English: ultrasonic motor
Because the excitation element is piezoelectric ceramic, it is also called a piezoelectric motor. The ultrasonic motor (USM) developed in the mid-1980s is a new type of driver that is driven by ultrasonic frequency vibration of functional ceramics. The ultrasonic motor is a typical electromechanical integration product, consisting of the motor body and the control drive circuit. The products involve many fields such as vibration science, wave science, materials science, tribology, electronic science, computing technology and experimental technology. Ultrasonic motors break the concept of traditional motors that obtain speed and torque from electromagnetic effects.
Compared with traditional motors, it has the following characteristics and advantages: low speed and large torque output; high power density; good start and stop control; can achieve direct drive; can achieve precise positioning; can be easily made into linear motion type motor; low noise: no electromagnetic interference and no electromagnetic interference; need to use wear-resistant materials (contact type USM) and high-frequency power supply, etc. But it also has its own shortcomings, such as: low power; short life, etc.
The two distinctive features of ultrasonic motors are: 1) Large torque output at low speed: 2) Large holding torque, with good start-stop controllability. The ultrasonic motor can output high torque because the excitation element uses piezoelectric ceramic materials with high power density. The torque of ultrasonic micromotors of the same size is 3-4 orders of magnitude higher than that of electrostatic micromotors: 1.2 orders of magnitude higher than that of electromagnetic micromotors, and the output speed is also lower than other types of micromotors. The holding torque of the ultrasonic motor is at least twice the maximum output torque. The large holding torque is because the friction between the stator and the rotor of the motor drives the rotor. Due to the above characteristics, the system connected to the ultrasonic motor does not require a gear reduction mechanism and a braking mechanism, simplifying the structure of the application system. Ultrasonic motors have attractive application prospects and have become a hot spot in research. Specifically, there are the following aspects: information machines, optical instruments, micro-robots, medical machines, detection systems, precision machining, etc. The development trend of ultrasonic motors is: high torque, small size, high efficiency and long life.