There are both kinds. Closed and open loop.
Some are simple voltage controllers, others use stepper technology and some use feedback from the motor to determine speed.
A closed loop will require feedback from the motor, to determine speed and correct it, either by tachometer or pulse detection.
A servo drive is any motor controller which uses a closed feedback loop to monitor the motors speed. This is normally accomplished through the use of an encoder or resolver.
In industry closed control is a closed loop feedback where a pump or motor has an encoder or feedback device to keep the operation regulated.
An open loop traffic signal just cycles on a schedule and has no "knowledge" of traffic patterns or current traffic. A closed loop system would have sensors letting it know when traffic was present and a controller that would make decisions based on the traffic conditions.
what does a graph look like of for a closed loop & one for an open loop of the controller's output over time for a step change in the desired value of 10% assume the controller is set at P.B. =100% and Ti=30 seconds
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 (see Open-loop controller). Stepper motors are similar to switched reluctance motors (which are very large stepping motors with a reduced pole count, and generally are closed-loop commutated.) An induction motor (IM) is a type of alternating current motor where power is supplied to the rotating device by means of electromagnetic induction.
closed loop system
Feedback oscillators have a closed loop gain of
In a closed loop system the gain without the feed back loop being closed is called open loop gain!!! e.g if forward gain is "A" and feed back factor is "B" then open loop gain is "AB" and closed loop gain will be [A/(A+B)]
Sudesh K. Sethi has written: 'Analysis of a motor-generator system containing a speed loop, current limit loop, and position control loop'
the motor should only rotate in a rated speed,if the speed is more than rated speed then the motor will be damaged........to control the speed of motor a rheostat should be connected to the field side of motor......by variying the rheostat we can control the speed of motor......
A cruise control is an example of a closed loop servo.
Closed