TRANSIENT RESPONSE IMPROVEMENT OF BUCK CONVERTER THROUGH SLIDING MODE CONTROLLER

A. A. SAHITO, M. A. UQAILI, A. S. LARIK, M. A. MAHER

Abstract


Power electronic converters are integral part of the modern power system. Fast dynamic  response  along  with low cost and  small  size of DC-DC converters are responsible  for  their  increasing  use  in  renewable  energy  interface,  electric vehicles, telecommunications, control and switched mode power supplies. Step  down  buck  converter  is  one of  the most commonly  used DC-DC converter  topology.  PI  controllers  failed  to  control  dynamics of buck converter under line and load variations. Sliding mode controller is a nonlinear controller and offers advantages of robustness, fast dynamic  response and ease of implementation. In this paper, SMC is  proposed to control dynamics of buck converter. Proposed controller is combination of linear control and nonlinear control. Linear control is implemented through PI and is derived from voltage loop of the buck converter. Nonlinear part of the controller is implemented through hysteresis. Inductor current ripple is used to select ON and OFF points of the hysteresis control. Proposed controller for buck converter is simulated using MATLAB®/SIMULINK® software. Simulation analysis confirms effectiveness of the proposed SMC. Overshoot in output voltage and inductor current is eliminated for initial transient and line variation. Very small overshoot in output voltage is observed for load variation.

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