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DRV5011: Magnet evaluation

Annie Liu
Genius 10295 points
Part Number: DRV5011
Other Parts Discussed in Thread: DRV5055EVM

Hi Team,

Customer used DRV5011 products to detect rotating shafts. The magnet has a pair of poles, the surface remanence is 50mT, the outer diameter is 1.9mm, and the inner diameter is 1.25mm. 

He would like to know how to evaluate the distance between the magnet and the sensor, and whether the magnetic field is satisfied? Because he only saw the simulation of rectangular magnets and cylindrical magnets on the corresponding product pages, is there any relevant simulation software to evaluate this application?

Best regards,

Annie

  • 0
    TI__Genius 15180 points

    Annie,

    There are various simulation software options they could use to simulate the magnet.  One open source option is FEMM (Finite Element Method Magnetics).  This software is free to download and provides 2D simulations. If setup as shown above, with the sensor in plane with the magnet, they might be able to put together a simulation using this option.

    www.femm.info/.../HomePage

    If the spacing is more complicated than this, then a 3D simulation is required.  There are tools such as the Maxwell 3D environment produced by ANSYS which is powerful and capable of fully simulating 3D space, but this is a licensed software and may not be an option he can consider.

    https://www.ansys.com/products/electronics/ansys-maxwell

    I also found this online tool which offers calculations for the magnet type you are describing:

    magnetrechner.de/.../diametrically-magnetized

    To verify the result from any of the above options, it may be most practical to to measure the field components empirically in the lab using a linear Hall effect sensor.  One option might be to use the DRV5055EVM which has a display which can be set to show the input field in mT.  If the magnet is slowly rotated near a sensor, the customer could measure the peak magnetic flux density at a given distance.  It is important to keep in mind the orientation of the magnet with respect to the sensor when doing this as this EVM uses the TO-92 package variant.  Also, this approach will include device errors such as sensitivity error and offset.