The influence of asymmetrical distribution of rotor's magnets on the cogging torque of the multipolar machine: Wpływ niesymetrii rozłożenia magnesów wirnika na moment zaczepowy maszyny wielobiegunowej

The paper presents the results of field calculations of cogging torque of a 12-pole torque motor with an 18-slot stator. A constant angular velocity of the magnet and the same size gap between n-1 magnets were assumed. In these conditions, the effect of change of the nth gap between magnets on the cogging torque was tested. Due to considerable length of the machine the calculations were performed for the 2D model. The nth gap for which the cogging torque assumed the lowest value was evaluated. The cogging torque of the machine with symmetrical magnetic circuit (the same size of gap between magnets) was compared to the one of the asymmetrical machine. With proper choice of asymmetry the cogging torque for the machine considered decreased by four times.