How Magnetic Bearings Work

What is an Active Magnetic Bearing?
An Active Magnetic Bearing (or AMB) is a type of bearing used in high-speed, rotating machinery that uses electromagnetic forces to levitate a rotating shaft in space. The shaft is maintained by actively controlling the electromagnets, leaving zero contact between the bearing and the rotating mass. This magnetic levitation allows a friction-free operation, elimination of many machine components, and a clean, reliable and efficient machine.


A typical AMB is made up of the following elements:


Typical components of an Active Magnetic Bearing.

Power amplifiers supply equal current to two pairs of electromagnets on opposite sides of a rotor. During normal machine operation, the shaft is maintained in the center of the stator. If an upset to normal operation occurs – surge, out-of-balance, etc. – the shaft will deviate from center position. Sensors will detect the attempted deviation and notify the controller. The control algorithms will adjust the currents to the electromagnets, pulling the shaft back to center. This constant tug-of-war is repeated by the system 20,000 times per second, ensuring a reliable, stable machine.

Active magnetic bearings from Synchrony are designed for high performance in the most demanding applications.


Synchrony had the first Magnetic Bearing system to withstand the MIL-STD 901D Shock Test

Dresser-Rand Advanced Steam Turbine Model with Synchrony Active Magnetic Bearings - Shock Test to MIL-STD 901D, 30+g's from underwater explosion.

MIL-STD 901D Shock test - See the video of the first AMB system to withstand 30+ g shock test!


Related Links

White Paper - Improving Rotating Machinery Performance with Dresser-Rand’s Synchrony® Active Magnetic Bearings (387 KB PDF)

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