Research Of The Electromagnetic And Heat Transfer In Permanent Magnet Synchronous Generator Of Off-grid Type Under Different Conditions

Off-grid wind power generation is an important part of new energy, it's impact on people's working life more and more,its technology development has aroused widespread attention .It is complex of the electromagnetic field and temperature field in permanent magnet wind turbine changes,when the generator works under different conditions ,of which wind speed and load conditions.As a core component of the off-grid wind power system, the research of electromagnetic field and temperature field in Permanent magnet wind turbine at different conditions is necessary.Taking a permanent magnet synchronous generator used in a 400w off-grid type wind power generation system as an analysis example.First of all,the 2-D model for electromagnetic field calculation is established. The electromagnetic parameters of the prototype operating with different loads under different speeds are calculated by using the field-circuit coupled FEM method. In the calculation process, take into account the impact of rectifier on permanent magnet synchronous generator in the off-grid wind power generation system.Secondly ,based on the structure of prototype, two new rotor structures are proposed. Through the comparison of the no-load flux leakage coefficient, anti-EMF waveforms and harmonic content of air-gap flux density in generators with different structures, the influence of structures on machines performance is studied .Then,based on the heat transfer theories, taking the losses determined from electromagnetic analysis as the distributed heat source, the 2-D FEM for temperature field analysis is established . The 2-D temperature field forced convection heat transfer outside the generator under three different conditions was solved based on two kinds of heat transfer theory. We can see that theoretical calculations based on finite element results are closer to experimental results.The temperature distributions in prototype operating with different wind speeds and the different output power using are calculated, effects of wind speeds and output power on generator temperature distribution could be obtained .At the same time ,the experimental results which obtained from the electromagnetic and thermal performance test studies are closer to the calculated results .Some useful conclusions are obtained, which could provide an important reference for the design and optimization of off-grid-type permanent magnet synchronous generator .The corresponding research can be made more detailed and deeply by the investigation, which not only improves the calculation precision of permanent magnet synchronous generator electromagnetic field and temperature field but also improves the electromagnetic structure of permanent-magnet generator at the same time, reduce the material waste problem, elevate the working performance and improve the operating reliability and security of off-grid wind turbine.