Speeding Thermal Analysis for Autonomous EVs

Solving thermal challenges is vital to AEV development. Siemens PLM’s new Simcenter integrated simulation package offers a high-fidelity, easy-to-use solution.

March 1, 2019

Bruce Morey

Siemens PLM emphasizes maintaining the digital thread in its thermal design software. (Image: Siemens PLM)

Siemens PLM recently introduced a new Simcenter software solution for thermal simulation used in autonomous electric vehicle (AEV) development. The product is designed to help engineers quickly solve heat-related challenges related to the vehicles’ high-power electronics.

Speed and ease-of-use were important considerations in development of this tool. While traditional CAE simulations are useful, automakers are finding that restricting simulations to a few experts leads to a slow and costly engineering process. The answer is software that a design-and-release engineer devoted to specific AEV components can exercise. In general, this has come to be known as the “democratization of CAE,” and Siemens PLM hopes to accelerate this trend with the new offering.

Integrated physics

The new Simcenter Solution for Design-centric Thermal Simulation for Auton- omous EVs combines three existing solutions in an easy-to-use format, with seamless connection among electrical, electronic and mechanical domains. (Image: Siemens PLM)

AEVs, with their power-hungry sensor fusion boxes, have significant thermal-management demands. While properly addressing these power and thermal loads is important even in combustion-engine automated vehicles, it is paramount in battery electrics. Keeping the battery pack not too cold, and the sensors and electronics not too hot, makes all the difference when every fraction of a kilowatt hour counts. The electronics alone, if not optimized, can reduce an AEV’s range by as much as 35%, according to Siemens.

The new integrated CAE solution package combines three of Simcenter’s CAE simulations: FLOEFD for 3-D thermal analysis; MotorSolve for electric motor design, and Flomaster, a 1-D CAE for electric powertrain thermal energy management. All three are now linked—for component thermal and electric powertrain performance, connectivity between simulation of electric motor performance and system simulation for electrical and thermal management.

FloEFD CFD is full-featured 3-D fluid flow and heat transfer analysis. It includes engineering models such as porous media, PCB and LED model. It is built into major MCAD systems such as Creo, CATIA V5, Siemens NX, Solid Edge, according to Siemens. It also includes an electronics cooling module for detailed thermal modeling of electronic models. Battery electrochemical-thermal simulation capabilities are available.

MotorSolve is Siemens’ design and analysis software for brushless DC, induction, switched reluctance and brushed DC machines. It is based on finite element analysis with automatic mesh refinement, post-processing and domain knowledge to compute design parameters that are of interest to a motor designer.

The third element, Flomaster, is a 1-D solver for thermo-fluid system or other simulations that can be captured in 1-D. For higher accuracy, individual components can be solved in 3-D using FLOEFD, and then summarized and connected in the 1-D Flomaster model. “The 1-D and 3-D CFD solutions are dynamically linked simulations,” said Puneet Sinha, MAD Automotive Manager at Siemens PLM.

In the hands of engineers

Just as important as the physics is the intended user: mainstream automotive engineers. Enhancing ease of use, according to Sinha, are simulation automation, a built-in database, and model representation from data.

“There is a seamless connection among electrical, electronics, and mechanical domains,” he said. There will also be some access to design optimization and generative design capabilities in this initial roll-out. He anticipates these features to be strengthened in future releases.

The combined package is especially useful for generating thermal “digital twin” simulations of the powertrain, processors, and sensors, according to Sinha. These and other key enabling technologies are anticipated to be used in next-generation AEV designs.

This latest tool can be viewed as a further development in the “democratization of CAE” trend among CAE providers in the last few years. This movement views accessibility of CAE to non-specialists as the next, vital step in making CAE useful to industry. This also means that the user of Siemens’ FLOEFD software, in particular, will not need to know about some of the trickier aspects of CFD, such as mesh creation, selection of a laminar or turbulence flow model, or what type of turbulence model to apply.