Low Voltage Driving Ultrasonic Motors Based On Multilayer Piezoelectric Ceramics

The development of aerospace, microelectronics, optoelectronics, and high-tech weapons requires high performance of motors. Traditional electromagnetic motors can not meet the needs. These areas call for a new generation of motors. Piezoelectric ultrasonic motor with high efficiency, simple structure, and miniaturization has been rapidly developed in the past two decades and has many successful applications. However, ordinary ultrasonic motor has high driving voltage, so that the system must be complex, even needs transformers which limits the development of ultrasonic motors. Therefore, lower driving voltage, simple structure has been focused.This thesis has designed, fabricated and tested a new ultrasonic motor with low driving voltage based on multilayer piezoelectric ceramic. Use a disk-type structure through the stator tooth and rotor surface to drive. The spring provides preload between them. Four multi-layer piezoelectric ceramics serve as the actuator. The vibration is tested using the Doppler Laser Vibration Testing method. B(0,3) and B(0,2) were chosen the best work for the motor mode.Piezoelectric ceramic is prepared using the dry trapping technology, and Pb(Mg_1/3Nb_2/3)O₃-Pb(Ni_1/3Nb_2/3)O₃-Pb(ZrTi)O₃ low co-firing ceramic powder. The structural parts use CNC techniques with CAD drawing and output tools. Use the standard 59Cu for metal parts. Preparation of test batches of motors were optimized, the final stator motor made of high 1mm, disc thickness 0.3mm, and the overall size ofφ9mm×16mm. Using laser Doppler Vibrometer tests the mode of stator surface vibration spectrum, and then get the motor vibration mode and its resonant frequency. Experiments show that the test result matches the theoretical design well. Pre-pressure, voltage and other factors have effect on the output torque. Experiments show that the motor with no load can drive under 5V_p-p, and can be obtain the best output torque at 1.8N and 15V_p-p. The best output torque is 1.2mNm. Experts group and patented searching shows that the structure with low driving voltage of 5V_p-p performs to a leading level.