Asynchronous motors are called induction motors, they represent the majority of the electric motors that exist in the market. These motors have a short-circuit rotor, that is to say, formed by aluminum bars that are installed in the cores of the grooves of the magnetic plate and at the ends are connected to each other by means of a ring (short-circuit ring). Because of this, the variable magnetic field created in the stator induces sinusoidal currents in the rotor cage bars, which in turn creates a magnetic field in the rotor that opposes the stator field. They may also have a coiled rotor, and this feature is less commonly used.
Since poles with the same polarity repel each other, we have the beginning of a force in the direction of rotation of the rotor. This rotates with a speed a little slower to the speed of synchronism and because of this characteristic, this type of motors can start directly from the network, without help of any other motor or even of devices of power electronics. An important aspect of this type of motors is the difference between the speed of synchronism and the speed rotor, called slip or slip vm3538.