Finite-Time Synergetic Controller Design for DC Microgrids With Constant Power Loads

The negative impedance characteristic of constant power loads (CPLs) can cause DC bus voltage fluctuations or even DC microgrid instability. In this paper, a nonlinear synergetic control method is used to guarantee the DC bus voltage stability of DC microgrids with CPLs. First, to regulate the capacitor voltage to its desired value, a macro-variable is defined using the synergetic control theory. Then, due to the sensitivity of the system to the parameters of the input voltage, the CPL, and the resistive load, and also to enhance the overall system performance, an improved macro-variable is introduced by adding an integral action. Finally, the finite-time synergetic controller is proposed to provide the finite-time convergence for the DC microgrid voltage and also to avoid the chattering phenomenon. The simulation and experimental results demonstrate the acceptable performance of the proposed controller.