Commandable areas of a modular converter for DC voltage imbalance mitigation in fuel cell systems

One of the challenges in fuel cell (FC) systems is the snowball effect. Due to repeated reactions, FCs may be destroyed or become unusable. Membrane drying is an important parameter in cell loss. A solution is to regulate water. By adjusting the FC current using a DC-DC converter, the amount of water produced can be controlled. One solution is to use separate DC-DC converters for each cell. Additionally, in FC systems, the output voltage is low. Therefore, DC-DC boost converters are used. To further increase the output voltage, these converters can be connected in series. Each FC operates autonomously depending on the conditions in which it is located. Consequently, a new unwanted phenomenon occurs in the structure of separate series converters. This problem is the voltage imbalance at the output terminals of these converters, which results from the unequal production of cells. Voltage imbalance can shorten FC life. To balance the voltage, a modular topology based on a DC-DC threelevel boost converter is used. The two-module system is simulated using MATLAB/Simulink. Using calculated duty cycles, the commandable areas of the proposed structure are examined for different operating points. The operation of this topology is validated by simulations and experimental results.