Research On Multi-Pulse Autotransformer Rectifier Units(ATRU)

With the rapid development of the power electronics, more and more rectifier devices have been used in various fields. Because of the non-linear nature of the rectifier devices, the input currents have significant harmonics and high total harmonic distortion. In the high-power occasions, generally we use the multi-pulse rectifier technology to improve the performance of rectifiers.This paper summarizes the law of the multi-pulse rectifier technology improving the performance of rectifiers through analyzing the principles of the traditional multi-pulse transformer rectifiers. Phase-shifting transformers is the core of the multi-pulse rectifiers. Compared with the isolation transformers, autotransformers have small transformer equivalent rating. If the application occasion doesn't need isolation, the autotransformers have obvious advantages.This paper researches on a new type of 12-pulse symmetric autotransformer rectifier, the equivalent rating of whose transformer is only 0.182 times the output power, thus greatly reducing the size and cost of the rectifier. On the basis of the theory and simulation analysis, the 9.2kW laboratory prototype designed weighs 2.8kg, and the total harmonic distortion (THD) of the input currents are less than 10%. To further improve quality of the rectifier input current waveform, this paper also researches on a new type of 18-pulse asymmetric autotransformer rectifier. The total harmonic distortion of the input currents of the 13.5kW laboratory prototype are less than 7%.