A 'Π'-type equivalent circuit of wound rotor brushless doubly-fed machines

The equivalent circuit is an important method for performance analysis of electrical machines. Since the brushless doubly-fed machine (BDFM) is a multi-variable coupled system, in view of complexity of conventional equivalent circuits, a concise 'Π'-type equivalent circuit of wound rotor BDFM was presented for easily and effectively calculating and analyzing the machine performance. Firstly, according to the basic principle of induction machines, a basic equivalent circuit of the BDFM was introduced. Considering specific working conditions of the BDFM, parameters of basic equivalent circuits were referred to the control winding. And then, at the basis of the basic equivalent circuit referred to control winding, a 'Π'-type equivalent circuit was derived. Next, parameter identification was studied, matters of circuit methods that need to pay attention to were discussed, and a testing method to obtain circuit parameters was put forward. At last, tests were conducted on the experimental rig of a 60 kW wound rotor BDFM. The testing results verify the effectiveness of the 'Π'-type equivalent circuit, the validity of parameter calculating and the testing method. © 2016 Chin. Soc. for Elec. Eng.