Hangzhou Delixi Group Co.,Ltd.

Frequency inverters(frequency converter) have become the most essential equipment now a days in the electrical motors and other rotating machines. We know that frequency inverters mainly accomplishes three kinds of work, i)Starting ii) Speed control and iii) Braking. It can be said that the frequency inverters enable us to control the motor in every aspect. But control of frequency inverters is also necessary because all the functions accomplished by the drives are mainly transient operations i.e the change in terminal voltage, current, etc are huge which may damage the motor temporarily or permanently. 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 AC Drives

In control system there are two types of systems, one is open loop an 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 out put 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 frequency inverters feed back loops or closed loop control satisfy the following requirements.

1. Protection 
2. Enhancement of speed of response
3. To improve steady –state accuracy

In the following discussions, we will see through different closed loop configurations which are used in frequency inverters irrespective of the type of supply they are fed, i.e dc or ac.

This article comes from vtdrive edit released