Beyond time-optimality: Energy-based control of augmented buck converters for near ideal load transient response

This paper presents a buck converter augmented with additional energy paths that enable a near null response to load transients. Fundamental performance limits, such as slew-rate limits, are overcome resulting in increased bandwidth with a response that is faster than previously established “minimum time” or “time optimal” control of conventional buck converters. An energy-based method is presented that allows simplified control of the augmentation branches. An efficiency analysis shows that power loss is dependent on load step size and frequency. Experimental results for a 12 V input, 5 V output, 25 W buck converter demonstrate that for 60 percent load steps the augmented converter has half the settling time, four times less peak-to-peak voltage deviation, and no inductor current overshoot as compared to the minimum time response.