Need of Compensation =>

1) In order to provide a suitable performance, it is required to adjust the control system design.

2) This adjustment of a control system is called compensation.

3) A device is inserted into the system for the purpose of satisfying the specification, this device is called a compensator.

4) Control system are designed to perform specific tasks, given a plant with transfer function G(s), the objective is to design an overall system to meet a set a specifications. The requirements imposed on the control system are generally related to accuracy, relative stability and spee of response.

5) These specifications may have to be modified during the design since the original specifications may not be satisfied.

6) If the specifications are not meet we would need to inroduce a compensator to get a desired result.

Types of Compensation =>

i) Series compensation

ii) parallel compensation

iii) Series- parallel compensation

I Series Compensation =>

when the compensator is placed in the feed forward path, it is called a Series compensation. It is also known as a cascade compensator.

Here G(s) repersent the compensator

II parallel compensation =>

When the compensator is introduced in the feedback path to produce an additional feedback, it is called a parallel compensation.

III Series-parallel compensation =>

In certain application, we need to introduce compensation in the forward path as well as in the feedback path. This type of compensation is called Series-parallel compensation