Analysis of a disk-type piezoelectric ultrasonic motor using impedance matrices

• Published in: IEEE transactions on ultrasonics, ferroelectrics, and frequency control Vol. 50; no. 12; pp. 1667 - 1677
• Main Authors: Kim, Y.H., Ha, S.K.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.12.2003; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Computational techniques; Couplings; Electrodes; Exact sciences and technology; Finite element methods; Finite-element and galerkin methods; General equipment and techniques; Impedance; Impedance matrix; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Mathematical analysis; Mathematical methods in physics; Mathematical models; Matrices; Matrix methods; Performance analysis; Physics; Piezoelectric actuators; Piezoelectricity; Resonance; Resonant frequency; Stators; Studies; Teeth; Transducers; Vibration analysis; Numerical method; Electromechanical coupling; Micromotors; Finite element method; Three dimensional model; Travelling waves; Ultrasonic motors; Piezoelectric transducers; Resonance frequency; Disks; Coupling factor; Modelling; Impedance matrix
• ISSN: 0885-3010; 1525-8955
• DOI: 10.1109/TUFFC.2003.1256307

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.