Research On Overload Protection Algorithm Based On Motor Parameter Identification

With the rapid development of science and technology in China,induction motor is not only the most used motor in traditional industrial and agricultural production,but also widely used power source in the field of electric vehicles and aerospace science and technology.In this regard,the overload protection technology in induction motor has become the focus of research.Based on the history and experience of motor maintenance equip ment,most motor failures can be divided into two categories,mechanical and electrical failures.Faults may be related to motor design defects,manufacturing defects,incorrect installation,misuse,lack of protection,or maintenance problems,but the end result generally falls into these two categories.According to the investigation,40～60% of the electrical faults of induction motors are caused by motor burning caused by high temperature of stator windings.There are many traditional overload protection methods,such as embedding thermocouple inside the motor to reflect the internal temperature.The shortcoming of this method is that it can only measure the temperature near the point.Another commonly used inverse time limit protection may not be ideal for different motors,which can not maximize the energy efficiency of the motor and affect the efficiency.Therefore,the overload protection of induction motor will be deeply studied in this essay.The traditional induction motor fault model was built to analyze the changes of parameter values under overload condition,determine how to effectively protect overload protection,and explore the resistance value of dynamic resistance on the basis of traditional resistance protection method,which became the difficulty of this essay.The overload protection method used in this paper is improved on the basis of the resistan ce overload protection method,which is a more intelligent protection method.Using MATLAB/Simulink simulation software to establish the mathematical model of induction motor,using th e least square algorithm for parameter identification,voltage,current and speed as input,outpu t stator resistance,so that the stator windings can be quickly and accurately to protect.The real-time identification of stator resistance is realized and the winding temperature is calculated by the resistance value.Because the new overload protection method studied in this paper is a protection method studied for the motor protector in practical application,it is difficult to avoid the influence of noise and other disturbances in the actual operation of the motor.In order to make the induction motor protection more accurate,the filter and the least square algorithm are used to reduce the disadvantage of the traditional least square method.Finally,a 1DPT160 M series variable frequency speed regulating induction motor is taken as an example to verify the feasibility of the proposed new overload protection method.This method is widely used,and is not limited by the motor model,and the average resistance value is measured so that the average temperature inside the motor can be indirectly obtained.It provides a new method for overload protection of motor protector.