A Novel On-Board DC/DC Converter Controller Feeding Uncertain Constant Power Loads

Abstract

DC shipboard power systems are usually under the threat of instability due to the incremental negative impedance of the constant power loads (CPLs) connected to the dc bus. The instantaneous power flow, which moves along the time-varying uncertain CPLs has to be estimated to enhance the control efficiency of the shipboard power grid. In this article, first, the estimation of the load power variation of uncertain CPLs in a shipboard dc microgrid is conducted in the finite time by adopting the finite-time disturbance observer method. The estimated load power is then received by the fixed-time terminal sliding-mode controller to stabilize the entire marine power grid, as well as tracking the reference voltage of the dc bus in the fixed time independent of initial conditions. A Lyapunov-based stability analysis rigorously proves the fixed-time convergence of the proposed disturbance observer-based controller. Finally, model-in-the-loop real-time simulations using dSPACE emulator are carried out under various operating cases to evaluate the practical implementation of the presented disturbance observer-based scheme.