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In the armature, an electromotive force is created by the relative motion of the armature and the field. When the machine or motor is used as a motor, this EMF opposes the armature current, and the armature converts electrical power to mechanical power in the form of torque, and transfers it via the shaft. When the machine is used as a ...
Armature control is the most common control technique for DC motors. In order to implement this control, the stator flux must be kept constant. To achieve this, either the stator voltage is kept constant or the stator coils are replaced by a permanent magnet. In the latter case, the motor is said to be a permanent magnet DC motor and is driven ...
Rotor (lower left) and stator (upper right) of an electric motor Stator of a 3-phase AC-motor Stator of a brushless DC motor from computer cooler fan.. The stator is the stationary part of a rotary system, [1] found in electric generators, electric motors, sirens, mud motors, or biological rotors (such as bacterial flagella or ATP synthase).
The difference is that the brushes only transfer electric current to a moving rotor while a commutator also provides switching of the current direction. There is iron (usually laminated steel cores made of sheet metal) between the rotor coils and teeth of iron between the stator coils in addition to black iron behind the stator coils. The gap ...
Workings of a brushed electric motor with a two-pole rotor (armature) and permanent magnet stator. "N" and "S" designate polarities on the inside axis faces of the magnets; the outside faces have opposite polarities. The + and -signs show where the DC current is applied to the commutator which supplies current to the armature coils
For a single armature winding, when the shaft has made one-half complete turn, the winding is now connected so that current flows through it in the opposite of the initial direction. In a motor, the armature current causes the fixed magnetic field to exert a rotational force, or a torque, on the winding to make it turn. In a generator, the ...
A compensation winding in a DC shunt motor is a winding in the field pole face plate that carries armature current to reduce stator field distortion.Its purpose is to reduce brush arcing and erosion in DC motors that are operated with weak fields, variable heavy loads or reversing operation such as steel-mill motors.
When a stator pole is energized, the rotor torque is in the direction that reduces reluctance. Thus, the nearest rotor pole is pulled from the unaligned position into alignment with the stator field (a position of less reluctance). (This is the same effect used by a solenoid, or when picking up ferromagnetic metal with a magnet.) To sustain ...