Vibration And Noise Analysis Of Permanent Magnet Brushless Motors Under Different Power Supply Modes

Permanent magnet brushless motor using permanent magnet replaced the exciting winding,the use of power electronic devices to replace the traditional commutator and brush,overcoming the traditional motor structure complexity,low reliability of the faults,with its high efficiency,low noise,high precision,etc.Widely used in aerospace,electric cars,household appliances and other fields.With the wide and deep application of permanent magnet brushless motor,the requirements for motor are increasing day by day.How to suppress the vibration and noise of motor is an important problem in the current research of motor.In this paper,a surface mounted 8-pole 24-slot permanent magnet brushless motor is taken as the research object.Starting from electromagnetic force,combined with structural mechanics and acoustic analysis,the electromagnetic field,structural mode,vibration displacement and acoustic response of the permanent magnet brushless motor are analyzed and studied,providing a basis for the subsequent improvement of motor vibration and noise.The main research contents are as follows:First of all,to a 8 a 24 slot permanent magnet brushless motor no-load and load of the two-dimensional electromagnetic field is analyzed,obtaining the air gap flux density,the analytical expression of the electromagnetic wave to determine the radial electromagnetic force of the amplitude of each harmonic component,the relationship between the frequency and order time,so as to lay a good foundation for the research of permanent magnet motor vibration and noise,and also provide theoretical basis for the subsequent finite element calculation.Secondly,a three-dimensional electromagnetic finite element model of permanent magnet brushless motor was established,and the distribution of air gap flux density and electromagnetic force wave of the motor center surface and motor end was simulated under different power supply modes.Fourier transform is used to obtain the corresponding spectrum information,which verifies the correctness of the analytical method above,and also provides the basic data for the vibration response analysis in the following paper.Then,a three-dimensional solid model of the permanent magnet brushless motor system is established,and the modal shape and modal frequency of the motor are simulated.The influence of windings and chassis on the modal frequency of the motor system is discussed and analyzed.According to the calculation results of electromagnetic field,whether the power supply mode can cause the resonance of the motor system is analyzed and judged,which verifies the rationality and reliability of the motor model design.Finally,the vibration velocity of the motor surface was obtained by calculating the vibration response for the two excitation force loading modes of centralized loading and segmental loading.The vibration speed was taken as the load,and the noise spectrum of the motor was obtained based on the acoustic boundary element method.The influence of the power supply mode and the electromagnetic force at the end of the motor on the vibration and noise was analyzed.The reliability of the analytical method is verified by vibration test.