy transfer from electronic generators to oscillatory system is mainly caused by non-optimal electrical matching between electronic generators and piezoelectric ultrasonic oscillatory systems. In the second part the problem of electric matching between electronic generators and ultrasonic oscillatory systems is analyzed. Ultrasonic oscillatory system is substituted with equivalent electrical circuit using Masons method. It is shown that input electrical impedance and resonant frequency of oscillatory system depend on parameters of work medium. Two types of electrical matching networks that are connected between electronic generator output and oscillatory system input are described. The optimal matching conditions for each type of electrical matching network are defined. It is shown that optimal electrical matching condition may be provided only if parameters of electrical matching circuit are adjusting in accordance with alternating parameters of work medium. The phase shift between voltage and current at output of electronic generator can be used as quantitative degree of electric mismatch. The dependence of power losses in output transistors of electronic generator from phase shift between output voltage and current is derived. The results of experimental studies that provide determining a range of variation of the electric parameters of oscillatory system in accordance with work medium properties variation are described at the end of second part. These experiments confirm impossibility to provide optimal electrical matching using non-regulated electrical matching circuits. The third part describes new method for maintaining optimal electric matching between electronic generator and oscillatory system in a width range of work media properties alternating and practical realization of this method. The practical realization is based on an automatic control of electrical matching circuits parameters.