Addressing Battery Pack Design Challenges

We are seeing a big increase in conversations about the demand for efficient, reliable, and safe battery pack systems. In this post we will look at some of the challenges that come with this design process and how Altair’s products can be leveraged to create high-performance battery packs from both mechanical and electrical perspectives.

Fig 1: Battery Model

Understanding the Challenges in Battery Pack Design

Designing a battery pack system involves several challenges:

Electrical Performance: Ensuring consistent and reliable electrical output is critical for the overall system’s efficiency. This can involve managing the electrical load distribution and preventing issues such as overcharging and deep discharging, which can degrade battery life and efficiency. Additionally, engineers must address electromagnetic interference (EMI) and electromagnetic compatibility (EMC) to prevent disruptions in the battery pack's operation and ensure it does not interfere with other electronic systems within the design.

Thermal Management: During operation, batteries generate significant amounts of heat, particularly during high discharge or charging rates. This heat must be evenly dissipated to prevent the formation of hotspots, which can cause uneven aging of cells, thermal runaway, and potential failure. This involves not only the design of cooling components but also the integration of advanced thermal simulation tools to predict and mitigate thermal issues during the design phase.

Structural Integrity: Battery packs are subjected to vibrations, shocks, and impacts during transportation, installation, and operation, especially in demanding applications like electric vehicles or industrial equipment. These mechanical forces can lead to physical damage of the cells or connections, potentially causing short circuits or performance degradation.

Optimizing Electrical Performance with Altair Feko, PSIM, Flux and SmartCtrl

While Altair is typically known for its flagship mechanical engineering tools, it also includes a very powerful electrical engineering portfolio that can aid in the battery pack design process.

Altair FEKO:

Electromagnetic simulation software that enables the analysis and optimization of a wide range of electromagnetic applications, including antenna design, electromagnetic compatibility (EMC), and radar cross-section (RCS).

• Electromagnetic Compatibility (EMC): FEKO helps in assessing and mitigating electromagnetic interference (EMI) within the battery pack. Ensuring EMC is critical to maintaining consistent electrical performance and avoiding potential disruptions.
• Antenna Design and Placement: In EVs, battery packs often need to accommodate communication antennas. FEKO can simulate antenna performance and optimize placement to avoid interference and maximize signal strength.
• Circuit Simulation: FEKO integrates with circuit simulators to model the entire electrical system of the battery pack, allowing for comprehensive analysis and optimization.

Fig 2: Battery Pack Enclosure Shielding Effectiveness using Feko

Altair PSIM:

Simulation and design of power conversion and motor controls. Ideal for users needing power conversion tools for motor drives, power supplies, microgrids, multi-level connectors and power storage/generation.

• Inverter and Converter Design: PSIM excels in simulating power electronic circuits, making it ideal for designing and optimizing inverters and converters used in battery packs. This ensures efficient power conversion and management within the battery system.
• Switching Transients Analysis: By simulating switching behavior, PSIM helps in understanding and mitigating issues related to switching transients, which can affect the reliability and performance of the battery pack.
• Accurate Battery Models: PSIM provides accurate battery models that can simulate the electrical characteristics and behavior of different battery chemistries. This is crucial for designing battery packs that perform reliably under various operating conditions. Seen in Fig 3 below.

Fig 3: PSIM Battery Model Example

Altair Flux:

Low-frequency solver in the Altair Electromagnetics portfolio. It finds its strength in automating the design of electromagnetic devices such as motors, generators, coils, sensors, and actuators.

Optimizing Magnetic Field Distribution: By accurately modeling the magnetic fields, engineers can design layouts that reduce stray magnetic fields that can have a negative impact on performance.

Charging Cable Optimization: By modeling the electromagnetic fields, Flux helps ensure efficient current distribution and minimizes electromagnetic interference (EMI), which is critical for the stable and reliable operation of the charging system for battery packs. Flux can also can simulate the electrical current distribution within the battery cells and interconnections.

Fig 4: Magnetic flux density shown in a cross section of a cable

 In addition to these core electronic solutions, Altair also offers the Altair Partner Alliance, which is a collection of partner products that can be accessed using the same licensing units as the core products. One of those products that could be useful in this operation is SmartCtrl from PSC.

SmartCtrl is a specialized tool for designing and optimizing control loops in power electronic systems. It can significantly aid in the battery pack design process by providing advanced features for controller design, stability analysis, and system performance optimization.

