Title :
Analysis of a disk-type piezoelectric ultrasonic motor using impedance matrices
Author :
Kim, Young H. ; Ha, Sung K.
Author_Institution :
LG Electron., Digital Appliance Res. Lab., Seoul, South Korea
Abstract :
The dynamic behavior and the performance characteristics of the disk-type traveling wave piezoelectric ultrasonic motors (USM) are analyzed using impedance matrices. The stator is divided into three coupled subsystems: an inner metal disk, a piezoelectric annular actuator with segmented electrodes, and an outer metal disk with teeth. The effects of both shear deformation and rotary inertia are taken into account in deriving an impedance matrix for the piezoelectric actuator. The impedance matrices for each subsystem then are combined into a global impedance matrix using continuity conditions at the interfaces. A comparison is made between the impedance matrix model and the three-dimensional finite element model of the piezoelectric stator, obtaining the resonance and antiresonance frequencies and the effective electromechanical coupling factors versus circumferential mode numbers. Using the calculated resonance frequency and the vibration modes for the stator and a brush model with the Coulomb friction for the stator and rotor contact, stall torque, and no-load speed versus excitation frequencies are calculated at different preloads. Performance characteristics such as speed-torque curve and the output efficiency of the USM also are estimated using the current impedance matrix and the contact model. The present impedance model can be shown to be very effective in the design of the USM.
Keywords :
finite element analysis; impedance matrix; piezoelectric actuators; ultrasonic motors; Coulomb friction; USM; brush model; disk type piezoelectric ultrasonic motor; dynamic behavior; electrodes; electromechanical coupling factors; impedance matrices; impedance matrix; metal disk; no load speed; performance characteristics; piezoelectric annular actuator; piezoelectric stator; resonance frequency; rotary inertia; shear deformation; speed torque curve; stall torque; three coupled subsystems; three-dimensional finite element model; traveling wave piezoelectric ultrasonic motors; vibration modes; Couplings; Electrodes; Finite element methods; Impedance; Performance analysis; Piezoelectric actuators; Resonance; Resonant frequency; Stators; Teeth;
Journal_Title :
Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on
DOI :
10.1109/TUFFC.2003.1256307