Research On Permanent Magnet Synchronous Motor Control System Based On Quasi-Z-Source Inverter

Permanent magnet synchronous motor(PMSM)have been widely used in motor drive systems with superior performance.Besides,the quasi-Z-source inverter(q ZSI)as a new inverter circuit improved from the Z-source inverter in 2007,has the function of adjusting the dc-link voltage and allowing the bridge arm to pass through by adding an inductance,capacitance and impedance network in the front section of the traditional inverter.The application of the quasi-Z source inverter in EV driving system has become one of the famous research in the field of electric transmission.This paper takes the PMSM driving system based on quasi-Z source inverter as the main research object,And mainly research on the inductor current ripple problem,dc-link control system and the effect of boost on motor speed expansion.After the research status of motor drive system and Z-source inverter was introduced.The mathematical model of the motor was first established,then the principle of vector control is analyzed,and the methods of Maximum Torque Per Ampere control and Field-weakening control are deduced,which provides the goal and theoretical basis for the research of the quasi-Z source inverter motor vector control system.After the principle and mathematical model of the quasi-Z source inverter boost are analyzed,the boost performance of multiple pass-through vector modulation strategies are compared.Then,the abnormal inductor current ripple during SVM6 control was found in subsequent researches.After the modulation wave functions were analyzed,When the two-phase modulation waves are close or equal,the through-vectors will overlap,causing the through-duty duty cycle to be missing,causing a large ripple in the inductor current.However,SVM4 control inserts the through vector only in the maximum and minimum two-phase modulation waves,which can effectively avoid the above abnormal working state,thereby reducing the inductor current ripple and lowering the inductor design index.The quasi-Z-source inverter motor system can extend the motor speed range by increasing the dc-link voltage.However,the increase of the dc-link voltage will increase the system loss,so the dc-link voltage given value is necessary to be reasonably designed.Traditional bus reference voltage calculation method was greatly affected by d,q axis current fluctuations.The fluctuation of the reference voltage will cause the fluctuation of thebus voltage,which will affect the stability of the system.A linear reference voltage calculation method based on speed is proposed in this paper.By using the characteristics of the current controller saturation when the motor is running in the constant torque zone,the influence of the d,q axis current fluctuations on the reference voltage is avoided.In addition,the amount of reference voltage calculation and the complexity of the voltage control system can be reduced.What’s more,the effect of adjustable bus voltage system on motor speed expansion is analyzed.In conclusion,compared with the traditional voltage source inverter structure,the motor constant torque and constant power operation area of the quasi-Z source inverter motor system can be effectively expanded.Finally,the simulation model of voltage source inverter and quasi-Z-source inverter vector control system were built by MATLAB/Simulink and PLECS simulation platform,and the correctness of the above theory has been verified by simulation results.