South Korea selects Leonardo DRS' full electric propulsion system for new KDDX destroyers.

Leonardo DRS has signed a contract with Doosan Enerbility to supply the integrated electric propulsion system for the Republic of Korea Navy's next-generation KDDX destroyer program. The agreement equips South Korea's first full-electric-drive surface combatants with advanced propulsion architecture designed to handle high-demand shipboard power loads. The program aims to deliver a class of at least six indigenously designed guided-missile destroyers.

The propulsion solution features Leonardo DRS 100-Series permanent-magnet motors paired with compact variable-frequency drives to optimize torque density and reduce engine-room footprint. This integrated architecture supports the fleet's multi-mission operational requirements while providing scalable power capacity for advanced combat and sensor systems.

Related topic: South Korea unveils KSAM-II surface-to-air missile to replace US-made SM-2s on KDDX destroyers

The KDDX is a future class of six South Korean guided-missile destroyers combining a Korean combat system and sonar with 48 KVLS-I and KVLS-II cells and a full electric propulsion system combining two LM2500+G4 gas turbines with permanent-magnet motors. (Picture source: Hanwha Ocean)

On September 17, 2026, Leonardo DRS signed a contract with Doosan Enerbility to supply its 100-Series permanent-magnet propulsion motors and matched variable-frequency drives for the South Korean Navy’s six KDDX destroyers, completing another major part of the machinery chain of the country’s first full-electric-drive surface combatant. The decision follows GE Aerospace’s September 1 selection for 12 LM2500+G4 gas turbines, and Hanwha Ocean’s July 31 contract for detailed design and construction of the lead ship, scheduled for delivery at the end of 2032. The KDDX is planned to be 159 m long and 20 m wide, with a light displacement of 7,100 tonnes, a full-load displacement of 9,000 tonnes, and a crew of 158. Its combat configuration will combine a Korean combat management system, integrated mast, fixed S/X-band AESA radars, sonar, 32 KVLS-I cells, 16 KVLS-II cells, a 127-mm/62-caliber gun, and eight anti-ship missiles. Unlike early mechanically driven Korean destroyers and the hybrid-electric FFX frigates, the KDDX's gas turbine output will be converted into electrical power and subsequently reconverted to mechanical power by low-speed permanent-magnet propulsion motors, placing propulsion and major ship electrical loads within the same power architecture.

Each KDDX destroyer will receive two 35.32-MW LM2500+G4 turbines, providing 70.64 MW (94,720 hp) of combined nominal prime-mover output before generator, conversion, distribution, motor, and auxiliary losses. Hanwha Aerospace will manufacture engine components, assemble and test the turbines, and provide domestic support, while NRTEC in Busan will manufacture their composite enclosures. Each enclosure saves more than 2,500 kg relative to the previous steel design, meaning a reduction of more than 5 tonnes per ship, while reducing enclosure noise by 60% and wall temperature by 25°F to 50°F. The LM2500+G4 retains the basic LM2500 footprint but incorporates a zero-stage high-pressure-compressor blisk, 33% greater airflow, and higher firing temperatures; South Korea already has a substantial support base for the engine family, with 163 GE marine gas turbines procured for 95 South Korean Navy ships. Downstream of those turbines, Leonardo DRS and Doosan Enerbility must turn gas-turbine output into controlled low-speed shaft power, and Leonardo DRS subsequently moves from the hybrid-electric equipment installed on 20 FFX Batch II, III and IV frigates to destroyer-scale full electric drive.

Leonardo DRS’s IED-LS 100 Series consists of line-shaft permanent-magnet synchronous motors covering a range of 5 to 31 MW per machine, which operate from 0 to 200 rpm with a 240-rpm overspeed limit and accept a voltage of up to 4,160 V; typical efficiency exceeds 97% across the power range. The motors use 40°C freshwater cooling, retain derated operation with 50°C cooling water, employ IEC Class H insulation and IP44 protection including flooding to shaft level, and can divide their windings into as many as four sectors and three-phase sets. IED-104 through IED-111 models retain a 159-in by 181-in cross-section (4.04 by 4.6 m), while length increases from 142 in (3.61 m) to 193 in (4.90 m), allowing torque capability to increase without requiring a different basic machinery space. These motors are hard-mounted to the ship foundation, use oil-film journal bearings, and directly drive the line shaft without a propulsion reduction gearbox. The specific KDDX motor variant, number of propulsion motors, and individual MW rating remain undisclosed, so the 31-MW family maximum cannot be treated as the ship’s selected motor output.

