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Commutator by the brushes and commutator rings, carbon brush is a brush. Brushless DC motor in it the main effect?
1 to change the current direction (in the commutator motor, the brush also plays for the role)
(2) the major axis of the electrostatic charge through the brush into the earth (ground brush) (output current)
3 the shaft (to) lead to the protection and rotor earth fault protection device for measuring the rotor-to-ground voltage of positive and negative
4 the external current (excitation current) through the brush and added to the rotation of the rotor (input current)
As the rotation of the rotor, brushes and commutator ring is always friction, and the moment will be in for a spark to the ignition loss, so the brush DC motor is in the wearing parts. In order to improve the life of DC motors, DC motors operating stability and reduce noise and electromagnetic interference, brushless DC motor to gradually replace the brush motor trend. AC motors do not generally constant magnetic field, so no need to commutator, thus no need to brush; but the size of the AC motor is generally greater. Electrical appliances are generally used in AC motors, such as electric fans, washing machines, refrigerators, air conditioners and so there is no brush, but also the use of DC motors, such as many electric shavers, small kitchen appliances, electric bicycles have carbon brush is DC motor (not including brushless) are. Use batteries are DC motor.
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