Research On Resonance Characteristics And Optimization Of High Frequency Ultrasound Therapy Deiver

Ultrasound is widely used in medical,processing,flaw detection,welding,cleaning,emulsification,extraction and other fields.High-frequency ultrasound can produce various physiological effects after it acts on the human body.By using these physiological effects,the unhealthy state of the body can be effectively improved.Therefore,ultrasound therapy has received widespread attention since its appearance.The resonant network has the advantages of low device loss,high power density,strong load capacity,and good electromagnetic compatibility.Inserting a resonant network between the piezoelectric transducer and the switching circuit can improve the operating characteristics of the system and make the system insensitive to changes in temperature and mechanical parameters.In view of the shortcomings of high cost,waveform distortion and power nonadjustability of existing ultrasonic physiotherapy products,an overall structure of the ultrasonic physiotherapy driver is designed and each module in the architecture is selected.The designed ultrasonic driver operating frequency is around 1 MHz.An electrical model of the ultrasonic transducer was established.An impedance matching network to compensate is designed for the effects of static capacitance.Aiming at the complex topology of the resonant network,the three-element resonant network is classified,and all the topologies are classified into two types of models.The feasibility of different topological structures under different input and output excitations is summarized.The working characteristics of four common two-element and three-element topologies are analyzed.LCC is selected as the resonant network module of the driver.The ultrasonic driver circuit model based on LCC resonant network is established,and the working characteristics of the resonant network are analyzed from the time domain.The effect of switching frequency on the working mode of the resonant network is studied.The state trajectories and state equations are given.Various ways of controlling power in the switching circuit are analyzed and the power control scheme of the circuit is designed.Aiming at the complex parameter design process of the existing ultrasonic driver resonant network,a multi-objective optimization model of the resonant network aiming at the output voltage and the input impedance angle is established.Using genetic algorithm,a set of optimal solutions of the resonant network is obtained.Simulation experiments are preformed to verify that the optimized results meet the requirements.The experimental platform was built and the software and hardware system was developed.An ultrasonic physiotherapy instrument driver was successfully fabricated.The voltage waveform of each node was collected by an oscilloscope.Through experimental tests,the ultrasonic driver can be safely and stably operated.