1, a machine that converts mechanical energy into DC electrical energy.
2, it is mainly used as a DC motor required for DC motors, electrolysis, electroplating, electrometallurgy, charging and excitation of alternators. Although in places where DC power is needed, also with power rectification components, the alternating current into direct current, but from the ease of use, the reliability of operation and certain work performance, DC motors can not be compared with alternators.
1, the principle of operation
Generator operation of the DC motor working model shown in the figure, the figure of the brush A and B between the external DC load, the motor is dragged by a prime mover to rotate in the counterclockwise direction. At the instant shown in the figure, the induced potential direction of element side ab is from end b to end a, the induced potential direction of element side cd is from end d to end c, and the direction of current ia in the element is B brush → d → c → b → a → A brush, and the element sides ab and cd generate electromagnetic force f, which acts in the direction of tangent to the circumference of the armature and generates the electromagnetic torque Tem, which is clockwise in the direction opposite to that of the motor rotation. After turning through the 180 position, the direction of the current ia in the element is from B brush → a → b → c → d → A brush, the direction of the current I in the external circuit remains unchanged, and the direction of the generated electromagnetic torque Tem is still clockwise.
2, working model
From the above analysis, DC motor as a generator operation, there are several characteristics:
(1) in each armature coil current ia for the AC, at the same time, the induced potential e is also AC.
(2) The potential between the brushes is DC, while the induced electromotive force e and the current ia in the element are in the same direction.
(3) The magnetic field generated by the armature current is also fixed in space.
(4) n is in the opposite direction to the electromagnetic torque Tem, which acts as a brake.