48-pulse Aviation Autotransformer Rectifier unit Based on Passive Auxiliary Circuit

To suppress harmonics on the source side of the aircraft power supply system. In this paper, a 48-pulse aviation autotransformer rectifier unit(ATRU) based on passive auxiliary circuit is proposed. The converter consists of a 12-pulse transformer rectifier unit(TRU), a zero-sequence impedance transformer(ZSIT), an interphase reactor (IPR) and passive auxiliary circuits(PAC). The AC voltage ripple on the secondary winding of the IPR can be extracted by controlling the on/off of the two phase-shifting switching devices in the PAC. By superposing the extracted ripple on the DC bus, the output voltage vector can be shifted by ± 3.75 °. In this case, the load voltage is synthesized by 48 voltage vectors with a phase difference of 7.5°, resulting in a 48-pulse DC output. The paper analyzes the operating mode of the converter and derives the expressions for the output voltage and input current. The relevant parameters and equivalent capacity of the converter are discussed. The feasibility and correctness of the proposed topology are also verified by simulation and experimental studies.