BRUSHLESS DC MOTOR TYPES|Online electrical engineering & Electrical Interview Questions

Tuesday, September 14, 2010


First of all what are Brushless DC motors?   In normal DC motors  carbon brushes are used for commutation.Whereas in Brushless DC motors power electronic devices are used for commutation.This type of commutation is called as Electronic commutation.

Based on construction of the motor ,BLDC motors are classified as In-Rrunner and Out-Runner.In In-Runner type, the stator encloses the rotor and in Out-Runner type,the rotor encloses the stator.

Where do you use the BLDC motors?
Almost everyone will be using computers.You must have seen the fans used for cooling your CPU.These fans are nothing but BLDC motors.They are all of Out-Runner type.Just take a PC fan which is not working,and break it and see.You will see stator windings with 4 poles or 2 poles around which a permanent magnet is placed which acts as rotor.The fan blades are attached to this rotor magnet.

1 comment:

amit. said...

1.When there is a sudden loss in the demand what happens to the transformer
and generation?

2.In a three phase system three wires are of colour red, yellow and blue are used
to discriminate each phase. Now how will you identify each phase wire without knowing the
colour and without any pre information?

3.what is reluctance torque?

4. Importance of trnasformer oil?

Please post the answers of these questions. I will post more questions very soon.