On the Effect of Claw Geometry on the Vibration of Single-Phase Claw-Pole BLDC Machines

In automotive auxiliary applications, where cost is typically the primary design criterion for mass-produced fractional horsepower drives, single-phase BLDC machines are usually preferred over their three-phase counterparts. These small drives are barely audible compared to the main drive system in automotive applications. However, single-phase BLDC machines have an inherently high vibration, which may excite nearby structures or components to produce noise. This study compares the vibration performance of single-phase claw-pole BLDC machines with different claw geometries using simulations and experiments. Along with the conventional rectangular claw shape, two well-known strategies for reducing noise and vibration by modifying the stator's claw geometry are compared. Moreover, the trapezoidal claw shape, which is more common in claw-pole stepper motors and alternators, is analyzed. Results of finite element analysis and experimental investigations indicate that, although skewing the claws could be a practical approach to mitigate the vibration, a trapezoidal claw shape can significantly reduce the vibration of these machines.