Analysis On Temperature Field Of Large Synchronous Machine Based On Numerical Method

Security and reliability act as the foundation for developing electric machineproducts as well as application in industrial system. The numerical analysis based onthe finite element method (FEM) is a kind of research method applicable for electricmachine design. Where large electric machine is concerned, decreaseof volume costper unit set always accompanyed with the increase of power density. For operatingsafty, we need strengthen cooling technology in order to make the temperature rise ofall parts of machine be limited in the tolerance range.Compared with the researchdepth and extension of traditional water cooling and hydrogen cooling technologyused in large electric machine, the research and application of air cooling andevaporative cooling technology act as direction of neotype cooling technologydeveloping still drops behind, which mainly results in the deficiency of understand tothe application feature of neotype cooling technology as well as the theoreticalanalysis of themselves. With the different merits of aircooling system andevaporative cooling system, it can be utilized for design optimization of largeelectrical machine (for example, application in 400MW hydro-generator and 50MWturbo-generator) by different compound model of cooling systems. Therefore, it isessential to research, in depth, investigate the temperature field of electric machinewith air cooling and evaporative cooling system.Research on the temperature field of large electrical machine, steady-state andtransient thermal analysis of magnetic and temperature field of rotor of synchronousmotor and temperature field of stator of evaporative cooling generator are studied.Concerned on the simulation model building and analysis of above thermal field, themain results achieved are as follows:First, according to the design feature of solid salient-pole synchronous motor,three dimensional temperature analysis model of solid salient-pole rotor has beendeveloded for the first time. Surface loss of rotor has been calculated by analytic andnumerical methods. Also, inner cooling system of rotor winding has been analyzed.Second, thermal analysis direct coupled with magnetic analysis, twodimensional analysis model of solid salient-pole synchronous motor start-on-line hasbeen develoded for the first time and all factors concerned on the electro-magneticand mechanical characteristic and temperature rise of rotor with air cooling systemduring starting investigated deeply, and the results of analysis can be applied toimprove design of cooling system for larger synchronous motor start-on-line. A7.5kW solid salient-pole synchronous model motor has been manufactured andtested. Also, frequency parameter of a 5000kW synchronous motor has beenmeasured.Third, according to the design of electrical machine, a general threedimensional temperature analysis model of stator with evaporative cooling systemhas been develoded for the firsr time. The analysis results indicate that thecoefficient of heat transfer on the internal surface of winding is the critical factor toeffectively control the accuracy in the thermal analysis, a formal method ofcalculating the temperature rise of evaporative inner-cooling windings by athree-stage function is proposed, and the function has the virtues of well-extensionand high compatibility.Forth, a concept of equivalent temperature rise function is proposed. Thisfunction can be applied to solve the problems such as when we need to make achoice between evaporative cooling system and other cooling systems.Fifth, aiming for solving above questions, application software has beendeveloped that corresponding finite element analysis program can be generated andrunning antomaticly.