Analysis And Experimental Research On Key Factors Affecting The Stability Of Ultrasonic Motors

Ultrasonic motor has a wide range of applications in many driving fields because of advantages such as simple and compact structure,small weight,small volume,large power failure retention,no electromagnetic noise and electromagnetic interference.But due to the nonlinearity of stator vibration during motor operation.The nonlinearity of the friction drive and other factors make the motor unstable during operation,which limits the application of its products.This topic comes from the research project of China Academy of Space Technology“Study on Light and Small Piezoelectric Ceramic Drive System for Micro-nano Satellite” and the “Study on Stability of Traveling Wave Rotary Ultrasonic Motor” in Hebei Province.The subject focuses on the key influencing factors of ultrasonic motor stability to carry out in-depth research on traveling wave rotary ultrasonic motor.The main contents and research results are as follows:(1)Analysis of key influencing factors of ultrasonic motor stability: From the perspective of ultrasonic motor structure design,material selection,stator elastomer and piezoelectric ceramic sheet cementation,temperature rise,the influence of various parameters on the stability of ultrasonic motor is studied.Electromechanical coupling analysis and stability studies provide direction.(2)Theoretical research on ultrasonic drive: The formation of traveling wave on the stator surface,the polarization partitioning and driving excitation of the piezoelectric ceramic sheet,and the operating mechanism of the stator surface mass driving the rotor are described in detail.It is clear that the stator amplitude is used as the rotor speed.Performance indicators lay the foundation for electromechanical coupling finite element simulation and optimization.Based on the Hamilton principle and based on the theory of vibration,the dynamic substructure method and the finite element method are used to analyze the electromechanical coupling of the stator.The electromechanical coupling equation of the stator assembly is obtained,which provides a theoretical basis for finite element simulation.(3)Electromechanical coupling simulation and optimization: finite element simulation of the process of electric energy to mechanical energy transformation induced by piezoelectric ceramic sheets,and respectively for stator elastomer thickness,tooth depth,stator elastic rib thickness,piezoelectric ceramic sheet The thickness,the division mode of the piezoelectric ceramic piece,the bonding method of the stator elastic body and the piezoelectric ceramic piece and the thickness of the rotor rib are simulated.The influence law of the stator-rotor structureon the electromechanical coupling is obtained,and the optimization of the stator-rotor structure is realized.The optimization results show that the modal aliasing phenomenon is improved,which provides a basis for prototype development.(4)Test and experimental research: Based on theoretical analysis and simulation results,the prototype machine was researched and fabricated.The vibration mode test was carried out on the structure before and after optimization by laser vibrometer,and the correctness of the finite element simulation mode separation result was verified.The cementation test of the piezoelectric ceramic piece and the stator elastomer was completed by controlling the cementing material,the pressing amount and whether the exhaust gas was designed.The impedance analyzer was used to analyze the performance before and after cementing,and a better bonding process was selected.The speed stability test of the ultrasonic motor is carried out,and the influence law of temperature rise on the stability of the motor is obtained.Through structural improvement and temperature closed-loop control,the speed stability of the ultrasonic motor is significantly improved.