SBIR-STTR Award

As with most forms of transportation, ships have weight and volume constraints relative to operational equipment. Conventional transformers, in use to convert high voltage electric power to lower voltages and vice versa, are both heavy and big. With recent advances in semiconductor devices and digital control, "Electronic Transformers" can replace conventional transformers while providing a factor of three weight and size reductions. Electronic Transformers can potentially also provide side benefits such as voltage regulation, power factor correction, VAR compensation, and low harmonics. The proposed Phase I effort will investigate the feasibility of developing such Electronic Transformers. Conventional transformers have the advantage of relatively low cost and high full-load efficiency. Thus, the value of the weight and size reductions, and power system benefits that the Electronic Transformers provide, will have to offset lower efficiencies and potentially higher costs. Systems analyses and trade studies may show that Electronic Transformers compete very well. AeroVironment will overcome the many technical challenges leveraging experience from recent transformer/inductor development projects and digital control development projects. By demonstrating feasibility, we will help enable the Navy to improve shipboard electrical systems operations, while reducing electrical equipment weight and volume claims.

Keywords:
POWER TRANSFORMERS, POWER ELECTRONICS, SHIPBOARD ELECTRIC PLANT

Shipboard power distribution requires both step-up and step-down transformation. Conventional 60Hz transformers, however, are both bulky and heavy. The proposed Phase II effort will develop a prototype 2.7MVA Electronic Transformer that combines high frequency switching power electronics and interphase transformer technology, with advanced digital signal processing for control. While a certain amount of technical risk is associated with this innovative approach, an order of magnitude size and weight reduction is potentially possible. Other potential benefits include voltage regulation, power factor correction, VAR compensation, and harmonic suppression. In Phase I we conducted: (1) Electronic transformer topology trades, (2) A detailed electronic transformer conceptual design, (3) An analysis of liquid-cooling techniques to obtain volume and weight reductions (4) Detailed cost analyses with bills of material, (5) Failure mode and effects analyses, and (6) A study summary – features, benefits, conclusions, and recommendations The recommended electronic transformer technology detailed in the Phase I report is applicable to a wide range of power levels, from kilowatt to multi-megawatt. As future advances in materials such as silicon carbide develop, electronics transformers will be even more attractive. AV, based on prior work, is fully qualified to develop electronic transformers over the full power range.

Keywords:
Power Transformers, Power Electronics, Shipboard Electric Plant