Analysis Of Core Loss And Vibration And Noise Performance Of Cage Induction Motor With Concentric Single-Double-Layer Star-Delta Winding

Three-phase induction motor is widely used in industrial production because of its simple structure,low price,convenient manufacture,reliable operation and easy speed regulation.However,the harmonic component of the air-gap magnetic potential is pretty large because the Y-type or ?-type connection is commonly used in three-phase stator windings of induction motor.On the one hand,the high amplitude of harmonic component in air-gap flux density will lead to the high core loss of the motor,which makes the efficiency of the motor difficult to improve and the heating more serious.On the other hand,the electromagnetic excitation force produced by the harmonic component of airgap magnetic field acting on the core of the motor will be stimulated,which would generate the vibration and finally result in electromagnetic noise.The motor noise might shorten the motor life,endanger human health and pollute the environment.In this paper,aiming at the harmonic problem of air-gap magnetic field in three-phase cage rotor induction motor,an improved stator winding—the concentric single-double-layer stardelta(CSDLSD)winding is proposed and studied to diminish the core loss and reduce the vibration and the electromagnetic noise.The main work is carried out as follow:1.Firstly,the background significance of improved motor winding is explained,the development history of stator sinusoidal winding at home and abroad is summarized,and the research status of stator sinusoidal winding for improving motor performance is introduced.Starting from two performances closely related to harmonics of air-gap magnetic field,the core loss and the vibration and noise,this paper expounds the theoretical methods of reducing core loss and vibration and noise of motor by domestic and foreign scholars.The optimal scopes of these methods are also probes.2.Based on the advantages and disadvantages of two kinds of induction motor stator sinusoidal windings – the combined star-delta series winding and the concentric low harmonic sinusoidal winding,a concentric single-double-layer star-delta(CSDLSD)winding is proposed.The working principle of CSDLSD winding is analyzed by analytic method.The air-gap magnetic potential caused by the stator winding is analyzed.The formulas for analyzing the air-gap magnetic potential caused by the stator winding and calculating the fundamental and harmonic winding coefficients are derived.3.Based on the classical Bertotti three-stage loss model,the influence of harmonic component in air-gap magnetic potential of CSDLSD stator winding on stator core loss is analyzed.The air-gap magnetic potential harmonic content and back electromotive force(EMF)harmonic content of CSDLSD winding,traditional double-layer short-pitch winding and combined star-delta sinusoidal winding are analyzed by two-dimensional(2D)finite element method(FEM)simulation.By using the method of segmental analysis of the stator core,the core loss of each part of stator core is compared when the above three windings are equipped.The result of FEM is consistent with that of analytical method.The improved stator winding can effectively reduce the core loss caused by the harmonic of air-gap magnetic potential.4.Based on the principle that the vibration and the electromagnetic noise of the motor mainly comes from the electromagnetic exciting force of the motor,combined with the air-gap magnetic potential theory of the CSDLSD winding in Chapter 3,the radial electromagnetic force of the motor is analyzed by the method of multiplying the magnetic potential and the permeability.The vibration type of the motor is deduced by the analysis of the force wave frequency and the natural vibration frequency of the motor stator.2DFEM simulation and 2D Fast Fourier Transform(FFT)are used to verify the influence of winding form on the amplitude of each harmonic wave,thus weakening the vibration force wave.Finally,the electromagnetic noise of the motor with three different windings is verified by the harmonic response software.A CSDLSD winding which combines the advantages of two kinds of stator sinusoidal windings is proposed in this paper.Its principle and the influence of the stator winding on the air-gap magnetic field of the motor are analyzed.The effect of the promoted winding on reducing the core loss of the stator and reducing the vibration and the electromagnetic noise is studied and verified by the FEM.The method can be used as a reference to improve the performance of the motor which has been produced and put into operation by changing the type of stator winding.