Research On Pmsm Drive Control System Bansed On Quasi-Z Inverter

Under the background of the rapid development of electric vehicles,it is of practical significance to study the vehicle permanent magnet synchronous motor(PMSM)drive system with high efficiency and high robustness.Quasi Z-source inverter(QZSI)consists of Quasi Z-source network and voltage source inverter.It is a new type of power conversion structure with dual functions of boost and inverter.This paper takes QZSI and PMSM drive control system as the research object,and conducts the following research on the application of QZSI in PMSM drive control system:Firstly,the effective operation interval of traditional QZSI applied to PMSM system is analyzed.According to the operation principle of QZSI and the mathematical model of PMSM,an improved SVPWM strategy with through vector is proposed.When the Quasi-Z source is applied to the motor system,the problem of dc-link voltage drop caused by the insufficient load range capability of the Quasi-Z source inverter is pointed out.According to this problem,the effective operation range of the permanent magnet synchronous motor drive system based on the QuasiZ source inverter(QZSI-PMSM)is studied.Through the simulation of dc-link voltage drop phenomenon,the correctness of the calculation results of effective operation interval is verified.Secondly,the improved QZSI topology and control strategy are studied.The paper proposes a new type of improved QZSI topology in response to the above problems,adding active support circuits to QZSI to enhance QZSI’s carrying capacity.The operating principle of the improved QZSI topology is analyzed,the capacitance parameters of the active support circuit and the control logic of the active device are designed.Then,the cascaded PI regulator is used to improve the stability of the dclink voltage closed-loop control system of the improved Quasi-Z source inverter.The simulation results show that the designed improved QZSI system enhances the load capacity and effectively improves the problem of dc-link voltage drop.Thirdly,the boost and speed expansion of the improved QZSI-PMSM system are studied.The speed expansion principle of the improved QZSI-PMSM system is studied,and the speed expansion ratio is calculated.Then the paper considers the limitation of the expansion ratio and proposes two PMSM boost and speed expansion strategies,the maximum modulation ratio control and the constant dc-link voltage control.The simulation results show that the improved QZSI can effectively expand the constant torque speed range of PMSM,which is consistent with the theoretical analysis results.Finally,an experimental study on the improved QZSI-PMSM system is carried out.The hardware circuit design and software program design for the experiment are completed.The improved control strategy of QZSI-PMSM system is verified.Experimental results show that improved QZSI effectively expands the speed capability of PMSM,reduces system losses,and enhances system robustness.