Electric Motor Winding – Definition and Types

A winding is a coil of multiple turns of conductor wire through which an electric current can flow to produce a magnetic field. In general, the windings used in electric motors are made up of copper wire. However, sometimes, aluminum wire is also used to form motor windings. Different types of electric motors have different types of windings. In this article, I will explain different types of windings used in electric motors.

What is a Motor Winding?

In an electric motor, the winding is a copper or aluminum coil of multiple turns wound around a magnetic core and produces a magnetic field when an electric current flows through it.

The primary function of a winding in an electric motor is to create a magnetic field inside the motor which is required for its working. Therefore, motor winding is one of the fundamental components in an electric motor which is responsible for working of the motor.

Construction and Function of Motor Winding

Motor windings are made up of insulated conductor wires, usually copper wires or aluminum wires. These conductor wires are wound around a magnetic core made up of steel laminations.

When an electric current flows through these motor windings, they create a magnetic field required to produce a torque in the rotor. This torque developed in the rotor is then utilized to drive the mechanical load attached to the motor shaft.

Hence, the main function of a motor winding is to transform electrical energy into mechanical energy through the electromagnetic phenomenon.

Types of Motor Windings

The different types of windings used in electric motors are given below −

• Stator Winding

• Rotor Winding

• Armature Winding

• Field Winding

• Open Winding

• Closed Winding

• Concentrated Motor Winding

• Distributed Motor Winding

• LAP Winding

• Wave Winding

Let us discuss each type of motor winding in detail one-by-one.

Stator Winding

In electric motors, the stator winding is the type of motor winding placed on the stationary part of the motor, called stator. In induction motors, the stator winding is placed in the slots cut in the stator core. In DC motors, the stator winding is wound around the magnetic poles.

Therefore, in DC motors, stator winding produced a constant magnetic flux in the machine. Whereas, in induction motors, the stator winding produces a rotating magnetic field in the motor.

Rotor Winding

The rotor winding is the type of motor winding which is done on the rotating part of the motor, i.e., rotor. The rotor winding is placed in the slots made on the rotor core.

In dc motors, the rotor winding is excited from a source of dc supply and act as the armature winding. In the case of induction motors, the rotor winding is closed through short circuit. In the synchronous motors, the rotor winding is excited from a DC supply to produce a constant magnetic field. The rotor winding is responsible for developing torque in the rotor and rotate it.

Armature Winding

In an electric motor, the armature winding is the main winding in which the electromagnetic torque is developed. In electric motors, the armature winding interacts with the magnetic flux produced by permanent magnets or electromagnets to produce a torque in the rotor.

The armature winding performs the following two functions in an electric motor −

• Induces an emf (electromotive force).

• Create torque to rotate the rotor and shaft.

Field Winding

Field winding is the motor winding that creates a magnetic field required for working of the machine.

In DC motors, the field winding is done on the stator and is excited by using a dc power supply. In induction motors, the field winding is also placed on the stator, but excited from an AC power supply. The field winding of synchronous motor is done on the rotor and is excited from a dc power supply.

Overall, the primary function the of the field winding in an electric motor is to produce main field flux required for working of the motor.

Open Winding

In electric motors, when ends of windings are brought to the terminals to make external connections, then this type of winding is called open-type winding. In simple words, open winding is one that can be left open at one or more points.

The greatest advantage of open winding is that it provides better flexibility in connections. The open windings are primarily used in ac motors like induction motors or synchronous motors.

Closed Winding

As the name implies, the closed winding forms a closed loop or path around the armature. This type of motor winding starts and ends at the same point. The flow of current through the closed winding takes place through the carbon brushes placed on the commutator.

In the case of closed winding, the armature current splits into several parallel paths. This type of winding is mainly used in dc motors and universal motor.

Concentrated Winding

When a motor winding is formed by winding multiple turns of conductor wire such that they are in series and forms a single coil of multiple turns, then it is called concentrated winding.

In other words, a motor winding in which all the winding turns have the same magnetic axis is called a concentrated winding.

This type of motor winding is used in the case when the number of poles and numbers slots are to be equal.

The concentrated windings are used in motors that have shorter axial length and large diameter, such as in salient pole synchronous motors.

This type of winding is always wound over one tooth of the stator or rotor core. The major advantage of the concentrated winding is that it has a very small winding head at the top and bottom of the electric motor.

Distributed Winding

The type of motor winding in which all the winding turns are arranged in multiple coils and are inserted into slots spread along the air gap is called a distributed winding.

This winding is used where the number of poles is not equal to the number of slots.

Some common examples of distributed windings are armature windings of induction motors and synchronous motors.

Lap Winding

The lap winding is formed by joining conductors in a way that the number of poles and number of parallel paths are equal. In this type of winding, each end of the coil is joined to the adjacent commutator segment as shown in the following figure.

The lap winding is used in DC machines that works at high currents and low voltages.

Wave Winding

The wave winding is another commonly used type of armature winding in DC motors. The type of motor winding which has only two parallel paths between positive and negative brushes is termed as a wave winding.

In the case of wave winding, the number of parallel paths is independent of the number of poles. However, the number of carbon brushes is equal to the number of parallel paths in the winding.

This type of winding is used in dc motors working on high voltages and low currents.

Conclusion

In conclusion, motor winding is an essential component of any electric motor. It is responsible for producing working magnetic field and developing electromagnetic torque to transform electrical energy into mechanical energy. Different types of windings are used in different types of electric motors. In this comprehensive article, I have explained different types of windings commonly used in electric motors.