Research On High Speed Switched Reluctance Motor With Amorphous Alloy Core

Electric vehicles industry is an important engine for future economic growth.The switched reluctance motor(SRM)has attracted a lot of attention from researchers in the field of new energy vehicles due to its simple and reliable structure,free of rare earth materials,high overload capacity,wide speed range and high cost performance.In order to increase the power density,high-speed SRM with low-loss materials are in line with the design concept of electric vehicles.Therefore,this thesis applies the amorphous alloy materials to high-speed SRM,and investigates the motor design principles,electromagnetic performance analysis methods,loss distribution and electromagnetic vibration characteristics of high speed SRM,taking advantage of the electromagnetic advantages of amorphous alloys.The main research work includes the following aspects:Firstly,the electromagnetic characteristics and analysis method of high-speed SRM with amorphous alloy core are studied.Amorphous alloy material has a lower saturation flux density and higher permeability.Based on these characteristics,the design principle of high-speed SRM with amorphous alloy core was proposed.In addition,the electromagnetic properties are heavily influenced by the processing technology and the high-speed SRM are characterized by local saturated flux density.To overcome these issues,an equivalent magnetic circuit model was proposed based on the divisional equivalent air-gap permeability.With this model,the magnetic field and inductance characteristics could be calculated quickly and accurately.The inductance and torque characteristics of amorphous alloy cores were investigated in comparison to silicon steel.Based on the proposed model,the influence of motor structure parameters and controller parameters on inductance characteristics and torque characteristics was analyzed with high power density as the optimization target.The inductance and torque characteristics were also compared and verified by means of prototype experiments.Secondly,the core loss of amorphous alloy and its influenc e factors are studied.As the loss characteristics of amorphous alloy are seriously affected by the edge deterioration and processing technology,a model for calculating core loss of amorphous alloy considering the effect of edge deterioration effect was proposed.Based on the loss experimental results of amorphous alloy rings,the influence of edge deterioration on core loss could be quantified,and an attenuation function between the variation of the geometrical parameters of the motor core and the effect of edge deterioration is established,which could be applied to the calculation model of core loss.The influence of edge deterioration on core loss of amorphous alloy was verified by experiments.And the influence of core materials and structures was compared through the proposed model.In addition,the influence of different processing technology and controller switching frequency on the core loss were analyzed.Subsequently,in view of the influence of amorphous alloy on motor loss distribution,the efficiency improvement method is explored.The application of amorphous alloy core changed the loss distribution of high-speed SRM.Due to the severe influence of AC losses on temperature rise and efficiency,the low accuracy and low computation efficiency of winding AC loss calculations neede d to be addressed.Therefore,an equivalent modeling method for calculating winding losses was proposed,taking into account the axial transposition of the windings.With this method,the winding AC loss could be analyzed for different permutation angles a nd frequencies.Based on the influence of core loss and winding loss on temperature rise,the influence of motor structure on output performance,the loss distribution and motor efficiency was analyzed,and the optimization method to improve efficiency were discussed.The loss distribution and on-load temperature rise characteristics of the prototype were tested and verified by loss separation experiment and on-load temperature rise experiment.Finally,the magnetostrictive effect and vibration characterist ics of amorphous alloy cores are studied.Due to the large magnetostriction coefficient of amorphous alloy materials,the vibration of the motor increased when the advantages of low losses were fully utilized.For the magnetostrictive vibration of amorphou s alloy and local saturation of high-speed SRM,a magnetostrictive vibration analysis model considering the influence of magnetic field saturation was proposed.The vibration characteristics of the motor under different operating conditions are analyzed by the finite element method,and the influence of the core structure and processing process on the vibration characteristics was analyzed.The optimization method of the vibration characteristics of high-speed SRM with amorphous alloy core was explored,which provides theoretical support for the comprehensive performance improvement of the motor.The vibration acceleration experiments of the prototype machine were used to verify the magnetostrictive vibration of the amorphous alloy core and the vibration characteristics of the motor.