Asynchronous electric motor: what it is, types, application

An asynchronous motor is a detail that finds wide application not only in production equipment, but also in household appliances. Designers have developed several types of asynchronous motors. Their device and principle of operation have their own features.

Induction motor and its types

The motor is called asynchronous, because its rotor produces rotational movements slower than the magnetic field of the stator. The latter is a stationary element of a generator or electric motor. The rotor is responsible for the movement of mechanisms.

The stator consists of a housing, and its ends are covered with bearing shields. The format of the bearings is sliding or rolling. It depends on the purpose and power indicator of the motor. Inside the housing there is a core with a winding.

According to the type of rotor, the devices are squirrel cage and phase. The squirrel cage rotor has no brushes and windings and is easier to maintain. The phase rotor is provided with windings, and metallographic brushes are needed to remove current from them. In terms of torque control on the shaft and smooth reduction of inrush current, the phase rotor is preferable. Short-circuit and overheating protection is often included.

In addition to the type of rotor, induction motors are characterized by such factors:

• The number of supplying phases.
• Method of installation.
• Mode of operation.

As for the number of supply phases, a distinction is made between single-phase and two-phase, as well as three-phase electric motors. The first two types are used in the home, since they are designed for connection to the 220 V network. Three-phase motors are more often used by workshops and production plants. The design is attached to the flanges. The motor works in continuous, short-term or repeated-short-term modes. Start-up and shutdown are usually automatic.

Principle of operation and advantages of the induction motor

Smooth start and reduction of inrush currents - the device solves these two main problems by increasing the rotor resistance.

• The magnetic field arises as a consequence of the current in the stator windings.
• It is the cause of the current in the rotor and therefore the magnetic field around this element.
• The rotation of the stator field is followed by the rotation of the rotor field.

Asynchronous motors have compact dimensions and simple construction. This applies to a greater extent to squirrel cage models. Devices with phase rotor have better start-up and the ability to adjust the speed due to the added resistance in the circuit, but at the same time their cost is at least one and a half times higher.

Applications

Single-phase induction motor is in many household appliances of low power, in construction and power tools. The drive is equipped with:

• Concrete mixers.
• Fans.
• Extractors.
• Some models of lawn mowers.

In industrial equipment it is used for automatic gate valves, cranes, winches, compressor and ventilation systems, pumps, machines for processing wood and metal. Asynchronous motor is used for modern electric transportation - bicycles, electric cars, scooters.