Author Topic: (distributed) air gap  (Read 113 times)

Offline romy

  • High Voltage Enthusiast
  • *
  • Posts: 32
  • Karma: +0/-0
    • View Profile
(distributed) air gap
« on: March 17, 2023, 07:47:14 PM »
i understand b-h curves (to a certain extend), the hanna curve and appreciate how toroids are chosen as a function of LI^2. after reading and watching vids quite a bit i still cant really, really grasp the "paradox", that first we invent materials of high permeability and then have to dillute/mitigate permeability with air gaps.

can somebody please point me to a good read on this or even put it in a way, so that it all finally falls into place?

Offline klugesmith

  • High Voltage Senior
  • *****
  • Posts: 632
  • Karma: +21/-0
    • View Profile
Re: (distributed) air gap
« Reply #1 on: March 17, 2023, 10:40:47 PM »
Reduced permeability, such as with discrete or distributed air gaps, is never good in a true transformer.
Transformers don't store energy; power goes into primary winding at the same time power goes out from secondary winding.

Air gaps are useful when we need to store energy in a magnetic field, as in a flyback converter or other SMPS converter.
The ferromagnetic core is useful for guiding the magnetic flux, so wire turns in one or more coils can be well coupled. (The turns mostly encircle the same magnetic flux.)
But the core saturates at some flux density, around 2T for iron or a fraction of 1T for ferrite.

For a given winding, and given core dimensions, an air gap reduces the inductance but increases the saturation current, in same proportion.
That increases the energy storage, which is proportional to L and to square of current.

In a traditional flyback core with air gap in middle of HV coil, the magnetic "reluctance" of airgap is much more than total reluctance of the flux path in ferrite.
Magnetic energy density at a place, in joules per cubic meter,  is (B * H / 2).
Flux density is about the same within core and inside the air gap, but H is vastly higher in the air gap.   The air gap volume holds more magnetic energy than the whole solid core (and the space outside the core, which has some leakage flux).
« Last Edit: March 17, 2023, 10:46:38 PM by klugesmith »

Offline romy

  • High Voltage Enthusiast
  • *
  • Posts: 32
  • Karma: +0/-0
    • View Profile
Re: (distributed) air gap
« Reply #2 on: March 20, 2023, 08:20:34 PM »
thank you. yes, im rather concerned with storage chokes (for now). i see how 1/2 x L x I^2 works out and obviously the gap helps storing magnetic energy but the original fuzziness remains: why not use lower permeability material in the first place. what is the difference?

im seeing flatter b-h (hysteresis-) curves with distributed air gaps which means lower permeability, right? maybe i should take a step away from these diagrams and look at it from another point of view?

today i want to find out how to get from 1/2 x L x I^2 to B x H. both stand for potential energy, yes?

(i wrote this several days ago, somehow it didnt get posted.)
« Last Edit: March 20, 2023, 08:22:53 PM by romy »

Offline davekni

  • Executive Board Member
  • *******
  • Posts: 2073
  • Karma: +109/-1
  • Physicist, engineer (electronic), and hobbiest
    • View Profile
Re: (distributed) air gap
« Reply #3 on: Today at 01:48:38 AM »
Quote
why not use lower permeability material in the first place.
Because there are few such materials, and none AFAIK with sufficient saturation flux density and low hysteresis.  That is why lower permeability materials are artificially constructed by adding air (or epoxy...) gaps.
David Knierim

High Voltage Forum

Re: (distributed) air gap
« Reply #3 on: Today at 01:48:38 AM »

 


