Research On Intelligent Soft Start And Running Protection Device For High Power Motor

AC asynchronous motor has the advantages of simple structure,reliable operation and wide application.It is an important power equipment in industrial and agricultural production.Therefore,the starting control and protection are always concerned by people.The motor in direct starting will produce 4 to 7 times of rated current,impact of the stator coil and the rotor cage,result large number of Joule heat,damage winding insulation,shorten the service life of the motor,and even affect the stability of power system;In addition,large starting torque ripple and small torque also limits the application of the motor.In order to improve the starting torque and reduce the starting current,this paper puts forward the soft start mode which is based on the discrete variable frequency,voltage ramp and current limiting.Realized control the motor with load or heavy load.Describes the development history of soft start technology and the categories of traditional soft start and the characteristics of electronic soft starter;analyzes the principles of single-phase and three phase AC voltage regulation circuit based on thyristors and control strategy of voltage ramp soft start,current limiting soft start and discrete frequency soft start and modeling and simulation.Taken three phase AC asynchronous motor as the research object,analyzed the electrical characteristics and protection principle of faults such as short circuit,over current,fault phase and ground fault,etc.According to various fault features,the corresponding protective measures are given.The hardware design and software design of the system are carried out,an embedded integrated control system is designed,which is composed of heavy load soft start,touch screen display and input and a variety of protection.The system parameters can be set by the touch screen and the system running state can be displayed in real time.When the system detects a fault,the touch screen displays the fault information,and the relay action to protect the system.Finally,the experimental results show that the system is feasible.