Electrical equivalent circuit models for brushless doubly-fed induction machines: A review

A brushless doubly-fed induction machine (BDFIM) has wide application potential in wind turbines, industrial drives, small hydropower plants, power supply of ships, aircraft starters, and electric vehicles. In electric vehicles, a BDFIM offers a robust structure without needing permanent magnet materials, slip-rings, and brushes, which makes it particularly suitable for heavy vehicles, such as buses, agriculture, and construction vehicles, where the low power density of a BDFIM is of less significance compared to that in passenger cars. To effectively analyze and control a BDFIM in various applications, it is essential to develop its accurate electrical equivalent circuit models. This article presents a comprehensive review of various electrical equivalent circuit models of BDFIMs in the literature with different levels of complexity. A full order model is complex, but can represent the complete electrical behavior of a BDFIM. By simplifying the full order model and neglecting certain parameters, a reduced order model requires fewer state variables due to practical approximations. The dynamic behavior of BDFIMs under various operating conditions is demonstrated in the article to showcase the effectiveness of these existing models. This review emphasizes the significance of electrical equivalent circuit models in the design, analysis, and control of BDFIMs. Future research directions for the model refinement are recommended.