Research On Speed Regulation Of Doubly-Fed Induction Machine Based On Field Oriented Control

Recently, the Doubly-Fed Induction Machine (DFIM) is becoming more and more popular in the motor drives because of the low cost and high reliability. This paper focuses on the research of DFIM which employs the Back-to-Back converter and the control strategy is the dual loop vector control based on the stator flux vector.The published literatures always use the dual loop control which contains the speed loop and the reactive power loop so far. The goal of control system can be not only the mode of speed loop and reactive power loop, but also the mode of speed loop and stator flux loop according to the modeling analysis. And generally speaking, the flux control is very important is the motor drives. However, few literatures have analyzed the pro and con of these two control mode. This paper tries to resolve the confusion of those two control strategies.By the theory analysis, this paper suggests that the DFIM system is stable under all working situation by using those two control strategies. The value of steady stator flux only depends on the torque current values in case of the stable grid voltage. Hence, the steady point of stator flux varies with the torque current. The flux current will be forced to be the limited state if the stator flux loop controller is PI controller and the reference vale of flux does not match the real flux value. Besides, this paper suggests that the mode of reactive power control can decouple the dual loop control but the mode of flux control can not do it because of the variation of flux steady value.This paper proposed that the flux outer loop employs the P controller in order to resolve the problem caused by the mismatch of reference value and real value of stator flux. The simulation mode is conducted in the Matlab/Simulink and the simulation results in many different situations verify the analysis proposed by this paper. The experimental setup is 4kW and the results show the validity of the flux control strategy which the outer loop controller is the P controller.