I. Introduction
In stand-alone generation applications, the doubly fed induction generator (DFIG) is commonly used because it can achieve variable speed constant frequency operation easily and only requires partial power conversion. However, the easily damaged brushes and slip rings reduce the overall reliability. Thus brushless doubly-fed induction generator (BDFIG) is developed with a special structure design, retaining DFIG’s advantages and canceling brushes and slip rings. With higher reliability and lower maintenance cost, BDFIG has good potential under severe stand-alone operational environments [1].