Operating charts for the Brushless Doubly-Fed Machine (BDFM)

Abstract

The Brushless Doubly-Fed Machine (BDFM) is an electrical machine that allows brushless operation in many applications where the Doubly-Fed Induction Generator (DFIG) is currently used. In recent years work on BDFM control means that the machine can now be run stably across its working range. However, little work has been done to define the working area in which BDFM can safely be operated without exceeding its material and stability limits. This paper sets out the theoretical backing for an operating chart of an ideal BDFM similar to that of the synchronous machine. It goes on to show that though the ideal chart gives the right form, non-ideal parameters (especially the finite magnetizing inductances) significantly effect the locations of the limits. Some preliminary experimental data obtained for a 225 frame size machine support the form of the chart. Finally it is shown how the operating chart can be used to chose appropriately sized converters for the BDFM.

Brushless doubly‐fed induction machines for wind turbines: developments and research challenges

“…More insight in the brushless DFIM operating principles can be obtained using a brushless DFIM electric equivalent circuit (EEC). The brushless DFIM EEC is a tool to determine this machines steady-state operating characteristics [30][31][32][33]. A simple per phase EEC that has all windings referred to the power-winding is presented by Roberts et al [34] and shown in Fig.…”

“…Standard EEC modelling techniques have been proven useful in determining basic operating characteristics [33,34], but magnetic saturation is often ignored. In addition, the extraction of EEC parameters from a brushless DFIM is not easy and obtaining a simple method to do so proves to be challenging.…”

Practical deployment of the Brushless Doubly-Fed Machine in a medium scale wind turbine

“…It is suggested in [5] that further limits should be placed on the electrical loading in each of the two windings to prevent either winding becoming excessively hot. The three electrnical loadings used are shown in table I.…”

“…The structure of such a chart for the BDFM is presented in [5]. The chart must be calculated from equivalent circuit parameters.…”