This paper proposes the construction of a real-time simulation testing environment for the electric propulsion systems of unmanned aerial vehicles (UAVs) using a real-time simulator and KDECAN communication equipment. The proposed real-time simulation environment enables the testing of flight controllers and control algorithms using real-time control communication commands that are identical to those used during actual flight. The KDECAN protocol is analyzed and utilized in the proposed real-time simulation environment for control communication. A reduced-size lift–cruise UAV with eight lift motors (for takeoff) and one cruise motor (for cruising) is used as the target hardware for real-time simulation. This is used to verify the construction of the real-time simulation environment. The final goal of this work is to construct a real-time simulation environment for the stable application of propeller-driven devices, and the findings confirm the independent operation of the lift and cruise motors in the constructed testing environment. Additionally, the real-time monitoring of the state of the electronic speed controllers is verified, suggesting that the testing environment can be utilized as a verification tool for the control algorithms and system design data of electric propulsion systems in actual devices in the future.

Lift–cruise-type unmanned aerial vehicles (UAVs) powered by hydrogen fuel cells often integrate secondary energy storage devices to improve responsiveness to load fluctuations during different flight phases, which necessitates an efficient energy management strategy that optimizes power allocation among multiple power sources. This paper presents an innovative fuel cell DC–DC converter (FDC) design for the hybrid power system of a lift–cruise-type UAV comprising a multi-stack fuel cell system and a battery. The novelty of this work lies in the development of an FDC suitable for a multi-stack fuel cell system through a dual-input single-output converter structure and a control algorithm. To integrate inputs supplied from two hydrogen fuel cell stacks into a single output, a controller with a single voltage controller–dual current controller structure was applied, and its performance was verified through simulations and experiments. Load balancing was maintained even under input asymmetry, and fault-tolerant performance was evaluated by analyzing the FDC output waveform under a simulated single-stack input failure. Furthermore, under the assumed flight scenarios, the results demonstrate that stable and efficient power supply is achieved through power-supply mode switching and application of a power distribution algorithm.