The Study Of The 11kW Three-phase Asynchronous Motor Protection Device

Three-phase Asynchronous induction motor as a kind of power equipment is widely used in industrial and agricultural production, but because of human action and environmental causes make motor failure frequently, protection against failures has always been widespread concern. Every year in China because of motor overload, imbalance of three phase current, phase fault caused by the damage increasing, not only caused serious economic loss, even endanger the safety of staff. So for motor protection device design, whether in economic perspective and security Angle has important significance.Compared with the traditional protection devices, the microprocessor as the core of intelligent protection device is a powerful data processing ability, can in time to protect and record fault. In this paper, under the present situation of the development of the three-phase Asynchronous motor protection device to protect the theory and to conduct a comprehensive analysis of the background for the motor common failures were studied, the main work are as follows.(1)this paper mainly carry out a detailed analysis for overload, phase failure, phase unbalance and phase fault current which occurs during 11 k W three-phase Asynchronous induction motor running frequently then established motor failure model in MATLAB/SIMULINK and gave monitoring and analysis for the stator current, torque, positive, negative sequence current of failure.(2)According to the fault analysis for overload, phase failure, phase unbalance and phase fault current proposed corresponding protection. At the same time for three-phase AC motor during operation will be attenuated DC component, an improved algorithm based on DFT, and by comparing the commonly used algorithms to verify the improved algorithm can better filtering decaying DC component.(3)Thesis build a modular design system based on Cortex-M3 series ARM processor as the core for 11 KW three-phase Asynchronous motor. the system is divided into acquisition module, processor module, protection action module, display module, communication module, power supply module. System software, divided into the main program, acquisition module, data processing module, troubleshooting module, communication module sections, this can save much time and convenient to the calling program. Parameters designed for different motors to avoid trouble.(4)Finally, experimental platform for a 5.5KW three-phase Asynchronous motor, the motor via a common fault simulation to test the accuracy and safety of the fault protection device. Experimental results show this fault protection device safe, efficient and reliable.