Linear Extended State Observer-Based Backstepping Sliding Mode Control For DC-Bus Voltage Regulation Under Constant Power Loads In DC Microgrids

In DC microgrids, Constant Power Load (CPL) is one of the causes to generate negative incremental resistance, which significantly reduces the stability margin and may lead to DC-bus voltage fluctuations. Therefore, the issue of handling the DC-bus voltage under the CPL is of considerable interest. In this paper, a Linear Extended State Observer-based Backstepping Sliding Mode Control (LESO-BSMC) strategy is proposed to enhance the robustness of output voltage for a boost converter under CPL and system uncertainties. A two-channel Linear Extended State Observer (LESO) is designed to estimate real-time disturbances caused by load variations, input-voltage fluctuations, and parameter mismatches, allowing for accurate compensation without relying on a detailed nonlinear model. The Backstepping Sliding Mode Control (BSMC) law is constructed based on the Lyapunov stability criteria to guarantee global stability, fast dynamic response, and reduced control chattering. Comprehensive simulations were conducted to confirm the effectiveness of the proposed algorithm for maintaining DC-bus voltage at 24 V under four scenarios. The obtained results demonstrate that the proposed LESO-BSMC strategy achieves high tracking performance, efficiency in disturbance rejection and robustness, faster dynamic recovery, and minimizes DC-bus voltage ripple in comparison to other strategies of PI-SMC and Adaptive BSMC (ABSMC), while significantly reducing switching activity as quantified by control-effort indices.