The low-altitude economy has been established as a strategic emerging industry,
driving the development of various new aircraft types, including electric
vertical take-off and landing (eVTOL) vehicles and industrial unmanned aerial
vehicles (UAVs). In this development, proton exchange membrane fuel cell
(PEMFC)/lithium-battery hybrid propulsion systems face challenges in balancing
fuel economy, stack durability, and implementability under stochastic
aerodynamic loads. Six energy management strategies (EMS) are systematically
evaluated in this study, namely Thermostat, Fuzzy Logic, State Machine (SM-EMS),
Power Following (PF-EMS), Dynamic Programming (DP-EMS), and a proposed
load-disturbance-based method (LD-EMS). These strategies are tested on three
distinct platforms, including a 2 kW fully simulated system, a 2 kW
hardware-based setup incorporating a real PEMFC stack and Li-FePO4
battery, and a 30 kW hybrid testbed. Experiments were conducted under synthetic
stochastic load profiles representative of gust-induced power transients. The
results indicate that LD-EMS achieves a total equivalent hydrogen consumption of
2.71 g (close to the DP-EMS optimum of 2.64 g and 19 % lower than SM-EMS) while
reducing fuel cell state-of-health degradation to only 0.0005 % over the test
cycle, which is an order of magnitude better than PF-EMS and SM-EMS. On the 30
kW platform under two distinct challenging profiles, LD-EMS maintains fuel cell
efficiency above 90 %, keeps the stack operating in high-efficiency zone, and
limits power switching events to 97 and 212 respectively over test cycles,
demonstrating robust scalability and transient suppression capability without
requiring prior mission knowledge. A five-dimensional evaluation framework is
introduced to compare the six EMS. In accordance with this framework,
platform-specific selection guidelines are established. Thermostat EMS is
recommended for small industrial UAVs where hardware simplicity dominates;
LD-EMS is the optimal choice for passenger eVTOL under unpredictable gust
conditions; and SM-EMS is preferred for commuter/regional aircraft operating on
fixed, repetitive routes.