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, electric smelting, charging and excitation of alternators. Although power rectifier components are used to convert AC to DC where DC is needed, DC motors cannot be compared to AC generators in terms of ease of use, operational reliability and certain work performances.
1. Working principle
The working model of the DC motor when the generator is running is as shown in the figure. Brushes A and B in the figure are connected to direct current. external load, and the motor is connected by a main motor drags to rotate in the reverse directionclockwise. At present, the figure shows that the direction of the induced potential of component side ab is from end b to end a, the direction of induced potential of component side cd is from end d to end c and the direction of the potential induced on the component side ab goes from end b to end a. The current ia in the component is Bbrush → d → c → b → a → A, the component sides ab and cd generate an electromagnetic force f acting in the tangential direction of the armature circumference will generate an electromagnetic torque Tem. is clockwise and opposite to the direction of rotation of the motor. After rotating 180 degrees, the direction of current ia in the element is from brush B → a → b → c → d → brush A. The direction of current I in the external circuit remains unchanged and the direction of the electromagnetically generated torque Tem remains clockwise.
2. Model ofwork
It can be seen from the above analysis that the DC motor has the following characteristics when operating as a generator:
(1) In each case, the current ia flowing in an armature coil is alternating and the induced electromotive force e generated at the same time is also alternating.
(2) There is a direct potential between the brushes, and the induced electromotive force e and the current ia in the element have 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, and the electromagnetic torque Tem acts as a brake.