High-performance unmanned aerial vehicles (UAVs) have become increasingly popular in applications across industrial inspection, forest patrol, and aerial photography. For high-performance UAVs, hybrid power systems consisting of proton exchange membrane fuel cells (PEMFCs) and Lithium batteries are usually recommended for improving their flight endurance. In this paper, a novel fully-active PEMFC-Lithium battery hybrid power system is designed f. High-performance unmanned aerial vehicles (UAVs) have become increasingly popular in applications across industrial inspection, forest patrol, and aerial photography. For high-performance UAVs, hybrid power systems consisting of proton exchange membrane fuel cells (PEMFCs) and Lithium batteries are usually recommended for improving their flight endurance. In this paper, a novel fully-active PEMFC-Lithium battery hybrid power system is designed for UAV applications. The proposed construction employs an automatic ON/OFF switch in parallel with a DC-DC converter to control the PEMFC and a second automatic ON/OFF switch replacing the commonly used DC-DC converter to control the Lithium battery. With this design, we enable the two energy sources to directly supply power through control of the ON/OFF state of the two automatic switches, thereby significantly avoiding energy loss in the DC-DC converter. The design further allows for separate or joint operation modes of the PEMFC-Lithium battery hybrid power system to be actively selected through combined control of the automatic ON/OFF switches and the DC-DC converter. On this basis, a simple and effective rule-based strategy can be designed for the energy management between the PEMFC and Lithium battery. Experimental results successfully demonstrate the feasibility of the proposed fully-active PEMFC-Lithium battery hybrid power system, with numerous simulations results showing that the proposed fully-active hybrid power syste. ••A novel fully-active PEMFC-Lithium battery hybrid power system was proposed.••Direct power supply was realized by automatic ON/OFF switches to avoid energy loss.••Simple and effective mode switch strategy was designed for the energy management.••The proposed construction can extend the service-life of PEMFC and Lithium battery.Proton exchange membrane fuel cellLithium batteryHybrid power systemUnmanned aerial vehicleUnmanned aerial vehicles (UAVs) have gained popularity in recent years, with wide-ranging applications across aerial photography, goods transportation, precision agriculture, remote sensing, border patrol, and other fields. The UAV market size has seen rapid global growth in both civil and military practices, with related industries and technologies making great breakthroughs,. As a fundamental elements of UAV applications, power systems significantly impact the endurance and flight performance of UAVs. In early years, UAV power systems made use of internal combustion engines (ICEs) are adapted from the automobile industry,. Though the ICEs exhibit strong power performance, their heavy weight, large size, noise, and vibration make them unsuitable for applications involving medium or small size UAVs, which require light and quiet power systems.Over the past decade, with an increasing focus on environmental protection and clean energy usage in industry, electric-powered UAVs, utilizing fuel cells (FCs) as power systems, have seen increasing development and application,,. In comparison with ICEs, FCs are lightweight, low noise, low heat dissipation while having high energy density and high energy conversion efficiency, which are key advantages for UAVs. Among various types of FCs, proton exchange membrane fuel cell (PEMFC) which utilize hydrogen fuel, is. In the conventional fully-active PEMFC-Lithium battery hybrid power systems, both the PEMFC and the Lithium battery are connected to the DC-bus line via DC-DC converters. Such a construction is able to control the output power and prolong the service-life of each energy source in an effective manner. However, the presence of two DC-DC converters significantly increases the volume and weight of the hybrid power system, while creating unavoidable energy losses. As such, it is vitally important to reduce the volume and weight of the power system while ensuring continued operation performance. Significantly, to reduce the energy losses associated with DC-DC converters, both the PEMFC and the Lithium battery should ideally directly supply power without two DC-DC converters.After consideration of the above requirements, we propose a novel simplified fully-active hybrid power system construction based on two automatic ON/OFF switches, as shown in Fig. 1 (a). This construction contains a DC-DC converter connected in parallel with an automatic ON/OFF switch (SW1). The diode is used to prevent the PEMFC from reverse power. Further, we employ a second automatic ON/OFF switch (SW2) to control the power output of the Lithium battery. As the PEMFC cannot be charged, we equip the PEMFC with a unidirectional buck-boost DC-DC converter that regulates its output voltage to.
