Research On Key Technical Of Explosion-proof Integrative Motor

In this dissertation,an 1140 V / 315 kW explosion proof integrated motor(EPIM)is investigated supported by the projects of Liaoning Provincial Department of Education's Innovation Team and Fushun Coal Mine Motor Manufacturing Co.,Ltd.Aiming to solve a series of problems under the integration of motor and variable frequency such as losses,temperature rise,earth short circuit and common-mode voltage caused by variable frequency driver.The main contents is listed as follow:(1)Analyzing the hardware in the variable frequency driver system of EPIM based on the system level model of power electronics,in order to improve the EPIM integration level,reduce the disturbance from system harmonics and decrease the system volume.Then proposed an analytical method to calculate the parameters of inductor and bus capacitor for the EPIM taking voltage drop,ripple current,stability of system and the influence between bus capacitor and DC inductor into consideration.This analysis method could give the design parameters of bus capacitor and DC bus inductor such as loss,ripple current,average temperature,life time and connection method.After all these analysis,a design scheme(two ends of DC bus series with DC inductor)is proposed to prevent short-to-ground error caused by harsh working conditions and loads variation in coal mine.Finally,the mode of energy transfer,distribution of voltage and current is investigated based on the simulation and experiment test when the error of one phase short-to-ground occurred in EPIM.(2)Aiming to determine the new limitations in variable frequency drive system caused by the loss and temperature rise after the integration of variable frequency drive system and motor.The loss calculation and temperature rise analysis of variable frequency drive system are of great significant for the optimal design of EPIM.Thus,the design method of main power electronics in variable frequency drive system was studied and a loss calculation and temperature rise analysis method was proposed.An electro-thermal coupled analysis model was established taking gate drive resistor,DC bus voltage and switching frequency into consideration.The loss calculation and temperature rise transient simulation of IGBT in the variable frequency drive system of explosion proof integrated motor was achieved based on this model taking character of hardware and none-ideal condition(speed variation,torque variation,etc.)current.A water-cooled heat sink was designed based on the analysis results,and the simulation and experimental test were finished(3)In order to solve the problem of common mode voltage of EPIM caused by variable frequency driver,a three-sector SVPWM modulation technique is proposed to suppress common-mode voltage.Firstly,the mathematical model of the EPIM in the two-phase rotating coordinate system is established.The traditional SVPWM and the modified SVPWM modulation principle and the common-mode voltage suppression theory are compared and analyzed.The minimum common mode voltage is as the aim of the modulating technique for the output of the variable speed system.And the adjacent space vector action time and the condition of the new sector are calculated and judged directly by the three-phase voltage,and the modulation sector is reduced from 6 to 3,reducing the impact of the transition between sectors.The problem of common-mode voltage caused by zero-vector operation time is reduced.The simulation and experiment were carried out.(4)Electromagnetic model,water cooling system and whole structure of the EPIM are designed.And the finite element simulation of electromagnetic field,loss and temperature field under the rated state is carried out.1140 V / 315 kW EPIM has been produced and the experimental platform was set up.The experimental study was carried out under no-load and load conditions respectively.The experiments under no-load and load conditions mainly include: the working and operating characteristics of EPIM,efficiency testing,the various parts of the temperature rise testing at different times,common-mode voltage suppression.The simulation and experiment are compared to verify the correctness of the proposed EPIM using the scheme proposed in this dissertation.