PI controller for avoiding integrator wind-up in systems with plant input saturation

The proposed PI controller constitutes a variable limit (VL) in the integral branch. The functioning of the VLPI controller is such that a closed loop always exists even at large inputs and high gains. Improved responses to a step function are shown by simulation of the motor speed loop and thereafter by the practical application of a separately excited DC motor. Also presented are the PI controller algorithm and realization procedures on a MC68000 microprocessor.