In a piezoelectric motor, electrical energy is converted into mechanical energy through the piezoelectric effect. The piezoelectric effect is a phenomenon where certain materials, known as piezoelectric materials, can generate an electric charge in response to mechanical stress or pressure, and conversely, they can change shape or deform when subjected to an electric field.
The basic components of a piezoelectric motor include a piezoelectric material, an actuator, and a rotor or load. When an electric voltage is applied to the piezoelectric material, it causes the material to deform due to the piezoelectric effect. This deformation generates mechanical motion, and the actuator attached to the piezoelectric material translates this motion into rotational or linear movement, depending on the motor's design.
There are mainly two types of piezoelectric motors: ultrasonic motors and piezoelectric actuators.
Ultrasonic Motors: Ultrasonic motors use the concept of standing waves to generate rotation. They consist of a piezoelectric material sandwiched between two metal plates (usually called stators) with a specially shaped rotor attached to the central axis. When an alternating current (AC) voltage is applied to the piezoelectric material, it expands and contracts, generating ultrasonic vibrations in the stators. These vibrations create standing waves in the stators, which, in turn, cause the rotor to rotate.
Piezoelectric Actuators: Piezoelectric actuators are used for linear motion applications. They typically consist of a piezoelectric material attached to a flexure mechanism. When an electric voltage is applied to the piezoelectric material, it expands or contracts, causing the flexure mechanism to bend. The bending motion results in a linear displacement, and this movement can be harnessed for various purposes, such as precision positioning in optical instruments, nanopositioning stages, and more.
The key advantage of piezoelectric motors lies in their compact size, high precision, and fast response. They can operate silently and are often used in applications where traditional electromagnetic motors may not be suitable due to size, noise, or precision constraints. However, they generally have lower torque compared to conventional motors and are more suitable for low-load and high-precision applications.