Robust Relay-Feedback Based Autotuning for DC-DC Converters

This paper addresses the design and practical implementation of a digital controller for switched-mode DC- DC converters with self-tuning capabilities. The proposed tuning technique is based on digital relay feedback and exhibits some features specifically developed to improve accuracy and robustness in practical applications. The most relevant property is the elimination of the measurement of the output voltage oscillation amplitude, which is critical from the accuracy point of view, if the oscillation amplitude is only a few least significant bits (LSBs) of the A/D converter. The proposed tuning technique is presented and the complexity of the resulting algorithm is further analyzed, its performances compared to other recently proposed tuning techniques. The described approach is simple, quite accurate, and robust. Experimental results on a 10 A, 1.5 V point-of-load converter are provided to show the effectiveness of the discussed approach.