Analysis of Large-scale Non-Overlap Winding Wound Rotor Synchronous Machine with Stator Slitting

Non-overlap windings have a downfall in that they result in a high quantity of magnetomotive force, sub- and higher-order harmonics, leading to core saturation, increased losses and vibration. Wound rotor machines with non-overlap windings and especially large yokes, result in massive core losses due to the high amount of flux generated in the machine. Stator slitting is proposed as a simple method to mitigate the core losses in the machine, while maintaining the desired electrical performance of the machine. It is shown that stator slitting increases the working harmonic and reduces the other sub-harmonics, evidenced by the increased average output torque and reduced torque ripple and core losses. The study is completed on a 5 MW 16/18 pole/slot wound rotor synchronous machine using finite-element analysis.