5 Replies Latest reply on Feb 1, 2018 1:36 AM by dougw

    Repulsive Electromagnetic Levitation by 4 coils


      Hi everybody

      I'm a Mechanical engineering student but interested in Electronics so I am somehow beginner.

      I'm working on magnetic levitation, both attractive(from top) and repulsive(from bottom). levitating from top was successful since there are so many articles and videos available but there isn't any article or guide about repulsive levitation!! I need to understand the fundamental of this type of levitation.

      It would be greatly appreciated if you share any article, Arduino code and schematic.


      Thanks so much


        • Re: Repulsive Electromagnetic Levitation by 4 coils

          The System contains two main parts:

          1. a big ring magnet (underneath or around the four coils, you cannot see it on your picture) and a small strong disk-like magnet. the big one is made out of ferrite, just search for ferrite ring magnet. the smaller magnet is a neodym magnet. Only with these components the system is unstable, and if you try to put the neodym magnet in the center of the ring magnet it will always gets attracted in one direction. this is cause of earnshaws theorem.

          so therefore you'll need a second part to get the neodym magnet floating:

          2. an adjustable magnetic field controlled by a microcontroler. it contains four coils made out of cupper wire, two hall-effect sensors and some sort of controller which will interpret the datas from the hall sensor and will drive the coils.


          The way it works is that the two sensors will measure the (two dimensional) position of the neodym magnet. one sensor will measure the position on the x-axis, the other one of the y-axis. now if the magnet for example moves slightly in the positive x-direction the sensor will measure it, and the controller has to drive the coils so that the magnet will get attracted back to the center. for that there are always two coils connected to each other, but with inverted polarity. so the one coil can push the magnet back to the center, and the coil on the other side can pull the magnet to the center. one hall sensor with two coils is a self contained system, the one system is responsible for the x-axis, the other one for the y-axis as said before. in praxis each sensor has to measure the position 1000 of times per second and the controller has to correct the position every time. if you want to control the coils with a controller and not with an analog circuit you have to consider that the controler is much more slower with calculating the right position than the magnet is moving. therefore you have to implement the controler as a PID-controler, which means it drives the coils mentioning the position of the magnet in the past and the calculated position in the future.


          the principle is nearly the same as with the attractive levitation, but instead of just correcting the position of the magnet in one direction you now have two directions..



          feel free to share your progress with your project, i made this account to answer your question because i'm interested in this topic too


          maxi l.

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