Hi.
I want to charge my capacitor bank with 72V-20A DC source.
The idea is to store 1KW in this capacitor bank and then to use this power to run some 450V electronics.
DC source is constant so capacitors can be "recharged" all the time. The capacitor bank should be made of 450V / 400uF capacitors and normal power consumption of our electronics is around 800 - 900W.
Does anyone has some DIY project on this or maybe some guide how to start ?
Regards !
btw 100000uf of stronger can also be used.
nescafe schrieb:
Hello,
it is not possible to store 1 kW in a capacitor bank, even if it is a very large one. But if you want to store 1 kWh this may be done, if there are enough capacitors of a suitable capacity and voltage. The bank might be much too large, heavy and expensive.
Bye
You've got lots of power available for the job, but the job itself doesn't make much sense to me. First off, do you mean that you want to draw 1 kW from the capacitors, or that you need enough capacitors to filter your 1 kW switching supply?
Second, a 1 kW class switching supply is _not_ a beginner's project. There's way too much that's bound to go expensively (and maybe dangerously) wrong.
What are you actually trying to do?
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net
------------------------- First off, do you mean that you want to draw 1 kW from the capacitors ?
-yes that's what i want
The bank might be much too large, heavy and expensive
- i agree that this could be a problem.
But i do have some additional questions. e.g. if i dismantle some 12/220 - 2kw - DC/AC converter and if i measure voltage on exit capacitor i will get around 250V. Ok. If i want to use this 250V to run some 2kw application ( working on this voltage ) everything works OK. I tested this.
So as far as i understand this i can make the same stuff but with 450V capacitor and with less electronic. Maybe i dont need capacitor bank ?
72VDC/20 amps is enough to support a 1KW load. The dc-dc converter will output whatever voltage it is designed for. The capacitor is just necessary for smoothing not to supply the raw power.
If you wanted reserve power for a prolonged period when the 72 volts isn't present, then a battery makes sense, or a super cap if the outage time is short. Then use that to store energy and convert it up to 450 for the load.
Can you tell us what you're trying to achieve,
*not* what you're thinking/doing.eg.
I have a 72V-20A DC source, I want to use it to power a 450V AC device.
I have the following components...
(This might be what you're trying to do, it's not clear...)
-- to run one 450V circuit. This circuit is used as some kind of controller and you can power it with 450VDC source.
To run properly the circuit needs minimum 300W.
---------------------
If you can replace the rectifier on the main transformer of the 2KW inverter with one that gives twice the voltage you'd be close to a solution, you'd then need to mess with the feedback to reduce the output voltage to 450V.
sounds dangerous and potentially expensive/exciting, especially if you don't have a schematic and understanding of how the inverter is supposed to work.
it might be better to put autotransformr on the inverter output to step it up and rectify the result.
This is for what? A battery powered "toob" amp?
-- ?? 100% natural
A "capacitor charger" is a device that repetitively charges up a capacitor bank, which is then discharged very fast to provide short pulses of very high peak power, e.g. for a flashlamp, railgun or coin shrinker. The design requirements for that job are quite different from just filtering a high current 450V DC supply, which is what it sounds like you're trying to do.
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net
OK, you've got 72V-20A DC source, that's
1440W - plenty of power but you need a transformer.Are you trying to use a car battery inverter to step the voltage up to 450V?
Are you trying to use a car battery inverter to step the voltage up to
450V?- yes. I'v done this before and it worked. There are of course few problems regarding this approach. Safety would be on the first place, but if the you do this with some basic/extra precaution then everything works ok. And it's quite exciting :-)
--------------------- Like Phil suggested if i go with capacitor bank i will not get what i need and beside this i would spend bunch on money for nothing.
------------------- What im doing
--------------------- I'v made electric car with reg. breaking. Its using 3phase 11kw motor and the only thing that i need is stronger DC/DC converter. I dont have time to explain how all this works but to control the motor i need 420 - 500V DC input. DC /DC converter is connected to this motor control. Btw. 3 phase approach is waaaay better then DC motor but as you can see there are some problems. I can rewind motor or use some other controller or do something else, but then again, that would not be me :-). To run the car smoothly in first gear i need around 2,5kw ( first gear with fast start and small hill ) afterwards normal consumption is much lower.
--------------------- Back to the problem ( and guys, please stay on this topic, we can talk about EV later ).
--------------------- I firstly connected 2x 2KW AC/DC 12/220V converters ( galvanic separated ) and it worked OK Then i was thinking, damn, there must be a way just to change the output capacitor and rectifier ( like Jasen suggested ) to make this work. So my next plan is to buy some 72V DC/AC inverter and to do just that. Change the capacitor and rectifier part.
--------------------- Would this be possible to do ?
How do you propose getting 450V from 72? Some sort of series-parallel switching?
That would appear to preclude switching , as described above. Define "all the time".
--
"For a successful technology, reality must take precedence
over public relations, for nature cannot be fooled."
(Richard Feynman)
OK...but the inverter you've got multiplies the voltage by 20.
That's three times too much - your 72V will turn into 1440V.
You need a different inverter or a way to divide the voltage.
Dividing the voltage is complicated.
Oh, now everybody knows the secret! Be careful the oil companies don't find out where you live.
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