Nonlinear digital PID controller for DC-DC converters

This paper introduces an approach for the design and implementation of a non-linear digital PID controller. The proposed PID controller includes nonlinear proportional, integral and differential gains that are selected based on the input error signal value to achieve significantly improved dynamic responses. This implementation uses an off-the-shelf digital PWM controller well suited for practical high-frequency SMPS applications. Simulation and experimental results are presented for a point-of-load 12 V-to-1 V, 40 A, 500 kHz dual phase synchronous buck converter to verify the improved dynamic performance of the non-linear digital controller.