Some suppliers of motor testing Allegro Microsystems www.allegromicro.com CTS www.ctscorp.com Dewesoft www.dewesoft.com Emerson Electric/NI www.ni.com Gantner Instruments www.gantner-instruments.com Hottinger Brüel & Kjær www.hbkworld.com Pickering Interfaces www.pickeringtest.com Synopsys/Ansys www.synopsys.com Yokogawa Test & Measurement www.tmi.yokogawa.com Tech focus | Motor testing 36 Regenerative braking How and when a vehicle enters regenerative braking is of interest to powertrain engineers, but how the driver interacts with the regeneration also needs to be considered. The current and power slowly ramp down as vehicle speed starts to decrease. The current then goes to almost zero but increases shortly after, despite the continued decrease in speed. At this point, the power goes negative, which indicates that there is power being put back into the battery. The vehicle continues to slow down and eventually the power goes positive. This indicates that there is no longer enough power being put back into the battery and this energy is now contributing to losses. This shows how regeneration can introduce additional losses. When designing a system that is operated by real users, this can be valuable information for choosing when to turn regeneration on or off. Regeneration can also affect user experience and data can help correlate things like hard or bumpy stops to unwanted effects on the powertrain. Examples of dynamic control In addition to power calculations, a test system can perform control transform calculations in real time. The ability to do space vector or DQ0 transforms will supply users with information to help determine whether the machine is behaving as expected. By recording the measured control variables with the CAN data output by the vehicle, control engineers can see if the machine is implementing what its controller thinks it is doing. Monitoring the control technique also allows users to understand unexpected disturbances. How the vehicle controller handles the transient will be of interest to engineers in electric powertrain groups. If there is too much current in the wrong axis, there could potentially be demagnetisation of the rotor. There may also be limits on how much current a system can handle. Simulation While physical testing is critical to gaining insight about motor performance, it has its limitations. Simulation enables technicians to expand testing by seeing inside the machine to reveal exactly what is happening (both now and in the future), as well as showing the health of the deepest inner workings of a motor. With simulation, engineers can explore various design options against different operating scenarios and make adjustments before production, during production and even while the motor is being used. Especially in scenarios in which physical testing is restricted by lack of visibility (owing to size or location of the test), simulation can quickly perform the calculations required to make an accurate assessment. The use of simulation in electric motor testing not only improves the speed and efficiency of the testing process itself, but also improves the quality, depth and reliability or certainty of the data collected. Simulation software can perform coupled multiphysics calculations, providing engineers with thorough assessments of complex systems — assessments that would be impossible to achieve one test at a time. Using simulation to run physical tests in a virtual environment, engineering teams can save time and costs. Simulation also reduces the number of design iterations and identifies problems before any hardware is built. This leads to a better, more robust design and ensures no surprises when it comes to the physical testing. In-motor sensing The latest in-motor sensor system uses an inductive position sensor rather than a resolver to measure the position of the rotor in the electric motor. A key advantage is that this can be integrated with a current sensor with vector control to reduce the cost and improve the performance. One way of doing that is measuring the fields inside the motor but the stator and motor magnetic fields overlap, creating a challenge for the measurement system. A new realtime algorithm is able to measure the field. This is implemented in a sigma delta architecture for low latency, which is critical for the powertrain January/February 2026 | E-Mobility Engineering Simulation [lets] engineers expand testing by seeing inside the machine to reveal what is happening now and in the future
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