Design And Manufacture Of 300W High Frequency Ultrasonic Power Supply And Control System

Pathological examination can provide histopathological diagnosis basis for clinical diagnosis,scientific research and the discovery of new diseases,and can make clear histopathological diagnosis for the vast majority of clinical cases submitted for examination,so it is regarded as the"gold standard"of clinical practice.The preparation of paraffin sections is the first and key step in pathological examination.According to the traditional tissue treatment process,the treatment time of the pathological tissue cells is too long,which will result in the delayed diagnosis of the pathology.Relevant studies have shown that under the action of specific frequency and power ultrasonic field,cell membrane surface will have sound hole effect,which changes the permeability of cell membrane and provides the possibility for greatly shortening the treatment of pathological tissue.So the design and manufacture a conform to the conditions and to maintain the sound hole effect of high frequency ultrasound power supply system,in conjunction with the particular reagent,provide clinicians with a rapid means of preparation of pathological tissue section,to mass diseases such as cervical cancer screening,pathological diagnosis provides the necessary equipment in the process of operation security.In this paper,based on the requirements of the subject,high-frequency ultrasonic power supply as the research object.Firstly,two kinds of power amplifier circuits used in digital amplifier are compared and analyzed,and the full-bridge circuit is selected as the power amplifier circuit of the system.Secondly,according to the working process of the system,the hardware circuit and software program of the power supply circuit,signal source circuit,PWM driver circuit,acceleration circuit,inverter circuit,booster circuit,current sampling circuit are analyzed and designed.In view of the drift of resonance points when multiple transducers are in parallel,the impedance analysis of the equivalent model of the ultrasonic transducer is carried out,and the parallel resonant frequency of the six 50W ultrasonic transducers is determined to be216KHz.Finally,after the simulation test of the software system,the PCB board was designed and welded and debugged according to the wiring rules of the PCB board diagram.After testing,the output signal frequency of the signal source circuit is 216KHz,the dead zone time is more than 58ns,the duty cycle is the same,and the phase is complementary.The peak voltage at both ends of the ultrasonic transducer is 245V,and the"sizzle"sound of the transducer during normal operation can be clearly heard.During the experiment,in order to further explore the optimal ultrasonic power density of cell tissue processing,the signal acquisition and processing circuit was designed as the core feedback circuit of the system to amplify,filter and discretize the collected cavitation signal.The complex sound field contains fundamental frequency,subharmonic,higher harmonic,continuous noise and other signals.Related studies show that with the increase of power density,the subharmonic signal will not be drowned by the background signal,so the subharmonic detection method is adopted to detect the cavitation state.However,the traditional subharmonic detection method is carried out under the condition of stable cavitation or transient cavitation with high ultrasonic power density,and the cavitation region studied in this paper is the critical cavitation region with ultrasonic power density far lower than the stable cavitation region.When the traditional subharmonic detection method is used to detect the region,the amplitude of a single subharmonic signal becomes unstable,which is not enough to characterize the cavitation state of the region.Therefore,based on the traditional subharmonic detection method,this paper takes multiple subharmonic signals as feature vectors and combines them into new combined feature vectors under the corresponding parameters,so as to realize the cavitation state representation of critical cavitation region.Finally,the idea of k-means clustering division was used to cluster multiple subharmonic signals in different states,and the optimal ultrasonic power density value of tissue processing was obtained to be 1.05w/cm~2,which was fed back to the signal source circuit to adjust the output power,so as to achieve the purpose of rapidly preparing high-quality pathological tissue sections in the optimal state.