Editor’s note: If you did not pay close attention to developments in superconductivity, you might think it’s all just research. Actually, a few superconducting products are slowly coming to commercialization. The program review here provides a peek into generator design from the Navy’s perspective. Success for the Navy means more efficient wind turbines. The review came from website of N.Y. state-based SuperPower Inc, a developer of superconducting products.
Large generators are used in the electric utility and shipbuilding industries to convert rotational input energy from a steam or gas turbine into electricity. The U.S. Navy is developing many new technologies to support its integrated power system (formerly ‘all electric ship’) program. Superconducting motors and generators for ship propulsion and on-board utility service are being evaluated for their applicability in this environment. Throughout, the abbreviation 2G refers to a second generation.
SuperPower Inc. — 2G wire manufacturer, coil manufacturer
Baldor’s Reliance Electric — motor and generator manufacturer, (Formerly Rockwell Automation)
General Dynamics – Electric Boat Division
Oak Ridge National Laboratory
Naval Research Laboratory
Naval Surface Warfare Center
HTS (high temperature superconducting) generators offer improved efficiency thereby reducing machine losses by as much as 50% compared to conventional generators of comparable size. In addition, HTS generators are substantially smaller and lighter than copper based machines. These advantages are attractive in a ship environment where space and weight are a premium. Heat and thermal cycling of conventional rotating machines are one of the biggest detractors to reliability and life expectancy. HTS rotating machines virtually eliminate these failure modes by operating a near constant cryogenic temperature.
The project team commenced work in the fall of 2005 and has completed a feasibility study to examine the advantages of HTS generators for naval applications and has also been awarded funding for a conceptual design/risk assessment study.
A typical superconducting generator configuration consists of the rotor with the HTS field windings spinning inside the stationary windings (stator) that surround the rotor core. The rotor assembly is typically cooled to cryogenic temperatures while the stator windings are maintained at ambient conditions. The HTS field windings will initially operate in the 25 to 40°K temperature range with dc magnetic field of up to 4 Tesla. As second generation (2G) materials become available with improved performance characteristics, higher temperature operation becomes viable. The field coils located on the rotor are cooled by a commercially available cryocooler using either cold gas or liquid as the heat-transfer medium.
The primary application of this technology is propulsion motors and generators for both military and commercial vessels. The technology developed under this program will be applicable to other uses such as large electric utility motors and generators, such as those in wind turbines.
Super Power LLC
Filed Under: Generators, News