Converting 230V AC to 1500V DC

[newbie_hs]

I need to convert 230V AC to 1500V DC.
I know basic AC to DC conversion using rectifiers.
But how l convert to 1500 DC.
I need a compact solution(portable).
Can you please suggest a circuit idea for the same⁸l

 

[danadakk]

Low current approaches :

https://www.voltagemultipliers.com/wp-content/uploads/2018/08/Multiplier-Design-Guideline.pdf

You need to answer Klaus's question s and I would add what accuracy/tolerance do you want ?
Does it need to be a regulated V ?


Regards, Dana.

 

[Easy peasy]

it can be easily done with a flyback ( or multiples ) having several outputs - say 3 of, stacked in series 500V each,

you can then charge the required caps on each output - to allow you to get the 4kA pulse for 400uS

there will be some droop of course - we have done 1.5kA this way no problem, you just need more 500VDC rated electro's

i/c = dv/dt, so for a droop of 50V over 200uS, at 4kA average, you need 16 milli - Farad total

or 48 milli-Farad on each 500V part of the series stack ( 48 mF = 48,000 uF )

To charge these caps is 10 sec say - total energy = 0.5 C. V^2 = 18 kJ ( / 10 sec = 1800 watts )

so 3 flybacks at 600W each, or choose a longer charge time, say 20 sec

this gives 3 sections at 300 watt each - much more do-able for a newbie doing a flyback.

For the caps - say we use 470uF, 550V rated, this is 103 caps per section ( 3 sections in series )

as these are about 35mm dia x 65mm high - this is starting to get a little on the biggish side already ( 25 litres just for the caps - say 20cm x 20cm x 80 cm to allow for the pcb and standoffs )

the good news is that a well laid out pcb for each section will easily handle the 4kA, ( 39A per cap - easily done repeatedly by good quality electro's - won't even get warm )

So there you go - 1 x psu for your rail gun prototype - just designed for you

- you 're welcome @newbie_hs


EP.

 

[FvM]

Load impedance hasn't been yet specified. Basic usage of suggested capacitor bank is ballistic discharge through SCR switch, self terminated at current zero crossing. Don't know if this fits the load requirements.

 

[Easy peasy]

This sentence appears to be cyclic / non-sequitur :

" MPT still applies to reactive loads where a conjugate impedance from source to load achieves MPT. "

if Tau = 26uS, this is less than 200uS / 5, so one can assume that nearly all the power will indeed be transferred - in your scenario.

In the example given we have 16mF and 10uH, which gives an unloaded Fo of 398Hz, an half cycle of 1.25mS, which is clearly too long for 200uS, however a loaded system with back emf will behave differently.

the Zo of the source here is SQRT (L/C ) = 25m-ohm, the peak current would be 60kA for a natural unloaded cycle.

if we linearly interpolate the rising current we reach 4kA after 41.67uS ( approx - actually sooner due to the shape of the sine curve ) again assuming unloaded with no back emf .

So - it would be interesting to observe the current shape, rise time and duration on a scaled down real world circuit/system, starting at lower voltages - to see what happens as things are scaled up.

 

[FvM]

Cockcroft–Walton multiplier

 

[Easy peasy]

Transformerless: rectify the mains, then a 2 stage boost converter to 1500V DC, the chokes need to be properly rated for the max terminal volts they see, you will need a 1700V SiC mosfet for the 2nd stage ( and 1700V SiC diode and very good layout ), the intermediate voltage is the geometric mean of the input and output volts ( ~ 700VDC )

there will be a little bit of a surge at turn on - as the booster has no current limit - and the caps will charge to peak mains with very high currents

so maybe a controlled SCR soft start to cope with that - then soft start the booster sections - you use the same gate drive to both

Then average current mode control of the 2 stage booster until you get to full volts

Happy engineering !

 

[mtwieg]

I need this power(6MW) only for 200uS.
May I know then portable solution will be possible or not

The load inductance is 10uH

Giving out tiny crumbs of information like this probably won't yield useful advice.

I'm guessing this is for making a pulsed magnetic field, like a magnetizer? Does it matter what shape the pulse is?

 

[KlausST]

Hi,

1mA? 1A? 1kA?

What allowed voltage ripple? Number with unit.

Klaus

 

[newbie_hs]

Current is 4000A .Ripple specification is not decided yet.

 

[FvM]

6 MW is unlikely to be supplied by 230 V, more likely 400 or 690 V three phase input.
Transformer with multi-phase rectifier (e.g. 6 or 12) would be the standard solution.

 

[KlausST]

Hi,

for 6MW I´ve only seen 10kV/20kV inpupt transformers.
6MW is nothing for a newbie. In my carrier I have experience with power regulation 2kV/3000A RMS but from a 10kV input / multi voltage output transformers.

Klaus

 

[BigBoss]

1500V DC, 4kA "Compact/Portable" solution ??
Is this a joke ??

 

[D.A.(Tony)Stewart]

I need to convert 230V AC to 1500V DC.
I know basic AC to DC conversion using rectifiers.
But how l convert to 1500 DC.
I need a compact solution(portable).
Can you please suggest a circuit idea for the same⁸l

Try again with more accurate details.

 

[KlausST]

Hi,

don´t use .PNG on photos.
Use .jpg and reduce file size to 100kBytes without losing thread related informations.

Klaus

 

[newbie_hs]

I need this power(6MW) only for 200uS.
May I know then portable solution will be possible or not

 

[dick_freebird]

Giving you a hint would only hasten your death. Pick another hobby.

 

[D.A.(Tony)Stewart]

1500V/4000A = 0.375 ohms for source and load.

To achieve MPT dictates you need twice the power to generate Maximum Power Transfer at 50% efficiency and thus twice the voltage and loop resistance. So you need 12 MW stored but is that exponential 200 us or at least 1200 Joules transferred?


6MW only for 200uS or 12 MW stored
What is you load inductance and DCR? What should Q be to attempt critically damped?
Then what value of C is required to store twice this amount of energy to be delivered or 2.4 kJ stored at 3kV.
Now you can computed C min and ESR max.

But what value of L will have a rise time faster than 200 us critically damped with L, C & R since this determines the resonant frequency and decay rate? We must assume the transfer switch Rs is 0 for now.

So tell me what are your results?

 

[tepalia02]

@Easy peasy What else should be taken into consideration while following your suggested design? Filtering, heat dissipation etc.?

 

[newbie_hs]

The load inductance is 10uH