Piezoelectric motors

In addition to the materials traditionally used in electrical machines, active materials are characterized by their ability to produce a mechanical action resulting from their own deformation under the effect of a generally reversible coupling of an electroelastic (electrostriction, piezoelectricity), magnetoelastic (magnetostriction, piezomagnetism) or even thermoelastic (shape memory alloys) type. Recent advances in this field have paved the way for a new generation of electric motors, grouped together under the name of piezomotors. The operating principle of these actuators is based on the alternating deformation of a fixed elastic structure based on active materials, capable of imparting a uniform driving motion to a moving part by friction. While motors based on magnetostrictive or shape-memory metal alloys are still in the field of research, piezoelectric motors are already an effective alternative for certain applications.

After a brief review of the electromechanical conversion of energy by the piezoelectric effect, this article analyzes the general principles underlying the operation of piezomotors, and then highlights the different families of piezoelectric motors. As the field is relatively new and still evolving, the overview of the most representative structures presented in 2 is by no means exhaustive. The reference structure, the ring-shaped travelling-wave motor, is then examined in greater detail at 3 . Finally, the specific problem of powering and controlling piezoelectric motors is addressed 4