Integrated Systems Design of Composite Casings for Power Electronic Converters for Aircraft Applications

Electrification of aircraft is central to achieving ambitious targets for reduction of aircraft fuel burn and associated emissions of greenhouse gasses including Nitrous Oxides and Carbon Dioxide. This PhD will develop and demonstrate methods for the integrated design of power electronic converters (PEC) with carbon fibre reinforced polymer (CFRP) cases, for the light-weighting and minimised volume of PEC in future aircraft. These integrated systems will form a module that can be easily slotted in and out of an aircraft's electrical systems, adding an additional benefit of reduced time out of service due to maintenance. The integrated design will take into account interdependencies with the wider on-board electrical power system.

A significant research opportunity exists to integrate the electrical and structural systems, to enable optimisation of the full aircraft performance. This includes, where possible within design thresholds, the development of materials with multifunctional roles. In particular the design of a modularised on-board electrical power system, with each module integrated with a section of composite structure that can be easily slotted in and out of the aircraft, or engine. This has the advantage of not only minimising volume and weight, but minimises the time an engine or aircraft is out of service. The concept of modular rafts has been proposed by the aerospace industry in the past, but further understanding of methods to closely integrate CFRP with electrical systems and components is required.

For the successful design of an integrated power electronic converter CFRP module, the project will identify the key design thresholds for the electrical power system, power electronic converter topology and electrical, thermal and mechanical properties of CFRP. The integration of the structural, thermal and electrical system introduces complex challenges and requires a multi-disciplinary approach. This includes the choice of converter topology, thermal management system, control circuitry, electromagnetic shielding and appropriate filters. Wider systems considerations include the system parameters, grounding topology and fault management strategy. The thermal management system may be possibly via air cooling, or liquid cooling may be required. The design interdependencies with the layup of the CFRP casing are critical to the integrated system design. An additional design challenge is that the integrated system must be robust enough to withstand the harsh operating environment, with the system experiencing a combination of low pressure, extreme temperature, vibration and moisture. Finally, the level of modularisation will also be taken into account. For example, the limitations on integrating auxiliary systems into the composite casing. The integrated systems designed in the project will be verified by the design, test and build of hardware prototypes.