Electric school bus manufacturer uses Simcenter Amesim for system simulation to optimize battery design and thermal management

Seeking more sustainable urbanization

According to the United Nations, urbanization is growing rapidly. By 2030, the world is projected to have 41 megacities with 10 million or more inhabitants. More people means more cars on the road and more air pollution as transportation represents one-third of pollutant emissions. It also means there is a limit to the number of cars the infrastructure will be able to accommodate, which is why it is so important to develop sustainable mass transportation solutions.

That’s one of the reasons why the leaders from the world’s largest cities, equal to 650 million people, decided to create the C40 Cities Climate Leadership Group to tackle climate change and drive urban action that reduces greenhouse gas emissions and congestion. They are pledging to procure only zero-emission buses by 2025, which they hope will lead to green and healthy “fossil-fuel-free streets.”

Simcenter Amesim vehicle model.

Enhancing the overall quality of life

From its founding in 2011, the goal of the Lion Electric Co., has been to provide sustainable public transportation. The firm, which is headquartered in Saint-Jérôme, Quebec, Canada, designs, engineers and manufactures all-electric school buses, midi/minibuses for special needs and urban transit as well as urban trucks. The firm believes transitioning to all-electric vehicles will lead to major improvements in our society, environment and overall quality of life.

Simcenter Amesim battery model.

Taking on new engineering challenges in product development

Developing an electric-powered bus presents new and challenging engineering considerations, such as the thermal management of the battery as well as its integration into the overall vehicle.

Raphael Ouellet, who is the powertrain product engineer on the Lion Electric engineering team, explains expectations are set at two levels: “First, in the case of a battery-powered vehicle, a subsystem analysis is required to have a precise view on how the drive cycles and charging scenarios would affect the battery’s capability to develop the appropriated thermal management solutions and identify coolant-flow balancing in cooling-heating loops to optimize overall thermal management. Secondly, from early development at the vehicle level, we expect to be able to assess the overall vehicle performance over real drive cycles in order to estimate a realistic range.”

All-electric Urban Class 8 truck.

Rapidly developing a robust electric powertrain

These considerations need to be understood at the beginning of the product development process. This enables Lion Electric to avoid recalls at the start of the production because of design errors, which could affect the safety of the vehicle but also implies additional costs and increased time-to-market. Then, to develop a battery and assess its performance once integrated into the complete vehicle early in the development cycle, the Lion Electric engineering team chose Siemens Digital Industries Software’s Simcenter™ Amesim™ system simulation software that is part of the Simcenter portfolio.

Lion Electric started from scratch modeling its battery design and thermal management. They were initially supported by Maya HTT, an engineering service company, that provided support and expertise to model the battery and help them through the iteration process until they found an optimized architecture. They started designing the cells and all the thermal exchanges of the cells first with the aluminum box, and then within the overall environment of the battery.

“Using Simcenter Amesim to reproduce the thermal exchanges within the battery and the forced-air cooling enabled us to define the best architecture for all the elements of the battery,” explains Ouellet. “Maya HTT provided the guidance we needed to find the right architecture.”

The battery’s open circuit voltage and internal resistance curves were identified in just a few clicks from the supplier’s datasheet using the three batteries data-sheet import app.

Once the battery had been designed, Lion Electric tested the performance of its physical twin in a climate-controlled room to adjust the digital model against the results. Thanks to the testing phase, the accuracy of the model was improved in terms of electrical performance and heat rejection.

“Using Simcenter Amesim allowed us to make the right decisions from the start and optimize time-to-market,” says Ouellet. “We are also able to run simulations for clients and offer them details about the expected range or expected payload for a specific use case.”

Battery cycle profile in Simcenter Amesim.

A user-friendly software that facilitates efficient reporting

Lion Electric’s satisfaction with Simcenter Amesim is reinforced by how easy it is to use and create reports. Indeed, Ouellet explains, “Simcenter Amesim helps us produce graphs and reports quickly, building presentations in no time. Also, many more variables can be considered compared to using spreadsheets calculations, which allows us to produce more refined results. Reruns are easy, so when my management requests modifications, I can quickly implement them.

“Simcenter Amesim has many benefits: The intuitive interface, powerful and optimized algorithms, the ease-of-use of data management (visualization, postprocessing, global parameters, etc.) and implemented tools (optimization, 3D visualization, etc.) enable us to save time to provide top management and customers with easy-to-understand results.”

Electric mini school bus.

Realizing lower production costs

“We have the same amount of time to develop our model, and by replacing spreadsheet software with Simcenter Amesim, we now can improve our battery performance assessment and go deeper into details for our analysis,” says Ouellet. “This same amount of time is then spent on developing, optimizing and building the most appropriate battery architecture and related thermal management. This allows us to bring a more reliable and mature product at the start of production.

“Overall, we believe this approach leads to lower product development costs. Indeed, if we have to modify a product after production has started, it can be very costly. Recalls covering design errors affecting the safety of the vehicle is an OEM nightmare, and we all work hard to avoid that.”

The time and cost saved thanks to the use of simulation enables Lion Electric to start looking for upcoming technologies. Ouellet explains, “When production on vehicles starts, we are already looking for ways to improve the systems for future generations. Efficiency is something that can always be optimized. Also, we control every aspect of our designs, making much better products than companies that electrify other companies’ chassis and vehicles.”