Optimization Design And Thermal Analysis Of Hybrid Excitation Double-Stator BSRM

Bearingless switched reluctance motor(BSRM)combines the advantages of magnetic bearings and switched reluctance motors,such as no mechanical wear,no lubrication,no noise,and high critical speed.BSRMs have broad prospects for development in flywheel energy storage,aerospace and other fields.Since the strong coupling between suspension force and torque seriously restricts the improvement of motor performance and further engineering application,a hybrid excitation double-stator BSRM is proposed in this paper based on the analysis of the existing research status of several self-decoupling structures.The motor can realize self-decoupling between torque and suspension force.In addition,the two degrees of freedom suspension force can also be decoupled.The topology and operation mechanism,mathematical model,ontology design,electromagnetic characteristic analysis,loss and thermal analysis,and optimization of the hybrid excitation double-stator BSRM are studied.The main work contents are as follows:Firstly,a novel hybrid excitation double-stator BSRM structure is proposed,which can improve the suspension force and reduce the iron loss while achieving the self-decoupling between torque and suspension force and two degrees of freedom in suspension radial direction.The topology is introduced and the optimal excitation mode of torque winding is selected.In addition,the generating mechanism of torque and suspension force is expounded.The mathematical model is established to provide the foundation for the subsequent ontology design,which is verified by finite element method.Secondly,based on the design objectives and requirements,the main body size is calculated.Then,the basic size design of the motor is gradually completed.ANSYS Maxwell is used to study basic electromagnetic characteristics of the motor,and the magnetic field,torque,suspension,inductance,magnetic linkage and coupling characteristics are analyzed respectively.Compared with the traditional double-stator BSRM,good performance is proved,including the improvement of suspension output capacity and the reduction of iron loss.Next,on the premise of analyzing and comparing three methods of calculating iron loss,the finite element method is selected to simulate the magnetic density and its variation law of the typical position point of the motor.Besides,the iron loss,copper loss and other losses are calculated and explained.Among them,iron loss and copper loss as the main heat source are imported into ANSYS Workbench software for thermal modeling and thermal analysis in a one-way coupling way.Based on the natural cooling condition,the simulation results of the temperature field under the two modes of single-phase conduction and transient operation are analyzed and compared in detail,and transient operation more closer to actual operation is selected.Finally,taking average torque,average suspension force and average iron loss as the three optimization objectives,the local sensitivity of seven optimization parameters is analyzed by single objective parameterization.The response surface optimization method is used in the three iterations optimization after optimization parameters are divided into three subspaces according to their influences on the objectives.And then the optimal solution after three iterations is selected in the optimal solution set according to the selection criterion.By comparing the performance of the combination of parameters after optimization with that before,it can be concluded that the torque and suspension characteristics are improved,and the overall temperature decreases obviously,which verifies the effectiveness of optimization design.