Power conversion products


Ultra EMS Development Corporation is an established supplier of power conversion equipment and systems to navies around the world. This has been achieved across a wide range of power conversion applications, by combining innovative solutions with a proven ability to meet the particular demands and specifications of the naval environment.

Power Conversion Equipment capabilities & products

Bi-polar Amplifiers
Bi-polar Amplifiers Image

Ultra EMS has a wide range of bi-polar, high efficiency Class D switching amplifiers for driving high inductive loads. They incorporate state-of-the-art design techniques using FET and IGBT switching topologies. Bi-polar amplifier units are incorporated into degaussing systems offered by EMS.


Militarized Drives
Militarized Drives Image

Ultra's Power Dense Naval Drive (PDND) is a highly flexible, general-purpose motor drive for high power (100-400HP) applications in an exceptionally small enclosure. This solution takes advantage of the advances made in the inverter technology within the commercial marine market. It uses the latest thermal, electrical and mechanical modelling techniques to deliver a fully capable, highly power dense solution suitable for the military environment.

Primarily dictated by the power quality requirements of Mil-Std-1399, the PDND is a fully regenerative, four-quadrant variable speed drive system incorporating a PWM front end to ensure that the harmonic distortion imposed on to the supply is less than 3%. This also provides the benefit of being able to operate at near unity power factor throughout the speed range.

The PDND is flexible and programmable, making it suitable for a wide range of induction and permanent magnet motors. Communication and remote control of the drive is available in all industry standard data formats.

The Fire Pump Motor Drive for the USS Wasp is a forced-air cooled 375HP (280kW) PDND. Its small footprint enables it to be fitted through the ship's hatches, making for a highly cost-effective installation.

Water-cooled variants for sealed enclosures are also available.

Specialized Motor Drives

The Mooring Capstan Controller for the Virginia Class Submarines demonstrates EMS's capability to supply specialized variable-speed drives to meet the particular demands of the submarine environment: non-standard control and feedback requirements, integrated ancillary functions, highly detailed hardware and software ILS requirements.

It achieves this through a modular design featuring scalable, configurable building blocks, suitable across a wide range of ratings, applications and motor types, and EMS's long association with submarine requirements.


Aircraft Ground Service Supplies (AGSS)
Aircraft Ground Service Supplies (AGSS) Image

The AGSS provide onboard electrical power for the servicing and maintenance of embarked aircraft. EMS offers AGSS power converters for both 400Hz, 3-phase AC supply, MIL-STD 704 and for 270V DC supply. These converters are to be installed on the UK's Queen Elizabeth II class aircraft carriers.

270V DC

The 270V DC converters generate a highly accurate, low ripple 270V DC supply from the ship's AC power supply.


  • High bandwidth control / regulation
  • Low input power distortion
  • Transformer isolation
  • High-performance 28V DC ancillary supply to the aircraft
  • Forced-air cooling
  • Cubicle configurations for normal power, high power and dual outputs


The 400Hz static frequency converters generate a high quality, 3-phase, 4-wire, 400Hz AC supply from the ship’s 3-phase, 60Hz power supply.


  • High bandwidth control / regulation
  • Very low distortion of input supply
  • Transformer isolation
  • 28V DC auxiliary supply
  • Forced-air cooling