Simulative and experimental investigation of damping strategies for electric motors

Kurzfassung

The electrification of transportation has placed increasing demands on the noise, vibration and harshness behaviour of electric drivetrains. In Permanent Magnet Synchronous Motors, electromagnetically excited radial vibrations of the motor housing produce tonal noise at discrete frequencies that cannot be addressed by conventional acoustic insulation. For motors already in production, where modifications to the electromagnetic design are not feasible, passive response-based damping solutions offer the most practical path to vibration reduction. This thesis presents a complete predictive design methodology for a friction-based dynamic vibration absorber array targeting the electromagnetically excited (4,0) resonance mode of an existing PMSM. A calibrated reduced-order finite element model of the motor was developed and validated against experimental modal data. Electromagnetic forces were projected into the reduced basis to serve as harmonic excitation. A mistuned leaf-spring friction plate absorber array was designed, modelled and manufactured, with its nonlinear friction interfaces represented by Jenkins elements and analysed using the Harmonic Balance Method. The nonlinear harmonic analysis demonstrated that under partial slip contact conditions the absorber array achieves up to 50% reduction in peak housing velocity at the motor resonance frequency, with the mistuned split-array configuration providing the best combination of effectiveness and robustness. A contact mechanics analysis revealed that the physical friction interface as manufactured operates in deep gross slip rather than partial slip, eliminating the stiffness coupling mechanism required for DVA effectiveness. This identifies friction regime verification as a mandatory step in any friction DVA design process. The developed simulation framework is validated, fully documented and directly reusable for other PMSM configurations, contributing a complete predictive design chain for friction DVA arrays on electric motors.