A Comparative Study of the Boundary Control of Buck Converters Using First- and Second-Order Switching Surfaces -Part I: Continuous Conduction Mode

A comparative study on the performance characteristics of the buck converters with boundary control using the first-order switching surface (sigma¹) and a recently proposed second-order switching surface (sigma²) is presented. Performance attributes under investigation include the average output voltage, output ripple voltage, switching frequency, and large-signal characteristics. Special emphases are given to investigate the effects of the equivalent series resistance of the output capacitor on the above attributes, and the sensitivity of the output voltage against the variations of the input voltage and circuit component values. Generally, converters with sigma² are found to exhibit better dynamic responses than the ones with sigma ¹. The theoretical predictions are favorably verified with the experimental results of a 120 W buck converter