TYPES OF DC MOTORS

Brushed DC
The brushed DC motor generates torque directly from DC power supplied to the motor by using internal commutation, stationary permanent magnets, and rotating electrical magnets.

Advantages
• Low initial cost
• High reliability
• Simple control of motor speed
Disadvantages
• High maintenance
• Low life-span for high intensity uses
Maintenance involves regularly replacing the brushes and springs which carry the electric current, as well as cleaning or replacing the commutator. These components are necessary for transferring electrical power from outside the motor to the spinning wire windings of the rotor inside the motor.

Brushless DC
Brushless DC motors use a rotating permanent magnet in the rotor, and stationary electrical magnets on the motor housing. A motor controller converts DC to AC. This design is simpler than that of brushed motors because it eliminates the complication of transferring power from outside the motor to the spinning rotor.

Advantages
• Long life span
• Little or no maintenance
• High efficiency
Disadvantages
• High initial cost
• More complicated motor speed controllers.

Stepper DC
A stepper motor (or step motor) is a brushless, synchronous electric motor that can divide a full rotation into a large number of steps. The motor's position can be controlled precisely, without any feedback mechanism. Stepper motors consist of a permanent magnet rotating shaft, called the rotor, and several electromagnets on the stationary portion that surrounds the motor, called the stator. To make the motor shaft turn, first one stator is given power, which makes the rotor gear's teeth magnetically attracted to the stator's teeth. When the gear's teeth are thus aligned to the first stator, they are slightly offset from the next stator. So when the next stator is turned on and the first is turned off, the rotor gear rotates slightly to align with the next one, and from there the process is repeated. Each of those slight rotations is called a "step." In that way, the motor can be turned to a precise angle.

Advantages
• Very precise rotation
• Huge torque
Disadvantages
• High cost
• More complicated motor speed controllers.
• Slow speed