A sliding mode controller for two-phase synchronous buck converters

Sliding mode (SM) controllers are known for their robustness and insensitivity to disturbances and plant parameter variations. However, since perfect sliding mode requires infinite switching, a quasi-sliding mode controller is developed with hysteresis control to limit the switching frequency to a desired fixed frequency. A SMC utilizing direct control is designed for a single-phase synchronous buck converter. Next, a technique to extend the SM controller for a multiphase synchronous buck converter is developed to ensure proper phase interleaving for a two-phase converter. Simulation results of the new controller on a two-phase synchronous buck converter are presented. The proposed controller allows reduced output voltage ripple and reduced transient effects.