The Research On High Torque Soft Starter Based On ARM

Three-phase asynchronous motor is widely used in industrial production due to the advantage of its solid and durable structure and simple maintenance.while during the period of total voltage start,the current is so big that having a great impact on the power system.Especially when dragging heavy load,the motor will not only have a big starting current but also be difficult to start.Traditional electronic soft starter uses the method of gradually increasing the stator voltage to the rated voltage to finish smooth ac asynchronous motor starting,reduce starting current and impact on the power system.Because three-phase ac asynchronous motor electromagnetic torque is directly proportional to the square of stator voltage,the electromagnetic torque will reduce a lot when the stator voltage reduce,so traditional electronic soft starters are not suitable to motor heavey load starting.In view of the heavy load starting difficulty in traditional electronic soft starter,this paper studies discrete frequency high torque soft starter based on ARM.The scheme adopts the advanced ARM controller with floating point arithmetic function as the core controller,introduces the AC/AC variable frequency theory to the motor soft start control,and uses the inversely parallel-connecting thyristors to regulate the stator voltage and its frequency during the motor starting period,because the voltage and frequency hierarchically change at the same time,which will ensure unchanged voltage frequency ratio during motor starting period,thus basically keeping the motor starting electromagnetic torque do not reduce,and making the motor at full load have large starting torque to start smoothly.After carrying on the thorough analysis of discrete frequency theory,this paper studies a kind of discrete frequency soft start triggering angle optimal selection principle,and motor heavy load starting simulation based on establishing the discrete variable frequency starting process simulation model,the simulation results show that discrete frequency starting method,in terms of overloading starting characteristics,superior to the traditional direct start,limit current start and ramp voltage start.This article has already used the 32-bit ARM controller with floating point arithmetic function to design the control unit and finish software and hardware design of the control system,and a motor intelligent protection system is designed Based on the completion of three-phase ac asynchronous motor discrete frequency soft start.Experiment results are presented,and they demonstate that the discrete variable frequency high torque soft starter based on ARM has advantages of fast calculation speed,low cost,high reliability,etc.This study demonstrates that the discrete frequency high torque soft starters based on ARM have good performance and have overcomed the deficiency of the traditional electronic soft starter.Simulation and experimental results have proved the correctness and effectiveness of discrete frequency theory.