Design Of Cooling System And Analysis Of Heat Transfer Characteristics In Mw High Speed Permanent Magnet Synchronous Machine

High speed machine has properties of high speed and high power density. Its volume is much smaller than that has the same output power In low speed range, which can save materials and space. Moreover, it has fast dynamic response because of its small moment of inertia. High speed can be directly connected with the load, which can eliminating the mechanical transmission of traditional apparatus and reduce noise and to improve the efficiency of transmission system. Therefore, high speed motor draws more attention in the military and civil aspect. But the high speed and high frequency bring problems such as loss, high temperature, difficult heat dissipation. Aiming at these problems, this paper carried out the following work:First, loss calculation is the foundation of motor cooling system design and temperature field calculation. Due to high speed and high frequency, loss calculation of high-speed motor is different from the ordinary motor. Calculation of stator loss should take the harmonic and rotational magnetization effect into consideration, while winding copper loss skin effect and proximity effect. The harmonic content in the permanent magnet cannot be ignored, so it is necessary to calculate the eddy current loss in the permanent magnet. Also the rotor surface wind friction loss should be considered. Calculate the above-mentioned loss.Second, based on theory of fluid motion, the air cooling system and water cooling system were designed whose designing procedure set the temperature of cooling medium at outlet firstly, and then according to heat generated by motor, flow of cooling medium and size of cooling structure were designed. A simplified model of motor was built to calculate the temperature of cooling medium at outlet. Compared with the set value, the cooling system was designed.In addition, based on the analysis of heat transfer characteristics of a motor, three-dimensional models with different cooling structure were built by CFX module, then setting boundary conditions, calculating heat transfer coefficient of insulation in stator slots, end winding, casing surface and water cooling casing, so as to calculate temperature field distribution of different cooling structure. Also, analysis and comparison of the effects to temperature field distribution of different cooling structure were done.Finally, in this paper the influence to temperature of different part of motor by different cooling parameter that includes flow of cooling air and water, temperature of cooling air and water, thermal conductivity of protective sleeve, eddy current loss of permanent magnet, area of the conduit was analyzed.