Engineers and scientists in China have started up the first Chinese ship with a permanent magnet motor system. The system promises to make quieter submarines that are much harder to detect, a major leap for China in a field where it lags a generation or more behind the West.
The report in China's official military news site and mentioned by China Defense Blog, says that a ship with a permanent magnet motor was tested in southern China, on Hainan island. The ship, docked at the Chinese naval base at Sanya, was tested on October 18th and "then reached the designated speed."
Permanent magnet motors work by passing electricity through wire windings, turning the windings into electromagnets. So far, pretty normal for a motor. The difference is that a permanent magnet motor adds permanent magnets—magnets typically made of rare earth metals that have their own permanent electromagnetic field—to the rotors in a motor. The electromagnetic coil is attracted to the permanent magnet, causing the motor to rotate. When the power is turned off the attraction ends and the motor stops.
Permanent magnet motors are by nature brushless motors and have several advantages of particular use to submarines. They are quieter, thus making the submarine equipped with them more difficult to detect. They are also more reliable and the parts last longer. They generate less electromagnetic interference, an important factor when you have dozens of electronic systems packed in a metallic tube. Finally, they are also smaller than competing motors, taking up less volume in the submarine.
This new means of power generation is fairly new, and the technology has yet to make it to an operational military submarine. The U.S. Navy plans to use the tech to power the upcoming Columbia-class ballistic missile submarines, set to go to sea in the mid 2020s. From the sound of it China's experimentation is still in the early stages—the China Military article doesn't even mention how fast the ship was able to travel, which implies it was actually pretty slow.
Experts estimate China's submarines are three decades behind U.S. submarines in terms of quietness, and China's scientists and engineers have been working furiously to level the playing field. While there are many factors that make submarines quiet China's fielding of permanent magnet motors will definitely help the country catch up in the field of undersea warfare.
Note: A previous version of the article referred to magnetohydrodynamic propulsion and not permanent magnet motor propulsion. We regret the error.