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.
Gas Turbines basically consist of three main sections:
DC motors comprise two key components: a stator and a rotor. In a DC motor, the stator provides a rotating magnetic field that drives the rotor to spin. The rotor is also designated as an armature, and the electric current flowing through it is attributed to armature current. The term "armature" refers to a device employed for implementation current to generate torque. The armature assembly is consisting of the armature core, armature winding, commutator, and brushes.
A simple DC motor employs a stationary set of magnets in the stator, and a coil of wire with a current running through it to produce an electromagnetic field aligned with the center of the coil. One or more windings of insulated wire are wrapped around the motor's core to concentrate the magnetic field.
DC motors are rated by their voltage, current, speed, and horsepower output. The number and methods of connection for the armature (rotor) and field also dictate motor operating characteristics. DC motors are roughly classified into two main types, namely permanent-magnet motors that utilize permanent magnets and are most regularly used for models, automobile auxiliary devices, and other applications all over the world, and winding-field motors that do not use permanent magnets which are used to be principally adopted for medium to large motors up to about one horsepower of output.
Permanent-magnet DC motors are categorized into the following three types by rotor type: a) Slotted type, b) Slotless type, and c) Coreless type.
The winding-field type is further categorized into the following three types according to the diversity in the method of connecting the field winding and armature winding: a) Shunt Motor, b) Series Motor, and c) Separate-field Motor
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.