The direct current (DC) motor is one of the first machines devised to convert electrical power into mechanical power. DC motors receive electrical power through direct current and transform this energy into mechanical rotation. The facility with which the DC motor lends itself to speed control has long been recognized. Compatibility with the new thyristors and transistor amplifiers, plus better performance due to the availability of new, improved materials in magnets, brushes, and epoxies, has also revitalized interest in DC machines.
DC motors are operated from corrected alternating current of from a low-voltage battery or generator source. DC motors employ magnetic fields that occur from the electrical currents produced, which powers the movement of a rotor fixed inside the output shaft. The output torque and speed depend upon both the electrical input and the design of the motor. We will discuss type and operation principles in slightly more depth over the following sections.
DC Motors Experts on Linquip
Behrooz Heidari Dehkordi
Alli Olarenwaju Akinyemi
In a DC motor, an armature rotates inside a magnetic field. The basic working principle of DC motor is based on the fact that whenever a current carrying conductor is placed inside a magnetic field, there will be mechanical force experienced by that conductor.
Brushless AC motors
The brushed DC motor is the original DC motor, dating back to Sprague’s initial design. As we have discussed already in this guide, the classic brushed motor features a commutator, to reverse the current every half cycle and create single direction torque.
An induction motor or asynchronous motor is an AC electric motor in which the electric current in the rotor needed to produce torque is obtained by electromagnetic induction from the magnetic field of the stator winding. An induction motor can therefore be made without electrical connections to the rotor.
A commutator is a rotary electrical switch in certain types of electric motors and electrical generators that periodically reverses the current direction between the rotor and the external circuit. It consists of a cylinder composed of multiple metal contact segments on the rotating armature of the machine.
All DC motors are single phase, but AC motors can be single phase or three phase. AC and DC motors use the same principle of using an armature winding and magnetic field except with DC motors, the armature rotates while the magnetic field doesn't rotate.
An understanding of electromechanical energy conversion, as exemplified by a motor, is based upon acquaintance with several fundamental concepts from the field of mechanics. In a DC motor, when the multipolar part’s field magnets are excited, and its rotor conductors are supplied with current from the supply mains, they encounter a force managing to rotate the armature in an anticlockwise direction. These forces collectively generate a driving torque which sets the armature rotating.
The insulated wire windings are connected to a commutator (a rotary electrical switch) that implements an electrical current. The commutator enables each armature coil to be energized in turn, generating a steady rotating force (known as torque). When the coils are switched on and off in sequence, a rotating magnetic field is produced that interacts with the different fields of the stationary magnets in the stator to generate torque, which causes it to rotate. These key operating principles of DC motors allow them to transform the electrical energy from direct current into mechanical energy through the rotating movement, which can then be used to propel objects.