| Conventional three phase rectifiers cause plenty of harmonics pollution to AC power lines and the other electronics equipments. Multi-pulse rectifier with auto-transformer can reduce the total harmonics distortion (THD) of the input current. In the applicaton fields that the isolation is not necessary, the rectifier with auto-transformer possesses the properties of small size and weight, high reliability, low EMI, which is suitable for wide line frequency.This thesis analyzes the multi-pulse rectifier techniques, and the harmonic injection techniques based on it, in order to reduce the harmonics of the input current further. 12-pulse auto-transformer rectifier unit (ATRU) is analyzed detailedly, and the method of current harmonic injection, according to the additional windings of the inter-phase transformers (IPT) is researched on. A resistor or a power factor correction (PFC) converter can be connected to the additional windings, to produce the expected current harmonic, so as to reduce the harmonics of the input current. One cycle control (OCC) technique has the merits of simple circuit structure, fast dynamic response, and input voltage perturbation injection. Therefore, a one cycle controlled Boost PFC is used as the current harmonic injection circuit. Simulation verifications are provided.The design of the 12-pulse ATRU, the main circuit and control circuit of Boost PFC are analyzed. Experiment results show that the THD of the input current of the 12-pulse auto-transformer rectifier unit with current harmonic injection, which can satisfy the limits specified in DO-160E, is much lower than the one without current harmonic injection.
|
PDF Full Text Request