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Innovative high VOLTage network battery concept

Periodic Reporting for period 2 - VOLT (Innovative high VOLTage network battery concept)

Reporting period: 2017-08-16 to 2019-02-15

VOLT is a R&T program dedicated to the Fast RotorCraft program funded by Clean Sky 2 JU. The aim of VOLT program is to develop HV Li ion battery prototypes to power up the engine and meet the HVDC network quality. VOLT battery (HVNB) shall meet TRL6 and PTF requirements.
Several steps have been performed since the beginning of the project.
The kick-off meeting and Product design review have been passed. Preliminary design review is completed.

The cell has been chosen to meet different requirements (power density, weight, volume…). This part is divided in two sub tasks: the preliminary benchmark and the accurate selection.
• The preliminary benchmark consists in comparing all cells with the temperature range, current needed and Weight energetic density.
• The accurate selection consists in verifying that the chosen cell can hold the discharge cycle provided.

Following its selection, the cell has been qualified to verify in detail that the cell can answer the needs of the project.
This part is very important as it gives us the limits of the chosen cell. We can then determine the boundaries of what the cell can withstand and what “power” it can provide.

A battery specification has been written, and a battery electrical architecture has been defined. A safety analysis has been performed and validated the electrical architecture with regard to the unwanted safety events.
The module architecture has been defined as well as the cell arrangements. Some tests on cells and modules according to the DO requirements have been performed. Nevertheless, some tests still need to be performed.
Constraints on weight and volume have been taken into account. This is illustrated through materials choices, minimizing weight while keeping expected mechanical properties or through a dead space minimization design for example.
The casing architecture has been defined, to respect constraints such as volume, installation and maintenance, access to connectors and lights, resistance to design loads…

Working scenarii and interfaces with the helicopter avionics have been defined. Safety constraints have been taken into account and addressed to the different sub-systems.
Weight has been estimated and weight saving opportunities have been identified. A compliance matrix to costumer specification has been edited.
Validation of the requirements is almost completed and a first verification plan has been started.

The equipment design has continued to progress up to completion of the mechanical design and electronics hardware definition:
- Modules integration
- Charger definition and integration
- Electronics (control and command) definition and integration
The long lead time items have been ordered to contribute to the first B1 model manufacturing.

In the mean time, a DDR has been supported in July 2018. Documents regarding the module architecture and battery design -both mechanical and electronical hardwares- and ICDs -both mechanical and electrical-, the compliance matrix, the safety and reliability of the system have been presented. Some open actions have been identified and are still ongoing.

The rework of some sub-assemblies proved to be necessary during the verification phase. The first B1 model delivery has been rescheduled to allow a satisfactory rework. The manufacturing and validation process is still in progress.
Designing and getting the safety of flight certificate for a high voltage battery allowing the start of the engine in a restricted volume and with weight constraint is a challenge which is about to be overcome by VOLT.

Mastering high voltage and high power Li-Ion batteries is an enabler for More Electrical Aircraft, making possible multiple new aircraft’s systems’ architectures. This will lead to more efficient aircrafts, thus greener and more cost efficient.
3D model of VOLT battery