New generation Power Distribution Systems for Advanced Air Mobility

Engineers at Rolls-Royce work on multiple innovations which are key to redefine Advanced Air Mobility (AAM) for the future. Our integrated design approach enables the development of complete solutions building on modular subsystems, ensuring the most efficient and safest operation of complete electrical systems powering Urban and Regional Air Mobility aircraft.

Rolls-Royce’s Electrical Power Distribution System (EDS) for Advanced Air Mobility distributes high-voltage, direct-current power to interconnect energy sources like battery or fuel cell with the electric motors of the aircraft. A modular and scalable design is being developed that can be adapted based on application and customer demand. Advanced EDS technology is key for the electrification of aviation, as the power distribution system can have significant impact on aircraft efficiency, safety, and weight.

At the core of the EDS sits a high-voltage power distribution unit (HV-PDU) carrying the intelligence and switches to control power flows. It is complemented by the high-voltage, direct-current wiring through which the current flows. Depending on power demand of the aircraft, several HV PDU’s can be combined, and the harness scaled accordingly.

Our Rolls-Royce Electrical team in Hungary has recently put our design of a HV-PDU featuring several novel features through validation and stress tests successfully. We talked to Lead Engineer László Csóti and Project Manager Gergely Deák about the development.

You have recently presented and validated your latest design of a High-Voltage Power Distribution Unit. Why is this a significant achievement?

High Voltage Power Distribution Unit

You have recently presented and validated your latest design of a High-Voltage Power Distribution Unit. Why is this a significant achievement?

Gergely: Our modular HV-PDU is the heart of the electrical distribution system we are developing for eVTOLs and electric commuter aircraft. How we control the power flows on board of the aircraft is crucial – energy losses during the transport of power across the aircraft need to be kept at a minimum, and the effects of potential short circuits in the system need to be mitigated. Keep in mind that we are dealing with voltage levels up to nearly a kilovolt, currents at system power levels need to be intelligently controlled, and the health of the wiring system monitored, to always ensure maximum operational safety of the aircraft. We want to get to type certification by 2027 to complement our propulsion portfolio for AAM, so it has been essential to start our learning process.

László: Our EDS design provides overcurrent protection to the Electric Propulsion Units, and it can reconfigure high-voltage lanes to maintain sufficient energy flow in case of emergency. We have also incorporated an innovative device monitoring the insulation health of the high-voltage lanes, in addition to voltage levels and the EDS temperature. The protection and monitoring functions will be enabled by an integrated controller developed according to DO-178C, DO-254 DAL-A with CAN and/or AFDX communication.

What is the greatest challenge you are solving with your work?

László Csóti, Lead Engineer Electric Distribution System

What is the greatest challenge you are solving with your work?

Gergely Deák: In addition to distribution, one of the key tasks of the Electric Power Distribution System is to protect the linked equipment in the case of a short circuit. The EDS connects all units, therefore, finding an optimal position for it is critical. This technology is not yet available in the market, and the requirements vary for different aircraft. We therefore develop and, test the component prototypes so that they fulfil the highest standards, with a modular and scalable system in mind that can be tailored to a custom solution to all our customers.

Gergely Deák, Project Manager

László Csóti: Safety and weight are the two greatest challenges in the aviation industry. To support high power density, our modular hardware has a compact, custom design with a particularly small footprint of the HV DC connectors. Our system, like our electric propulsion units, will be air-cooled and we use thermally optimised copper busbars that contribute to the mechanical integrity and high efficiency. Our PDU controller can be tailored with custom interfaces to fit the varying customer requirements. On a higher level, I would say that we are shaping a completely new industry, the market for Advanced Air Mobility, and solving the power distribution challenge is an integral part.

Gergely: Urban and Regional Air Mobility are areas of application where breakthroughs in technology within this decade will make it possible that fully electric or hybrid-electric aircraft cross the sky above us. We channel all our resources into developing various systems boasting the highest possible quality and safety for these aircraft. Our prototypes that have powered smaller aircraft in the past years have proven that this is feasible. We are now working on further developments in partnership with our customers to have electric technology implemented as general market practice for short- and mid-haul flights.

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