Controllability Insurance of the Boost Converters Dedicated to Fuel Cell Management System

The lifetime of a fuel cell stack can be increased by controlling the cells separately. In such a topology, it is imperative to use a high voltage conversion ratio. The isolated step-up DC-DC converters can be a good solution but the efficiency is the major challenge. Connecting the output capacitors of classical converters like boost converters can cope with the problem of efficiency. However, the inequality of injected powers by different cells originated from the commands of the energy management system can lead to reducing the corresponding capacitor voltage. If the output capacitor voltage became lower than the corresponding converter input voltage, its controllability would be lost. An equalizer system that can send energy from the series connection to lower voltage cells is proposed in this paper to ensure the controllability of the boost converters in such a connection. The simulation and experimental results confirm the validity of the proposed equalizer.