Question

Automatic control of closed loop system with encoders

Answer 1

As indicated by the name, this type of control method requires the use of some peripheral device that closes the loop back to the drive. The device that is commonly used is the tachometer, or tach generator, as it is sometimes called. I can show you with the help of image given above.
Closed-loop control is a bit more complex, but yields a great improvement in motor-speed regulation. The key to the success of this scheme is the tachometer (T) or feedback device. A speed reference is given to the AC or DC drive. The actual speed, determined by the tach, is fed back to the drive. Both the speed reference and feedback are combined into the summing circuit. The summing circuit produces an error signal. That error signal is now the speed reference that is sent to the power and logic control, which translates the signal into faster or slower motor speed.