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Indra HVDC Distribution system

Periodic Reporting for period 3 - INDIS (Indra HVDC Distribution system)

Reporting period: 2020-10-01 to 2021-09-30

The goal of this project is the development of a new primary electrical power distribution system (PPDS) to be integrated in an aircraft/plane platform from the aircraft manufacturer Piaggio Aerospace.

The situation to be solved by the INDIS project is the increase of the aircraft electrification and power increase in the small aircrafts, helicopters and new air vehicles (LR-drones, RPAS and future air taxis). All new platforms will be based in Total Electrical Aircraft (including propulsion) or in the MEA concept (more electrical aircrafts), where most of the aircraft systems are based in electrical power and in some cases, also in of hybrid propulsion.

Therefore, INDIS project is being developed to solve this situation, over the short term of new future SAT (Small Aircraft Transport) or even, over big modification in the legacy SATs.
So, from the moment that aircraft platforms (aircrafts, planes, helicopters, RPAS,..) need to kept is size, or even more to reduce size, the new electrical aircraft systems, as core of these new aircrafts, need to be as most efficient, as smallest, as more powerful as possible.
And in order to achieve these requirements, INDIS project will use new components and technologies to perform a new power distribution based in these concepts of intelligence for power management, protections and system efficiency, and new technologies of high voltage (HV) for size & weight reduction. But the bigger difficulties for development, is to be able to introduce in a small available space, a lot of smart switches, to manage/protect a lot of electrical loads (more than in legacy aircraft). In the pass and currently, these systems manage no so much electrical loads, at low power and with single behavior managed by pilots, therefore, with very low capability for automation, new aircraft functions & operations for efficiency increase.

Regarding to the environmental green objectives targeted by the European Commission through the CleanSky2 program (CS2), being part of the H2020 European Frame program, the goal of the INDIS project is to achieve an electrical power distribution system more efficient and that allow finally to produce some more electrical aircrafts and in a feasible way, as long as this new electrical system will be the core and the backbone of the new electrical air platforms. The CS2 program has as one of its main pillars the development of more electrical aircrafts (MEA) or even, total electrical aircraft (TEA), in order to achieve an general aircraft more efficient, competitive and capable to achieve a reduction in contaminant emissions and noise.
INDIS system will optimize the power distribution in low voltage (LV), by increasing power density and allowing a better control of the power installed, load and protections management. INDIS will alsod evelop the elements and items for distribution, load management & protection in a new HVDC-network. The HVDC allows a global reduction of weight & volume in the onboard electrical system.

Then, the INDIS electrical power distribution system developed by INDRA has been based in the following points or principles:
- Smart management of the electrical power.
- Weight and volumen optimization.
- Same or higher compliance levels in safety, redundancy and segregation requirements at aircraft level where electrical system will be a critical one.
- Integration of DC networks in air platforms, as in low voltage networks (LV or 28Vdc) as in high voltage networks (HV or 270Vdc).

In order to achieve these objectives, INDRA has get advantage of its previous experience in SSPCs (Solid State Power Controllers) and it has also developed new specific SSPCs for high power and some new local controllers (or CMCs), that jointly with traditional contactors, has allowed to build a new subassembly named as “S-Contactors” (or smart contactor).

The general control of the system has been based in the mix of local controllers and main controller.

INDIS system has been also development under principles of segregation and redundancy and dissimilarity to ensure future safety criteria at aircraft level.

Despite the distribution elements in LVDC and HVDC, a new and regulated power converter, has been developed, to trasnfer LV energy to HV network. This converter has been designed using a new topology more efficient and using a modular approach, for future scalability in aorcraft or other applciations.

The Project has been developed under several phases:
- Phase-1, for requirement analysis and agreement of baseline with the customer.
- Phase-2, for concept and preliminary design and pre-prototypes preparation, for risks reduction and technological feasibility analysis.
- Phase-3, for detail design and application of changes coming from pre-prototypes validation.
- Phase-4, for critical development with the generation of all the documentation for manufacturing and mounting.
- Phase-5, for PCBs and subassemblies mounting, and validation actions.
- Phase-6, for units mounting and validation at equipment level.
- Phase-7, for final pre-integration at INDRA facilities and verification tests, by using own a/c emulators designed by INDRA itself.
- Phase-8, for customer delivery and INDRA support to SAT Rig integration activities.

Four protyopes has been developed (LV-PPDU, HV-PPDU-L, HV-PPDU-R and DCDC-PCU), tested and integrated in benches, additionally to dedicated HW and SW tools for interfacing, remote control and monitoring propose.
During the proposal, several technologies were proposed to be analyzed to achieve the objectives of size, weight, flexibility, automation, safety and power management, so, during this initial concept phase, most of these criteria were analyze and tested over several pre-prototypes.

So, concept of high power SSPCs as in LV and in HV were validated and also matching with the concept of new smart switches.

As already commented before, the technologies used along this Project have been the following:
- High power SSPCs technologies using SiC devices for HV channels and Si devices for LV channels.
- Smart contactors to be used in power input channels and in reconfiguration channels (800-1000A), but using technologies for control, monitoring and protections used in similar way tan in INDRA’s SSPCs.
- Intelligent control based in a “triple-redundancy” concept and mix of centralized control (at system/unit level) and distributed/local (at commutation/protection device level).
- Optimized regulated power conversion based in new components and technologies (SiC devices, local control, planar magnetics devices, modular approach with interleaving technic, …).
- New designs for power connection based in new INDRA power terminals with captive solutions.
- New mechanical and cooling solutions for weight and volume optimization and cooling optimization by natural conduction/convection.

Finally, it is important to highlight that depending of the required functionality, safety (DAL, dissimilarity, reconfigurability, protection speed and redundancy), ones or another devices were better. So a mix configuration between LV and HV SSPC and S-switches was proposed and selected.
INDIS SW system emulator and IPMS
INDIS Project logo
INDIS HV-PPDS simulation model