Meanwhile, the cogging torque takes the minimum value and then becomes zero (position 5 and 9).
Thus, the cogging torque is decreased by notch on the rotor .
However, the cogging torque value has increased slightly rather than decreased.
The cogging torque values of the PMSG without and with the pole shifting have been obtained from the setup of the torque measurement system in Fig.
4, when the PMs are placed at the equal angle on rotor surface without the pole shifting, the maximum peak to peak value of the cogging torque has been measured about 0.6 Nm.
As a function of the angle rotation of the rotor with the pole shifting, the cogging torque values of the PMSG are also given in Fig.
In DRFPMG, if the slots were aligned in radial direction, the cogging torques produced by both of the air gaps were in phase with each other.
The cogging torque values obtained before and after shifting the slot openings are given in Table 1.
A combination of three methods, changing magnet pole arc width, changing slot opening width, and shifting of slot openings, was applied simultaneously (combined effect) for further reduction of cogging torque.
The possibilities to reduce cogging torque are considered in this work.
Pillay, "Cogging torque reduction permanent magnet machine", IEEE Transactions on industry applications, vol.
Iraolagoitia Influence of Constructive Parameters on the cogging torque in PMSMs.--P.1-5.