Zero sequence blocking transformers for multi-pulse rectifier in aerospace applications

Abstract

Auto-Transformer Rectifier Units (ATRU) have been widely adopted in aircrafts due to its simplicity and reliability. In this paper, Zero Sequence Blocking Transformers (ZSBT) are employed in the DC link to realize parallel rectifier bridges for ATRU, being the proposed 24-pulse rectifier. A starconnected autotransformer is used in this topology to divide the primary side voltage into four three-phase voltage groups, among which there is a phase shift of 15°. The autotransformer then feeds the load through rectifier bridges, which are in parallel with ZSBTs. Compared to the traditional method that is using six interphase transformers to parallel the rectifier bridges, the proposed 24-pulse rectifier only requires four ZSBTs. This will contribute to a reduction of weight and cost of the entire system. The operation principle of the ZSBT is analyzed, and the kVA rating design of each component in the proposed unit is also explored. The kVA rating of ZSBT is only 0.034 times of the rated power. Moreover, this topology can eliminate low-order harmonics in the AC supply current. An 18 kW prototype is built up for tests. Both simulations and experiments have verified the main features of the proposed 24pulse rectifier in terms of higher efficiency, higher power factor and lower total harmonic distortions.

A novel 12‐pulse full‐wave rectifier with simple circuit configuration

“…One is to increase the number of output voltage of phase‐shifting transformer by further subdividing the phase shifting. Several 12‐pulse rectifiers are obtained by the above methods 16–21 . Figure 1A shows the conventional 12‐pulse full‐wave rectifier that is obtained by this method.…”