Research on Frequency Regulation Characteristics of a Bar-Shaped Piezoelectric Motor Driven by in-Plane Bending Modes

Abstract

Machining errors and change of temperature cause frequency difference between two operating modes of piezoelectric motors to become larger. The motor efficiency drops dramatically. To address this problem, frequency adjustment features of a classic piezoelectric motor are researched. The motor is driven by a composite stator including a hollow metal cylinder whose outside surface is symmetrically flattened. Four PZT plates are bonded onto outer surfaces of metal. A PZT plate is used to simultaneously excite two bending modes. Other floating PZT plates, frequency adjustment elements, connect to external loads. To discuss influences of additional electric loads on frequency difference of two vibration modes, motor dimensions are carefully designed. Frequency regulation mechanism is analyzed by discussing electrical and mechanical properties of piezoelectric motors. To verify frequency regulation principle, a prototype motor is assembled and tested. The frequency difference is initially 0.730 kHz, and can be maximally adjusted to 0.216 kHz.