A novel asymmetrical connection balance transformer for traction power supply
Balance transformers can usually eliminate the zero sequence current and suppress the negative sequence current. This paper develops a novel approach for balance transformers, which is different from the traditional one with two-phase or three-phase symmetrical windings. First, the basic principle and the connected scheme of the transformer are clarified. Second, this paper derives the relationship between the primary and the second windings from a mathematical model for the new approach. Third, the balance condition (i.e. the neutral current in the primary side is zero) and the decoupling condition of the two-phase system are also obtained. Finally, the correctness and feasibility of the new approach are verified by the experimental results of a 1-kVA model transformer. Compared to the traditional balance transformers, the new approach has better performance and can be applied to the two-phase or single power supply, such as the traction power supply in electric railway.
Connection scheme, balance condition, asymmetrical winding, traction power supply