Analysis Of Temperature Field Of Brushless Doubly Fed Machine And Study Of Magnetic Field Characteristics Under Eccentricity

Because of the large power and bad working conditions,the wound rotor brushless doubly fed machine has large heat output during long time running.If these heat can not be emitted in time,it will seriously affect the stability and life of the motor.Based on the theory of heat transfer,the finite element method is applied to analyze and calculate the steady temperature field of a wound rotor brushless doubly fed machine.It is important to determine whether the temperature rise of motor is in the safe range,which is very important for the safe operation of the motor.In addition,the air gap eccentric fault is one of the main faults of brushless doubly fed induction motor,and the motor performance index are affected by it,therefore,to study the characteristics of air gap magnetic field and eccentricity of brushless doubly fed machine eccentric case detection method,has very important significance.This paper takes the wound rotor brushless doubly fed machine as the research object,analyzes the three-dimensional steady temperature field of the motor,and studies the air gap magnetic field characteristics of the motor when the eccentric fault occurs.Based on electromagnetic field theory,numerical method and finite element method,the first loss of the motor is calculated,and the calculation accuracy in the effect of temperature,the three-dimensional model of the motor was simplified and divided according to the calculation of the temperature field of basic electric machine theory to determine the various parts of the equivalent thermal conductivity and heat transfer coefficient,finally.According to the calculation of the loss as the heat load of heat,the calculation of 3D temperature field of the motor by using ANSYS workbench,and compared with the experimental results,verifies the correctness and rationality of the calculation model and calculation results of the motor temperature field,and provides a basis for the optimization design of brushless doubly fed machine.According to the theory of electromagnetic field,two dimensional finite element model of motor is built,and the air gap flux density distribution,air gap magnetic field harmonic component and iron consumption of the wound rotor brushless doubly fed machine under static eccentric and dynamic eccentric are analyzed.By analytical method analysis and calculation of air gap magnetic field characteristic of the motor,the magnetic field characteristics include magnetic characteristics of the motor under normal operation,the eccentric fault characteristics of the magnetic field,and the two are compared,thus obtained the harmonic characteristics of air gap magnetic field signal,which is used to diagnose fault of eccentricity of the motor,at last by using the finite element simulation proves the validity of the harmonic magnetic field in air gap eccentric fault diagnosis of motor characteristic signal method,and the motor dynamic eccentricity fault as an example,studies the relationship between the amplitude and eccentricity fault signal of motor dynamic eccentricity,the results provide the basis for the accurate detection of winding type brushless doubly fed motor.