Calculation And Analysis Of The Electromagnetic And Temperature Fields In Off-grid Wind Generator Under Different Conditions

Nowadays, there is an energy crisis in the world, which forces the humans to try to develop the new energy. Wind power is one of the new energies which has most rapid development and mature technical conditions. That brings the new hope to solve the energy problem for the humans. The off-grid wind power is an important part of new energies, and its universal application has greatly improved people's material and cultural life, who are far away from conventional grid.Firstly, in this paper, a permanent magnet synchronous generator was taken as an analytical example, the basic structure parameters of generator were introduced and the 2-D electromagnetic field model was established. Using time step finite element method, the distribution of electromagnetic field was calculated when the permanent magnet generator operates under load and no load conditions at different speeds. Terminal voltage and armature current waveform of the generator were simulated when the generator worked with rectified load by 2-D transient electromagnetic field and deoxidization device coupling method.Then, the generator internal field was calculated using field and road coupling method when generator operated in asymmetric short-circuit condition. Short-circuit currents were calculated in short-circuit fault condition between lines and single phase when the permanent magnets are in different positions.Last, the 2-D temperature field model of generator was established based on the electromagnetism and heat transfer theories, and the temperature rise to the stator winding resistance value influence was considered .The surface heat transfer of the cabinet was calculated by using a computational method of analytical and numerical coupling, new ideas were proposed for surface heat transfer of the cabinet of permanent magnet synchronous generator.2-D transient temperature field of three- phase short circuit in low speed were analyzed and calculated, the variations with time of temperature distribution in the different generator internal positions.The electrical magnetic field and temperature field of off-grid type wind generator were analyzed in this paper taking finite element method and a small wind power performance test system was build. At the same time, temperature-rise test was done under no-load, load and short circuit, and the error of experimental values and the calculated value was within the limits of the engineering requirements, so the correctness of the calculation method was proved.