Simcenter Amesim How Simcenter Amesim can help you in the battery pack design for electrical vehicles

As battery is widely used in nowadays electric and hybrid vehicles, battery pack design becomes a critical issue for car manufactures. Simcenter Amesim can not only help you in the battery pack design, but also enables you to evaluate its performance through detailed simulation of the whole vehicle.

Let's go through this step-by-step and check out how to:

1. Configure your battery pack,
2. Evaluate your battery performance,
3. Study your battery aging.

1 – Configure your battery pack

One of the first tasks in battery pack design is to define the technology and the number of cells to use to meet the technical requirements. For example, a technical requirement is shown in figure 1, which defines the desired voltage, power and energy.

Figure 1: an example of the technical requirement for a battery pack

In Simcenter Amesim, it is easy to take these requirements and generate a battery pack that meets these requirements. This is done by using the battery pre-sizing tool which can be opened directly from the generic battery pack model as shown in Figure 2. In this tool, you can specify the technical requirements of the battery pack, such as:

• the cell technology (among a list of available technologies: LFP, NCA, NMC),
• number of cells in parallel,
• and the targets for voltage, power and energy.

The battery pre-sizing tool calculates the resulted battery pack according to the entered technical requirements. For example, if you choose NCA as the battery technology, then enter 400 V, 100 kW and 20 kWh respectively for the voltage, power and energy targets, the resulting battery pack, as shown in the results (Figure 2), will have 110 cells in series and 50 Ah of capacity for each cell. When you click on the OK button, the resulting battery pack will be applied to the generic battery model.

Figure 2: battery pre-sizing tool opened from the generic battery pack model

2 – Evaluate your battery performance

You can evaluate the performance of the battery pack in an electric vehicle simulator as shown by the sketch in Figure 3. In this sketch, the battery pack is connected to the electric drive of the vehicle; the battery liquid cooling system is coupled with the vehicle's air-conditioning system. This sketch allows you to simulate the battery pack's behavior for any driving cycle. Figure 4 shows an example of the simulated current, voltage, state of charge and temperature of the battery pack for a NEDC driving cycle.

Figure 3: an example of the electric vehicle simulator
 

Figure 4: simulated battery pack response for a NEDC driving cycle

3 – Study your battery aging

Besides evaluating the battery performance, Simcenter Amesim can also help you study battery aging. Simcenter Amesim has many pre-calibrated battery models that include aging modeling. These models have been validated by experimental data for different technologies. With these models, you could easily evaluate the aging behavior of a specific battery technology. Figure 5 presents an example of studying battery aging for different charging strategies of the electrical vehicle. The battery model in figure 5 has the same configuration as shown previously: 110 cells in series and 50 Ah of capacity for each cell. However, the battery pack uses the pre-calibrated NCA model with aging. This sketch simulates how the battery pack ages after a year of use in an electrical vehicle.

Figure 5: an example of sketch to study the battery aging

Figure 6 shows one of the simulation results of the sketch in figure 5. The daily use of the vehicle includes 4 driving cycles and a full charge. The daily temperature change is also taken into account in the simulation. The result shows that the battery will loss 2% of its capacity after a year of use.

Figure 6: battery pack aging with a specific charging strategy

In summary, with its various battery models and associated tool, Simcenter Amesim can help you in the battery pack design from configuring the pack, evaluating its performance to studying its aging behavior.

Going further

Designing battery pack for electrical vehicle

Evaluating battery model parameters from datasheets

About the author

An LI is product manager in the electrical team for Simcenter Amesim since 1 year. His activities center on the modelling of electrical storage systems (battery and ultra-capacitor). He holds a PhD in electrical engineering and has more than 4 years' experience in battery modeling and characterization.