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Motor classification

 

Depending on the purpose, on the expected operating modes and conditions, on the type of power supply, etc., all electric motors can be classified according to several parameters: by the principle of obtaining the operating moment, by the method of operation, by the nature of the supply current, by the method of phase control, by type of excitation, etc. Let us consider the classification of electric motors in more detail.

AC electric motor

Occurrence of torque

Torque in electric motors can be obtained in one of two ways: by the principle of magnetic hysteresis or purely magnetoelectric. Hysteresis motor receives a torque through the hysteresis during magnetization reversal of a magnetically solid rotor, while magnetoelectric motor torque is the result of the interaction of the explicit magnetic poles of the rotor and stator.

Synchronous motor

Today, magnetoelectric motors rightfully constitute the lion's share of the total abundance of electric motors used in so many fields. They are divided by the nature of the supply current into:

  • DC motors

  • AC motors

  • universal engines.

Unlike a magnetoelectric motor, the magnetization of the rotor relative to its geometrical axes is allowed in the hysteresis motor, and this particular feature does not allow the general laws of magnetoelectric conversion to be extended to the synchronous operation mode of the hysteresis motor.

Watch - Device and principle of action of the simplest electric motor and How to make a simple electric motor in 10 minutes

Motor classification

Motor classification


DC motors

DC motor

In a motor that is powered by direct current, the motor itself is responsible for switching the phases. This means that although a direct current is supplied to the electric machine, nevertheless, due to the action of the internal mechanisms of the device, the magnetic field turns out to be able to maintain the rotor torque (as if an alternating current acts in the stator winding).

The device and the operation of the DC motor: 1 - anchor, 2 - shaft, 3 - collector plates, 4 - brush assembly, 5 - armature magnetic circuit, 6 - inductor magnetic circuit, 7 - field windings, 8 - inductor body, 9 - side covers 10 - fan, 11 - feet, 12 - bearings.

A DC motor consists of a fixed part called an inductor and a moving part called an anchor. Depending on the design, permanent magnets can be located on the inductor on the inductor, which simplifies the design, but does not allow you to adjust the magnetic flux of the motor, affecting its speed.

By the method of creating a moving magnetic field, DC motors are divided into:

  • valve (brushless)

  • collector.

Brushless motors have electronic inverters in their design, which carry out phase switching. Collector motors are traditionally equipped brush collector units, which are designed to purely mechanically synchronize the power of the motor windings with the rotation of its moving parts.



Excitation of collector motors

DC motor collector

According to the method of excitation, collector motors are of the following types: with independent excitation from permanent magnets or from electromagnets, or with self-excitation. Permanent magnet excitation motors contain magnets on the rotor.Self-excited motors have a special anchor winding on the rotor, which can be connected in parallel, sequentially or mixed with a special excitation winding.


Ripple motor

A pulsed current motor is similar to a DC motor. The difference lies in the presence of lined inserts on the core, as well as additional lined poles. In addition, the ripple current motor has a compensation winding. Such engines are used in electric locomotives, where they are usually powered rectified alternating current.


AC motor

AC motors, as the name implies, are powered by alternating current. They are synchronous and asynchronous.

For synchronous AC motors, the stator magnetic field moves at the same angular velocity as the rotor, while asynchronous motors always have a certain lag (characterized by the slip value s) - the stator magnetic field in its movement seems to be ahead of the rotor, which in turn is always seeks to catch up with him.

High-power synchronous motors (with a capacity of hundreds of kilowatts) have field windings on the rotor. The rotors of less powerful synchronous motors are equipped with permanent magnets, which form the poles. Hysteresis motors are also, in principle, synchronous.

Stepper motors - This is a special category of synchronous motors with high precision control of rotation speed, up to discrete step counting.

Valve synchronous jet engines are powered through an inverter.See this topic:Modern synchronous jet engines

Squirrel cage induction motor

Asynchronous AC motors are distinguished by the fact that their angular velocity of rotation of the rotor is always less than the angular velocity of rotation of the magnetic field of the stator. Induction motors are single phase (with starting winding), two-phase (a capacitor motor also applies to them), three-phase and multiphase.

Three-phase squirrel-cage induction motor design

An asynchronous electric motor consists of both a fixed (stator) part and a moving (rotor) part, which are held by bearings 1 and 11 installed in the side covers 3 and 9. The rotor consists of a shaft 2, on which a magnetic circuit 5 with a winding is fixed. The motor stator consists of a housing 7, to which a magnetic circuit is attached 6. A three-phase winding is laid in the grooves of the magnetic circuit 8. The terminal box cover 4 and the impeller protective cover 12 are also attached to the housing.


The phase rotor has a three-phase winding, made by the type of stator winding. Some ends of the coils are connected to the zero point ("star"), while others are connected to the slip rings. Brushes are imposed on the rings, making sliding contact with the rotor winding. With this design, it is possible to connect a starting or adjusting rheostat to the rotor winding, which allows changing the electrical resistance in the rotor circuit.

See also - Differences between induction motors and DC motors, Differences between squirrel-cage and phase-locked induction motors

Asynchronous motor with a frequency converter for smooth control of shaft rotation speed due to changes in frequency and supply voltage:

Frequency Converter Induction Motor

Universal Brush Motors

The universal collector engine can operate at least from direct, even from alternating current (50 Hz). Has serial excitation, is used in household electrical applianceswhere a rotation speed higher than the maximum for conventional AC motors of 3000 rpm is required. As a rule, the power of such engines does not exceed 200 watts. Meets thyristor control universal engine speed.

An improved version of the universal motor is a synchronous motor with a rotor position sensor, where the role of the collector is played by an electronic inverter.

Other useful articles on this topic:

Types of electric motors and the principles of their work

Characteristics of induction motors

How to determine the rotation speed of an electric motor

How to check the electric motor

How to disassemble an induction motor

Types and arrangement of revolutions of collector engine speed

Motor and servo control with Arduino

See also at i.electricianexp.com:

  • How to distinguish an induction motor from a DC motor
  • Types of electric motors and the principles of their work
  • Modern synchronous jet engines
  • Squirrel cage and phase rotor - what is the difference
  • What you need to know about modern electric motors

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