An alternative to the linear control techniques, which are based on small signal averaged models, is the sliding mode control. That method uses instantaneous models of the switched power converter to design robust controllers. The large signal modelling allows not only to control the system behaviour around the steady-state, but also the start-up transient. This paper presents the design of two sliding mode controllers that regulate the output voltage of a synchronous buck converter and limit the start-up peak current. A terminal sliding mode control is designed and compared with a first order sliding mode control, which is called here as a conventional sliding mode control. The study shows that the terminal sliding mode control presents lower transient time to reach the final value as compared to 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.

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