Direct-Current Motors

– Compound-Connected DC Machine

Introduction
• The Brushed DC motor is not as widely used today as
in the past, but it is still being used, especially at the
low-power level.
• Focus is on topics of interest to the mechatronics
engineer
– Shunt-connected dc motor
– Permanent-magnet dc motor
• A simplified method of analysis is used rather than an
analysis wherein commutation is treated in detail. As
a result the dc motor is the most straightforward to
analyze of all the electromechanical devices.

Elementary Direct-Current Machine
• It is instructive to discuss the elementary two-pole
dc machine prior to a formal analysis of the
performance of a practical dc machine.
• The two-pole elementary machine is equipped with:
– Field winding wound on stator poles
– Rotor (or armature) coil
– Commutator
• Two semicircular copper segments mounted on the shaft at the
end of the rotor and insulated from one another as well as from
the iron of the rotor.
• Each terminal of the rotor coil is connected to a copper segment.