PMDC Motor

Characteristics

Characteristics of PMDC motors are similar to the characteristics of dc shunt motor in terms of torque, speed and armature current. However, speed-torque characteristics are more linear and predictable in PMDC motors.

Applications Of Permanent Magnet DC Motors
Permanent magnet dc motors are extensively used where smaller power ratings are required, eg in toys, small robots, computer disc drives etc.

Advantages
1.For smaller ratings, use of permanent magnets reduces manufacturing cost.
2.No need of field excitation winding, hence construction is simpler.
3.No need of electrical supply for field excitation, hence PMDC motor is relatively more efficient.
4.Relatively smaller in size
5.Cheap in cost

Disadvantages

1.Since the stator in PMDC motor consists of permanent magnets, it is not possible to add extra ampere-turns to reduce armature reaction . Thus armature reaction is more in PMDC motors.
2.Stator side field control, for controlling speed of the motor , is not possible in pemanent magnet dc motors.