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In this Q&A with Ed Thaxton, chief technology officer and vice president of business development for Leonardo DRS Naval Power Systems, we discuss: why permanent magnet motor solutions are better than other electric solutions like superconducting synchronous motors; and progress on full-electric and hybrid-electric propulsion for the US Navy’s Columbia-class submarine and South Korea’s FFX II destroyer.
Breaking Defense: What are the driving forces behind naval platform electrification around the world today?
Thaxton: One is having the capability to illuminate targets that are farther away with higher-power radars like the SPY-6 Air and Missile Defense Radar for ballistic missile defense. That’s key; they need more power for that.
They also need to have more power for directed energy weapons for defense against missiles and drones. UAVs are readily disabled by directed energy weapons, which require energy storage magazines for continuous power. Then there’s fuel economy and a desire to reduce CO2 emissions.
One driver that doesn’t get talked about as much is ASW, anti-submarine warfare. Electric drive is quieter for naval applications and the Columbia-class submarine is electric drive. They didn’t pick that propulsion system because it’s noisy.
Surface ships are doing something similar. The DDG(X) commitment to electric drive is partly due to the advanced weapons and radars they want to carry, but it’s also due to ASW. They will have acoustic requirements for that ship that are similar to DDG 1000, perhaps even tighter.
Breaking Defense: You presently provide electric and hybrid-electric propulsion for several, major US and international submarine and warship programs such as the US Navy’s Columbia-class ballistic missile submarine and the Republic of Korea FFX-II guided missile frigate. What’s the status of those programs?
Thaxton: For Columbia, we provide the entire full-electric-drive system: switchboards, medium voltage distribution, and the variable frequency drives that control power to the motor. We make the propulsion system and also the converter that provides power from the main distribution system to ship service.
It’s a considerable scope of the ship and it’s all electric. It’s one of the first modern examples of an all-electric ship. It’s certainly the first modern example of an electric drive for a nuclear submarine.
They’ve begun construction of the ship and in terms of the electric drive system, we’ve provided a complete system that’s been fully powered and tested on a land-based system that they’re continuing to do now. For Navy ships like this, they fully test on land ahead of time and then later they use the system for training. The first motor was delivered to Electric Boat last fall.
FFX II is a South Korean Daegu-class frigate with an important ASW mission, and we are providing the hybrid-electric drive to the eight FFX-II ships now under construction. DRS Naval Power Systems is also providing the hybrid-electric power to the improved Chungnam-Class FFX-III, and we expect to provide the same for the upcoming FFX-IV.
What’s unique about the FFX II program is that the hybrid-electric system is a forward fit. It’s an existing mechanical-drive ship that we fit with a whole hybrid-electric drive system without changing the engine room size or arrangement. One of the unique features of that motor is that it fits between the main reduction gear and the thrust bearing.
To explain, in this ship, the turbine runs gear and the gear runs the shaft. When it’s operating on electric drive, the gear is de-clutched and the electric motor runs the shaft by itself.
The motor is actually wrapped around the output shaft with no bearings. It’s supported by the thrust bearing. That’s one of the ways we were able to make it much smaller.
Breaking Defense: I understand you’re competing for the T-AGOS 25 program, a planned class of seven TAGOS-25 class ocean surveillance ships.
Thaxton: We are teamed with Bollinger Shipyards, a ship builder that’s manufactured all the previous classes of T-AGOS ships. Proposals are in and we’re expecting an award Q2.
The ship pulls a towed array for ASW and requires electric drive for quiet operation. We have offered a particularly high-tech electric drive system that’s compact and extremely quiet to meet the ship’s ASW mission.
Breaking Defense: Leonardo DRS specializes in the use of permanent magnet motor solutions. Why do you say this technology is better than the use of other electric solutions like superconducting synchronous motors?
Thaxton: I’ve spent most of my career working on electric drive, and everyone’s finally doing it now. The reason that everyone is doing it is for fuel economy on small ships, as I mentioned earlier. Most navies can’t afford to spend the gas driving around without an electric drive because it increases fuel economy by a factor of two at low-speed operation.
We accomplish that with permanent magnet motor solutions, which are half to one-third the size of competitive motor technologies. An electric motor for FFX-II, for example, weighs about 35 tons, while a conventional machine would weigh 90 tons to do the same job. You have to float that weight.
Breaking Defense: Do you think that weight advantage will last?
Thaxton: Technically yes. However, eventually other people will adopt permanent magnet technology. Other technologies will not close that gap. Induction motors will not be able to achieve that size or efficiency, just like in electric vehicles. Other motor technologies such as superconducting synchronous motors are too complicated and lack industrial support. The main reason is business; there’s no getting around it. Just like in electric vehicles, permanent magnet machines are the long term solution.
It’s no secret that most electric cars have permanent magnet motors. Tesla uses them and so do other manufacturers with products like the Ford Mustang Mach-E and F-150 Lightning, and Kia’s EV6. They even use permanent magnet motors for cruise now because they’re more efficient.
Those are small applications and other people will eventually be able to use that technology at a larger scale. We were an early adopter of permanent magnet technology and have been doing this since the ‘90s. We’re the only ones today that do them at the scale we’re at now.
In addition, there’s a huge infrastructure associated with electric drive for vehicles and for industrial electric drive in mills and plants. That represents an investment of billions and billions of dollars that is not paid for by the Navy but can be leveraged by the Navy.
That’s not the usual case. If you look at what the Navy does with gears in destroyers and submarines, there are unique manufacturing capabilities associated with those gears that are mainly Navy oriented and supported by the Navy. Any enhancements that are needed are paid for by the Navy.
Alternatively, electric drive, switchgear, and all of the supporting technology for electrification in industry is something that the Navy can leverage. So rather than driving a motorboat to get somewhere you’re sailing, you can surf on this wave of industrial, commercial technology and leverage it.
We’re a company that takes that commercial technology and adapts it to the Navy’s use. What’s not ready for prime time is superconducting synchronous motors that depart from industrial standards. Some work has been done on them for propulsion, but there’s not an industrial base around it.
Breaking Defense: What is on the horizon for electric power and propulsion?
Thaxton: This technology is going to continue to advance. Power converters for electric motors are advancing under something like Moore’s Law in the semiconductor world.
Again, billions of dollars of investment in this technology means that it’s all going to get smaller and more power dense with better power quality. The Navy basically can look forward to leveraging those advancements for decades to come, while also creating a more healthy industrial base in the grand scheme of things.
Breaking Defense: Final thoughts?
Thaxton: There’s not a technology barrier with electric drive. We’ve just got to get to it and start doing it. Until then, we’re steering a parked car.
The US Navy is going full electric with the Columbia-class submarine, but we haven’t seen it become operationally prevalent. We need to commit a ship to all-electric drive.
Once we do that, the advantages I’ve been discussing will become apparent. We’ll start reaping them and finding out other things that we can do. Electrification is not a technology barrier, it’s an application/engineering barrier.
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