To mitigate the additional losses caused by the multi-slot multi-layer winding in traditional coil designs for polyphase permanent magnet synchronous generators

each turn of the coil is usually made of multiple parallel strands. However

the imbalance in leakage potential among parallel strands leads to significant circulating currents and circulation losses. To address this issue

a novel approach called the multi-slot combined transposition method is proposed

which can effectively balance the leakage potential and reduce circulation losses by combined transposition of the parallel-strand slot portionacross different layers and different slots. Taking a 2.7 MW polyphase permanent magnet synchronous generator is taken as an example

the three-dimensional field-circuit coupled finite element model is established to calculate the circulation losses of the stator winding. The calculation method of circulation losses is validated by the experiment data. On this basis

a comparison is made between the circulation losses of coil windings with the multi-slot combination transposition method and those of traditional coil windings. The results show that the circulation losses of stator windings can be reduced by 67.43% with the multi-slot combined transposition method.