* Recent Topics and Posts

post Re: Question regarding VTTCs and x-rays
[Vacuum Tube Tesla Coils (VTTC)]
V-Troxi
Today at 02:42:03 PM
post Re: DRSSTC fails to oscillate
[Dual Resonant Solid State Tesla coils (DRSSTC)]
npmarshall
Today at 01:49:09 PM
post Re: DRSSTC fails to oscillate
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
Today at 03:59:13 AM
post Re: DRSSTC fails to oscillate
[Dual Resonant Solid State Tesla coils (DRSSTC)]
npmarshall
Today at 03:16:44 AM
post Re: DRSSTC fails to oscillate
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Rafft
Today at 02:58:29 AM
post Re: (distributed) air gap
[Beginners]
davekni
Today at 01:48:38 AM
post Re: DRSSTC fails to oscillate
[Dual Resonant Solid State Tesla coils (DRSSTC)]
npmarshall
Today at 01:47:59 AM
post Re: A few questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
Today at 01:42:14 AM
post Re: DRSSTC fails to oscillate
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
Today at 01:31:51 AM
post Re: Question regarding VTTCs and x-rays
[Vacuum Tube Tesla Coils (VTTC)]
klugesmith
March 20, 2023, 11:59:01 PM
post Re: primary spacing
[Dual Resonant Solid State Tesla coils (DRSSTC)]
thedoc298
March 20, 2023, 11:10:11 PM
post Re: (distributed) air gap
[Beginners]
romy
March 20, 2023, 08:20:34 PM
post Question regarding VTTCs and x-rays
[Vacuum Tube Tesla Coils (VTTC)]
V-Troxi
March 20, 2023, 06:57:34 PM
post Re: A few questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ako
March 20, 2023, 03:07:01 PM
post DRSSTC fails to oscillate
[Dual Resonant Solid State Tesla coils (DRSSTC)]
npmarshall
March 20, 2023, 02:21:05 PM
post GDT output buffer
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
March 20, 2023, 04:32:07 AM
post Re: A few questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
March 20, 2023, 02:26:02 AM
post Re: More induction heating
[Electronic Circuits]
Alberto
March 20, 2023, 12:02:52 AM
post Re: A few questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ako
March 19, 2023, 08:51:54 PM
post Re: A few questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
March 19, 2023, 06:26:07 PM
post A few questions
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ako
March 19, 2023, 05:16:46 AM
post Re: Self Oscillating Half Bridge Wonder
[Solid State Tesla Coils (SSTC)]
davekni
March 18, 2023, 05:58:34 PM
post Re: Self Oscillating Half Bridge Wonder
[Solid State Tesla Coils (SSTC)]
madhurya
March 18, 2023, 12:07:42 PM
post Re: primary spacing
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mads Barnkob
March 18, 2023, 07:30:21 AM
post Re: primary spacing
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
March 18, 2023, 04:45:04 AM
post Re: primary spacing
[Dual Resonant Solid State Tesla coils (DRSSTC)]
MRMILSTAR
March 18, 2023, 03:45:14 AM
post Re: primary spacing
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
March 18, 2023, 02:15:42 AM
post Re: More induction heating
[Electronic Circuits]
Alberto
March 17, 2023, 11:14:10 PM
post Re: (distributed) air gap
[Beginners]
klugesmith
March 17, 2023, 10:40:47 PM
post (distributed) air gap
[Beginners]
romy
March 17, 2023, 07:47:14 PM
post Re: Plasma Toroid
[Solid State Tesla Coils (SSTC)]
Uspring
March 17, 2023, 06:47:10 PM
post Hello, I do stupid high voltage and other experiments for videos
[Hobby Sites]
breezetix
March 17, 2023, 06:37:48 PM
post UCC21520 and/or UCC27321P schematics?
[Electronic Circuits]
breezetix
March 17, 2023, 06:29:37 PM
post 1940's 10kW Variac Stack quick cleanup and setup
[Transformer (Iron Core)]
breezetix
