Research On Control System Of Three Phase Permanent Magnet Synchronous Motor Based On Current Source Inverter

In the early stage,due to the low energy storage efficiency of the inductor and the low frequency of the switching device,the inductance value of the current source inverter was relatively large and the efficiency of the whole system was low,so the motor drive system mainly adopted the voltage source inverter.With the development of high temperature superconducting materials,inductance energy storage efficiency becomes higher,especially the rapid development of wide band gap semiconductor Si C and Ga N recently,the value of inductance selection decreases,and the motor drive system based on current source inverter has become a new research hotspot.In this paper,the current source inverter of three-phase permanent magnet synchronous motor control system whose first stage is DC-DC converter is taken as the research object.Firstly,the mathematical model of the selected topology structure is given,and based on the three-phase filter capacitor on the output side,a three-loop control system is constructed.Considering the mathematical model based on the dq axis coordinate system,the motor and the capacitance equation have the rotation cost coupling term,the feedforward decoupling strategy is adopted,and the design method of the engineering controller is used to design the parameters.Secondly,based on the two basic requirements of current source inverter modulation strategy,the power switch principle and space current vector diagram are given.By referring to the SVPWM modulation strategy of the voltage source,the current vector sector judgment,the current vector action time and the PWM switch signal realization method of the current source are analyzed,which lays a foundation for the subsequent motor drive system.Thirdly,in view of the similarity of current source inverter and Boost converter topological structure,the voltage pumping characteristics of current source are analyzed according to the particularity of current source topological structure and Boost converter analogy.Then,the relationship between DC-DC converter and bus inductance selection is studied by using voltage pumping characteristics.The formula of the relation between switching frequency,current source modulation ratio and bus current ripple of DC-DC converter is given.Based on the permissible maximum current ripple,the inductance selection principle is given.Finally,according to the voltage pumping characteristics of the current source inverter,the motor speed range of the current source is divided into four regions:constant torque region,voltage pumping region,variable modulation ratio region and weak magnetic field region.Adjust the modulation ratio of DC-DC converter to achieve constant torque region and voltage pumping region;The variable modulation ratio region is realized by changing the current source modulation ratio.Based on the voltage source’s voltage negative feedback magnetization method,the current source’s magnetization control strategy is given.