Getting Started

Adding an Integrator

One approach to eliminating the steady-state error is to add an integrator. You can do this by selecting Add Pole/Zero and then Integrator from the right-click menu.

Figure 4-45: Adding an Integrator

Adding an integrator changes the gain margin from infinity to 10.5 dB. Since the gain and phase margins are now both finite, the Nichols plot displays a vertical line for the gain margin and a horizontal line for the phase margin.

The linked LTI Viewer automatically updates to show the new response.

Figure 4-46: Step Response for a Compensator Consisting of a Gain and an Integrator

The steady-state value is now 1, which means the steady-state error has been eliminated, but the overshoot is 34% and the rise time is about 0.7 second. You must do more work to create a good design.

Adjusting the Compensator Gain

Adding a Lead Network