Structure And Thermal Analysis Of Hybrid Excitation Axial Flux Motor Based On Amorphous Alloy Materials

The amorphous alloy axial flux motors(AAAFMs)have the advantages of compact structure,high power density and high efficiency.With the global warming and energy crisis becoming more serious,research on AAAFMs has been more and more popular in recent years.In addition,due to the high frequency and low iron loss characteristics of amorphous alloys(AA),it has received a lot of attention and application in recent years.It has achieved good results in replacing magnetic steel sheets as stator cores in axial flux motors.However,because of the high hardness,thin and brittle characteristics of AA,it is not easy to be cut and processed.The secondary processing has a large impact on its electromagnetic properties,therefore,in the manufacturing process of the motor,special consideration is needed for its manufacturing process.First of all,in view of the sensitivity of AA materials to mechanical stress,the structure of axial flux hybrid excitation motor based on AA materials is designed and analyzed in this paper.Two different topology structures of hybrid excitation axial flux motor,Kaman and Torus,are compared and analyzed,mainly about the magnetic circuit structure,stator fixed structure,cooling system and rotor pole structure.The mechanical strength of stator core,stator fixed structure and rotor is analyzed and calculated to verify the reliability of the structure designed in this paper.Secondly,the finite element method is used to analyze the rotor dynamics and modal vibration mode of the motor,and the deflection of the shaft and modal vibration mode of the rotor are calculated and analyzed respectively.Then,the critical speed of each stage of the rotor is obtained by using the Campbell diagram analysis,and the rotor safety and reliability in the operation process are verified.Thirdly,the correctness of the temperature field analysis method is verified by the test of a prototype.Then,the coupled calculation of temperature field and fluid field of the hybrid-excitation AAAFM are implemented,and the overall temperature distribution,local overheating position and the flow state of the internal fluid of the motor are obtained.A rotor temperature rise suppression method is proposed to provide centrifugal fan blade on the outer surface of the rotor to increase the turbulence intensity of air in the engine.Based on the computational fluid dynamics(CFD)method,the effects of the number and length of blades on the air friction loss and rotor temperature rise of the fully enclosed hybrid-excitation AFM are analyzed.Finally,for the water-cooled fully enclosed hybrid-excitation AFM with end caps,a method for suppressing the temperature rise of the rotor by installing air blades at the rotor shaft and opening vent holes in the rotor bracket to improve the air turbulence in the machine was proposed.Based on the CFD method,the heat dissipation effect of the rotor under the three structures of rotor bracket opening,rotor bracket opening matching rotating shaft fan blade and conventional rotor structure without opening vents is compared and analyzed.Based on this,the effect of the number of vent holes and the outer diameter of the vent holes on the air friction loss and rotor temperature rise of a fully enclosed hybrid-excitation AFM was calculated.