SuKoBa Supercapacitors for lifetime optimization of battery hybrid storage systems

/ January 01, 2021 - December 31, 2023

SuKoBa: Supercapacitors for lifetime
optimization of battery hybrid storage systems - design methods and control algorithms

Partners	Consortium leader Skeleton Technologies The automotive supplier AVL
Funding	BMWK
Duration	01.01.2021 - 31.12.2023
Scientists	Dr. Wei Wei Shan, Tatjana Dabrowski, Matthias Wecker

Event details

Location

Fraunhofer IEE

Date

January 01, 2021 - December 31, 2023

Optimization of battery systems by integrating supercapacitors for high-performance applications

If electric battery systems are used for applications with short-term high power peaks, it is often difficult to design them economically due to the physical relationship between capacity and maximum power. In such applications, it makes sense to combine the batteries with supercapacitors (SuperCaps) in order to relieve the former of the power peaks. The aim is to achieve a more advantageous design in terms of the size, service life and costs of the storage system.

Examples of applications in which such hybrid storage systems can be used:

Stationary storage systems, which are used for transient grid support for fast primary control and synthetic inertia, among other things
Electric vehicles, especially commercial vehicles, with limited range and frequent starting and braking.

It is qualitatively known that in such applications, the service life of the batteries can be significantly improved by combining them with SuperCaps, which in turn results in a reduction in the required battery capacity and an improvement in the system costs over the entire service life (total cost of ownership). However, until now there has been a lack of tools that allow systematic system design and operational optimization, taking into account the influence of operating parameters on aging.

The aim is therefore to develop suitable methodology along with design tools and control procedures based on the proposed joint project, for the cross-application use of hybrid storage systems. The overarching objective is then to open up the use of battery storage systems for high-performance applications in which economic application has not been possible to date.

Project results

Demonstrator for a hybrid storage system consisting of lithium-ion batteries and supercapacitors — © Fraunhofer IEE
Demonstrator für einen Hybridspeicher aus Lithium-Ionen Batterien und Superkondensatoren

Close-up of a demonstrator for a hybrid storage system consisting of lithium-ion batteries and supercapacitors. — © Fraunhofer IEE
Demonstrator für einen Hybridspeicher aus Lithium-Ionen Batterien und Superkondensatoren aus der Nähe.

Development of a cross-application design tool for hybrid storage systems

As part of the SuKoBa project, a design tool was developed for hybrid energy storage systems that uses both batteries and SuperCaps. The focus is on reducing battery aging while at the same time optimizing system size and costs.

The tool integrates a non-empirical physical-electrochemical degradation model BaSiS (link), which enables accurate simulation of battery behavior under realistic operating conditions. It can be used to investigate the influence of different system configurations and energy management algorithms on the design and cost of the hybrid storage system.

Accordingly, this design tool receives the load profiles of the application, the expected service life and the parameters for the cost and ageing model as input variables. The result is the cost and size of the hybrid storage system with DC-DC converter.

Development of a management and control tool to optimize the operation of hybrid storage systems

For the "grid" application, the control implementation of the power split between the battery and SuperCap was carried out. The following power control variants were investigated for the topology of the hybrid storage system:

Passive coupling of battery and SuperCap
Active control of the SuperCap current
Active control of the battery current
Active control of battery and SuperCap module

The core element of the control of the hybrid storage system is the power distribution between the battery storage module and the SuperCap module. In this context, a large number of power splitting options were modeled and evaluated.

More detailed information and specific results can be found in the final report. (Expected in September 2024)

Development of a demonstrator for the hybrid storage system, demonstration of the storage concept and the control methods for the grid and vehicle use cases

A great deal of experimental work was carried out to verify the design procedures. In the project, demonstrators designed with the tool were built and tested for various applications in the laboratory. In the process, the safe fulfillment of the function was demonstrated in compliance with all relevant boundary conditions.

BaSiS: Further development and integration of the electrochemical model and aging

In the SuKoBa project, the electrochemical SuperCap model BaSiS CAP was further developed in collaboration with the manufacturer Skeleton Tech.

It was coupled to the lithium-ion aging model BaSiS LIB. For the model parameterization, many measurements were carried out in the laboratory to determine the parameters for the BaSiS LIB model.

We would like to thank our consortium partners and the BMWK for a very successful project.

More Information about BaSiS Software

www.battery-simulation-studio.com

Research Projects

/ January 01, 2021 - December 31, 2023