Design And Optimization Control Of Four-quadrant Frequency Conversion System For High Power Factor Dual PWM Motor

With the development of society and the advancement of science and technology,the research on power quality has got more and more attention by the country,and it is of great significance to solve the pollution problem of power equipment to the power grid.In modern industry,the large-scale use of non-linear loads,such as motors and diode rectifiers,has injected a large amount of reactive current and harmonic current into the grid,seriously affecting the quality of the power grid.dual-PWM converter is widely used in rail transit,steel industry and other fields due to its high power factor,energy bidirectional flow and low harmonic content,which improves the pollution of power grids.Among them,the voltage type dual-PWM converter has a wide range of voltage regulation and many advantages in application,and has attracted more and more scholars’ attention.Therefore,this paper studies the voltage-type dual-PWM converter system as the research object.This paper first studies the basic principles of a dual-PWM converter system.The mathematical model of PWM rectifier is established,and different modes of modulation are compared.Several operating modes of PWM rectifier are analyzed in detail.According to the basic theory of four-quadrant operation of three-phase asynchronous motor,the conditions of four-quadrant operation of three-phase asynchronous motor and its power balance are analyzed..Secondly,design the components of the dual-PWM converter,including the single-phase digital phase-lock loop based on the second-order generalized integrator of the rectifying part,and the double-close-loop controller design based on proportional integral adjustment;Inverter motor constant voltage frequency ratio control inverter design,simulation analysis and experimental verification for each link;analysis of power balance relationship of dual-PWM four quadrant converter system based on PWM rectifier,PWM inverter and asynchronous motor.Thirdly,the problem of harmonic current generation under the light load of dual-PWM converter is studied,and the causes of harmonic generation are analyzed.The current inner loop controller based on quasi-proportional resonance is designed to suppress current harmonics.The effects of various parameters on the performance of the proportional resonant controller are analyzed,and the simulation analysis and experimental verification are carried out.The voltage external loop controller based on sliding mode variable structure for suppressing DC voltage ripple is designed and verified by simulation.Finally,a dual-PWM converter hardware experiment platform based on DSP28335 controller is built.The controller application program is written,the human-computer interaction interface is designed,and a complete dual-PWM converter system is established.At the same time,the experiment of the tow experimental platform composed of dual-PWM converters was carried out to verify the reliability and stability of the system.