Analysis and Validation of Current Ripple Induced PWM Switching Noise and Vibration for Electric Vehicles

<div class="section abstract"><div class="htmlview paragraph">Electric motor whine is a major NVH source for electric vehicles. Traditional mitigation methods focus on e-motor hardware optimization, which requires long development cycles and may not be easily modified when the hardware is built. This paper presents a control- and software-based strategy to reduce the most dominant motor order of an IPM motor for General Motors’ Ultium electric propulsion system, using the patented active Torque Ripple Cancellation (TRC) technology with harmonic current injection. TRC improves motor NVH directly at the source level by targeting the torque ripple excitations, which are caused by the electromagnetic harmonic forces due to current ripples. Such field forces are actively compensated by superposition of a phase-shifted force of the same spatial order by using of appropriate current. A feedforward harmonic current generation module is developed, which allows the application of harmonic current commands to a motor control system with adjustable magnitude and phase. In the 3-phase, 8-pole AC machine with concentrated windings of this study, both 5<sup>th</sup> and 7<sup>th</sup> electric order harmonic currents are injected in the stationary reference frame to cancel the 6<sup>th</sup> electric order torque ripple in the synchronous reference frame, which corresponds to the most dominant 24<sup>th</sup> mechanical order. Test data confirm that TRC is highly effective in reducing the motor whine by 10+ dB over a wide range of motor torque. Loss study is also performed which shows TRC has a minimal impact on the motor efficiency. Overall, TRC offers a flexible NVH solution without hardware change and has minimum impact on motor performance or efficiency. The technology has been successfully implemented in GM’s Ultium electric propulsion systems.</div></div>

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Maximum Pulling Force Calculation of Permanent Magnet Tractor Motors in Electric Vehicle Applications

Gong,

Chang,

et al. 2024

SAE Technical Paper Series

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<div class="section abstract"><div class="htmlview paragraph">In electric vehicle applications, the majority of the traction motors can be categorized as Permanent Magnet (PM) motors due to their outstanding performance. As indicated in the name, there are strong permanent magnets used inside the rotor of the motor, which interacts with the stator and causes strong magnetic pulling force during the assembly process. How to estimate this magnetic pulling force can be critical for manufacturing safety and efficiency. In this paper, a full 3D magnetostatic model has been proposed to calculate the baseline force using a dummy non-slotted cylinder stator and a simplified rotor for less meshing elements. Then, the full 360 deg model is simplified to a half-pole model based on motor symmetry to save the simulation time from 2 days to 2 hours. A rotor position sweep was conducted to find the maximum pulling force position. The result shows that the max pulling force happens when the rotor is 1% overlapping with the stator core. The impact of asymmetric air gap as well as temperature is analyzed for comprehensiveness. It shows that the asymmetric air gap can cause about 2.7% higher force. Finally, the dummy non-slotted cylinder stator is swapped with a slotted stator for better model fidelity. FEA shows that the slotted stator can have 21% lower force than a dummy cylinder stator. Although the method and conclusions proposed in this paper are based on a case study of one motor, they are still valid and applicable to other traction motors in a more generalized sense and can serve as a good reference for the EV motor industry for a safer and more efficient manufacturing assembly.</div></div>

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Analysis and Validation of Current Ripple Induced PWM Switching Noise and Vibration for Electric Vehicles

Cited by 4 publications

References 14 publications

Experimental investigation of vibro-acoustic noise analysis in the switched reluctance motor through transient model-based multiphysics analysis for electric vehicles applications

Experimental investigation of vibro-acoustic noise analysis in the switched reluctance motor through transient model-based multiphysics analysis for electric vehicles applications

Torque Ripple Cancellation to Reduce Electric Motor Noise for Electric Vehicles

Maximum Pulling Force Calculation of Permanent Magnet Tractor Motors in Electric Vehicle Applications

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