Numerical Calculation And Analysis Of Electromagnetic Field And Thermal Field Of Variable-Frequency Induction Motor

Recently technology of variable-frequency adjustable-speed is the most active and makes the fastest development among AC speed regulation. It makes the frequency a kind of resource which can be made the most use of. Squirrel-cage induction motor is the energy conversion devices which are the most wildly applied in various production processes and its great significant to ensure them to work safely in the condition of frequency conversion. Therefore, the further research on the operations of squirrel-cage induction motor on different frequencies is an important guidance to ensure the safe and high efficient production.According to the feature of the subject, this thesis firstly introduces Type- Y160M1-8, the common squirrel-cage induction motor which realizes the basic theory of variable-frequency adjustable-speed and also briefly analyses variable-frequency adjustable-speed, applied variable frequency converter, SPWM technology and converting mode; through calculating the starting current and starting torque of the motor on different frequencies, analyses the starting performance of the motor in the condition of variable-frequency adjustable-speed, and analyses the steady performance of the motor in the condition of variable-frequency adjustable-speed combined with impedances of stator and rotor, losses, efficiency, power factor and mechanical properties of steady course on different frequencies.The physical model and math model of the motor are established in the condition of assumptions. Magnetic field with constant torque is calculated using flowchart of dual convergence method on different frequencies. According to the change of flux in different positions such as yoke, tooth, air gap, the change of flux is summarized.This thesis finally introduces the calorific foundation of thermal field; analyses transmit heat differential equation and boundary condition; illuminates calculation problem of 2-D thermal field in engineering practicality; calculates the thermal field of the rotor with finite element method and draws the conclusion of the thermal field of the rotor on different frequencies. The validity of the thermal field model and the correctness of the calculated values are verified by experimental results derived from a prototype motor.