The influence of leakage inductance on multi pulse rectifier based on the modulation theory

This paper presents a low harmonic 12 pulse rectifier. Then in order to investigate the influence of leakage inductance on 12 pulse rectifier. A set of improved switching function method is proposed. To obtain the mechanism that input current harmonics can be suppressed by circulating current of DC side, this paper analyzes the relationship between input current, output current and circulating current of DC side. The amplitude and phase of the triangular circulating current are identified when the harmonic is suppressed most greatly. According to the comparative results with the conventional rectifier, the salient features of system are identified. By using Fourier series, the formulas of improved conventional switching function and improved circulation modulation switching function are derived respectively. Then the input line current formulas of conventional 12 pulse rectifier and proposed low harmonic 12 pulse rectifier are derived respectively considering the leakage inductance of transformer. Through theoretical analysis, the relationship between the transformer leakage inductance and the harmonic value of the input current is obtained. The experimental results verify the correctness and effectiveness of the proposed theory, which provides accurate scientific basis for the analysis of other types of multi pulse rectifier.