Thermal Management with Altair HyperWorks or Altair SimLab

Thermal management is a critical aspect of battery pack design. Altair’s HyperWorks includes a handful of CFD solvers that could aid in this process, for this purpose lets look at little closer at Altair Acusolve.

Altair AcuSolve

A powerful CFD solver that can assist in the battery design process by providing detailed insights into fluid flow and thermal management.

• Heat Generation and Dissipation: As mentioned before, battery cells generate heat during charging and discharging. AcuSolve can simulate the heat generation within the battery pack and analyze how this heat is dissipated. This helps in designing efficient cooling systems, such as liquid or air cooling, to maintain optimal operating temperatures.
• Thermal Distribution: AcuSolve provides detailed thermal maps of the battery pack, identifying hot spots and regions with uneven temperature distribution. This information is crucial for optimizing the thermal design to ensure uniform temperature across all cells, enhancing performance and longevity.
• Cooling System Design: AcuSolve can simulate the fluid flow within cooling systems, such as liquid cooling channels or airflow paths in air-cooled designs. This helps in optimizing the design of these systems to ensure effective cooling and minimal pressure drop.

Webinar: Achieve Battery Thermal Management System Requirements using Altair CFD Solutions

Fig 5: Acusolve Simulation Results

Altair SimLab

A powerful simulation environment that aids in the battery design process by providing advanced capabilities for pre-processing, simulation, and post-processing across multiple physics domains.

• Comprehensive Analysis: SimLab supports multiphysics simulations, enabling the analysis of thermal, structural, and electromagnetic behaviors within a single platform. This holistic approach is essential for understanding the complex interactions within a battery pack.
• Heat Generation and Dissipation: SimLab can simulate the heat generation within battery cells and analyze how this heat is dissipated through the battery pack. This helps in designing effective cooling systems, such as liquid cooling channels or air-cooling strategies.
• Automated Workflows: SimLab supports the creation of automated workflows that streamline the simulation process. This allows for rapid iteration and optimization of battery pack designs, reducing development time.

Fig 6: Thermos-electric-CFD analysis in SimLab

Ensuring Structural Integrity

Battery packs must endure mechanical stresses during their lifecycle, including vibrations, impacts, and structural loads. Altair offers many tools that can aid in this process including Altair SimLab, Altair Inspire, Altair HyperWorks and Altair SimSolid. For this purpose we are going to focus on the latter two solutions.

Altair HyperWorks

A complete suite of industry-leading simulation tools that includes capabilities for FEA, CFD, Topology Optimization and multi-disciplinary simulations.

• Detailed Stress Analysis: Using the built-in OptiStruct solver, it enables detailed FEA to evaluate the stress and strain on battery pack components under various loading conditions. This includes static, dynamic, and impact loads that the battery pack might experience during its lifecycle.
• Crash and Impact: Using Radioss, users can simulate crash and impact scenarios to ensure that the battery pack can withstand extreme conditions without failure. This is crucial for automotive applications where battery packs must endure crash impacts.
• Vibration Testing: HyperWorks can simulate the effects of vibrations on the battery pack, which is essential for applications like electric vehicles where the battery pack is subjected to constant vibrations.

Fig 7: BEV Battery Pack Impact Testing using Radioss

Altair SimSolid

Altair SimSolid offers a unique approach to structural analysis, providing rapid and accurate simulations without the need for mesh creation or geometry simplification. SimSolid is ideal for quick design changes, early in the development process.

• Fast Simulation: SimSolid performs simulations directly on CAD geometry, bypassing the time-consuming meshing process. This allows for quick iterations and design changes.
• Complex Assemblies: Because it requires no mesh creation, it can handle large assemblies common with battery packs, providing detailed insights into their structural performance.

Fig 8: Vibration simulation results in Altair SimSolid

There are many other products within the Altair portfolio that can aid in different steps in the battery pack development process like Altair Twin Activate and Embed for systems simulation to address voltage, current and temperature; Electrode microstructure manufacturing simulation with Altair EDEM and other. Altair has put together a great summary of these tools you can find here: Battery Design and Simulation Software.

As the demand for new battery technologies continues to evolve, users can fall back on the trusted technologies and expertise from Altair. If you have any questions, don’t hesitate to contact us.