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Message ID: 2274     Entry time: Mon Nov 16 15:18:10 2009
Author: haixing 
Type: Update 
Category: SUS 
Subject: Stable magnetic levitation without eddy-current damping 

By including a differentiator from 10 Hz to 50 Hz, we increase the phase margin and the resulting

magnetic levitation system is stable even without the help of eddy-current damping.

The new block diagram for the system is the following:

 block_diagram_new.png

Here the eddy-current damping component is removed and we add an additional differential

circuit with an operational amplifier OP27G.

In addition, we place the Hall sensor below the magnet to minimize the coupling between

the coil and the Hall sensor.

The resulting levitation system is shown by the figure below:

mag_levi_new.jpg

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