Design and experimental verification of DC-DC autotransformer prototype

It is a necessity to use DC-DC transformers when interconnecting two DC systems with different voltages levels. This article designs the prototype of bidirectional DC-DC autotransformer (DC AUTO) and voltage step-up unidirectional DC AUTO (UUDAT). The article firstly illustrates the electrical primary system in experimental prototype, then studies its control strategy and the corresponding control system framework. Finally, the article analyses the operating characteristics of the prototype. The experimental results manifest that the bidirectional DC-AUTO transformer and the UUDAT are all capable of transmitting DC power as required. Taking interconnecting two DC systems with voltage level of 375V and 750V as instance, the capacity of the converter using DC AUTO technology will only be 50% of the capacity using conventional DC/AC/DC technology. The theoretical deductions and the experimental results have all demonstrated that DC AUTO technology will not only ensure low building cost but also lead to low transmission loss.