Analysis of common mode circuit of BDFG-based ship shaft power generation system

In brushless doubly-fed generator (BDFG)-based ship shaft power generation system, the two back-to-back converters bring two common mode voltage sources and BDFG's two sets of stator windings provide several common mode current branches, which make the common mode circuit complicated. This paper have listed the common mode current loops and proposed an equivalent common mode circuit model based on lumped parameters for the system. The common mode impedances of the system have been acquired by measuring and calculating. The common mode current loop consists of two sets of stator windings and two back-to-back converters has been discussed with emphases. Simulation and experimental results agree with each other well and they verify the validity of the proposed model and the analysis about common mode circuit.