Research On Hybrid Excitation Type Bearingless Permanent Magnet Generator And Its Predictive Control

With the development of the industry technology and the aggravation of the environment pollution,the demand for the clean energy is increasing as the days passed,in which the electric energy has become a cornerstone of the modern society for economy,safety and the convenience of transportation.However,the conventional permanent magnet synchronous generator(PMSG)has the problem of the mechanical wear,machine noise and short service life,and it is difficult to adjust the magnetic field of the motor under varying load conditions.These defects result in a poor dynamic response performance,which influence the quality of power supply and the stability of the power system.Aimed to solve the above problems,a hybrid excitation bearingless permanent magnet generator(HEBPMG)is proposed in this dissertation.The novel HEBPMG which integrates the advantages of the conventional PMSG and magnetic bearings,has a wider range of application prospect in power supply of micro-grid and grid-connected power generation system.The project is supported by Key Research and Development Program of Jiangsu Province(BE2016150)and Jiangsu Province “Qinglan Project”(2014).In this dissertation,the power generation principle,the radial suspension generation mechanisms,mathematical model,forecast direct control have been researched.The main contents are as follows in four parts:1.In order to solve the problems of the conventional generator that the bearing wear and difficult control of the magnetic field under complex condition,the HEBPMG is proposed in this dissertation,in addition the structure and operation principle is analyzed.Furthermore,a mathematical model of the HEBPMSG is built considering the rotor eccentricity and Lorentz force.2.The distributions of magnetic flux densities in the air gap,suspension characteristics and power generation performance of the HEBPMSG are analyzed based on finite elements analysis(FEA)software ANSYS/Maxwell,and the parameters are also designed and optimized.The validity of the mathematical model is verified under different conditions,thus the theoretical foundation of the control strategy is provided.3.In view of the delay time of sampling and computing for the traditional direct torque control(DTC),a forecast direct torque control and suspension force strategy is presented combining with the basic theory of predictive control.The control system of the HEBPMG can be divided into 3 sub-systems of suspension,rotation and power generation,and the predictive control of the system is operated based on the winding flux observer and predictor.The simulation model of forecast direct torque control and suspension force control is established by Matlab/Simulink.The simulation results indicate that the proposed control method has validity and reliability,and better robustness while load changing4.According to the operation principle and design requirements,the software and hardware circuit of the control system for HEBPMSG are designed based on a controller chip of TMS320F2812.According to the signals of voltages,current,rotation speed and displacement,the operating state of 3 sets of windings can be controlled,and thus the steady rotation and suspension is realized.The interference immunity experiments under variable load are processed.The feasibility and high-efficiency of predictive control strategy are verified by the experiment results.