Performance Invariant Noise Reduction of a Plug-In Hybrid Electric Drive Using an Innovative Skewing Concept

In this paper, a review of skewing options for noise reduction in permanent magnet synchronous machines is given. The electromagnetic force excitation in electric machines can be reduced with a rotor skew for particular orders. The skew leads to a global reduction of the radial force modes acting on an e-machine stator creating a phase shift between the skewed segments. Even with perfect global force compensation, the forces still act locally. This changes the purely radial excitation into a radial-axial mixed mode. The skewing pattern defines the axial component of the excitation mode. The Eigen modes, frequencies and structural resistance against the excitation depend on the axial component. Different layouts are investigated to find an optimized design.Next to electromagnetic and structural simulations, in-car and component test bench measurements prove of the mentioned effect. This way a performance and application neutral design was found that significantly reduces the level of the main noise order.