Research On Electromagnetic Characteristics And Temperature Rise Of Hybrid Excitation Synchronous Machine

The hybrid excitation synchronous machine（HESM）is composed with two machines,which has two excitation sources.The HESM has the advantages of adjustable air gap magnetic flux,high torque density,high efficiency,it has broad application prospects in wind power generation,aerospace,vehicles and other fields.Due to the complicated topology and excitation adjustment methods of HESM,its electromagnetic performance and control methods are different from conventional permanent magnet machines.The electromagnetic characteristics,temperature rise and coordinated control strategy of HESM were studied in this paper.Firstly,in this paper,in order to analyze the electromagnetic performance of the HESM,the 3-D finite element analysis（FEA）are required with a large amount of calculation.And the analytical method based on subdomain method is time-saving,but the saturation of the core cannot be considered.A 3-D equivalent magnetic network（EMN）model is established.This model takes the uneven saturation of stator teeth and rotor pole shoes,flux leakage between magnet and stator slotting into account,which can quickly predict the electromagnetic performance of the HESM.In the modeling process,according to the relative position of stator and rotor during the rotation,an corresponding equivalent air-gap permeance model is established to accomplish the dynamic analysis.Based on the EMN model,the air gap flux density,flux linkage,ect.of the HESM are calculated.The calculation results are compared with the results of FEA and experiments to verify the accuracy and effectiveness of the EMN model,which provides a quick initial design method for other HESMs with 3D magnetic flux path characteristics.Secondly,according to the structure,heat conduction and heat dissipation characteristics of the HESM,the thermal resistance and loss are calculated,and the equivalent thermal network（ETN）model of the HESM is established.In the ETN model,the heat dissipation coefficient of each surface in contact with the external air and internal air is determined;the excitation and armature windings are equivalent,and the heat transfer coefficient of the excitation winding and the armature winding is determined.Based on the ETN model,the steady-state temperature rise of the HESM is calculated.The calculation results are compared with the results of temperature field to verify the effectiveness of the ETN model,which provides a fast thermal calculation method for other HESMs design with similar cooling conditions.Finally,Based on the previous analysis of the operating characteristics and calculation of the electromagnetic characteristics of the HESM,the mathematical model is established.In the Simulink,based on the mathematical model,the simulation model of the HESM machine is constructed,and the construction process and the functions of each module are expounded.In addition,the efficiency optimal control system is constructed.the current distribution method of the coordinated control strategy is derived.the performance of the HESM is analyzed,and compared with the i_d=0 control strategy,which proves the superiority.