Research On Model Predictive Control Of Soft-Switching Quasi-Z Source Inverter

With the development of economy and society,new energy has been paid more and more attention by the state and society.With the continuous development of industrialization,the use of electric energy has become more and more extensive.As the most important electrical equipment in industrial production,the motor is more and more important for the power supply of the motor.The inverter is the main equipment for power supply to the motor.Since its proposal,the quasi-Z-source inverter has the advantages of single-stage boost,continuous inductor current,and capacitive voltage stress compared with voltage source inverters and Z-source inverters.Low-level characteristics have been widely concerned by scholars at home and abroad.Various derivative structures,soft-switching technologies and various control methods for quasi-Z-source inverters have been continuously proposed.In this paper,the soft-switching technology of Z-source inverter and related model predictive control algorithms are studied.The specific work is as follows:1.Aiming at the hard-switching working state of traditional quasi-Z source inverters,a soft-switching topology of quasi-Z source inverters that can realize soft-switching action without additional external auxiliary circuits is proposed.The boost coefficient relationship between the inverter and the traditional quasi-Z source inverter are verified,the control scheme in the traditional quasi-Z source inverter can be directly applied to the soft-switching quasi-Z source inverter.2.Improvements have been made on the basis of the traditional model predictive control algorithm.By inputting the characteristics of the inductor current,which has only two current values in the straight-through state and the non-straight-through state,the inductor current can directly determine whether to enter the straight-through state,thereby avoiding the tedious operation of calculating all switch states is required in each cycle.Under the experimental conditions,the calculation amount of predictive control decreases by 50%.At the same time,the required weight coefficients in the cost function are reduced from 3 to 1,which greatly reduces the debugging and design difficulty of the cost function.3.Based on the proposed soft-switching quasi-Z-source topology and the related model control algorithm,the software and hardware are designed.The hardware part gives the calculation process of the parameter values of the main components,describes in detail the working principle of each part of the auxiliary circuit and the calculation methods and steps of the relevant parameters,and builds the relevant circuit;the software part carries out the function of each part of the control program.Described in detail,the possible problems of each part of the program in software design and the design of key parameters are given.4.The proposed soft-switching topology and predictive control algorithm are simulated by MATLAB/Simulink simulation software,and the theoretical feasibility of the circuit topology and the improved model predictive control algorithm is verified.Then the STM32H743IIT6 is used as the main control chip to build a soft-switching quasi-Z source inverter experimental prototype to verify the inverter topology and the improved predictive control algorithm,and prove the soft-switching quasi-Z source inverter topology proposed in this paper and the feasibility of the improved predictive control algorithm.