NVH-Simulation of Salient-Pole Synchronous Machines for Traction Applications

In comparison to electrical machines designed for industrial applications, the noise, vibration and harshness (NVH) behavior is more important in traction applications. Naturally, costumers demand a smooth running drive train over a wide operating range. In contradiction to that, electrical machines can emit high pitch discrete sounds which might be interpreted as a defect or failure of the drive train. In previous investigations, permanent magnet synchronous machines (PMSM) or induction machines (IM) have been investigated for traction applications. However, salient-pole synchronous machines (SPSM) are used for traction applications as well. Nonetheless, their NVH-behavior has not yet been analyzed in detail. In this paper, a method to simulate the vibration at the stator surface of a SPSM is discussed. At first, the exciting electromagnetic forces are calculated analytically as well as numerically. Moreover, a 2D-FEM modal analysis is done. The results of this simulation are compared to experimental results. Furthermore, the method which combines 2D-FEM eletromagnetic simulations and analytical calculations to calculate the surface deflection is presented. In a final step, the calculated results are compared to measurement results of the surface vibration.