Real Time Voltage Control based on a Cascaded Super Twisting Algorithm Structure for DC-DC Converters

This paper proposes a second-order sliding mode control (SOSMC) law, based on a super twisting algorithm, aimed at regulating the output voltage of a DC-DC buck converter. A closed-loop system is designed consisting of two distinct nested loops organized within a cascaded super twisting algorithm structure. Several sliding mode control algorithms are here surveyed for the regulation of a DC-DC buck converter. The super-twisting algorithm of second order sliding mode is also experimented in a HIL system. The comparative evaluations include comparing the output voltage transient responses to load step changes for all developed sliding mode control algorithms and the start-up responses of the output voltage to step changes of the input voltage of the buck converter. Furthermore, theoretical considerations, numerical simulations and experimental results from a laboratory prototype are compared, at different operating points, for all surveyed control methods. It results from the simulations and experiments that the designed super twisting algorithm achieves the fastest convergence, a consistent chattering reduction, the smallest settling time under loaded situations and small steady-state error during load changes over all contrasted control methods.