HIGH-POWER ISOLATED MODULAR DC-DC CONVERTER SYSTEM FOR HEAVY-DUTY FUEL-CELL-BASED ELECTRIC VEHICLES

Abstract

Electric Vehicles (EVs) have attracted researchers' attention to further develop and enhance this strategic area. Compared with fuel-based vehicles, EVs are more demanded nowadays due to their high performance and new modern features. Integrating renewable energy sources such as PV and fuel cells (FCs) to EVs expand this technology's research area to increase system reliability. In addition, it enables an on-board charging feature, which can extend the mileage range of EVs. FC electric vehicles (FCEVs) introduce more challenges to the researchers to integrate this type of renewable energy source to charge the EV battery while driving. This work addresses and evaluates an isolated DC-DC converter for FCEV, where a high-power modular power converter is developed for such applications. Since the FC produces a relatively low voltage, a high gain DC-DC converter is required to step up the voltage to meet the battery's rated voltage. This is achieved through an input-parallel output-series Cuk-based DC-DC converter. The system's small-signal model is obtained to implement battery charger control using the constant current control method. Furthermore, equal power-sharing between the converters through power balancing control is presented to ensure equal current sharing at the input side and maintain equal output voltage with a mismatch in the system modules. Fractional-order PI (FOPI) controllers are utilized to further enhance the system and overcome the drawbacks of conventional PI controllers. Then, the proposed topology was examined through different performance indices such as gain, efficiency, power density, sensitivity, and FC current ripple content analysis. The presented concept has been elucidated through simulation using Matlab/Simulink platform.