Research on the impact of inter-turn short circuit faults on the electromagnetic and thermal characteristics of closed oil-cooled back-wound high-speed permanent magnet generator

The oil-cooled back-wound high-speed permanent magnet generator (OBHPMG), is suitable for the aerospace field, gas turbines, and flywheel energy storage due to its high efficiency as well as high-power density. However, the high-power density operation of the generator inevitably results in a significant temperature rise, particularly when inter-turn short circuit faults (ISCFs) occur in the windings. In order to clarify the electromagnetic as well as thermal characteristics of the OBHPMG under the different ISCF degrees, it is of great significance to research the electromagnetic and temperature field variation characteristics of the generator at various inter-turn short circuit faults degrees. Firstly, the electromagnetic field of the 40 kW OBHPMG is investigated at normal operating in this paper, the rotor eddy current densities as well as stator core magnetic flux densities distribution is determined. Secondly, based on the model of the generator ISCF, the effects of the winding different ISCF degrees on the rotor eddy current densities and stator core magnetic flux densities are further explored in detail. The variation characteristics of the rotor current loss as well as stator core magnetic flux densities under the winding different ISCF degrees are revealed. Finally, the effect of the different ISCF degrees on the windings and permanent magnets temperature is analyzed in depth by combining the variation mechanism of the electromagnetic loss. The temperature variation characteristics of the OBHPMG with the different ISCF degrees are obtained, and the cooling effect of the OBHPMG under the ISCF is clarified. It provides a theoretical basis for clearly mastering the variations in the performance of the generator under the windings ISCF in this paper.