Ship Propulsion 36.5 MW HTS Motor

American Superconductor (AMSC), partnered with Northrop Grumman, has designed, assembled and completed testing of the 36.5 MW ship propulsion motor for the U S Navy, under contract with the Office of Naval Research (ONR).  ONR provided more than $90 million to design and build the HTS motor.  The HTS rotor, designed by AMSC and containing HTS wire and coils from AMSC, is shown on the left of this photograph.

On March 28, 2007, AMSC and Northrop Grumman announced the successful completion of factory acceptance testing for the world’s first 36.5 megawatt (49,000 horsepower) high temperature superconductor (HTS) ship propulsion motor.

In comparison with the conventional copper motors being used on the first two DDG 1000 hulls, the HTS motor is less than one-half the size and weight, and is more efficient over a much wider range of ship speeds.  This results in weight and space advantages, enabling increase payload capacity for both naval and commercial vessels.

Benefits

• High Power Density: The HTS field winding produces magnetic fields higher than those of conventional machines resulting in smaller size and weight.

• High Partial Load Efficiency:  HTS motors have higher efficiency at part load (down to 5% of full speed), that  results in savings in fuel use and operating cost.  The advantage in efficiency can be over 10% at low speed.

• Low Synchronous Reactance: HTS air-core motors are characterized by a low synchronous reactance which results in operation at very small load angles.  Operating at a small load angle provides greater stiffness during the transient and hunting oscillations.

• Harmonics:  HTS motors generate voltages free of harmonics.

• Cyclic load insensitivity:  HTS motor field windings operate at nearly constant temperature unlike conventional motors and, therefore, are not subject to thermal fatigue.

• Maintenance:  HTS motors compared to conventional motors will not require the common rotor overhaul, rewinding or re-insulation.