Second order sliding mode control of a buck converter with output capacitor ESR and ESL

A second order sliding mode (SOSM) buck controller with near-optimal transient response characteristics has previously been described. This paper shows that the performance of this controller can degrade very significantly in the presence of output capacitor equivalent series resistance and inductance (ESR and ESL, respectively). The reasons for this degradation are developed here, and include the introduction of trajectory discontinuities by the ESR/ESL. This paper then presents a modified SOSM buck controller specifically designed to work well in the presence of ESR/ESL. Simulation results demonstrate the superior performance of the new design in a practical point-of-load buck converter.