Magnetic Bearings - The Inside Story

Learn more about the technology and find answers to questions about using magnetic bearings in your applications.

Is this technology brand new?

The basic principles of electromagnetism have been applied to motors and generators since the late 19th century, and the principles of magnetic levitation were demonstrated in the 1940s. What’s changed is the increased stability, miniaturization, simplification, and cost-effectiveness of magnetic bearings, so they can be used in a wide variety of high-performance motors, generators, turbomachines and more. Recent advances have allowed magnetic bearing technology to be taken out of the laboratory and applied to wide variety of rotating equipment.

How costly is this technology?
As with many other devices that involve electronics, magnetic bearing systems have benefited from the decreasing cost and increasing capability of electronic components such as digital processors and power transistors. Today’s magnetic bearings are much more cost-efficient than they were only a few years ago. Often, the decision to use magnetic bearings instead of oil-lubricated bearings can be economically justified just by the elimination of the oil lubrication system. The bearing vibration monitoring capabilities of the magnetic bearing can also eliminate expensive vibration monitoring equipment. Finally, there are large operating cost advantages related to the elimination of frictional losses, reduced maintenance, and improved machine reliability.

Are active magnetic bearings (AMB) very complicated?

Although the electronic hardware and the control algorithms to control the rotor are complicated, these are virtually invisible to the user, in much the same way that a cell phone is complex, yet easy to use.

Aren't magnetic bearing controllers and electronics large and cumbersome?
This has been true in the past, but Synchrony has changed all that with design innovations like in our Fusion® and NovaGlide™ magnetic bearing products. The Fusion magnetic bearing controls are built-in to the magnetic bearing housing itself, offering tremendous reductions in complexity and size compared with traditional magnetic bearings. Synchrony's NovaGlide™ magnetic bearings use compact, external controls for applications that require it, and these controls are so small and simple they can be mounted either on or near the machine.

Does the tuning of AMBs require an engineering specialist with an advanced degree? How long does tuning and optimizing take?
It once took many days to levitate the rotor, and weeks to optimized AMB performance. But Synchrony’s integrated development environment (IDE) has now significantly reduced the time required for these operations. Included in the IDE are powerful tools to measure the stability of the magnetic bearing system and to optimize control parameters. As a result, optimization of the magnetic bearing system often takes hours, not weeks.

Does final tuning of AMB have to be done in the field?
A new machine will require optimization under prototypical operating conditions to ensure high performance. However, identical machines will require no field tuning.

How hard is it to connect AMBs to a controller?
Fusion® bearing connections use one set of wires for DC power and optionally one Ethernet cable for communications, greatly simplifying the process. NovaGlide™ systems can be preconfigured with proper cable length and connectors, simplifying the installation.

Is it difficult to interpret the information from AMBs?
Not any longer - Synchrony's health monitoring software displays the information graphically through a GUI interface and simplifies the interpretation and readability of all data. Vibration, force, and temperature data can all be graphically displayed through a web browser.

What happens if the AMBs of a rotating machine is overloaded - must the bearings be restarted to gain control?
Synchrony’s algorithms maintain stability even if the magnetic bearing capacity is exceeded through high static or dynamic loads caused by surge, stall, mechanical shock, or other transients. The software algorithm recognizes this condition and automatically compensates to ensure that once the condition has passed, the controller immediately and stably centers the rotor and normal operation continues. No restart is required.