Abstract:The analytic model of the energy method is used for the calculation of the optimal slot width for suppressing cogging torque of the servo permanent magnet motors, followed by an analysis of the reasons for the errors in the numerical results of the analytical method and the finite method by using the finite element method to solve the cogging torque, with a tentative inquiry into the relationship between the width of different slots and the cogging torque. The cogging torque increases first and then decreases with the increase of the slot opening length. With its value approaching near the optimal slot width calculated by the energy method, the cogging torque decreases, which result is in line with the theoretical prediction, while with an error of 0.41 mm at the extreme point. In view of the flaw of offline difficulty resulting from too small groove widths, an improvement has thus been made in the analysis model of energy method, with the line diameter used as the slot width to explore the relationship between the optimal slot increment and the change of the slot torque. With the value of the optimum notch increase being 1.2 mm, the optimum notch width is 2.35 mm, and the cogging torque is 17.8 mN·m.