Sliding Mode Control for DC-DC Converters with Unknown Constant Power Load in Renewable Energy Systems

DC microgrid technology has drawn extensive research attentions in recent years. It is regarded as a critical issue to obtain fast DC bus regulation and stability when feeding both different kinds of loads, including resistive loads and constant power loads (CPLs). A sliding mode control (SMC) design strategy is presented in this study for DC-DC converters with unknown CPLs. Firstly, disturbance observers are constructed to accurately reconstruct the multiple disturbances. By integrating disturbance compensations, the proposed composite controller is finally constructed for the converter system. Simulations are compared with existing integral sliding mode approaches to demonstrate the effectiveness of the presented controller. The presented approach is characterized by higher voltage tracking accuracy, better dynamic properties and stronger disturbance rejection ability in the presence of various working conditions.