DC and AC Power Quality Control for Single-Phase Grid-Tied PEMFC Systems With Low DC-Link Capacitance by Solution-Space-Reduced MPC

The low-frequency current ripple, which is inherent in the two-stage single-phase grid-tied fuel cell power system, gives harmful effects on fuel cell stack itself and causes a reduction in the lifetime, efficiency, and operating performance of system. This article first presents a direct current control scheme to improve the dc and ac power quality with a dc-link voltage notch filer and a proposed improved model predictive control (MPC) method. However, since the number of the switching states is low, the fuel cell dc current and grid current may suffer contaminated and distorted, when the conventional MPC algorithm implementation is straightforward. With the aid of feedforward duty ratio and the rotation angle of reference grid current, the optimization space can be reduced in real time, avoiding evaluating all the feasible virtual-vectors, and then the improved MPC has been proposed. Finally, the correctness and effectiveness is verified by the simulation and experiment results.