Simulation gives electric car batteries a boost

Advanced CFD software is being used to develop batteries for the next generation of hybrid and electric cars as part of the US Department of Energy's EV Everywhere challenge.

EV everywhere is the latest in a series of clean energy challenges, announced by US President Barack Obama in March 2012. It is designed to develop plug-in electric vehicles, within the next 10 years, that are as affordable for the average family as today's fossil-fuelled vehicles. The initiative is intended to save money by cutting fuel costs, reduce US dependency on foreign oil, and mitigate the impact of energy production and use on climate change.

The US Department of Energy (DOE) has invested $225 million in encouraging the wider adoption of plug-in electric vehicles. Part of this initiative has led to collaboration between Ansys, a provider of simulation software, General Motors, the DOE's National Renewable Energy Laboratory (NREL) and ESim, which designs software and associated hardware modules for vehicle power systems.

Over the past two and half years, the team worked on a DOE-funded project, Computer-Aided Engineering for Electric Drive Vehicle Batteries (CAEBAT), to combine new and existing battery models into engineering simulation software to shorten design cycles and optimise batteries for increased performance, safety and lifespan. In order to achieve these goals the team has been modelling thermal management, electrochemistry, ion transport and fluid flow.

As a result of the work, a battery model is now standard in ANSYSFluent, the computational fluid dynamics solution. This capability is designed to help battery developers reduce the product development cycle for battery design.

By drawing on a unique approach pioneered at NREL, collaborators integrated disparate physical battery scales (electrodes, cell, pack and full vehicle) and multiple physical phenomena (electrochemical, thermal, fluid and structural) – factors that have been a key barrier to effective simulation. In addition, the team blended established detailed 3-D field simulation technologies with systems-level simulation. They also extended the reach of the technology by ensuring that these new tools can interact with current and future battery models.

‘The emphasis in the software integration has been to provide a flexible array of modelling choices that can support several categories of battery researchers, cell manufacturers, pack integrators and vehicle manufacturers that deliver fast and accurate results,’ said Jan Aase, director of vehicle systems research lab at General Motors. ‘With a concise plan for rapid deployment to the industry, the software solutions created through this project are already helping designers and engineers at GM to accelerate the pace of battery innovation and development for future electric-drive vehicles.’

Throughout the remainder of 2014, the team will refine automation techniques for battery cell and pack-level simulations and continue to validate the models with experiments. Collaborators plan to implement cycle-life and abuse (such as overheating) models. NREL's multi-particle model, with ability to model mixture of active materials with different particle sized, will be incorporated as well. At the pack level, state-of-the-art simulation is further advanced by developing innovative reduced-order models, derived and calibrated from the cell-level models and carefully validated through experiments — all designed to enable a balance between model fidelity and computational cost. These efforts contribute to the development of a complete battery cell and pack-level design tools that will be available in the future product releases.

‘The CAEBAT project has been a great opportunity for Ansys. We are partnering with other recognised leaders in EV battery technology to develop and deliver powerful modelling tools that can be used by all battery manufacturers to accelerate production of safe, reliable, high-performance and long-lasting EV batteries that make vehicles more fuel-efficient and sustainable’ said Sandeep Sovani, director of global automotive industry at Ansys.

GM awarded Ansys a subcontract to create battery software tools that will help accelerate development of next-generation EV batteries. The project was a result of a competitive procurement through NREL that was presented to GM in 2011.

 ‘The EV Everywhere Grand Challenge: Road to Success’ reports on made from January 2013 to 2014.

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