Research On Overload Protection Technology Of Intelligent Motor Protector

With the application of power electronic technology,the overload protection technology of motor protector is developing in the direction of intelligence.In the micro grid DC power supply system,the running of the motor may be affected by the current fluctuation caused by the change of power and load.Therefore,it is paid more and more attention on research on the overload protection technology of intelligent motor protector in DC power supply system.In this paper,aiming at the characteristics of overload operation of the motor in DC power supply system,the model of motor temperature rise has been analyzed.The overload protection scheme of intelligent motor protector has been studied.By combining the current increment protection method,the current increasing rate protection method and the maximum protection method,the protection schemes are determined to realize the overload protection and short circuit protection.Based on PIC microcontroller,the hardware design and the software design of overload protection in intelligent motor overload protector are carried out.The hardware system includes power supply circuit,signal sampling circuit,maximum protection circuit,relay switch circuit,delay circuit,driving circuit and hybrid switching circuit.By use of C language,software system completes system initialization,current signal acquisition,temperature rise model calculation,the implementation of protection,parameter display and other functions.The corresponding anti-interference design is also finished.In addition,the overload protection experimental scheme of intelligent motor protector is studied on and the overload protection test system has been designed.The experimental test proves that each function module has good performance and the whole protector has good effect on overload protection and short circuit protection.