Reduction of cogging torque and torque ripple in Modulated Pole Machines by geometrical changes

In recent years significant improvements in the field of Modulated Pole Machines (MPMs) have been achieved, especially in electric vehicles applications. MPMs such as Transverse Flux Machines (TFMs) are known for producing high torque densities; though further research and improvements are needed to reduce the inherently high cogging torque and torque ripple. This paper will present a method of reducing these undesirable features of TFMs through simple geometric changes, such as changing the tooth span of the stator teeth. It will be shown that a combination of varying tooth spans rather than a uniform tooth span for the whole machine helps to reduce the cogging torque and torque ripple of the machine without a significant effect on the overall torque output.