Noise and Vibration Characteristics of the Single-Phase Claw-Pole BLDC Machine with Different Stator Topologies

Single-phase brushless DC (BLDC) machines inherently suffer from high cogging torque and torque ripple because of their special magnetic structure, such as an identical number of slots and poles and an asymmetric airgap. These characteristics make their noise and vibration more severe than that of three-phase machines. However, in automotive auxiliary applications, where cost is usually the main design criteria for mass-produced fractional horsepower drives, single-phase BLDC drives are a cost-effective alternative to their three-phase counterparts. These small drives are barely audible compared to the main drive system in automotive applications. However, they can excite surrounding structures/components to develop noise. Claw-pole single-phase BLDC machines have been introduced as a low-cost alternative for conventional mass-produced sub-fractional horsepower salient-pole single-phase BLDC drives in fan applications. In the manufacturing process, noise mitigation techniques such as skewing the claws and adding auxiliary slots can be applied without additional cost. This paper will discuss the main noise and vibration characteristics of different claw topologies of such single-phase claw-pole BLDC machines, including straight and skewed claws, and their combinations with auxiliary slots, as well as V-skewed claws. The 3D magnetic and structural finite element analyses indicate that the implementation of skewed and V-skewed claws can effectively reduce structure-borne noise in this machine topology.