Sharif Digital Repository

This paper presents a new method for implementing the direct torque control (DTC) on the brushless doubly fed induction machines (BDFM) in presence of turbulence in voltage grid. It is supposed irrupts in three phase voltage grid suddenly. Effects of these events on closed-loop operation are inevitable and in some cases could lead to system instability. It presumed that grid voltages disturbance effect on back-To-back converter's outputs is negligible. Control of a complex machine is problematic. Hence, firstly has explained performance of the control method on BDFM, Proposed a new method for reducing turbulence effects of system operation afterward. Simulation results on BDFM model with... 

In this paper, a new scheme for position control of a mechanical load driven by a permanent magnet DC motor and a gearbox is presented. The gearbox is assumed to have some amount of backlash. The paper derives a model for the backlash nonlinear behavior. It then proposes a new control structure composed of feedback and feed forward control systems. The feedback control system is designed based on zero backlash. The feed forward part is employed to minimize the backlash effects. The new method is evaluated via simulations in MATLAB/SEVIULINK environment. Simulations results are provided to show the response of the proposed technique to various input references. © 2006 IEEE  

In this paper, a neural network based implementation of space vector modulation (SVM) of a two-level voltage fed Inverter is proposed. This network has the advantage of very fast implementation of SVM algorithm, particularly when a dedicated application- specific IC chip is used Instead of a digital signal processor (DSP). The proposed neural network consists of several subnets, a counter and a logic circuit. Subnets are used to Implement the stages of SVM algorithm while the counter is used to apply the switching state vectors in their specified times to Inverter. The logic circuit generates the Inverter switches commands according to the outputs of the subnets. The scheme has been... 

Brushless doubly fed induction generators (BDFIGs) show commercial promise for wind-power generation due to their lower capital and operational costs and higher reliability as compared with doubly fed induction generators. This paper presents a vector-control scheme for a BDFIG operating as a variable-speed generator. The proposed vector controller is developed on the power-winding stator-flux frame and can be used to control both the speed and the reactive power. The machine model and the control system are developed in MATLAB. The test results show that the proposed controller has good dynamic performance when changes in speed and reactive power are applied. © 2009 IEEE