A Study of Adaptive Feed Forward and Feedback Control Methods for Sliding Mode Controlled Dc-dc Buck Converters

Switching frequency acts as a major role, while applying sliding mode control to dc-dc buck converter, switching frequency is affected by line and load variations. To reduce switching frequency deviation to line and load variations, an adaptive feed forward control is used, that varies hysteresis band according to the change of input voltage. Several methods of varying hysteresis band of the hysteresis modulator are possible. In this work adjusting the power supply is to be considered. An adaptive feedback control scheme that varies the control parameters (i.e. sliding coefficient) according to the change of output load is proposed. This paper presents a complete investigation into the problem and gives the effectiveness of the desired solutions. In this method implementing the proposed adaptive control strategies are discussed, simulation results gives that the adaptive control methods are capable of reducing the switching frequency variations, simulation have been done in MATLAB /Simulink to verify the results.