E-Mobility Engineering 019 | In conversation: Stephen Lambert l WAE EVR l Battery case materials focus l Quality control insight l Clipper Automotive Clipper Cab digest l Optimising battery chemistries insight l Powertrain testing focus

70 May/June 2023 | E-Mobility Engineering Some suppliers of EV powertrain testing services China EOL Expertise +86 138 2522 4911 www.eolexpertise.com Germany Atesteo +49 2404 9870 0 www.atesteo.com FEV +49 241 56890 www.fev-sts.com HBM   +49 6151 803 0 www.hbm.com IABG +49 89 6088 0 www.iabg.de Siemens +49 800 5090100 www.siemens.com Teamtechnik +49 71 41 7003 0 www.teamtechnik.com India IASYS +91 20 6770 0400 www.iasys.co.in Slovenia Dewesoft +386 356 25300 www.dewesoft.com Sweden Hexagon +46 8 601 26 20  www.hexagon.com Switzerland Speedgoat +41 26 670 7550 www.speedgoat.com UK Drive System Design +44 1926 678310 www.drivesystemdesign.com Integral Powertrain Testing +44 1908 972 550 www.powertraintesting.com Intertek +44 116 296 1620 www.intertek.com Ricardo +44 1273 455611 www.ricardo.com UTAC +44 117 403 0640 www.utac.com USA Unico +1 262 886 5678 www.unicous.com Each one creates different design and measurement challenges for test systems, the company’s expert says. “Doing a benchmark measurement on a wheel motor is very difficult, for example, owing to problems with access to the components,” he says. There are also several mechanical aspects to consider, he adds. For example, e-motors are attached to the vehicle body with much stiffer mounts than IC engines, which creates different NVH characteristics, and the high levels of torque from low rpm feed very large loads into the body, affecting durability as well as vibration and noise transfer. When characterising noise and vibration using frequency response functions, for example, testing is always important for identifying themost important modes. “At the level of the e-drive itself, performing an experimental modal analysis remains essential, because laminated stator housings with windings are very non-linear in their responses, and are difficult tomodel without test-based correlation,” he says. Shaping test plans Powertrain testing is complex, and typically follows the V model, in which the ‘V’ stands for verification and validation while also evoking the shape of the letter as an aid to visualising the flow of a development process and the relationship between the engineering and testing phases. The engineering phases run down the left side of the V from top to bottom, progressing from user requirements engineering through system requirements engineering, and architecture engineering and design, down to fabrication of hardware and coding of software. On the right, the testing phases flow from bottom to top, from unit testing through subsystem and up to 1 MW, along with multiple AC dynos covering a broad range of torque and speed values. At the low-speed, high-torque end are machines that can handle up to 5000 Nm continuously, while the high end includes machines that run at up to 20,000 rpm. Also, multiple accessory gearboxes allow commercial vehicle and off-highway powertrains to be tested. From a design perspective, new EV powertrains also come in a wide range of system layouts, the rotating machinery testing provider points out. These encompass motor technologies and system architectures such as single and dual motors per axle, wheel motors, and inverters that are either separated from or closely integrated into the e-motor system. Siemens’ Simcenter is designed to predict NVH performance using a combination of real and simulated hardware and dedicated software packages, and can be used at any stage of development (Courtesy of Siemens)