March 17, 2023, 06:13:48 PM
post Re: Welding a MOT
[Transformer (Iron Core)]
breezetix
March 17, 2023, 06:12:08 PM
post Re: Creating arcs off my variac lol, popped my igbts
[Transformer (Iron Core)]
breezetix
March 17, 2023, 06:04:53 PM
post primary spacing
[Dual Resonant Solid State Tesla coils (DRSSTC)]
thedoc298
March 17, 2023, 05:44:14 PM
post Re: My second DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
March 17, 2023, 04:48:59 AM
post Re: Can a segmented secondary coil work?
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
March 17, 2023, 04:42:07 AM
post Re: Driverless Single Mosfet Relay interrupted SSTC? - [All kinds of problems]
[Solid State Tesla Coils (SSTC)]
davekni
March 17, 2023, 02:55:19 AM
post Can a segmented secondary coil work?
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Hafting
March 17, 2023, 12:09:07 AM
post Re: Driverless Single Mosfet Relay interrupted SSTC? - [All kinds of problems]
[Solid State Tesla Coils (SSTC)]
TiagoBS
March 16, 2023, 07:52:19 PM
post Re: More induction heating
[Electronic Circuits]
klugesmith
March 16, 2023, 07:32:14 PM
post My second DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Miki_407
March 16, 2023, 03:40:21 PM
post Re: More induction heating
[Electronic Circuits]
Alberto
March 16, 2023, 12:04:01 PM
post Re: induction heating
[Electronic Circuits]
romy
March 16, 2023, 08:12:37 AM
post Re: Plasma Toroid
[Solid State Tesla Coils (SSTC)]
davekni
March 16, 2023, 05:41:56 AM
post Re: More induction heating
[Electronic Circuits]
davekni
March 16, 2023, 05:32:24 AM
post Resonant LC with signal generator to heat mercury
[Electronic Circuits]
klugesmith
March 16, 2023, 03:53:17 AM
post Re: More induction heating
[Electronic Circuits]
klugesmith
March 16, 2023, 01:30:31 AM
post Re: More induction heating
[Electronic Circuits]
Alberto
March 16, 2023, 12:17:32 AM
post Re: induction heating
[Electronic Circuits]
petespaco
March 15, 2023, 11:53:29 PM
post Re: Plasma Toroid
[Solid State Tesla Coils (SSTC)]
alan sailer
March 15, 2023, 05:26:43 PM
post Re: More induction heating
[Electronic Circuits]
romy
March 15, 2023, 03:56:29 PM
post Re: More induction heating
[Electronic Circuits]
romy
March 15, 2023, 03:53:31 PM
post Re: induction heating
[Electronic Circuits]
romy
March 15, 2023, 03:51:10 PM
post Re: More induction heating
[Electronic Circuits]
klugesmith
March 14, 2023, 11:00:41 PM
post Re: More induction heating
[Electronic Circuits]
Alberto
March 14, 2023, 10:28:05 PM
post Re: induction heating
[Electronic Circuits]
petespaco
March 14, 2023, 05:01:44 PM
post Re: More induction heating
[Electronic Circuits]
romy
March 14, 2023, 03:00:36 PM
post Re: induction heating
[Electronic Circuits]
romy
March 14, 2023, 02:03:42 PM
post Re: Cockroft-walton resistors
[Voltage Multipliers]
MRMILSTAR
March 14, 2023, 04:04:32 AM
post Re: Cockroft-walton resistors
[Voltage Multipliers]
dbach
March 13, 2023, 10:41:49 PM
post Re: Cockroft-walton resistors
[Voltage Multipliers]
alan sailer
March 13, 2023, 08:25:38 PM
post Cockroft-walton resistors
[Voltage Multipliers]
dbach
March 13, 2023, 05:59:40 PM
post Re: More induction heating
[Electronic Circuits]
Alberto
March 13, 2023, 09:08:46 AM
post Re: More induction heating
[Electronic Circuits]
petespaco
March 13, 2023, 06:15:51 AM
post Re: Ramped SSTC - Power Supply Question + General Improvements
[Solid State Tesla Coils (SSTC)]
davekni
March 13, 2023, 02:10:47 AM
post Re: More induction heating
[Electronic Circuits]
davekni
March 13, 2023, 12:21:01 AM
post Re: Ramped SSTC - Power Supply Question + General Improvements
