Improved Quasi-Z Source Direct Matrix Converter Based Im Torque Tracking System

Quasi-Z Source Direct Matrix Converter(QZS-DMC)is a new type of circuit topology that has emerged in recent years.As an integrated structure,QZS-DMC is simpler in terms of structure.Its control strategy is relatively simpler and faster,and the structural topology is easier to modularize and integrate.Asynchronous motors are one of the most widely used motors in industry and agriculture due to their simple structure,relatively high cost performance,high efficiency and adaptability to harsher environments.In this paper,the improved QZS-DMC is used in the asynchronous motor drive system,direct torque control(Direct torque control,DTC)is adopted,and the direct torque control based on the improved QZS-DMC(improved QZS-DMC-DTC)is designed.The system realizes the combination of the advantages of the two and proposes an improvement to the traditional DTC algorithm.The torque tracking algorithm with the method of inserting zero vectors is adopted to make the system achieve better dynamic performance.First,the topology and working principle of the improved Quasi-Z source inverter are introduced,combined with the equivalent circuit,its mathematical model is established,and it is compared with other various Z-source inverters.The influencing factors of the impedance source parameters of the improved Quasi-Z source inverter are analyzed in detail,and the parameters are designed.Secondly,the topological structure of the improved QZS-DMC is analyzed,and its boost working principle is explained in detail.On the traditional DMC dual space vector modulation,the position of the through zero vector is improved to form an improved dual space vector modulation strategy.Through detailed simulation and preliminary experimental verification,as well as comparative analysis with traditional direct matrix converters,the feasibility and superiority of the improved QZS-DMC topology and control strategy are verified,and the improved QZS-DMC is,Output and voltage transmission have better results than above.Thirdly,a direct torque control system based on the improved QZS-DMC asynchronous motor(improved QZS-DMC-DTC)is designed to realize the four-quadrant operation of the asynchronous motor.It realizes the combination of the improved QZS-DMC space vector modulation strategy and DTC technology.The system simulation model is established,and the system speed and torque output are better,which proves that the control method can combine the advantages of the two.Finally,the characteristics of the DTC method and the existing torque ripple problem are deeply analyzed,and an improved QZS-DMC-DTC torque tracking control improvement scheme is proposed for this defect.The simulation and experimental results verify the correctness and effectiveness of the proposed improvement plan,improve the AC speed regulation performance and meet the energy-saving requirements,and provide convenience for actual research and design.