New approach to cogging torque simulation using numerical functions

The paper presents a new method for simulation of the cogging torque in a PM machine. The method benefits the numerical functions for modeling the magnetic system of the electrical machine. To compute the cogging torque by the numerical functions, it is necessary to model the permanent magnets and permeance of the machine. In this paper, we introduce two improved numerical functions to model them. The first one is capable of modeling the permanent magnet and it is called the MMF function. This function numerically states the MMF drop on the machine air gap respect to the angular location. The other function models the air gap accurately while the stator saliency due to the teeth is also considered. This function is called the permeance function. The described procedure has been tested on a constructed PM machine. Then the model is simulated and verified by FEM and experiment results.