DESIGN OF ACTIVE MAGNETIC BEARING Presented By JADHAV

“DESIGN OF ACTIVE MAGNETIC BEARING” Presented By JADHAV MANORANJAN A. Guided By Prof. S. B. BELKAR

Introduction Magnetism Magnetic field

Magnetism Magnetic Flux Density B = magnetic flux density m = magnetic permeability H = magnetic field m 0 = permeability of free space mr = relative permeability diamagnetic paramagnetic ferromagnetic multiple loops of wire, n

Magnetism Magnetic Field Magnetic field, H, is found around a magnet or a current carrying body. H i (for one current loop)

Magnetism Lorentz Force f = force Q = electric charge E = electric field V = velocity of charge Q B = magnetic flux density

Magnetism Lorentz Force Simplification: Source: MIT Physics Dept. website

Magnetism Lorentz Force Further simplification: Analogous Wire B i f force perpendicular to flux!

MAGNETIC BEARING �Bearing which supports a load using magnetic levitation Advantages of magnetic bearings: § § § contact-free no lubricant (no) maintenance tolerable against heat, cold, vacuum, chemicals low losses very high rotational speeds Disadvantages: § complexity § high initial cost

MAGNETIC BEARING TYPES �PASSIVE MAGNETIC BEARING Not electrically controlled, Permanent magnets �ACTIVE MAGNETIC BEARING Electrically controlled, Electromagnets

Model of Active Magnetic Bearing �Principle of operation: Magnetic Levitation

Active Magnetic Bearings Elements of System � Electromagnet � Rotor � Stator � Position Sensor � Controller � Amplifier

�Radial Bearing Configuration: for radial force balancing �Axial Bearing Configuration: for axial force balancing �Position Transducers:

Auxiliary Bearing System

Control system: �Sensors � Controller � Power Amplifiers

Principle of radial and axial force Where ,

magnetic flux in the air gap

permeances of bias & axial control fluxes Pb & Px The axial force

Analysis of AMB system using Finite Element Method

Performance relative to hydrodynamic bearing REQUIREMENTS MAGNETIC BEARING HYDRODYNAMIC BEARING High loads low high Speed high low Sealing Not required Unbalance no yes Losses Very low high

ADVANTAGES OF AMB • NON CONTACT MOTION • HIGH ROTATING SPEED • NO LUBRICATION • INCREASE IN OPERATING TEMPERATURE RANGE • ACTIVE NATURE

DISADVANTAGES OF AMB • NO LINEARITY • ROTOR HEATING • LARGER SIZE • HIGH COST

APPLICATIONS OF AMB • Image display unit • High precision lathe • Turbo expander • Turbo compressor • High speed milling • Machine tool spindle • Maglev Trains

Applications Maglev Trains Maglev = Magnetic Levitation � 150 mm levitation over guideway track à undisturbed from small obstacles (snow, debris, etc. ) �typical ave. speed of 350 km/h (max 500 km/h) à what if? Paris-Moscow in 7 hr 10 min (2495 km)! �stator: track, rotor: magnets on train Source: Discovery. Channel. com

Applications Maglev Trains Maglev in Shanghai - complete in 2004 - airport to financial district (30 km) - world‘s fastest maglev in commercial operation (501 km/h) - service speed of 430 km/h Source: www. monorails. org

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