Introduction To Asynchronous Motors

Introduction

Asynchronous motors are divided into two forms according to the rotor structure: squirrel-cage (squirrel-cage asynchronous motors) and wound asynchronous motors.

Asynchronous motors that operate as electric motors. Because the rotor winding current is induced, it is also called an induction motor. Asynchronous motors are the most widely used and the most demanded of all types of motors. About 90% of the machines powered by electricity in various countries are asynchronous motors, of which small asynchronous motors account for more than 70%. In the total load of the power system, the electricity consumption of asynchronous motors accounts for a considerable proportion. In China, the electricity consumption of asynchronous motors accounts for more than 60% of the total load.

An asynchronous motor is an AC motor whose ratio of the speed of the load to the frequency of the connected grid is not a constant value. Induction motor is an asynchronous motor with only one set of windings connected to the power supply. In the case of not causing misunderstanding and confusion, induction motors can generally be called asynchronous motors. The IEC standard states that the term "induction motor" is actually used as a synonym for "asynchronous motor" in many countries, while other countries only use the term "asynchronous motor" to represent these two concepts.

History

The asynchronous motor was invented in 1885 by the Italian physicist and electrical engineer Ferraris. In 1888, he put forward an experimental report and made a strict scientific description of the rotating magnetic field, which laid the foundation for the future development of asynchronous motors and self-starting motors. Ferraris believed that the rotating magnetic field theory he proposed and the new products he developed had far more scientific value than material value, so he deliberately did not apply for a patent for his invention, but demonstrated these latest developments to the public in the laboratory. results. He also advocated the use of alternating current systems. That same year, Nikola Tesla patented an induction motor in the United States. A year later, Mikhail Dolivo-Dobrovolsky invented the cage induction motor. The development of asynchronous motor is rapid. For the same size asynchronous motor, the rated power has developed from 5.5kW in 1897 to 74.6kW in 1976. Squirrel-cage asynchronous motors are the most widely used asynchronous motors.