A Comparative Study of Terminal and Conventional Sliding-Mode Startup Peak Current Controls for a Synchronous Buck Converter

An alternative to the linear control techniques, which are based on small-signal averaged models, is the sliding-mode control (SMC). That method uses the instantaneous models of the switched power converter to design robust controllers. The large-signal modeling allows controlling not only the system behavior around the steady state but also the startup transient. This article presents the design of two sliding-mode controllers that regulate the output voltage of a synchronous buck converter and limit the startup peak current. A terminal SMC (TSMC) is designed and compared with a first-order SMC, which is called here a conventional SMC. The study shows that the TSMC presents lower transient time to reach the final value than the conventional one because of its finite-time convergence property. It also achieves better performance in terms of line and load regulation. A power converter prototype of 150 W/100 kHz is assembled, and both sliding-mode controllers are digitalized and implemented in a microcontroller. Numerical simulations and experimental results validate the proposal.