Re: Permanent magnets as coil cores?

In article <5apg241m4gkpcuhsje4gbbiqabp6q9u0j2@xxxxxxx>,
markrrivet@xxxxxxxxxxx says...
What are the benefits of using a permanent magnet for a coil core.
I recently came across a design for a switching power supply that used
magnets as cores for the inductor. I have never heard of such a thing,
except maybe in speakers.

If there is DC current flowing in the coil, it reduces the amount of
flux "swing" that can happen without saturating the core. Or looking
at it from another angle, you need a physically larger (more $$) core
to do the same AC work if it is also carrying DC. Using a permanent
magnet to counteract the DC flux allows a smaller (cheaper) part to
be used. Used to see these in the vertical section of TV's in the
days before power IC's.
.

Relevant Pages

  • Re: Is it possible to use permanent magnets to assist a motors power efficiency?
    ... You will need to make something similar to a rectangular transformer core. ... A box of staples, some copper magnet wire, and a pair of appropriately sized ... Stronger magnets can be used but you want ... After winding the coils onto the staples place the magnets either side of ...
    (sci.physics.electromag)
  • Re: Another PFC question
    ... How do I calculate what the flux density in the core will be, to make sure I avoid saturation. ... The value of 4.44 I assume I would change to 4.0 for a square wave, as the inductor is bieng switched at 100khz. ... According to the litrature I have, the MPP cores saturation flux density is about 8000 gause. ...
    (sci.electronics.design)
  • Re: MEET THE BHARATIYA WHO TOOK ON STEPHEN HAWKING
    ... > But does he tell us whether the core of any star is hot or cold? ... > our sun has a very strong magnetic field. ... > the core unless it is very cold, and permanent magnets as we know from ...
    (sci.physics)
  • Re: Permanent magnets as coil cores?
    ... magnets as cores for the inductor. ... flux "swing" that can happen without saturating the core. ... currents, and a different one for "negative" currents. ...
    (sci.electronics.repair)
  • Re: Switching on giant electromagnet
    ... One of the reasons such magnets are so huge is ... that the core has to concentrate the field in the gap. ... other hand put it into the gap, there is really a strong field. ... centimeters and the gap area approaches probably one squaremeter ... ...
    (sci.electronics.design)