Thermal Field Analysis Of Brushless Doubly-Fed Reluctance Machine

With the rapid development of power electronic technology, the AC machine speed control system is more and more applied to high performance requirements field. The brushless doubly fed machine is a new kind of AC machine developed in recent years. Due to its brushless and non-slip ring structure, reliable operation, high performance as well, has widely considered wide concern and research.In this paper, the magnetic and thermal field of the 150kw racial laminated reluctant brushless doubly fed machine (BDFM) are researched. As a novel AC machine, the BDFM has the advantage of simple structure, reliable operation, and high performance advantages. In recent years, it is extensively researched. According to the model of the racial reluctant brushless double fed machine in Xiangtan motor company, the temperature property was analyzed in this paper. The result will provide a design guide and engineering application for the further research.The structure of BDFM is very complex, and the practical operation of the machine is a very complex project. Also the heat conducting progress is complex physical progress. So to describe this physical progress exactly, it is necessary to exactly calculate the value of every heat source and the thermal parameter of every component of the machine. Because of the thinness of the insulation layers in strands and turns of the stator, they are always be out of consideration when the thermal fields were calculated in the past machine analysis. However, because the heat conduction of the insulation area is very small, even a thin insulation layer area may have a significant difference of temperature. So the effect of insulation layer can not be ignored. In this paper the result with the windings and insulation layers model simplified was calculated and the effect of the machine thermal field with insulation considered was researched.In this paper, the losses were calculated, and the empirical formula how to calculation heat conduction and heat coefficient was analyzed. Based on the acceptable calculation precision, the stator winding and the insulation layer was simplified by equivalent method. Using the finite element method software ANSOFT and ANSYS, the magnetic and thermal field were joint simulated and the thermal condition was analyzed. The influence to the machine temperature with the factors of different insulation material and different cooling method was discussed. Taking 150kW BDFM as the researched object, the 2D and 3D temperature was calculated with using the finite element method. This research will offer guides to the further research and design of BDFM. It has very important significance to the engineering application.