Research On Loss In Three-Phase Asynchronous Motor Under Harmonic Environment

The three-phase asynchronous motor accounts for a large part of the industrial field in our country.How to keep the three-phase asynchronous motor running steadily and how to improve its working efficiency have always been the focus of attention.It is of great significance for energy conservation and environmental protection.In view of the above problems,the loss of three-phase asynchronous motor needs to be analyzed.When the power grid is polluted by harmonics,the motor runs under non-ideal conditions,which will increase the difficulty in analyzing and calculating loss.So we need an effective way to solve the problem.In order to study the influence of harmonic environment on motor loss better,we need to suppress and eliminate harmonics first,so as to establish a more ideal working environment of the motor,and then compare with the motor loss in the harmonic environment.We hope to eliminate harmonics better.Considering the superior compensation characteristic of active power filter,we take active power filter as research object and adopt appropriate control strategy to ensure better control effect.Therefore,based on the above background,the main contents of this dissertation are as follows:The energy consumption analysis based on the motor equivalent model does not apply to this case when the supply voltage of the motor is non-sinusoidal.In order to find a new method with clear physical meaning,the motor equivalent model was established to analyze its applicable conditions,the power relationship of asynchronous motor is analyzed.Based on this,the energy equivalent method is proposed,and the equivalent motor model is used to calculate the internal loss.The loss calculation software is compiled by MATLAB tools,the validity of the method and the correctness of the software have been verified by an example.The acquisition of command current and harmonic current compensation are the keys to the active power filter.A simplified mathematical model is established for the single injection active power filter.Taking into account the model of uncertainty,the active disturbance rejection control is used for current tracking.Furthermore,the singular perturbation method is used to analyze the stability of the active disturbance rejection controller.The simulation experiment is designed to compare the traditional proportional-integral-derivative control and the ADRC.The simulation results show that the ADRC is superior to the traditional proportional-integral-derivative control in the fastness,stability and accuracy of the current tracking.The comparison and analysis of the motor losses in the harmonic environment and the ideal environment are carried out.The design experiments show that the elimination of harmonics is helpful to reduce the motor losses.