Decentralized Power Allocation Strategy for Fuel Cell/Battery/Ultracapacitor Hybrid Power Systems in Electric Propulsion Aircraft

Aviation electrification is a promising solution to tackle the global energy crisis, which fosters electric aircraft. Besides, hybrid power systems involving the fuel cell, battery, and ultracapacitor are promising to provide propulsion power. Serving as the key device, fuel cells suffer from undesirable operation conditions, e.g., start-stop transition, heavy load, light load, and power variation, which degrade their operation efficiency and lifespan. To address this issue, a decentralized power allocation strategy is proposed in this article. In this method, the ultracapacitor is regulated based on a virtual capacitance to handle dynamic power demand. Besides, the battery is exploited to undertake partial steady-state load power when in heavy- and light-load conditions, allowing the fuel cell to operate in the high-efficiency range to the greatest extent possible. Consequently, both dynamic and steady-state power allocations are realized, ensuring high-efficiency and reliable operation of the hybrid power systems. Meanwhile, note that the control algorithms in this method for all three units are implemented based on their local information, respectively, no dedicated communication network is required. Finally, the validation of this strategy is proven by hardware-in-loop (HIL) test results in various scenarios.