Predictive torque control of brushless doubly fed induction generator fed by a matrix converter

In this paper, a predictive torque control (PTC) approach for brushless doubly fed induction generators (BDFIG) fed by matrix converter is developed and investigated. Unlike the traditional DFIG, the BDFIG needs lower maintenance cost because it operates without slip rings and brushes. Furthermore, as a promising alternative to the traditional back-to-back inverter, a matrix converter is employed owing to its high power density. Thus, the advantages of BDFIG and matrix converter have been brought together in order to obtain a wind energy conversion system that has high power density as well as high reliability against mechanical faults. To overcome the drawbacks of the cascaded control structure, such as slow dynamic response and reduced control bandwidth, the torque of the BDFIG is controlled by a PTC method. Therefore, the discrete-time model of the BDFIG supplied by the matrix converter is first derived ad inserted into the predictive control routine. For examining the performance of the developed control strategy, simulations based on MATLAB/Simulink are carried out under steady-state and transient conditions. The test results indicate that the presented system exhibits good steady-state and dynamic performance.

I. Introduction

The wind turbine manufacturers prefer the use of Doubly Fed Induction Generator (DFIG) owing to its unique advantages of operating at variable speeds with good performance and the requirement of reduced size power converter. The solution constitutes one of the most favorite concepts in the wind energy conversion [1]. However, the major drawback of the DFIG is that it demands the use of many mechanical parts (brushes and slip rings) to be able to control the rotor circuit through the power converter. This drawback decreases the reliability of the system while increasing the maintenance margin owing to the brushes and carbon accumulations on the internal components [2].