Design, test and demonstration of an inverter for HLFC compressor applications utilizing a Model-Based Systems Engineering approach

Hybrid laminar flow control (HLFC) is an aircraft technology with the potential to reduce fuel consumption by actively sucking air from the boundary layer on the leading edge, thus increasing laminar flow length and decreasing drag. Especially in the context of a greener aviation and possible new fuels, such as hydrogen or bio fuels, saving fuel becomes increasingly important. Within the Clean Sky 2 program, this technology is investigated for the main wing (HLFC-Win project) and for the horizontal tailplane (ECHO project). In both projects, the compressor and the corresponding inverter are key components in order to ensure the HLFC functionality. Harsh compressor requirements, e.g. high mass flow and compression ratio at limited available space, make this system technically challenging. Owing to the multidisciplinary design environment, it is obvious that a system development process including safety assessment had to be established to ensure an appropriate equipment design fulfilling the CS-25 and project requirements. The process and its elaboration will be described in this work. The present work also aims on the development of a miniaturized inverter prototype with a model-based systems engineering (MBSE) approach, which implements the process defined in advance. This inverter prototype covers the basic functionalities for a given turbo-compressor. One major challenge is that the compressor is driven by a permanent magnet synchronous motor (PMSM) operated at a very high speed (> 100,000 rpm) in a high cruise flight altitude. This makes a robust, sensorless and fast processing control crucial. Therefore, the given compressor needs to be initially identified since the characteristic was unknown. Moreover, the limited available space requires an optimal thermal management during the design and operational phase. The developed inverter and its control were tested for functionality and operability in an experimental setup. Even if some functionalities are still missing, the feasibility for a small-sized inverter for high motor speeds and electrical power (> 5 kW) will be demonstrated.