A new auto-inductive harmonic-suppression transformer and its harmonic equivalent circuit model

According to the demand of harmonic suppression and reactive power compensation for large-power electrical ac/dc converter systems, this paper proposes a new auto-inductive harmonic-suppression (AIHS) transformer and a corresponding inductive filtering technology, analyzes its harmonic model constructed by the transformer windings and the full-tuned circuit under the specific harmonic frequencies, and establishes the harmonic equivalence circuit model. Based on this, this paper reveals the filtering mechanism of the new inductive filtering technology, and obtains the necessary impedance condition of the new transformer and the tuned condition of the full-tuned circuit to suppress the main harmonic currents in the secondary windings. Finally, a test study on a railway traction prototype system with the AIHS-type single-phase traction transformer is performed to verify the correctness of theoretical analysis, and present the good inductive filtering performance that the new transformer has.