DC Motors
UNIVERSIDAD AUTONOMA DE COAHUILA
FACULTAD DE SISTEMAS
DC Motors
Catedrático: Ing. Gustavo Mendoza Leal
Alumno: Alfredo Valdés Cárdenas
Introduction
A DC motor is a type of electrical machine that converts direct current into mechanical power by means of a magnetic field. DC motors are widely used in field applications because of their many advantages over AC motors such as speed control, high starting torque, quick starting, stopping, reverse and acceleration and free from harmonics found in AC. Applications of DC motors include but are not limited to:
Transportation such as electrical locomotives, rapid transit systems and trolley cars
Cranes, hoists and in conveyers
Rolling mills
Constant speed lathes
Centrifugal pumps, fans, blowers, reciprocal pumps and machine tools like drills.
Elevators, heavy planers, air compressors and intermittent high torque loads
The theory behind DC motors:
According to Faraday’s law of induction, an electromotive force can be created by applying a magnetic field over an electrical circuit. A coil of wire with a current running through it generates an electromagnetic field aligned with the center of the coil. The direction and magnitude of the magnetic field produced by the coil can be changed with the direction and magnitude of the current flowing through it.
A simple DC motor has a stationary set of magnets in the stator and an armature with coils around a soft iron core that concentrates the magnetic field. The ends of the coils are connected to a commutator. The commutator allows each armature coil to be energized in turn and connects the rotating coils with the external power supply through brushes. The total amount of current sent to the coil, the coil's size and its core dictate the strength of the electromagnetic field created. By turning on and off coils in sequence a rotating magnetic field can be created. These rotating magnetic fields interact with the magnetic fields of the magnets (permanent or electromagnets)
FACULTAD DE SISTEMAS
DC Motors
Catedrático: Ing. Gustavo Mendoza Leal
Alumno: Alfredo Valdés Cárdenas
Introduction
A DC motor is a type of electrical machine that converts direct current into mechanical power by means of a magnetic field. DC motors are widely used in field applications because of their many advantages over AC motors such as speed control, high starting torque, quick starting, stopping, reverse and acceleration and free from harmonics found in AC. Applications of DC motors include but are not limited to:
Transportation such as electrical locomotives, rapid transit systems and trolley cars
Cranes, hoists and in conveyers
Rolling mills
Constant speed lathes
Centrifugal pumps, fans, blowers, reciprocal pumps and machine tools like drills.
Elevators, heavy planers, air compressors and intermittent high torque loads
The theory behind DC motors:
According to Faraday’s law of induction, an electromotive force can be created by applying a magnetic field over an electrical circuit. A coil of wire with a current running through it generates an electromagnetic field aligned with the center of the coil. The direction and magnitude of the magnetic field produced by the coil can be changed with the direction and magnitude of the current flowing through it.
A simple DC motor has a stationary set of magnets in the stator and an armature with coils around a soft iron core that concentrates the magnetic field. The ends of the coils are connected to a commutator. The commutator allows each armature coil to be energized in turn and connects the rotating coils with the external power supply through brushes. The total amount of current sent to the coil, the coil's size and its core dictate the strength of the electromagnetic field created. By turning on and off coils in sequence a rotating magnetic field can be created. These rotating magnetic fields interact with the magnetic fields of the magnets (permanent or electromagnets)