Study On Control Strategy And Simulation Of The Double-fed Electric Machine Speed Control System

At present, the biggest advantage of doubly-fed electric machine is that it can makethe slip power feed to the grid, or feed it from grid. The double-fed electric machinespeed control system has high reliability and low cost advantages, and it can change thedouble-fed electric machine stator side reactive power by adjusting the amplitude, phaseand frequency of the rotor side converter, so it is widely used in the field of motorcontrol.This paper mainly studies the control strategy of double-fed electric machine speedcontrol system and its simulation. This paper first briefly describes the basic workingprinciple of the double-fed electric machine speed control system, analyzes anddiscusses the power flow of the doubly-fed electric machine in the run-time underdifferent conditions,then deduces the mathematical model of the doubly-fed electricmachine in three-phase stationary coordinate system in detail, and it shows thatdouble-fed electric machine is a high, strong coupling, complex nonlinear systemthrough analyzing the mathematical model, which has a guiding significance for thestudy of doubly-fed electric machine control strategy. And then it uses stator fluxoriented and derives the mathematical model of the doubly-fed electric machine in thesynchronously rotating coordinate system MT.It uses the double-loop control system ofusing the speed of the double-fed electric machine and reactive power of the stator-sideas control targets in the outer ring and the component of rotor current in the M, T-axis asinner control objectives. And this control method can independently adjust the motorspeed and the reactive power of the stator side of double-fed electric machine,anddouble-fed electric machine can achieve running in the sub-synchronous andsuper-synchronous state.Beause the biggest advantage of doubly-fed machine is that itcan make the slip power feed to the grid, or feed it from grid, and it uses the AC-DCconverter.Then this paper analyses of the basic principles of three-phase voltagehigh-frequency rectifier circuit in detail and derives a mathematical model ofthree-phase voltage high-frequency rectifier circuit, and using voltage oriented, as wellashysteresis current control to control the network side converter. The control strategycan realize the advantages of high power factor, rapid dynamic response, two-way flowof energy, and low harmonic content of the doubly-fed electric machine.Then it builds a double-fed electric machine speed control system simulationmodel in MATLAB simulink environment, simulation results are analyzed to verify thefeasibility of the control strategy used.Finally, based on the system simulation,it simply introduces the part of controlsystem hardware and software designs of the double-fed electric machine speed controlsystem.Control system hardware part regards the main controller chip TMS320LF2407as the cores,which TI ’s manufactures and is dedicated to electric machinecontrol,TMS320LF2407mainly completes data collection,vector control and interruption protection, etc.TMS320LF2407carry out written algorithm to obtain therequired PWM signal to control the IGBT turn-off of the main circuit, then realize thestator flux oriented vector control of doubly-fed electric machine speed control system.