In the analysis of DC motor commutation,if the effects of armature reaction and leakage flux are not considered,the commutation of elements shall occur in the geometric neutral zone of the main magnetic field.However,during actual operation,the main magnetic field also significantly influences the commutating zones.Based on the winding structural characteristics of permanent magnet DC motors,the commutating zone width for simplex wave windings was deduced.When this width failed to meet requirements,the induced electromotive force(EMF)generated by commutation elements cutting the main magnetic field notably affected the commu-tation process.In further research,the positions of commutation elements in the main magnetic field were examined at different commu-tation timings,and the calculation formula for the main magnetic field cutting EMF and the power consumption were deduced.By intro-ducing the main magnetic field cutting EMF into the classical commutation theory formula,the commutation process for asymmetric front and rear spans of the second pitch was mainly analyzed.Consequently,the direction and angle for quantitative offset of the magnet-ic pole centerline/neutral line or brush were deduced.Prototype testing validates that the proposed method optimizes the motor's mechani-cal performance.This technology overcomes the limitations of traditional brush position adjustment methods,providing a practical engi-neering approach for the winding design,brush carrier,and stator installation structure of micro and small DC motors.