Development Of Improved Quasi-Z Source Inverter Based On TMS320F28335

The energy crisis in the 21 st century has become increasingly fierce.With the gradual depletion of fossil fuels,new energy sources are being researched and developed around the world.The distributed generation technologies represented by wind power generation and photovoltaic power generation have attracted much attention.Distributed generation involves microgrid technology,and inverters are the core of microgrid technology.The traditional inverter is a step-down inverter,usually adding a DC/DC converter at the previous stage to form a secondary structure and reducing system transmission efficiency.In addition,conventional inverters do not allow the same bridge arm to conduct at the same time,otherwise a short circuit will damage the inverter.Therefore,the dead time must be added to the switching signal,but the addition of the dead time will cause the output waveform to be distorted.The improved quasi-Z source inverter(SB/SL-q ZSI)can make up for the shortcomings of traditional inverters.This article based on TMS320F28335 SB/SL-q ZSI hardware and software design and experimental prototype development.Firstly,the circuit topology and working principle of SB/SL-q ZSI are described in detail.The Z source network with low voltage stress and high voltage gain is emphasized.The five control strategies of the Z-source inverter are analyzed,including simple boost control strategy,maximum boost control strategy,constant boost control strategy,third harmonic injection control strategy and through-section SVPWM control strategy.By comparing the operating principles of various control strategies,timing diagrams,voltage quality and other characteristics,this paper finally selected a straight-through segmented SVPWM control strategy.Secondly,the system hardware design uses Altium Designer 14 to draw schematics of each circuit: IRF2136 three-phase bridge driver chip as the core driver circuit,voltage and current detection circuit,filter capacitor,LC filter circuit for filter inductor,IGBT overvoltage,overcurrent The protection circuit and power circuit using LM7824 chip,and finally made a double-layer PCB board map.Again,the system software is designed.Using the TMS320F28335 under the CCS3.0 version development platform,a straight-through segmented SVPWM main program,an interrupt program,and a system protection subroutine are designed.Each program flow chart is given.At the same time,the current double closed-loop control method is used to control the asynchronous motor.Then,SB/SL-q ZSI and ZSI simulation models were established on the MATLAB/Simulink simulation platform.The simulated waveforms of the SB/SL-q ZSI and ZSI system simulation waveforms,the straight-through segmented SVPWM trigger pulse simulation waveforms and the DC bus voltage,capacitor voltage and output AC voltage are obtained.The results of observational simulation waveforms are consistent with the theoretical analysis and verify the correctness of SB/SL-q ZSI,reflecting its superiority over ZSI.Finally,the SB/SL-q ZSI prototype testing platform with TMS320F28335 as the control core was set up.The three-phase squirrel-cage asynchronous motor was used as the load to measure the output voltage,capacitor voltage,trigger pulse,and motor speed waveform.Comparing with theoretical values,the overall data error is within 10%,verifying the feasibility of the improved quasi-Z source inverter.