PI-Sliding mode controller for an islanded dc microgrid with constant power load

Islanded dc microgrids using renewable energy resources are attracting increased attention due to the global interest in reducing the usage of fossil fuels and increased environmental pollution associated with conventional energy sources. A dc-dc boost converter is an integral part in most of the islanded dc microgrids. It is reported in the literature that dc-dc boost converter exhibits instability problems when it is delivering a constant power load (CPL). A simple single loop PI controller fails to maintain stability with CPL. In this paper a dual loop PI controller and a PI-sliding mode controller are presented to overcome the instability issue. The simulations were carried out in MATLAB/Simulink to verify the performance of the controllers. The PI-sliding mode controller is capable of maintaining stability of the system and is found to be robust against input voltage variations and parameter variations.