Analysis on Noise Source of Claw Pole Machine in Duplex Three-Phase and Belt-Driven System

The acoustic noise, which is generated in a belt-driven integrated starter and generator (BSG) system, is the recent issue. By many studies, it has been known that the noise can be caused by both radial and tangential components of electro-magnetic force. A duplex three-phase claw pole type machine is widely used in the BSG system. In this case, due to its structural feature and difficulty in control, additional noises at unexpected frequency can be generated. In this paper, a method to analyze noise sources was proposed and applied to a prototype that is the duplex three-phase and claw pole type machine designed for BSG system. First, the electro-magnetic force was calculated by a finite-element analysis considering the unbalanced current measured by the experiment. The obtained force was decomposed according to the frequency and then analyzed. Through the force harmonics, additional noises according to the frequency, which are generated by the unbalanced claw shape in the axial direction and current imbalance between phases, were deduced. Finally, the predicted noise sources were compared with the noise measured through the experiment.