Improved Time Optimal Control of a Buck Converter Based on Capacitor Current

Time optimal control (TOC) is a technique to provide fast transient recovery in dc-dc converters. Prior published approaches are incomplete in the formulation of TOC because they ignore voltage-deviation effects on inductor-current and load-current dynamics during a large-signal recovery. An accurate TOC algorithm based on capacitor current is presented. This method achieves minimum transient recovery time for load transients and tracking in a buck converter. The minimum recovery time is preserved even with a transient-detection delay. This control configuration ensures large-signal stability in a sense similar to that of sliding-mode control. The results are demonstrated in an experimental buck converter that uses a digital control algorithm.