Unity Power Factor Fault Tolerant Control Of Open-End Winding Linear Vernier Permanent Magnet Motor

Among the development of the linear permanent magnet motors,the linear vernier permanent magnet(LVPM)motor has the advantages of high electromagnetic properties such as high thrust density of the cursor motor,high efficiency and high power density,which highlights advantages in applications such as rail transportation.This article will set a primary permanent magnet type linear vernier permanent magnet motor as control object,which has high thrust density,high power density and suitable for long-distance travel like rail transit.Based on the analysis of the structure and electromagnetic characteristics of the LVPM,in order to improve the LVPM motor driven performance an open winding dual inverter topology with high redundancy and high power output capability is proposed.Based on the three-phase LVPM motor open-end winding system,a simple,efficient and low switching frequency dual inverter SVPWM strategy is proposed.On the other hand,considering the low power factor characteristics of the LVPM motor and the high reliability requirements in rail transit applications,a fault-tolerant control strategy with unity power factor is proposed.A simulation model is established for the proposed modulation strategy and control algorithm,and also an experimental system is built.Both of simulation and experimental results all proved the correctness and effectiveness of the three-phase LVPM motor open-end winding system and its modulation strategy and control algorithm.The main research contents of the paper are as follows:1.The topological structure of three-phase LVPM motor and its electromagnetic properties such as magnetic field distribution,back electromotive force,and positioning force are analyzed.The mathematical models of LVPM motor in different coordinate systems is established,and the basic power supply principle of open-end winding topology is also been analyzed.The analysis lays the foundation for subsequent in-depth research.2.The space voltage vector of the open-end winding dual-inverter topology is analyzed.By analyzing the vector distribution,a novel dual-inverter SVPWM modulation strategy is proposed.The modulation strategy has the characteristics of easy implementation and low switching frequency.The simulation model is established to verify the feasibility of the modulation method.3.According to the low power factor of LVPM motor and to improve the reliability of system,a unity power factor fault-tolerant control strategy is proposed based on the flying capacitor type open-end winding topology to ensure continuous operation after inverter breakdown.The active and reactive power of the motor is decoupled completely and the reactive power pressure in power-side inverter is released.The MATLAB model is built to perform simulation analysis.4.The open-end winding driven experiment system of LVPM motor based on DSP is designed with the detailed development process of hardware and software to provide a reliable and stable platform for experimental research.5.A complete three-phase LVPM motor open-end winding experimental system is built and the experimental test program is also given.The correctness and effectiveness of the proposed dual inverter modulation strategy and unity power factor fault-tolerant control is been verified by experimental results.