Research And Design Of Double-fed Machine Speed Control System

Doubly fed control system of induction motor is a kind of superior performance electric drive control system,by design proper control system can realize the rotor AC excitation control,adjust the rotation speed according the concept of asynchronous motor slip,in constant speed according to the characteristics of operation of synchronous machines,in drag load has the characteristics of DC motor.It not only reduces the capacity of the converter with the same power motor,but also increase the degree of freedom of the excitation control.Because of the flexibility of system control method,the doubly fed motor has the broad application prospect in the fields of industrial transmission,wind power and pumped storage power station.The research object of this paper is the winding asynchronous motor,it belongs to a kind of double fed motor,the control system has the common characteristics of the doubly fed machine and its unique advantages in the same time.In this paper,we study the control strategy of doubly fed induction motor when it is in electric operation state.Firstly,the structure,vector diagram,equivalent circuit,principle of operation and speed control and energy flow of the synchronization of asynchronous motor.Secondly,this paper introduces the basic structure and characteristics of doubly fed speed control system and the selection of controller whose principle and operation characteristics in the control system,and then space vector modulation technique and the field oriented control have been introduced,control strategy of the inverter part has been studied detailed,thus we can give the switch tube of the inverter accurate trigger pulse according to the 900principles precise,out of step of stator and rotor and energy decoupling can be eliminated fundamentally.The last,excitation transfer and the start process of the motor has been explained and we research and design the most critical part of lag angle control of the whole system.We can achieve energy decoupling by adjusting a phase relationship between stator and rotor magnetic potential,different amplitude of the power angle characteristics by adjusting excitation current modulation,speed control by adjusting the rotor excitation current frequency.The performance analysis and theory research of the control system has been studied on the basis of all above,and the simulation model of the whole control system has also been established.Through theoretical analysis and simulation experiments we can get the waveform simulation and comparison,with the simulation results of the control system performance analysis and research,the feasibility of this control strategy excellent steady-state performance and dynamic characteristics,the doubly fed synchronous motor running,then we can lay a theoretical basis for future research and practice.