Permanent-magnet propulsion reduces both machinery volume and losses: Leonardo DRS places comparable torque at roughly half the size and weight of an equivalent induction-machine installation, while eliminating rotor windings, brushes, slip rings, and rotor excitation losses. In a 50-kW, 6,000-rpm comparison, a PM synchronous drive achieved 94.1% system efficiency against 90.1% for an induction drive, reducing proportional losses from 9.9% to 5.9%; this smaller-scale test does not establish KDDX performance. At the IED-LS scale, a motor delivering 30 MW mechanically at exactly 97% efficiency would require 30.93 MW electrical input and reject 0.93 MW as losses, while a 97.5% efficiency would reduce input to 30.77 MW and losses to 0.77 MW. Direct drive also removes the reduction gearbox, gear-mesh vibration, gearbox lubrication equipment, and associated mass between a high-speed gas turbine and the low-speed propeller shaft, although generators, motors, bearings, pumps, shaft alignment, and propeller cavitation remain potential acoustic sources during anti-submarine operations.

The two turbines’ 70.64-MW rating cannot be equated with either net electrical generation or available shaft power because energy must pass through generators, switchboards, distribution equipment, VFDs and propulsion motors while simultaneously supplying ship services. The VFDs regulate motor frequency, voltage, torque, and speed across the 0 to 200 rpm operating range, electrically separating propeller rpm from gas-turbine speed and replacing the large mechanical reduction ratio of conventional gas turbine propulsion. This also changes casualty tolerance: propulsion depends on maintaining a continuous path through generation, buses, converters, VFDs, cooling and motors, so a switchboard or converter casualty can remove shaft power even if the turbine and motor remain intact. Conversely, generated capacity can be distributed between propulsion and radar, combat system computers, electronic warfare equipment, communications, pumps, cooling, and hotel loads instead of being mechanically committed to a shaft. Generator ratings, distribution voltage, motor quantity, bus arrangement, and redundancy have not been disclosed, preventing a reliable calculation of KDDX net shaft power from the turbine total.

The KDDX will use part of this electrical architecture for its 48 vertical-launch cells, comprising 32 KVLS-I cells and 16 larger KVLS-II cells, plus eight anti-ship missiles and a 127-mm/62-caliber gun. The KVLS-II development was completed in September 2025 with design targets of 180% of the original KVLS footprint, up to 135% of its length, 185% of its weapon-load capacity, and 135% of its exhaust-handling capacity, allowing larger Korean strike and air defense weapons. The KSAM-II (Ship-to-Air Missile-II), derived from the L-SAM technology base for KDDX and FFX Batch IV ships, is intended to engage aircraft and cruise missiles; its production infrastructure was completed in March 2026, and the first test-launch prototype round emerged in July. The 48-cell figure therefore does not represent 48 equivalent air defense shots because weapons must be distributed between two launcher sizes and among air defense, anti-submarine and land-attack missions, except where individual missiles permit multiple packing. Launcher dimensions, magazine allocation and weapon mass consequently compete for displacement and internal volume on the same hull that must accommodate the electric propulsion machinery.

Electrical demand also includes the integrated mast’s four fixed radar faces, which provide a 360° coverage through S-band and X-band phased arrays alongside IRST, IFF and VHF/UHF communications equipment. The S-band radar handles longer-range air and ballistic missile detection and tracking, while the X-band radar addresses shorter-range aerial and sea-skimming or surface targets; the S-band array has roughly 4,096 elements, compared with 4,350 on the AN/SPY-1D(V), although element count alone cannot establish detection range. These arrays add continuous electrical and thermal loads because radar transmit-receive electronics and processing equipment require both power and cooling, as do propulsion converters and motors. The overall six-ship KDDX program is valued at 7.8 trillion won ($5.4 billion), and the remaining five ships are planned for delivery by 2036. The lead-ship contract itself is valued at 838 billion won and runs from July 31, 2026 to June 30, 2032, before final delivery activities.

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Written by Jérôme Brahy

Jérôme Brahy is a defense analyst and documentalist at Army Recognition. He specializes in naval modernization, aviation, drones, armored vehicles, and artillery, with a focus on strategic developments in the United States, China, Ukraine, Russia, South Korea, Türkiye, and Belgium. His analyses go beyond the facts, providing context, identifying key actors, and explaining why defense news matters on a global scale.