COMSOL aids EV drivetrain efficiency enhancement with Multiphysics Simulation

As real-world machines become increasingly dependent on Multiphysics, COMSOL offers a suite of Multiphysics simulation tools that enable engineers to determine and improve the efficiency of an electric drivetrain, right from the design and conceptualisation stage itself. A major part of an EV drivetrain is the electric motor, and the COMSOL Multiphysics Simulation suite allows assessment of radial- as well as axial-flux motors, which are increasingly gaining popularity for their advantages of higher power and efficiency in a smaller footprint.

On September 26, Autocar Professional, in association with COMSOL, organised a technical webinar on the topic - Improving efficiency of an electric drivetrain by using Multiphysics – and Sharath BN, Technical Specialist, COMSOL, gave an in-depth overview about how the Multiphysics simulation suite helps engineers to conduct Multiphysics assessment of the various constituents of an EV drivetrain, by considering electromagnetics, vibrations, heat transfer, and solid mechanics.

The webinar delved into how COMSOL’s Multiphysics simulation tool can model an e-motor’s electro-mechanical parameters such as torque, and magnetostriction, and help in the calculation of losses as well as thermal analyses. The tool also allows assessment of demangnetisation and electromagnetic breakdown. Furthermore, engineers can also conduct various optimisation assessments such as parameter, shape, and topology optimisation.

BN explained that the COMSOL tool also has proof-of-concept (PoC) models such as 8-rotor, and 48-stator poles, in its simulation suite. The COMSOL Multiphysics suite also offers readymade CAD data, as well as offers dedicated features for motor modelling such as the magnet feature which can be used to ascertain magnetisation direction.

“After the EM analysis, the next step is modelling of the iron and copper losses in the motor, as well as assessment of the lamination losses. The COMSOL suite allows loss calculation as well as helps compute the time-to-frequency losses. Once losses, which are also dependent on the temperature and affect the electromagnetic behaviour, the temperature-efficiency maps can be plotted, and this empowers engineers to accurately predict the electric vehicle’s range using these temperature-efficiency data points,” he determined using a presentation.

As a case study example, BN pointed out that the COMSOL Multiphysics simulation suite has been leveraged by researchers at Tier-1 major Bosch to undertake a coupled thermal and electromagnetic analysis, wherein using simulation, they were able to cut down the prototyping time, and bring the model quicker to the market.

Motor Vibration Analysis
The COMSOL Multiphysics simulation suite allows both electromagnetic analysis in 2D, coupled with structural analysis in 3D. “The minute deformation of the stator affects the torque generated by the stator, and this deformation can be identified in the 3D structural analysis of the motor,” BN explained. He further added that the suite also allows vibroacoustic analysis, to determine the noise parameters. In this assessment, all electromagnetic, structural, as well as acoustics analysis of the motor, against its speed, are conducted.

COMSOL also offers motor optimisation by virtue of parameter, shape, and topology optimisation features in its Multiphysics simulation tool. The suite also supports Multiphysics such as electromagnetics, heat transfer, and structural mechanics, for the topology optimisation of an axial-flux motor.

With an objective to maximise the torque output of an EV motor, and aiming to reduce the size of the e-motor magnet by 10 percent, the COMSOL Multiphysics simulation suite also allows parameter optimisation of the e-motor. As per the examples showcased in the webinar, the result obtained reflected around 2.8 percent increase in the motor’s torque or power, while conserving losses. The result of shape optimisation study further showcased a significant drop in torque ripple from 9.8 to 4.5 percent. The notable reduction was achieved while maintaining the motor’s average torque as well as the initial design.

The COMSOL Multiphysics simulation suite enables detailed 3D models as well as structural CFD analysis by leveraging different CAD models, as well as allowing a holistic assessment by considering various physics parameters, including electromechanics, heat transfer, vibrations, and solid mechanics.

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Comsol webinar on Improving Electric Drivetrain Efficiency with Multiphysics Simulation