Distribution Characteristics Of Electric Field In Stator Winding Of Variable Frequency Motor And Study On The Mechanism Of Discharge Mechanism

Frequency conversion motor is one of the indispensable important equipment in modern industrial system.It is widely used in various social fields such as rail transit,aerospace,ships and ships because of its advantages of convenient speed regulation,economy and energy saving.Mainly adopts frequency conversion motor to feed speed control pulse width modulation(PWM),square wave inverter output pulse voltage is rising along the steep and wide frequency band,via cable transmission to the motor end easy overvoltage and generated in the motor stator winding voltage distribution,makes the local electric field in the stator insulation system is too high,resulting in damage to the stator winding insulation structure,speed up the frequency conversion motor run time electric insulation aging.And frequency conversion motor stator in recent years of grounding fault frequently occurs as a result of insulation is weak,the frequency conversion motor stator winding through simulation research on the voltage distribution characteristics and pulse overvoltage under electric field distribution characteristics,and through the discharge test to explore the development rule of the stator insulation structure of discharge of stator insulation system failure mechanism study is of great significance.Based on type JL2100 frequency conversion motor stator winding structure,construction of the stator end winding groove and a finite element model,calculate the stators winding slot part and the end of the distribution parameters,using circuit simulation software to build high frequency equivalent circuit,stator winding adopts the method of combining theory and simulation research of the stator winding turns on voltage distribution characteristics.Then,based on the voltage distribution of the windings and the finite element model of the stator windings,the electric field distribution characteristics of the motor slots are further studied.The results show that the further the winding conductors are arranged,the greater the voltage amplitude to the ground.By increasing the rising time of the input voltage,the distribution of the voltage to the ground can be effectively improved.At the same time,it is found that the maximum electric field intensity appears at the chamfer of the upper turn of the motor groove.In the stator winding end insulation layer,the electric field is concentrated near the notch.As the pulse voltage amplitude increases,the electric field in the low resistance halo layer on the end surface first increases and then transfers to the nonlinear halo insulation layer.With the increase of rising edge time,the maximum field intensity in the low resistance halo-proof layer decreased obviously,and the surface electric field distribution at the end was improved.For stator insulation structure of electrical aging mechanism,set up a platform electrical aging test pressure discharge,summarizes the sample partial discharge development process,the study found that the sample partial discharge in the first place in development in the square wave voltage rising tallied,falling edge,in the process of voltage amplitude increases,the voltage waveform flat area also gradually appear discharge phenomenon,late to test whether the rising and falling or flat area are intense discharge occurs.The variation law of discharge characteristic parameters of samples with different frequencies is investigated,and it is found that with the increase of frequency,it can promote the discharge of samples,and the discharge phenomenon is more violent.