Modeling And Simulation Of Internal Feedback Chopper Cascade Speed Control System Based On SVPWM And Soft Switching

China's energy shortage,therefore,the development of new energy-saving technology is particularly important.The fan and the pump in the country a large number of major people's livelihood applications in a large number of wide distribution,power consumption.Now the actual application of more frequency control and cascade speed control two speed mode.Through the performance analysis and price comparison and other factors to consider,decided to use cascade speed mode.Cascade speed control of the object is mainly winding motor,relative to the frequency control,cascade speed program price advantage is in the high-power fan,pump speed and other fields.Cascade speed control system is mainly in the chopper link switch IGBT switching loss is relatively large,while the inverter is often composed of thyristor three-phase bridge inverter,this inverter is relatively large harmonic,easy The problem of subversion.Resulting in the entire speed control system power factor is low,poor system stability and other issues.The main work and improvement of the paper are summarized as follows:(1)In-depth study of the principle of asynchronous motor chopping cascade speed control system,the establishment of chopper tandem system mathematical model,and on this basis,the main circuit parameters of the design methods and principles;(2)In order to solve the problem of poor stability of cascade speed control system,the double-closed-loop control scheme is adopted in the chopping part of the cascade speed control system,and the current loop and the speed loop are designed according to the typical system and the typical system.(3)In view of the problem that the switching loss of the IGBT is chopped in the cascade speed control system,this paper adopts the passive lossless soft switching technology and applies it to the chopping section of the cascade speed control system.This reduces the switching losses of the switch IGBT.And the related parameters in the passive lossless soft switching circuit are designed.(4)In this paper,the SVPWM control algorithm is applied to the cascade speed control system in order to solve the problem that the inverter in the cascade speed regulation system is relatively large,the inverter is prone to subversion,and the system power factor is low.Inverter to improve the system's power factor and reduce the voltage,current waveform harmonic components.(SVPWM)modulation technology is analyzed in detail,and the control algorithm applied to the three-phase bridge type voltage type active inverter is summarized.Finally,the dynamic simulation tool SIMULINK is established by MATLAB software.The simulation model of the internal feedback chopper cascade speed control system based on SVPWM and soft switch is used to set and simulate the parameters in the simulation model,and the obtained voltage and current waveform are analyzed.The power factor of the cascade speed regulation system is improved by analyzing thepower factor of the cascade speed control system and the switching loss of the switch.The analysis results show that the switching loss of the chopper part switch tube is almost zero.Therefore,this paper concludes that the internal feed chopper cascade speed control system based on SVPWM and soft switch can achieve the purpose of improving the system power factor and reducing the switching loss.