Clean Sky, E-taxi, power electronics, power conversion, 10kW, 100kW, bidirectional power converter, green taxiing

Description of the Project

Design and development of a bidirectional power converter and motor controller for aeronautical application. This converter will be integrated in the aircraft as part of the new landing gear (advanced landing gear) based in electrical movement. This converter will be part of the electrical system associated to the advanced landing gear system. This system will allow aircraft taxing (taxi phase) by electrical motors instead of aircraft engines, which ones will be kept in standby and therefore reducing fuel consumption, COx/NOx emissions and environmental and noise impacts around airports. This new application is named as e-TAXI.

Main challenges for this project have been to reach a TRL6 level and at the same time to be compliant with the main aeronautical requirements for future aircraft integration in a short time and in safe mode.

The converter shall have a high power/weigh in order to comply with aircraft guidelines where weight and dimensions restrictions are a key driver. Moreover, the converter, or also named as MCU (Motor Control Unit), have been designed as bidirectional in order to give electrical energy (coming from aircraft electrical network or new energy storing system) and control to the new electrical motors electrical energy to the electrical motors in the wheels and but also, to be able to recover energy from the system and recharge the new energy storing system.

Another challenge of the project have been targeted in the use of high voltage, in order to reduce weight and dimensions of the system but ensuring safety aspect.

On the other hand, the E-TSIN converter (MCU) have been designed to be easily scalable/modulable (from 10kW to 100kW) to be applicable for different aircraft models and some other and similar future applications. So, in the future, units could reduce/increase its nominal power (and then update weight and dimensions) or to keep current design but connecting several units in parallel working under master/slave configuration, although scalability/modularity solution will depend of factors as cost, integrability, global dimensions and global weight.

And of course, the design was done in the final step of the project to be compatible with aircraft main rules (safety, reliability, maintainability and operability).

The project has been developed in 3 main steps, with an initial phase of technology assessment and concept design, where also analysis of modularity and validation of this modularity concept was applied through 3 pre-prototypes.

In a second phase, a complete development process according to the initial specifications and several prototypes targeted in TRL3-4 were performed and verified, including a preliminary integration with the e-TAXI system.

Finally, a third phase was performed for evolution of the design according to the final e-TAXI specification, improvements in the design and SW and with target to reach a TRL5-6 level.

And in this final phase, TRL6 level was achieved, with the manufacturing of a pre-serial manufacturing of four units, that were tested in INDRA facilities at unit level, and system level (with other parts of the e-TAXI program). Also a final pre-qualification /Thermal, mechanical and EMI/EMC) was successfully performed.

It is also important to highlight that the design of the MCU was designed to include also three additional functionalities as:

HVDC and control of the clutch function with a dedicate internal constant current converter
Battery charge and discharge with and additional power circuit

The project duration was initially estimated in 51 months, but finally, the project was enlarged to 66m due to the project difficulties, evolution of the aircraft baseline and the big impacts of the COVID pandemic.

But despite this issues, the project has achieve all the objectives and with a big recognition from the TM (Safran Landing Systems) and the CSJU about the results obtained and the support performed by INDRA and CEIT for the e-TAXI global objectives.

The next internal steps of this projects is to going on qualification, maturity and formal aeronautic process to achieve in a short time a TRL9 and get authorization for aircraft installation for flight tests.

Moreover, other scenarios of application and opportunities are currently under discussion between Safran Landing Gear and the E-TSIN consortium.

Industrial Partners

Indra

Indra´s Role

Indra is the project leader, performing not only all the coordination and management tasks but also the topology and design validation tasks. Indra also has developed the power part and mechanical envelope of the TRL3 design (including MCU and the complete TRL6 development. TRL3 improvement and maturity tests were performed also in Indra, at Aranjuez facilities, so as verification, integration and pre-qualification tests over the TRl6 prototypes.

CEIT-IK4, In San Sebastian, was in charged in the definition and development of the pre-prototype, TRL3 SW, modularity study and parallel control and support to all activities of the TRL6, including SW evolution and adaptation.

SAFAN, if the “Topic Manager” of the proposal and e-TAXI system integrator. Safran also develop by itself and partners, the electrical motor (and all associated parts) and the e-TAXI controller unit. Also in in charge of integration in aircraft and perform control and power interfacing.

Universities and Technology centres

https://www.ceit.es/en/

https://www.ceit.es/en/areas-investigacion/transporte-energia/vehiculos-electricos-redes-distribuidas/e-tsin

Technologies used

Active Rectifier Units, Transformer Rectifier Units, High Power density, High frequency, Zero Voltage Switching, Total Harmonic Distortion, Power Factor, EMI filter.