| With the development of new energy vehicles,sewage treatment,and other applications,high efficiency,high speed,and high power density drive motor have been widely investigated.And it promotes the rapid development of the high-speed permanent magnet synchronous machine(HSPMSM).However,due to its characteristics,such as high speed and high loss density,its mechanical structure and thermal management become difficult to be designed,which restricts the development of HSPMSM to higher speed and power levels.some problems in the design procedure of the system are summarized and analyzed.Some problems in HSPMSM design are summarized in terms of the rotor topological structure,the loss,the mechanical stress,the rotor dynamics,and thermal management technology.So,this dissertation focuses on multidisciplinary analysis to improve the precision and efficiency of the characteristic analysis and calculated methods.In HSPMSM design,the characteristics are affected greatly by mechanical and thermal limits.Meanwhile,it is subject to complicated constraints among multidisciplinary.Firstly,the principle of two rotor topological structures is concluded according to multiphysics characteristics.And the solid permanent magnet HSPMSM is selected as the research object of this paper.Then the electromagnetic,thermal,and mechanical limits on the dimension,speed,and power level are studied.Especially,the thermal effect on mechanical characteristics is emphasized.Based on this,the optional range of the speed and power limits for the safe operation of HSPMSM is deduced.Multiphysics coupled relation in HSPMSM design is proposed,including electromagnetic coupling,electromechanical coupling,magnetic-thermal coupling,thermo-mechanical coupling,as well as ontology and drive coupling.To improve the calculation accuracy of mechanical characteristics,this paper proposed the stress analytical models under different operation conditions,including the static,constant velocity,variable speed,constant temperature,and variable temperature working conditions,and also the critical speed calculation method considering the comprehensive influence factors.Then the influence degrees of interference assembly,rotational speed,and operation temperature on the rotor stress and critical speed are investigated in detail.As for the necessity of considering the thermal effect on mechanical characteristics,two thermal effects are proposed: the effect of temperature on material properties and the thermal stress caused by thermal expansion characteristics.Then using both the analysis method and numerical calculation,the stress and critical speed calculation with the consideration of two thermal effects are established,respectively.The result shows that the two thermal effects are detrimental to mechanical characteristics.The effects of linear variable temperature conditions with different temperature gradients on stress distribution were compared with the effect of the constant temperature condition.Based on all influence factors,a higher precision standard of strength checking is proposed.There is a deviation between the estimated value by the current HSPMSM design process and the actual value,because too many practical factors are ignored.This deviation may cause the HSPMSM design to be insecure.Therefore,the influences of rotor structure and uneven temperature distribution corresponding to the actual cooling system should be considered in the final mechanical check.And the fluid-thermalstress-mode coupling analysis model is established.Finally,this paper presents a complete and detailed HSPMSM comprehensive design process with emphasis on the interactions between temperature and mechanical constraints.Several prototype experiments verify the validity and applicability of the proposed design process.This work provides references for the high precision and efficient optimization design of HSPMSM in these application fields. |
