The more complex motor controller can accurately control the speed and torque of the motor, and may also be a part of the closed loop control system of the mechanical control position. For example, the CNC lathe needs to accurately control the position of the tool according to the preset curve, and compensate according to the load and external forces to maintain the tool in the given position.

The motor controller can be operated manually, remotely or automatically. It can only include the functions of starting and stopping the motor, and can also include other complex functions. Motor controllers can be classified according to the type of matching motor, such as driving permanent magnet synchronous motor, servo motor, series or shunt DC motor, or AC motor.