How does a DC generator work? What is the difference between an alternator and a DC generator?

The armature is driven by a motor to rotate at a constant speed counterclockwise, and the coil sides a b and c d cut the magnetic lines of force under the magnetic poles of different polarities respectively, and induce electromotive force.

The working principle of the DC generator is to convert the alternating electromotive force induced in the armature coil into a direct current electromotive force when it is drawn from the brush end by the commutator and the commutation effect of the brush. Because the electromotive force drawn by the brush A through the commutator segment is always the electromotive force in the coil side that cuts the N-pole magnetic field line. So brush A always has a positive polarity, and in the same way, brush B always has a negative polarity. Therefore, the brush end can draw out the pulsating electromotive force with the same direction but varying size.

What is the difference between an alternator and a DC generator?

An alternator uses silicon diode rectification, so it is also called a silicon rectifier generator. A DC generator is a machine that converts mechanical energy into DC electrical energy. The difference between the two generators is as follows:

1. Different structures The alternator does not have a commutator, and the DC generator has a commutator. Because the generator uses a closed conductor to cut the magnetic lines of force to generate current, the magnitude and direction of the current will change with the direction of coil rotation, which is alternating current; and if the direction of the generator's output electricity does not change, that is, outputting direct current, then one more replacement is required. to the device.

2. The alternator generates alternating current in different scopes of use, which can be directly used as AC motor and AC facility power supply, and has a wide range of use; while DC generators are mainly DC motors, electrolysis, electroplating, electric smelting, charging and excitation of alternators etc. to provide direct current.


Generators refer to mechanical equipment that converts other forms of energy into electrical energy. It is driven by water turbines, steam turbines, diesel engines or other power machinery, and converts water flow, air flow, fuel combustion or nuclear fission into mechanical energy. generator, which is then converted into electrical energy by the generator.


Generators are widely used in industrial and agricultural production, national defense, science and technology and daily life. There are many forms of generators, but their working principles are based on the law of electromagnetic induction and the law of electromagnetic force. Therefore, the general principle of its construction is: use appropriate magnetic and conductive materials to form magnetic circuits and circuits that conduct electromagnetic induction with each other to generate electromagnetic power and achieve the purpose of energy conversion.

Post time: Jun-02-2022