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DRV401: Demagnetization problem

jie qian
Prodigy 245 points
Part Number: DRV401

Hello!

i  have a question, if the DRV401 is in normal operation,and the measured current is 250A, now, i set the Demag pin to high at least 25.6 μs to start a Demag cicle. in this situation， the probe circuit will still work normally? and the compensation circuit will still work normally?  in other words, in this situation, DRV401 will still work normally?why? and is there any negtive influence or harmful toDRV401?

if i set the Demag cicle start every 1minutes when the DRV401 is in normal operation ,is ok? 

thanks very much! and best regard!

jie qian.

  • 0
    TI__Mastermind 26485 points

    Hello Jie Qian,

    A demag cycle excites the compensation core in order to remove its magnetization.  If there is current in the primary circuit then the compensation core could possibly not be cycling through both saturation directions. It is recommended you do a Demag cycle when there is no current on the primary.

    The demag function is trying to randomize the field by saturating the core in both directions and slowly decaying that siganl.  If a current is on the primary then one side of the signal will get amplified and the other direction may not have enough current to compensate for the primary and saturate the core.  This could create a larger offset.  The DRV401 will not get damaged but the core could get magnetized more instead of less.

  • 0 in reply to Javier Contreras4
    Prodigy 245 points

    Hello,Javier,

    "A demag cycle excites the compensation core in order to remove its magnetization",the compensation core you means the magnetic core ? please see the figure,

    "The demag function is trying to randomize the field by saturating the core in both directions and slowly decaying that siganl" -"the core",you mean the probe core?

    so the demag cycling works on magnetic core or probe core?

    Thanks !

  • 0 in reply to jie qian
    TI__Mastermind 26485 points
    Hello Jie Qian,

    The Demag works on the compensation core (magnetic core). The probe core during normal operation is saturated in both directions and should not get permanently magnetized as it is always getting saturated in both directions during normal operation.

    "A demag cycle excites the compensation core in order to remove its magnetization",the compensation core you means the magnetic core ? please see the figure.
    Yes.

    "The demag function is trying to randomize the field by saturating the core in both directions and slowly decaying that siganl" -"the core",you mean the probe core?
    No, demag is only for the magnetic core.