Driver Circuit Design of a Circular Ridge-wave Ultrasonic Motor

• Main Authors: Jhang,Yun-Jyun, 張昀竣
• Other Authors: Yu,Tai-Ho
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/28979096302943593965

碩士 === 國立聯合大學 === 電子工程學系碩士班 === 105 === This thesis aimed to design and compare two types of ultrasonic motor-driven circuits, and to determine the optimal resonant frequency for these ultrasonic motors with the help of the ANSYS simulation analysis tool. ANSYS was first used to build the finite element model (FEM) of an ultrasonic motor stator. This model had 20,935 elements and 25,712 nodal points. Next, the stress changes that the model undergoes when it is in its static, transient, and steady states were analyzed based on the ultrasonic motor stator's boundary conditions and load. Two-phase electrodes (A and B), which were produced by grinding carried out on the outer surface of a 2mm-thick piezoelectric tube, were then pasted onto a stainless steel base, thus creating an ultrasonic motor stator. The F(1,4) flexible traveling wave mode was excited on the motor stator's ridge when the drive circuit’s resonance frequency was 35.04 KHz. The mode changes from static to transient, and then toward a steady state, so as to allow the traveling wave to drive the rotor's positive and reverse rotations. The design of the drive circuit prioritized the phase separation of the original signal's waveform (the signal lagged by 90°), as this was the key to determining the positive and reverse rotations of the ultrasonic motor. With a TLP250 isolation driver IC and L6384E high voltage half bridge driver IC serving as the cores, a comparison was made and circuits were integrated, including interlock circuits, half-bridge inverters, and LLCC series-parallel load-resonant converters. To determine the ultrasonic motor stator's resonance frequency, the HP 4194A impedance analyzer was used to measure the stator's resistance curve and equivalent circuits, while the admittance curve generated from the PASCO 850 was used to verify the figures. The performance test for the ultrasonic motor showed that the L6384E-based drive circuit performed better, achieving a maximum drive voltage amplitude of 200 Vpp, a drive frequency of 35.04 KHz (with preload below 1Nt), a maximum torque of up to 22.6 mN-m, a maximum speed of 334 rpm, and a 25% increase in electromechanical conversion efficiency. The simulation and actual measurement results were consistent, confirming that the ultrasonic motor-driven circuits designed in this study have achieved their objectives.