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Magnetic bearing

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Magnetic bearing

  1. 1. PRESENTED BY : BISWAJIT SWAIN MECHANICAL ENGINEERING REGD. NO. : 1121367047 7th SEMESTER RADHAKRISHNA INSTITUTE OF ENGINEERING AND TECHNOLOGY,BHUBANESWAR.
  2. 2. CONTENTS:            BEARING MAGNETIC BEARING DESCRIPTION BASIC OPERATION CLASSIFICATION MAGNETIC BEARING PERFORM ADVANTAGES DISADVANTAGES APPLICATION CONCLUSION REFERENCE
  3. 3. BEARING  A Bearing is a machine element which support another moving element.  It permits relative motion between the contact surfaces of the members while carrying a load.  Most bearings support rotating shafts against either radial or axial
  4. 4. MAGNETIC BEARING  A Magnetic bearing is a bearing which supports a load a load using magnetic levitation.  A Magnetic bearing support moving machinery without physical contact,for example,they can levitate a rotating shaft
  5. 5. and linear moving machinery elements,without contact with rotor,this is accomplished by electro magnet(bearing) which attracts a ferromagnetic material(rotor),using this principle rotor can be suspended in magnetic field which is generated by bearing.
  6. 6. DESCRIPTION  It is difficult to build a magnetic bearing using permanent magnets due to the limitation imposed and techniques using diamagnetic materials are relatively undeveloped.  As a result, most magnetic bearing require continuous power input and an active control system to hold the load stable. Because of this
  7. 7. BASIC OPERATION  An active magnetic bearing (AMB) works on the principle of electromagnetic suspension and consists of an electromagnet assembl y, a set of power amplifiers which supply current to the electromagnets, a controll er, and gap sensors with
  8. 8. •The power amplifier supplies equal bias current to two pairs of electromagnets on opposite sides of a rotor. This constant tug-of-war is mediated by the controller which offsets the bias current by equal and opposite perturbations of current as the •The gap sensors are usually inductive in rotor deviates from a differential mode. nature and sense in its center position. The power amplifiers in a modern commercial application are solid state devices which operate in a pulse width modulation (PWM) configuration. The
  9. 9. Classification  According to Control action – Active – Passive – Hybrid  According to Forcing action – Repulsive – Attractive  According to Sensing action – Sensor sensing – Self sensing
  10. 10. •According to Load support – Axial or Thrust – Radial or Journal – Conical •According to Magnetic effect – Electro magnetic – Electro dynamic
  11. 11. MAGNETIC BEARING PERFORM  Lubrication Free  Clean & Contamination Free  Reliability  High Surface Speed  Low Vibration  Low Energy Consumption  Non-Contacting  Submerged Operation
  12. 12. aDVANTAGES Highest speeds are possible even till the ultimate strength of the rotor.  Absence of lubrication seals allows the larger and stiffer rotor shafts.  Absence of mechanical wear results in lower maintenance costs and longer life of the system.  Adaptable stiffness can be used in vibration isolation,passing critical speeds, robust to external disturbances 
  13. 13. DISADVANTAGES  Include High Cost.  Large in Size.
  14. 14. APPLICATIONS  Magnetic bearings are increasingly used in industrial machines such as compressors, turbines, pumps, motors and generators.  Magnetic bearings are commonly used in watt-hour meters by electric utilities to measure home power consumption.  A new application of magnetic bearings is their use in artificial hearts.
  15. 15. CONCLUSION  Magnetic bearings advantages and applications have been discussed .  Electromagnetism and Control system technologies have been introduced .  Design of thrust and radial magnetic bearings have been studied .  Control of a rotor by rigid rotor and flexible rotor models have been studied .
  16. 16. REFERENCES  Schweitzer, G., Bleuler, H. and Traxler, “Basic Properties and Applications of Active Magnetic Bearings.  Chiba, A., Fukao, T., Ichikawa, O., Oshi ma, M., Takemoto, “Magnetic Bearings & Bearingless Drives.  Maslen, E., “Magnetic Bearings”, University of Virginia.

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