How does a DC Motor wok?

Question

can anybody explain step by step or as much as they know about a DC Motor

Answer 1

On any motor, you have a fixed magnet called a "stator" and a moving magnet called a "rotor." Rotor is typically afixed to the shaft.

Stator can be a set of permanent magnet or a coil. But the magnetic poles on the stators are fixed, and they are inter-twined. SNSNSN and so forth.

The rotor has coils and they are connected to an electrical source by a brush and the contacts. The contacts are on the shaft and the brush is on the case. Realize, the connection changes as the rotor turns but more on this on the next step...

At one point, the coils on rotors are magnitized in one way. Let's say South and North. As it is true with any magnet, then the South on the rotor gets attracted to the North on the stator, and the North on the rotor gets attracted to the South on the stator. Thus the shaft moves.

Now, at this point, the shaft rotates enough that now the brush contacts in a way that the poles on the rotors are reversed. Now, the souths and the norths on the rotor gets attracted to the next set of norths and south on the stator.

The process continues.... and the shaft eventually makes one complete revolution, and on and on....

This is the best I can do for you on typing only.

Answer 2

Working Principle Of A DC Motor :

A motor is an electrical machine which converts electrical energy into mechanical energy. The principle of working of a DC motor is that "whenever a current carrying conductor is placed in a magnetic field, it experiences a mechanical force". The direction of this force is given by Fleming's left hand rule and it's magnitude is given by F = BIL. Where, B = magnetic flux density, I = current and L = length of the conductor within the magnetic field.

Fleming's left hand rule :

If we stretch the first finger, second finger and thumb of our left hand to be perpendicular to each other AND direction of magnetic field is represented by the first finger, direction of the current is represented by second finger then the thumb represents the direction of the force experienced by the current carrying conductor.

When armature windings are connected to a DC supply, current sets up in the winding. Magnetic field may be provided by field winding (electromagnetism) or by using permanent magnets. In this case, current carrying armature conductors experience force due to the magnetic field, according to the principle stated above.

Commutator is made segmented to achieve unidirectional torque. Otherwise, the direction of force would have reversed every time when the direction of movement of conductor is reversed the magnetic field.
This is how a DC motor works.

Back EMF :

According to fundamental laws of nature, no energy conversion is possible until there is something to oppose the conversion. In case of generators this opposition is provided by magnetic drag, but in case of dc motors there is back emf.

When the armature of the motor is rotating, the conductors are also cutting the magnetic flux lines and hence according to the Faraday's law of electromagnetic induction, an emf induces in the armature conductors. The direction of this induced emf is such that it opposes the armature current (Ia) . The circuit diagram below illustrates the direction of the back emf and armature current. Magnitude of Back emf can be given by the emf equation of DC generator.

Significance Of Back Emf:
Magnitude of back emf is directly proportional to speed of the motor. Consider the load on a dc motor is suddenly reduced. In this case, required torque will be small as compared to the current torque. Speed of the motor will start increasing due to the excess torque. Hence, being proportional to the speed, magnitude of the back emf will also increase. With increasing back emf armature current will start decreasing. Torque being proportional to the armature current, it will also decrease until it becomes sufficient for the load. Thus, speed of the motor will regulate.
On the other hand, if a dc motor is suddenly loaded, the load will cause decrease in the speed. Due to decrease in speed, back emf will also decrease allowing more armature current. Increased armature current will increase the torque to satisfy the load requirement. Hence, presence of the back emf makes a dc motor ‘self-regulating’.

Types Of DC Motors :

DC motors are usually classified of the basis of their excitation configuration, as follows -

Separately excited (field winding is fed by external source)
Self excited -
a.) Series wound (field winding is connected in series with the armature)
b.) Shunt wound (field winding is connected in parallel with the armature)
Compound wound -
1.Long shunt
2. Short shunt

For more info visit :

https://www.electrikals.com/

Answer 3

You have to look this up elsewhere, you wont understand it without a picture, some things you need pictures for.

http://en.wikipedia.org/wiki/DC_motor

Answer 4

Go to this website they almost everything you want to know!