Research On The Structural Modeling And Dynamic Characteristics Of Typical Rotor System For High Speed Electric Machine

High speed electric machines can connect to working machine directly and leave out the traditional speed increasing part,due to the advantages of small volume,high efficiency,low noise and little vibration,they are widely used in high speed machine tool,air compressor,energy storage flywheel and cogeneration.However,the dynamic characteristics of rotor system is ambiguous,and the promotion of high speed electric machines are restricted for the lack of scientific evidence.Therefore,the structural modeling and dynamic characteristics of special rotor system for high speed machines are in need of research.(1)A dynamic model of rotor system which considered the interference fit of motor axis and rotor is constructed.The contact stiffness of interference fit is calculated though the theory of contact element.The calculation of rotor dynamic characteristics is completed by matlab program.This model,due to the full consideration of the interference fit between motor axis and rotor,make the calculation more accurate.(2)The dynamic model of rotor system for high speed electric machine is constructed,and the dynamic characteristics of this kind of rotor is calculated though the technology of mathematical simulation.The attachment stiffness matrix of preload beam element and the contact stiffness of interference fit among locating piece,rotor and pressing part for the preload rotor system are calculated.And the preload rotor system dynamic model for the high speed machine is constructed.The effect of preload rotor and bending moment are considered sufficiently,therefore,the calculation of rotor stiffness is reasonable.(3)The dynamic model of tie-bolted fastened rotor for high speed machine which is based on the interface element and contact stiffness theory is built.The fastened rod,motor axis,rotor and steel tube are equivalent to double rotor model,and the five part are linked into one rotor system which make the model more impeccable.And the contact interface between motor rotor and axis are equivalent to the element which only have contact stiffness.The link between all the matrixs is completed.The differential equations in this model are solved though newmark-?.(4)The laws among static stiffness,mode of vibration,critical speed and dynamic response of the three kind of motor rotors are revealed in the model.And the dynamic characteristics of three kind of typical rotors are contrasted.It is revealed that the static stiffness and critical speed increase with magnitude of interference in the interface-fit rotor.And the length of shaft-extension end have the most impact in the critical speed.The static stiffness and critical speed increase with the tension in the preload rotor and tie-bolted fastened rotor,but it has no effect on the dynamic characteristics if the tension beyond 100000N.(5)Build the high speed machine test bench,and test the static stiffness and natural frequency.The result showed that the calculate values agree well with the experimental ones,and the error are below 6%,therefore,the correctness of theoretical analysis is verified.The work offers important theories and effective approaches for the design of high speed machines rotor system,and have important engineering reference value.