Research On The Control Of VSCF Doubly-Fed Asynchronous Machine

The double-fed control strategy for wound-rotor induction machine is investigated in this paper. The double-fed machine's mathematical model and the control of the double- PWM converter are also studied.The stator side of the doubly-fed generator directly connect to the grid. The rotor side connect to the grid by the dual-PWM converter.The rotor side inverter use the stator's flux field oriented vector control to achieve the generator speed's regulation. And the grid rectfier use the grid's coltage field oriented synchronous PI control to achieve the purposes of DC voltage constant and power factor under unit.According to the characteristics of the system operation and control object, firstly carry on the simulation research in the Matlab / Simulink environment. The author establish a integral model of timing system with doubly-fed asynchronous motor to simulate the system in different operation conditions. The simulation results show that the control system has good dynamic and static characteristics, fast response, and the doubly-fed motor can achieve power decoupling control.In order to research the timing system in laboratory, this thesis designs an experimental platform to research the work principle and control strategy of doubly-fed motor. An wound synchronous motor is used to simulate the doubly-fed synchronous motor. And it supported by the double-PWM converter and the control system with DSP as the core. On this paltform the thesis completes the experiment that under the non-load condition to simulate the whole process of the super-synchronous and under-synchronous electical running of doubly-fed synchronous motor. Experimental results show that this system platform can be used to achieve variable speed and constant frequency operation for doubly-fed asynchronous motor, timing result is obvious, running is stable.