5-megawatt High Temperature Superconductor Propulsion Motor Passes Initial Navy Tests

Successful testing of prototype validates AMSC's electromagnetic, mechanical and thermal analytical models and establishes commercial viability of HTS ship propulsion motors

Westborough, MA — American Superconductor Corporation, an electricity solutions company, has announced that the prototype 5-megawatt (MW) High Temperature Superconductor (HTS) ship propulsion motor it designed, developed, and built for the United States Navy has successfully completed the Navy's rigorous initial test program. Under the Navy's supervision, the 5-MW HTS motor successfully completed load and ship mission profile dynamic simulation tests which were conducted at the Navy's Center for Advanced Power Systems (CAPS) at Florida State University in Tallahassee. CAPS also repeated and confirmed the IEEE-115 no-load as well as partial load tests that had been previously conducted at the ALSTOM facility in Rugby, England.

The tests were designed to evaluate three Navy goals: to establish the full power capability of the motor with several longer heat or endurance runs; to establish as accurately as possible important machine parameters by a variety of methods; and to investigate its dynamic performance in a simulated at-sea environment.

The motor was developed by AMSC under contract with the Navy's Office of Naval Research (ONR) to prove the viability of HTS technology for both military and commercial marine propulsion. AMSC manufactured the HTS rotor system integrated with a cryogenic refrigeration system. ALSTOM Power Conversion (ALSTOM) designed and manufactured the stator, marine drive electronics and performed the factory testing of the HTS motor and drive system.

"Reports on the performance of the 5-megawatt HTS motor under both full power and realistic operating conditions continue to be impressive," said Rear Admiral Jay Cohen, Chief of Naval Research. "The successful application of HTS technology to naval ship propulsion would provide the Navy with unique design options for our All-Electric Ship Programs."

The cumulative positive test results achieve yet another important benchmark in the development of HTS rotating machinery, and provide important validation for the follow-on ONR Program, in which a 36.5-MW (49,000 hp), 120 RPM HTS motor currently being built by AMSC and Northrop Grumman will be delivered to the Navy in the summer of 2006. Additional specialized testing for the 5-MW motor is planned to take place at the Naval Surface Warfare Center, Carderock Division in Philadelphia.

This larger motor, sized for the Navy's future DD(X) ship, benefits from the successes achieved in the earlier ONR 5-MW development and test program. AMSC and Northrop Grumman have already successfully completed the first two phases of the three-phase development process with successful preliminary design and detailed design reviews. The third phase, which is currently in progress, is the actual fabrication, factory acceptance testing, and delivery of the 36.5-MW motor to the Navy.

"Our alliance with the Navy has been an outstanding experience and we are pleased with the results of the thorough development and testing process for the 5-MW motor," noted Greg Yurek, CEO of American Superconductor. "In fact, the test results for this motor are drawing worldwide attention from both military and commercial ship builders. American Superconductor is meeting with prospective customers to identify their specific requirements for electric ship propulsion motors and we are targeting a launch customer in calendar year 2006."

HTS motors are ultra-compact, measuring as little as one-third the weight and one-half the size of copper-based motors of the same power and torque rating, which means Navy ships could carry more fuel and munitions and could have more room for crew's quarters and weapons systems, and commercial ship owners and operators could carry more passengers and cargo. In addition, HTS motors operate with higher fuel efficiency and are expected to have lower maintenance costs than their conventional copper counterparts. The substantial advantages offered by HTS ship propulsion motors are expected to be provided at a production cost equivalent to conventional motors of the same power and torque rating.

Test Program and Results:
CAPS operated the motor at full load (5-MW) and at full speed (230 RPM) for a total of 21 hours, and confirmed that the motor achieved steady state temperature both in the rotor and in the stator. The actual temperatures measured correlated closely to results predicted by AMSC and ALSTOM for the machine. This load testing demonstrated that the HTS motor meets its specified performance and power rating under the stresses of operating conditions. An important aspect of the new results obtained at CAPS on the 5-MW motor is the validation of AMSC's electromagnetic, mechanical and thermal analytical models for HTS ship propulsion motors - a vital step in the development cycle for advanced electrical machines.

To simulate operation of the motor in an at-sea environment up to Sea State 5 (simulating a moderately strong sea), the CAPS testing imposed an increasing scale of 0.5% to 10% in torque variations on the motor. The test results confirmed that the motor should perform as designed in representative sea states. To complete the test program, CAPS performed "hardware-in-the- loop" simulation tests. In this test phase, direct control of the motor system emulated the way the motor, drive, and entire ship's integrated power system (IPS) would respond during transients.

For additional information about AMSC's marine propulsion HTS motors, please see http://www.amsuper.com/products/motorsGenerators/shipPropulsion.cfm.

SOURCE: American Superconductor Corporation