help-rapid cap bank charging

[Mag Man]

Okay?

So what size are your step-up transformers in Volt-Amperes?

What sort of iron ar you using for your core that can handle 5000 - 10,000 gauss without going into saturation?

How are you protecting your IGBT and your capacitor bank from the massive inductive kickback and resulting voltage and current spikes of the collapsing magnetic field of your coil?

 

[Mag Man]

100va transformers, 2.5"x3" soft iron core(standard iron), 600amp flyback diode

 

[Mag Man]

I can't see timing but I think that when the IGBT is on, there is a point where the capacitors are down to 50 volts.
So you have the power line shorted to 50 volts. (for a time) This must be stressful on the transformers.

 

[Mag Man]

The voltage drop on caps is~50vdc @ 10-20mS fire, at the present time I am only able to sustain 300vdc peak during ~70mS repetition cycle, I need 500vdc steady.
Indeed stressful to transformers, but they are still alive after considerable testing. I
understand this whole system needs bottom up engineering, however for the mean time proof of concept is the name of the game, any working solution to achieve goal
(5000-10000 gauss, variable)

 

[Mag Man]

As TCMTECH has mentioned, magnetic materials, to which iron and steel belong to, have a saturation flux density. Once that you reach saturation, no matter how much electromotive force you apply, you will not get additional flux density. At least not on the steel's surface area.

Good magnetic steels saturate around 16,000 Gauss.

 

[Mag Man]

I need 5000-10000 gauss, and I am using a 2.5" x 3" core, single pulse delivers
@ 500vdc, currently only able to maintain 300vdc, also working on efficiency
of coil assembly, using hand wound randomly engineered unit

 

[tcmtech]

So you have roughly 600 VA of transformers trying to supply several tens of kilowatts worth of power from a circuit hat has a at best 3600 watt working limit to fire a high current capacitive discharge into a soft iron core inductor that although it could have good magnetic permeability qualities more than likely has terrible magnetic admittance properties amongst other critical magnetic criteria.

And for protection ou have a basic single diode flyback type protection circuit that ultimately slows the inductive reactance of the iron and coil down even further while forcing them to absorb and dissipate near 100% of the energy being put into them.

Wow! Just when I thought a person couldn't make an electric heater more complicated and somehow less efficient.

I stand corrected.

"Random Engineering? Is that a technical term of just pulling ideas out of your butt and seeing what doesn't burn down or kill you while hoping something gainful falls in your lap?

 

[ronsimpson]

The voltage drop on caps is~50vdc @ 10-20mS fire, at the present time I am only able to sustain 300vdc peak during ~70mS repetition cycle, I need 500vdc steady.

don't understand
? The voltage on the caps is 300 to 250 (peak to peak)
OR
? The voltage on the caps is 300 to 50 (peak to peak)

 

[spec]

Hy Mag,

Here is the circuit I have arrived at. It is only notional for discussion.

Instead of answering the question in your post, it addresses the requirement, 120V 30A 60Hz input to highest possible magnetic field.

​

CIRCUIT FUNCTION
(1) The circuit uses no mains transformers between the mains supply and the bridge rectifier. This means that the capacitor will receive the maximum current at the positive and negative voltage peaks of the input voltage sine wave.
(2) The maximum voltage across the capacitor will be 110V * 1.414 (root 2) = 155.54- 2V (bridge VF)= 153.54 V peak. Call it 153V.
(3) The pass element is a GTO thyristor because they are probably easier to drive and potentially offer the highest current rating/cost ratio compared to an IGBJT, which tend to be expensive. The switching element is immaterial in terms of the circuit basic function at this notional stage though.
(4) The remaining diodes return the energy stored in the inductor back to the capacitor when the the pulse terminates.
(5) Because the input voltage is now 153V rather than 500V, the winding on the inductor will need to be adjusted accordingly.

INDUCTOR
(1) The inductor characteristics have a radical and overwhelming influence on the performance of this, or any other circuit, including the original circuit.
(2) The inductor core: material, dimensions, shape, and eddy current insulation, needs to be optimized.
(3) Likewise, the inductor windings need to be optimized. My first thoughts are that about five parallel windings will be required to minimize skin effect.
(4) It is not clear from the OP's posts, if the magnetic field generated by the inductor is required to do any work. If not, in theory, the circuit will use no power. Of course, because inductors particularly are far from perfect, there will be losses, but these can be minimized by good design. Note that pure inductors and capacitors do not dissipate any power because their voltages and currents are 90 degrees out of phase.

 

[crutschow]

I was considering dc/ac converter circuitry such as used for automobile cigarette
lighters, ie; 10-20amp 12vdc input = 120vac 33amp output(4000watt),adapting this
technology to achieve 500vdc(bridges) 30+amps. No market for such a thing therefore nothing manufactured

Your math is way off. You can't get more power out then you put in.
20A @ 12V = 240W giving 240W/120V = 2A at the output at 100% efficiency.