High Power Factor Field Weakening Control Of Field-modulated Permanent Magnet Linear Modulation Motor With Open-end Winding

The linear motor traction system has become a research hotspot in the field of rail transit because it eliminates the traditional rotary linear conversion mechanism and has the advantages of fast response,high acceleration and high efficiency.Field-modulated Permanent Magnet Linear(FMPML)motors have the advantages of high thrust density,high efficiency,and low cost.They have good application prospects in long-distance applications such as subways and maglev trains.However,the low power factor of this type of motor is its obvious disadvantage.On the basis of dual power supply,this paper proposes a 180° vector control strategy based on improved SVPWM.This control strategy has a simple structure and is a simple extension of star connection control.Secondly,on the basis of the flying capacitor open winding topology,the power factor characteristics of the inverter are studied,and a high power factor control strategy is obtained.In addition,the combination of field weakening control and power factor improvement,a high-rate factor field weakening control strategy is proposed.The feasibility of the two control strategies proposed in this paper is verified through theoretical analysis,simulation and experiment.The main research contents of this paper are as follows:1.The mechanical structure of the FMPML motor in this thesis is analyzed and the electromagnetic characteristics are simulated and analyzed.The commonly used reference shaft system and coordinate transformation of motors are introduced,and the mathematical model of FMPML motor is established under different reference shaft systems.In addition,the power supply principle of the open-winding topology is analyzed and the mathematical model is established,which lays the foundation for the proposal and verification of the open-winding control strategy in this paper.2.The basic space voltage vector that can be generated by the dual inverter is calculated.In addition,the traditional SVPWM is analyzed and an improved SVPWM is proposed.Aiming at the dual-supply open-winding topology,a 180° control strategy based on improved SVPWM is proposed.The control strategy is simulated and its dynamic and static performance is analyzed.The feasibility of the control strategy is verified by simulation.3.Combining the low power factor characteristics of FMPML motor with the characteristics of flying capacitor open-end winding topology power factor compensation,a flying capacitor open winding high power factor control strategy is given.Combining power factor compensation and field weakening,a field weakening control strategy based on flying capacitor topology is proposed to further broaden the speed range of the motor system.4.A driving experiment platform with TMS320F28377 S as the core was set up and outline the software and hardware design of the platform.On this basis,a photo of the experiment platform is given and the function of each experimental instrument in the figure is introduced.The experimental results of the two control strategies are obtained through experiments.Analysis of the experimental results confirmed the effectiveness of the two control strategies proposed in this article.