Design And Research Of Piezoelectric Ultrasonic Traveling Wave Motor Based On PZT Film

Micro Ultrasonic Motor(USM)is a new type of motor which is designed and manufactured by MEMS technology.It has the advantages of small size,rapid response,high torque at low speed,low noise,strong anti-electromagnetic interference and selflocking ability,and thus has a broad prospect in the field of aerospace,precision rotor positioning system and biomedical applications.The USM uses the inverse piezoelectric effect of the piezoelectric material to produce ultrasonic vibration of the stator under the drive of AC voltage,and drives the rotor to rotate through the friction force between the stator and rotor to realize the torque output of the motor.Since the stator is in a state of continuous vibration during the operation of the motor,it is one of the important tasks in the design of high performance USM to study the energy loss in the process of stator vibration.Traveling wave ultrasonic motor(TWUM)was selected as the object in this paper.The vibration characteristics of stator under different modes was intensively studied by theoretical derivation and finite element method,and it indicated that the energy loss mainly was attributed to the anchor damping dissipation of support structure in the vibration process,and a new design method of motor support structure and stator structure was proposed to reduce the energy loss in motor work and improves the quality factor of stator vibration.Finally,the prototype of TWUM was fabricated by chemical deposition and deep reaction ion etching.The TWUM designed and manufactured is the smallest traveling wave type USM in the world.The main contents of this paper are as follows:The first chapter investigates the development of USM and the present research situation at home and abroad which pointing out the challenge of ultrasonic motor research,and then puts forward the research target of this paper.In the second chapter,the concepts of piezoelectric effect and vibration mode were introduced,and the characteristic parameters of PZT ceramics are deduced and calculated.At last,the generation process of traveling wave in stator and the mechanism of electromechanical friction coupling drive and the motion path of contact point were deeply analyzed.In the third chapter,the advantages and disadvantages of disc and ring stator structure were compared,and the design scheme of USM support structure and stator was given.The influence of structure parameters(such as substrate thickness,PZT film thickness and support beam width)on stator performance was analyzed.In the fourth chapter,the modal,steady state and transient analysis of the ultrasonic motor stator based on PZT thin film was carried out by using the finite element software.The stator dynamic characteristics under different driving voltages were compared,which provides the basis for the optimization and design of the TWUM.The fifth chapter briefly introduces the manufacturing process of the ultrasonic motor stator.The prototype of the ultrasonic motor has been made,testing and analyzing the performance of the motor has been finished also.The sixth chapter summarizes the full text,and introduces the research results of this paper and arranges the next research work,then puts forward the problems needing attention in the future.