34 The collected data enable users to determine torque per ampere (TPA) values. Next, they select the highest TPA values and identify the corresponding Id and Iq values to construct the MTPA curve for each step in total current magnitude. Finally, this MTPA curve is implemented into the motor control algorithm with continuous monitoring of each parameter ensuring optimal motor performance under all conditions. MTPA testing and validation require a motor drive setup (typically a PWM drive and a PMSM motor) that implements an FOC scheme, plus a power analyser capable of accurate AC power measurements on high-current signals and mathematical computations on the captured data. Traditional power measurement systems also typically lack visual feedback or recorded data, significantly limiting the traceability of the measurements. During an invehicle powertrain measurement, test engineers typically want to measure a certain set of powers, voltages or currents and they need visual feedback to indicate when they have achieved their given setpoint. Without feedback, it is difficult to know if the vehicle has achieved a certain loading point and for how long it has operated at that point. Control engineers will also use this feedback to monitor the Id and Iq control variables. Visual feedback gives the engineer insight into how the vehicle responds to different disturbances or whether they have met their setpoints. The use of visual feedback is vital for competitor vehicle benchmarking where control strategy or powertrain performance are largely unknown. Traditional power measurement systems also lack a method of correlation and feedback to external systems. This is necessary to correlate their power signals to the environmental data often collected by existing data acquisition systems. GPS, video, temperature and the vehicle status give an engineer significantly more insight into what was happening during the test. Hard braking, swerving to miss an obstacle or harsh traffic conditions may affect a vehicle output or demonstrate a bug in the vehicle control. Without GPS or video, engineers rely on the driver’s memory to recall these events. A proper test run would need to incorporate external test conditions to achieve full transparency of the test results. Traditional mobile DAQ systems were not intended for high-frequency and high-voltage signals generated by inverters. Mobile DAQ systems have sample rates that max out at around 100 kS/s, which is more than enough for structural or frequency data but does not provide sufficient bandwidth to obtain good power accuracy from a PWM inverter. These inverters, which turn on and off at high voltages and at frequencies greater than 20 kHz, require a much higher sample rate to accurately measure RMS voltages and currents. Traditional mobile DAQ systems are also unsuitable for higher voltages, which is an issue with DC bus voltages upwards of 900 V. These measurements can be made with voltage probes, but there will be a decrease in accuracy. January/February 2026 | E-Mobility Engineering Measuring the back electromagnetic field (EMF) in brushless permanent magnet motors (Image: Ansys/Synopsys) Traditional power measurement systems lack visual feedback or recorded data, limiting the traceability of the measurements
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