15.1.1 Anti-Windup and Initialization

The PI controller has minimum and maximum limits of output to keep the output within practical values. If a non-zero error signal persists for a long time, the integral component of the controller keeps increasing and might reach a value limited by its bit width. This phenomenon is called integrator windup and must be avoided to have a proper dynamic response. The PI controller IP has an automatic anti-windup function, which limits the integrator as soon as the PI controller reaches saturation.

In certain applications, such as motor control, it is important to initialize the PI controller to a proper value before enabling it. Initializing the PI controller to a good value avoids jerky operations. The IP block has an enable input to enable or disable the PI controller. If disabled, the output is equal to the unit input, and when this option is enabled, the output is the PI computed value.