Research On Key Technologies Of Variable Speed Permanent Magnet Synchronous Generator

Permanent magnet synchronous generator PWM rectifier has the characteristics of small current harmonic component?adjustable power factor?small DC voltage fluctuations and energy can flow bidirectional,etc.It can be widely used in areas of the special vehicles powered,ship powered,hybrid cars,new energy,etc.In this dissertation,variable speed permanent magnet synchronous generating system as the research subjects,adoption a combination of research methods includes the use of theoretical analysis and software simulation and experimental verification.The main aspects were studied in design and optimization of permanent magnet generator in the PWM converter control ? variable speed control strategy of permanent magnet synchronous generation system and Permanent magnet synchronous generators Harmonic Analysis and Suppression,ect details are as follows:First,this dissertation introduces the basic structure of the variable speed permanent magnet synchronous generator system,expounds the basic working principle of generator and converter,established the mathematical model of permanent magnet synchronous generator and PWM rectifier,which lay the foundation of research work for subsequent chapters.Variable speed permanent magnet synchronous generator is studied under the condition of the converter controlled to have a grasp of the running characteristics.Permanent magnet generator stator voltage balance equation under the condition of the PWM converter isd = 0 vector control and the constraint relationship between the stator voltage and dc bus voltage,which are deduced;The permanent magnet generator stator voltage and power factor will change with the electromagnetic power change,and their laws are studied,clarified the basic principle of active power regulation for the variable speed permanent magnet synchronous generator system;Refining the important operation characteristics for variable speed permanent magnet synchronous machine side converter under the condition of isd = 0 vector control.Then this dissertation has conducted intensive studies in the design and optimization of Permanent magnet generator under PWM converter control.Traditional design and analysis model of synchronous generator adopted direct connected to grid is no longer suitable for variable speed permanent magnet synchronous generator because permanent magnet synchronous generator(PMSG)connected to the DC bus through a full power converter.This dissertation presented the design analysis model for variable speed permanent magnet synchronous generators which was the combination of "Circuit Calculation" and "parameter calculation" method of the classic motor design theory and the basic principles of vector control variable speed permanent magnet synchronous generator.Based on this model,simulated annealing algorithm(Simulated Annealing,SA)has been used in optimized design with optimal efficiency target of 840 k W permanent magnet synchronous generator.Finally,non-load finite element simulation and load simulation of 840 k W permanent magnet synchronous generators has been run by using the finite element method and MATLAB simulation analysis,the engineering value of design optimization method this dissertation proposed has been verified by the simulation results.Secondly,this dissertation has done research of PWM converter control strategy of variable speed permanent magnet synchronous generating system.On the basis of PMSM-PWM phasor diagrams and mathematical models,converter isd = 0,the constant terminal voltage and unity power factor control strategies are studied,the steady-state operating characteristics of variable speed permanent magnet synchronous generator under different control strategies has been theoretical analyzed and derived.The variation of the generator stator phase voltage,phase current,power factor and ultimate power has been summarized.And a composite control strategy has been proposed for variable speed permanent magnet synchronous generating system based on these three control strategies,which made the permanent magnet synchronous generator can be applied to work in a variety of different load and speed,improved the operating efficiency of the generator.A speed sensorless control method based on the estimated current model has been proposed on the basis of permanent magnet synchronous generator model analyzes.The method calculated the estimated current value according to the obtained equivalent motor model by the known parameters,the estimated speed is corrected by the current value of the error between the actual and estimated detected current values,and then obtained rotor position by estimated speed integral.This method is very stable at high speeds,the maximum speed error is less than 0.2%,has a strong low-speed operation load capacity,greatly extends the operating range of permanent magnet synchronous generator,overcome the limited scope of application robustness and instability by the algorithms combined with existing state switch.And harmonic analysis of permanent magnet synchronous generator is studied.In variable speed permanent magnet synchronous generator,a space harmonic magnetic field caused by the uneven air gap permeance of motor iron core slot and uneven distribution of stator winding space,and the permanent magnet synchronous generator is connected to a PWM inverter,inverter modulation makes the stator current with the time harmonic to produce magnetic field,as a result of producing the harmonic losses.Therefore,the mechanism of the variable speed permanent magnet synchronous generator system harmonic analysis is particularly important.In this dissertation the space harmonic magnetomotive force of permanent magnet synchronous generator is analyzed,and aiming at the commonly used methods of SVPWM modulation for rectifier,SVPWM modulation strategy based on vector control is analyzed,the influence of the modulation ratio and carrier frequency on the regional loss of permanent magnet synchronous generator,using the joint simulation of Ansoft under SVPWM modulation strategies,the effect of modulation ratio and carrier frequency for permanent magnet synchronous generator on harmonic loss to be studied.Finally,in this dissertation,variable speed permanent magnet synchronous generating system is studied experimentally and a 840 k W AC permanent magnet generator system prototype has been designed and manufactured.In addition,we build an experimental platform 840 kw permanent magnet synchronous generator rectifier besides introducing a prototype system component.Then,the system hardware circuit and the control software are designed in this dissertation.At last,experimental prototype and verification motor analysis and design theory and PWM rectifier control strategy presented in this dissertation by experiment.The experimental data has been processed and experimental results and experimental waveforms have been analyzed.The experimental results verify the correctness and the validity of theoretical,and verify design method proposed in this dissertation.