Control of Electrical DrivesPublished on 24/2/2012 and last updated on 30/7/2018
Electrical drives have become the most essential equipment now days in the electrical motors and other rotating machines. We know that electrical drives mainly accomplishes three kinds of work,Please Rate this Article
- Speed control
That’s why the need of controlling the drives rises and there are various methods and equipment's to control different parameters of the drives which are discussed later.
Closed Loop Control of DrivesIn a control system, there are two types of systems, one is open loop and the other is closed loop control system. In open loop control system the output has no effect on the input, i.e the controlling phenomenon is independent of the output, on the other hand closed loop control system is much more advanced and scientific, here the output is fed back to the input terminal which determines the amount of input to the system, for example if the output is more than predetermined value the input is reduced and vice-versa. In electrical drives feedback loops or closed loop control satisfy the following requirements.
- Enhancement of speed of response
- To improve steady-state accuracy
Current Limit ControlDuring the starting, we know if precautionary measures are not taken there is a chance of huge current flow through the motor circuit. To limit the current and sense the current fed to the motor, current limit controller is installed. The feedback loop does not effect the normal operation of the drive but if the current exceeds the predetermined safe limit, the feedback loop activates and the current is brought down below the safe limit. Once the current is brought down below the safe limit the feedback loop again deactivates and in this way the control of current takes place.