Non-isolating DC/DC converter for a fuel cell powered aircraft

Abstract

Fuel cells in aircraft applications are gaining more and more interest because of higher possible efficiency and increasing air pollution standards. A necessary supplement is an efficient, lightweight and reliable DC/DC-converter to adjust the weak fuel cell characteristic to the voltage level of buffer batteries and drive inverters. Cosmic radiation, condensation, strict EMI-limits and significantly increased creepage distances impair a light and efficient converter. This paper explains approaches to solve those technical difficulties, especially a way to fulfill EMI standards without a large and heavy EMI-filter and introduces the first converter's application, a fuel cell powered UAV. The converter is developed with a strictly scalable design. Therefore an up-rating to multi megawatt applications for larger aircraft is discussed and possible occurring challenges are evaluated

Electric Power Systems in More and All Electric Aircraft: A Review

“…Depending on the application, uni-directional or bi-directional converters can be employed. For instance, a battery pack necessitates a bi-directional converter to interface with a bus, while a uni-directional converter would suffice to connect a fuel cell to a bus [81]. PE converters are generally classified as ac/ac (frequency changer), ac/dc (rectifier), dc/ac (inverter), and dc/dc (dc converter).…”

Discussion on Electric Power Supply Systems for All Electric Aircraft

“…A non-isolated topology could be used to integrate the sources into the electrical power supply system. In publications [69] and [103] on a MEA and a fuel cell-powered small electric aircraft, step-up converters are used. The converter for the battery has to be bidirectional to enable charging and discharging, while the converter connecting the fuel cell can be unidirectional [69], [103].…”

Advanced aircraft power electronics systems — The impact of simulation, standards and wide band-gap devices

“…We have already seen how the introduction of wide band gap devices can lead to both higher switching frequencies and lower losses in principle, however it is clear that there are still significant issues for the designer to overcome to ensure that the design will operate within the EMC constraints in an aircraft. As we move from More Electric Aircraft to All Electric Aircraft, there will also be a greater need to interface with and dynamically control fuel cells or batteries (or both) and this is where advanced, high reliability DC/DC converters will have a huge role to play, particularly with wide band gap device [37].…”