Research On The Control Strategies Of Open-Winding Permanent Magnet Motor System Based On Five-leg Inverter

Due to the high power density,simple structure,high efficiency and excellent operation performance,Permanent Magnet Synchronous Motor(PMSM)has been widely employed in application of electric propulsion system.The open-end winding PMSM(OW-PMSM)with the neutral point opened drived by two inverters can achieve the wide speed operation.However,the cost of OW-PMSM driving system is greatly increased because of the extra inverter.This thesis proposes a kind of OW-PMSM driving system based on a switch-reduced five-leg inverter to cut down the cost of proposed driving system and it’s modulation strategy and operational characteristics have been studied.Firstly,this paper introduces the operating principle of dual inverter driving system in detail.On this basis,the topology of OW-PMSM driving system based on five-leg inverter has been derived and the operating principle of OW-PMSM driving system based on five-leg inverter has been analyzed.On the basis,the distortion of three-phase current and the characteristics of zero sequence current caused by the dead-time of inverter and the 3rd back-EMF harmonic have been analyzed and the zero sequence current suppress strategy has been proposed based on dead-time compensation and 3rd back-EMF offset to improve the system performance.Secondly,the simulation model of OW-PMSM driving system based on five-leg inverter is established via the software of MATLAB/Simulink.The output performance of the driving system under ideal conditions has been simulated.And the simulation comparison of the driving performance of the proposed system with and without adopting the zero sequence current suppress strategy has been given,too.The validity of the zero sequence current suppression strategy has been verified by the simulation results.Finally,the hardware platform based on the TMS320F28335 and CPLD has been established and the software of DSP and CPLD has been programed.The good performance of OW-PMSM driving system with the zero sequence current suppress strategy has been verified by comparing the experimental results,and the feasibility of the driving system has been verified by the load changing and speed regulation results.