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josh1234

Sun Aug 05 2012, 03:54PM

Registered Member #5969 Joined: Mon Jul 30 2012, 09:27PM
Location: ringwood
Posts: 14

i have a circuit for a boost converter by uzzors but i see people are saying it is quite low power and it takes a long time to charge a big cap bank
how could i improve its output power or its efficiency
is it the inductance
the switching frequency
the duty cycle
or is it a mixture if so which and how can i calculate it

MArked One

Sun Aug 05 2012, 08:35PM

Registered Member #3688 Joined: Mon Feb 14 2011, 07:39PM
Location: Europe
Posts: 38

I was thinking about this problem, And came to two Alternative options (to boost converters or inverters):

What if the 12v is used to drive An electric motor (the more efficient the better) and the motor's shaft is coupled to the shaft of An identical motor, which would Act As An Alternator. The output could be used to drive A transformer, and the resulting frequecy would be A function of the motor's speed.

Any guesses on efficiency?
Helpful equations?

The other Approach would be to use ultracaps and low voltage SLAs and not to use converters At All. The trigger would have to be more complex than An SCR though due to the Vdrop.

Kind Regards,
Ivan Kozlov

brandon3055

Sun Aug 05 2012, 10:45PM

Registered Member #4548 Joined: Mon Apr 23 2012, 03:52AM
Location: tasmania
Posts: 271

You can get small 150w inverters really cheap and they are basically gust an smps with a dc-ac converter on the output

Pieznice29

Wed Aug 08 2012, 07:48PM

Registered Member #3918 Joined: Sun May 29 2011, 08:42PM
Location:
Posts: 34

As a few have mentioned before, almost all 12-240v inverters have an internal 300V DC bus which is then chopped up to form a sine wave. You could just tap that directly.

Dr. ISOTOP

Wed Aug 08 2012, 11:44PM

Registered Member #2919 Joined: Fri Jun 11 2010, 06:30PM
Location: Cambridge, MA
Posts: 652

Pieznice29 wrote ...

As a few have mentioned before, almost all 12-240v inverters have an internal 300V DC bus which is then chopped up to form a sine wave. You could just tap that directly.

This.
Or you could rectify the output directly for a plug-and-play solution.

josh1234

Thu Aug 09 2012, 12:43PM

Registered Member #5969 Joined: Mon Jul 30 2012, 09:27PM
Location: ringwood
Posts: 14

but i was thinking about using an inverter so i can run it of a battery so it will be portable

brandon3055

Fri Aug 10 2012, 03:04AM

Registered Member #4548 Joined: Mon Apr 23 2012, 03:52AM
Location: tasmania
Posts: 271

Have a look at some of these

jpoopdog

Sun Nov 04 2012, 11:33PM

Registered Member #6188 Joined: Wed Aug 15 2012, 08:34AM
Location:
Posts: 23

josh1234 wrote ...

but i was thinking about using an inverter so i can run it of a battery so it will be portable

From the looks of things i dont think you are capable of building an inverter, or at least sourcing the components, your just looking for someone to directly say "yes, an inverter will work".

Using an inverter is a bad idea , unless you were to convert the 120/240vAC into something like 500v using a transformer, then rectifying that into your capacitor bank, in which case you simply buy an inverter that can give you the amperage you desire.
Tell me though, what is the voltage/capacity of the bank you wish to charge?

The ZVS is a good design which i think you can change to put more current through. However, i myself am going with this one http://www.instructables.com/id/DC-DC-HV-Boost-Converter/ , with this one i beleive that it is only limited by how much power your supply can provide, as well as the mosfets maximum current. Whatsmore this design is extremely small and wont take up so much space, so it wont matter if you have big bulky batteries attached to your charger, also, it turns off when the target voltage is reached, unlike your inverter which might explode or something if you overcharge the capacitor bank.
the mazzili ZVS i think put out 40W, this one though can apparently do 85W or more, again, limited by the batteries maximum output.

josh1234

Tue Nov 06 2012, 04:00PM

Registered Member #5969 Joined: Mon Jul 30 2012, 09:27PM
Location: ringwood
Posts: 14

the cap bank is 5000uf at 400v

vk2fro

Fri Nov 16 2012, 09:18AM

Registered Member #3930 Joined: Sun Jun 05 2011, 07:27PM
Location: Sydney, Australia
Posts: 33

The ZVS design is both a good design and so simple you can build it dead bug style like I did to see if I had an issue with my PCB. There are minimal parts and the transformer can be easily obtained by gutting an old tube television for its flyback. The first arcs from mine made me jump and they melted the end of the wire - plenty of power once through a bridge of fast diodes to charge caps.

It is a good idea to monitor the voltage though - the ZVS wont shut off by itself, unless you build the uzzors2k design which has voltage sensing.

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