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Capacitor charger for 400V and 82mF bank

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Apr 10, 2022
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I need to design a charger for a 400V-82mF capacitor bank from 50Hz ,220V mains. Charging time must be less than 30 seconds. There is no extra load other than capacitors. After charging, capacitors discharges to xenon lamps when triggered, then charging again.
I don't know which topology best fits with this kind of application. A full wave rectifier with doubler would be ok but the power factor is very low (~0.3).


must it repeatedly recharge the caps?
If so, what is flash rate?
If it must flash every 30 secs, then thats 220W.

So you will be talking two flybacks in parallel off of a PFC i reckon...each current regulated to 0.5Amp.....or make them charge at higher rate at first, so you charge at more constant power, say.

Do you need isolation?
You could make it 3 secondaries each of 130V....then series them...this means less voltage referred to your primary side
Yes it must repeatedly recharge caps. One flash after 30 seconds. Insulation is not needed.
Thanks for idea, i will simulate it and check.

if you dont need isolation, then just do a single stage buckboost straight off the mains, with little input capacitance........just make it PFC'd.....use SIC diodes if you will be in CCM.

A dual sepic ( 180 deg phase shifted ) off the rectified mains will give high PF and enough power to bring the volts up, 1200V SiC mosfets and diodes .....

Also, you could do a "low side Buckboost" that has a low side FET....and has the load referred ("grounded") to its input.

A full wave rectifier with doubler would be ok but the power factor is very low (~0.3).
Villard doubler charges 80,000 uF to +400 VDC in 27 sec.
Current is drawn in 6A bursts. The 56uF cap adopts DC charge thus it can be electrolytic type.

Power factor is low as expected. I tried attaching an inductor in different ways in hopes to improve power factor. Not finding successful arrangement...
I think the 56uF cap admits just enough Amperes to do the job in 27 seconds. Evidently power factor error is not the sort that falsely elevates Ampere levels in the system.

The 1 ohm resistor is unnecessary.
Output charge level can eventually reach 650 V if not stopped.

Villard doubler 220VAC 6A to 82mF cap 400VDC 27 sec.png

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