Robust adaptive composite control of DC–DC boost converter with constant power load in DC microgrid

Abstract

Power electronic loads are penetrating in DC microgrid. These loads are usually regarded as constant power loads (CPLs) with negative impedance characteristics, which seriously affect the dynamic performance of DC bus voltage and may result in instability of the DC microgrid system. To improve the performance and stability of a boost converter with CPL, proposed herein is a robust adaptive composite control strategy, which mainly includes two control loops. An affine nonlinear mathematical model is established. Based on the differential geometry theory, the minimum phase problem is analyzed under different output functions. In the inner control loop, the inductor current is linearized by using exact feedback linearization theory to a linear system. Meanwhile, sliding mode control method is studied to control the linear system, and an adaptive law is designed to update the sliding mode switching gain. In the outer control loop, the output voltage is regulated by proportional–integral control technology to achieve no steady-state error for the DC bus voltage. Furthermore, the robustness of the closed-loop system is verified, and the global asymptotic stability of the control system is proved. Compared with the existing method, both simulation results and experimental results verify the validity and superiority of the presented control strategy.