AC Motor vs DC Motor
Electric motors can be divided into two types: alternating current (AC) electric motors and direct current (DC) electric motors. A DC electric motor will not run when supplied with AC current, nor will an AC motor run with DC current.
Structure of AC Motor
AC electric motors are further subdivided into single phase and three phase motors. Single phase AC electrical supply is what is typically supplied in a home. Three phase electrical power is commonly only available in a factory setting.
DC electric motors are also split into types. These include brush motors, brushless motors, and stepper motors.
Of these types, brush electric motors are by far the most common. They are easy to build and very cost effective. Their major drawback is that they use carbon brushes to transfer electrical current to the rotating part, and these brushes wear over time and eventually result in the failure of the electric motor.
The DC brushless motor eliminates the brushes, but is more costly and requires much more complicated drive electronics to operate.
A stepper motor is a special type of brushless motor that is used primarily in automation systems. A stepper motor uses a special type of construction that allows a computerized control system to “step” the rotation of the motor. This is very important when controlling a robotic arm.