What is a Permanent Magnet DC Motor (PMDC Motor)?

Updated: Jun 21, 2021

A Motors that transform direct current electrical energy into mechanical energy are known as DC motors. Almost all types of DC motors have an internal mechanism, either electromechanical or electronic, that changes the direction of current in a part of the motor on a regular basis.

A Permanent Magnet DC (PMDC) Motor is a DC motor with permanent magnet poles. The magnets are radially magnetised and placed on the cylindrical steel stator's inner sides. This motor does not have a field coil. It generates torque by the interaction of armature flux and permanent flux. Basically, permanent magnets are used to generate the magnetic field required for DC motor operation.

PMDC motor is shown in the figure below.

Construction of Permanent Magnet DC Motor (PMDC Motor)

A Permanent Magnet DC (PMDC motor) is made up of two major parts. An armature and a stator. The stator, which is a steel cylinder. The magnets are placed on the stator (cylinder's) inner sides. The N-pole and S-pole of each permanent magnet are alternately facing the armature. That is, if one magnet's N-pole is facing the armature, the next magnet's S-pole is also facing the armature.

The moving section consists of armature and bearings. Brushes and a commutator are included in the armature. The armature is consist of slots that contain the armature winding. Brushes are used to supply current to the commutator, which functions as a converting device. By connecting the brushes' terminals to the DC supply, the armature receives power.

The working principle of a Permanent Magnet DC Motor (PMDC Motor)

An armature rotates inside a magnetic field in a PMDC motor. A magnet is used to create the magnetic field. It may be an electromagnet or a permanent magnet, depending on the type of magnet used. Between the armature field flux and the permanent magnet field flux, magnetic induction occurs. A torque is generated by the interaction of these fluxes.

Applications of Permanent Magnet DC Motor (PMDC Motor)

Permanent magnet dc motors are widely used in various market segments such as like Coordinate measuring machine (CMM), Lawn Mower, Door Automation, Laboratory Fermenter, Tennis ball machine, cricket bowling machines, AGVs, Laboratory stirrers & Shakers, Door Automations, Solar Cleaning robots and many others.


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