[Solid State Tesla Coils (SSTC)]
ZakW
March 13, 2023, 12:17:09 AM
post Re: More induction heating
[Electronic Circuits]
klugesmith
March 12, 2023, 11:43:38 PM
post Re: More induction heating
[Electronic Circuits]
Alberto
March 12, 2023, 10:39:41 PM
post High Voltage Caps Clearout
[Sell / Buy / Trade]
ColinHeath
March 12, 2023, 10:39:05 PM
post Re: More induction heating
[Electronic Circuits]
davekni
March 12, 2023, 09:46:24 PM
post Re: 160mm DRSSTC project
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mathieu thm
March 12, 2023, 09:23:23 PM
post Re: Next Gen DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Hydron
March 12, 2023, 07:52:30 PM
post Re: Next Gen DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
dannybeckett
March 12, 2023, 06:45:50 PM
post Re: More induction heating
[Electronic Circuits]
Alberto
March 12, 2023, 09:04:53 AM
post Using dual-resonant Tesla Coils to create non-thermal resonant hydrogen plasma.
[Dual Resonant Solid State Tesla coils (DRSSTC)]
joabel1971
March 11, 2023, 10:03:58 PM
post Re: Tesla coil is a quarter-wave resonator I’snt it ?
[Dual Resonant Solid State Tesla coils (DRSSTC)]
joabel1971
March 11, 2023, 09:15:23 PM
post Re: High Power / High Freq. IGBT Gate Driver
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
March 11, 2023, 02:20:13 AM
post Re: High Power / High Freq. IGBT Gate Driver
[Dual Resonant Solid State Tesla coils (DRSSTC)]
dannybeckett
March 11, 2023, 12:24:07 AM
post Re: More induction heating
[Electronic Circuits]
davekni
March 11, 2023, 12:13:11 AM
post Re: More induction heating
[Electronic Circuits]
Alberto
March 10, 2023, 09:42:29 PM
post Re: More induction heating
[Electronic Circuits]
davekni
March 10, 2023, 08:38:36 PM
post Re: High Power / High Freq. IGBT Gate Driver
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
March 10, 2023, 08:06:23 PM
post Re: induction heating
[Electronic Circuits]
petespaco
March 10, 2023, 05:13:44 PM
post Re: First DRSSTC 1.3b DRIVER
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Alex_1996
March 10, 2023, 05:07:20 PM
post Re: First DRSSTC 1.3b DRIVER
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Alex_1996
March 10, 2023, 04:38:21 PM
post Re: First DRSSTC 1.3b DRIVER
[Dual Resonant Solid State Tesla coils (DRSSTC)]
klugesmith
March 10, 2023, 04:25:12 PM
post Re: First DRSSTC 1.3b DRIVER
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Alex_1996
March 10, 2023, 03:53:56 PM
post Re: High Power / High Freq. IGBT Gate Driver
[Dual Resonant Solid State Tesla coils (DRSSTC)]
dannybeckett
March 10, 2023, 01:39:57 PM
post Re: induction heating
[Electronic Circuits]
romy
March 10, 2023, 10:27:36 AM
post Re: More induction heating
[Electronic Circuits]
Alberto
March 10, 2023, 09:48:10 AM
post Re: More induction heating
[Electronic Circuits]
petespaco
March 10, 2023, 03:51:40 AM
post Re: High Power / High Freq. IGBT Gate Driver
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
March 10, 2023, 03:00:09 AM
post Re: High Power / High Freq. IGBT Gate Driver
[Dual Resonant Solid State Tesla coils (DRSSTC)]
dannybeckett
March 10, 2023, 01:03:19 AM
post Re: More induction heating
[Electronic Circuits]
Alberto
March 09, 2023, 10:51:52 PM
post Re: More induction heating
[Electronic Circuits]
petespaco
March 09, 2023, 07:06:03 PM
post Re: High Power / High Freq. IGBT Gate Driver
[Dual Resonant Solid State Tesla coils (DRSSTC)]
dannybeckett
March 09, 2023, 02:25:33 PM

Sitemap 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 
SimplePortal 2.3.6 © 2008-2014, SimplePortal