In the past 10 years, with the rapid development of power electronics technology, computer technology, automatic control technology, the electric transmission technology is being faced with a history of revolution, namely AC drive replaces DC speed and computer digital control technology to replace the analog control technology has become the trend of development. AC variable frequency speed regulation of motor is a main means of saving electricity, improving process flow, improving product quality, improving environment and promoting technology progress. This provides a huge market and development space for the motor.
Along with the electric power electronic technology, micro motor technology, automatic control theory, the progress of the "electronic control of the motor and has a successful example, the traditional AC and DC drive characteristics, using automatic FM mode, from the fundamental solution to the oscillation, hinder the synchronous motor widely used step, and has high operation efficiency and reliability good, wide speed range, good dynamic response, suitable for the advantages of high speed, harsh environment, has become the symbol of the development of electric drive.

The limitations of the small motor has the following points: (1) the past must have a power transmission mechanism (such as gear box) the volume of the motor increases and the decline in energy efficiency, and to achieve a high speed process needs a certain time. (2) it is difficult for the past motors to take into account both miniaturization and high power output. As a result, research and development of new principles of electrical machinery to meet the new development needs, such as the development of ultrasonic motors.

Previous motors used the interaction of electric current and magnetic field. The ultrasonic motor using the inverse piezoelectric effect of piezoelectric materials have, namely in the alternating electric field, the piezoelectric material will produce expansion phenomenon, through the conversion of all kinds of vibration mode and coupling, the electric energy can be directly converted into mechanical vibration energy, and use the device into operation of the rotary friction or other way. The utility model has the advantages of simple structure, small size, light weight, large volume torque, fast response, no magnetic noise, etc., and has been used in automatic zoom cameras, watches, printers, robots and other fields.

Because of its low temperature and vacuum resistance, the motor has been used in aviation and aerospace fields.

The motor is superior to the traditional electromagnetic motor in continuous motion and precise control field. The motor has the application prospect in the industrial control system, the automobile special-purpose electric appliance, the ultra high precision measuring instrument, the office automation equipment, the intelligent robot and so on.