Design Of High Frequency Chopping Cascade Speed Control System For Wound Asynchronous Motor

Large Wound-rotor induction motors,such as pumps and fans,are used in many areas all over the world,this kind of motor driving system applies cascade speed control system universally,which is economic and simple.But the traditional cascade speed control system's low power factor and serious harmonic pollution have greatly affected its further development.In the current background of energy-saving emission reduction,it is of great theoretical and engineering significance to study how to save energy and improve the efficiency.In this paper,the structure and working principle of the cascade speed control system are described,and then the factors of low power factor are analyzed.A kind of speed control scheme which adding chopper device IGBT in the rotor DC circuit——high frequency chopper cascade speed control system is studied.The working principle,equivalent circuit and power factor with this new method is studied in great detail.The working characteristics of IGBT device is analyzed.At the same time,the circuit design and parameters of the main circuit are calculated,including IGBT buffer circuit design and calculation,parameters calculation of filter inductor and energy storage capacitor.Secondly,the model of this system is built by using MATLAB/Simulink software,according to the system block diagram,the simulation results of the system show that the system works efficiently.Finally,TI's TMS320F28335 microprocessor is used as the control core of the system,and the all-digital realization method of the chopper cascade speed control system is constructed.According to the block diagram of the chopper cascade speed control system with double current loop,speed and current.The main circuit and the control circuit are designed.Main circuit mainly by the rectifier bridge,inductors,capacitors,IGBT and inverter bridge and other components;The control circuit includes,current detection,ADC sampling,PWM pulse generator,IGBT driver and I/O interface circuits.The program flow charts of main program,current feedback,velocity feedback,fault protection and PI regulator are drawn,and set up a test platform,the control system for testing and verification.The platform I built tests the dynamic performance of the chopping speed control system of the wound induction motor,get some ideal experimental waveforms,the experimental results show that the chopper cascade speed control system is reliable and the design is feasible.The chopper cascade speed control system is a practical AC speed control system,which is an ideal speed control system for pumps and other large motor load drag systems' engineering.