Research On The Direct Torque Control Of Brushless Doubly-Fed Machine

Now, a large number of applied AC machines are mainly the synchronous machines and induction machines. Generally, synchronous machine and induction machine can not be used together because of the structural differences. The brushless Doubly-Fed machine(BDFM) not only has a simple structure of rotor cage, but also has the fine characteristics of the wound rotor induction machine and synchronous machine that can operate on both the synchronous and asynchronous status, not only can be used as an adjusting-speed machine, but also as a variable-speed constant-frequency(VSCF) generator, and the doubly-fed electricity can be realized under the brushless case.This paper introduces the BDFM the working principle and operation mode,next derive the network mathematical models and d-qmathematical models of the wound-rotor BDFM,and the simulation model based on d-q reference frame is established. Basic on Matlab / simulink modeling, simulation and experimental methods to analyze several operating modes in the open-loop characteristics, the results of the simulation test results analysis, closed-loop control BDFM study provides an important the oretical basis and valuable conclusions.Then create voltage and current mathematical equation, torque control is derived matrix,and in the use of Matlab / Simulink model of BDFM control the use of closed-loop direct torque control simulation, the simulation results are analyzed. The results showed that: direct torque control than the vector control is relatively less online computation, the direct torque control is relatively simple, the speed and torque response speed is relatively fast. In this paper, direct torque control method, as applied to the actual provision of a theoretical basis..Direct Torque Control of torque ripple on the great influence on their own, this article torque ripple of digital systems and processes of the production of mathematical analysis method, indicating an important factor in generating a torque ripple and torque of the sampling time hysteresis width. BDFM direct torque control performance improvement can be effectively broken down by vector method, optimization method and the improved switching table torque hysteresis comparator method, to achieve the purpose of reducing torque ripple.Finally, a summary about the thesis is made. Some suggestion is proposed for next work.