Analysis and Design of an Adaptive-Step-Size Digital Controller for Switching Frequency Autotuning

An adaptive-step-size autotuning algorithm and controller for power converters' switching frequency optimization with improved convergence performance is presented in this paper. The controller automatically tracks and determines the switching frequency of a power converter in order to achieve the highest power conversion efficiency under variable operating conditions including temperature variation effects, component aging effects, component's manufacturing process differences, input voltage changes and load current changes. The adaptive-step-size function results in improved adaptive controller convergence speed, convergences error and stability. In this paper, the proposed autotuning control loop for a power converter is theoretically analyzed and its design and stability criteria are developed. The developed algorithm operation is verified by experimental results obtained from a proof of concept prototype.