Batterysimulation and -emulation

Simulation models for Lead-Acid or Lithium-Ion batteries can be implemented in different ways depending on the modeling approach. They are based on equations and systems of equations.

A simulation model for batteries possesses input parameters (e. g., current and ambient temperature) and output parameters (e. g., voltage) which are calculated based on the underlying equations and on the present state of the battery (e. g., SOC).

Furthermore, model parameters are necessary that differ for the specific batteries. For several modeling approaches parameters can be stored in the form of characteristics to update these during the simulation, e. g., according to the temperature. Other models perform physical processes.

A model is always a simplified picture of reality, since the exact description of reality is often too complex. In principle, the initial difficulty in battery simulation is to choose the correct modeling approach for the specific issue and the acceptable model simplifications.

In doing so, in particular for application in the industry, there must be an appropriate ratio between cost and benefit. After choosing an appropriate modeling approach, challenging issues are the model development, the implementation and the parametrization.

In  BaSiS-LIB and BaSiS-LAB the user can choose between a higher accuracy and higher computational speed via a control parameter. For these reasons, no absolute specifications for precision are possible.

The models have been developed in a 6-step process:

1. Gain understanding of the problem
2. Choice of a modeling approach
3. Model development
4. Simulation
5. Validation of the simulation
6. Further development or another iteration of the steps 3-5

The models describe the current known and relevant physical/electrochemical processes in Lithium-Ion and Lead-Acid cells. Depending on the industry, the model can support development processes in industry in various manners.

Battery manufacturer:

Via the alteration of the constructive data of a cell (layer thickness, cell structure) and the chemistry of the cell in a few clicks, a manufacturer may partially renounce the construction and testing of battery prototypes and thereby save money. Moreover, a manufacturer obtains detailed insight into processes of the battery and, thus, may optimize the cell design and the manufacturing. The analysis of sensitivities to individual parameters is possible as well.

Automobile manufacturers and suppliers:

In the automotive industry Hardware-in-the-loop (HIL) systems are used to perform tests fast and cost-efficient. In  doing so, a real device under test (e. g., E-vehicle, battery management system) is connected to an emulated battery system. The advantage of battery emulation is that arbitrary states of the battery can be adjusted in a few seconds, whereas this may take several hours to days within real systems. Since the actual test proceeds partly very fast, the use of a battery emulator may save a lot of time and money in this case. Furthermore, the influence of aged batteries can be examined in a fast way, while in real tests even longer periods would be required.