fast cap bank charger
josh1234, Wed Aug 01 2012, 12:31PMcould i use a simple 12vdc to 240vac inverter and then rectify the output to make a fast cap bank charger you could make a high power output 150w in a small package
Re: fast cap bank charger
blackgrunge, Wed Aug 01 2012, 04:58PM
It depends on voltage you want to charge the capacitor bank at. The caps I was using for my design were rated for 450v so I was charging them to ~360v off of 120v mains power. So obviously if you need to charge your caps at above ~240v you would need some sort of voltage multiplying rectifier. If you're trying to charge your caps at 240vdc then at 150w you need diodes in your rectifier rated for at least 240v and ~1amp.
I assume if you need to use an inverter then you are trying to charge you cap bank with a car battery which I would advise against since the more you deplete the battery the lower the voltage is going to be unless you use a car battery voltage regulator (which are ~$20). Honestly, you would be much better off charging your cap bank off of mains power with a step up or step down transformer it's much simpler and much cheaper (no inverter and no voltage regulator).
blackgrunge, Wed Aug 01 2012, 04:58PM
It depends on voltage you want to charge the capacitor bank at. The caps I was using for my design were rated for 450v so I was charging them to ~360v off of 120v mains power. So obviously if you need to charge your caps at above ~240v you would need some sort of voltage multiplying rectifier. If you're trying to charge your caps at 240vdc then at 150w you need diodes in your rectifier rated for at least 240v and ~1amp.
I assume if you need to use an inverter then you are trying to charge you cap bank with a car battery which I would advise against since the more you deplete the battery the lower the voltage is going to be unless you use a car battery voltage regulator (which are ~$20). Honestly, you would be much better off charging your cap bank off of mains power with a step up or step down transformer it's much simpler and much cheaper (no inverter and no voltage regulator).
Re: fast cap bank charger
Ben Solon, Wed Aug 01 2012, 06:02PM
Or if you are trying to be semi portable, a smps dcdc converter is a much better option. A couple hundred watts is easily acomplished without a bulky inverter, and the best part is that it can be regulated to the volt.
Ben Solon, Wed Aug 01 2012, 06:02PM
Or if you are trying to be semi portable, a smps dcdc converter is a much better option. A couple hundred watts is easily acomplished without a bulky inverter, and the best part is that it can be regulated to the volt.
Re: fast cap bank charger
Yanom, Thu Aug 02 2012, 06:56PM
I built a CW circuit that gives me ~300v and ~600v outputs from the 120VAC wall socket.
Yanom, Thu Aug 02 2012, 06:56PM
I built a CW circuit that gives me ~300v and ~600v outputs from the 120VAC wall socket.
Re: fast cap bank charger
josh1234, Thu Aug 02 2012, 06:59PM
do you have any circuit diagrams for a good smps dc/dc converter that i could use to charge a cap bank
josh1234, Thu Aug 02 2012, 06:59PM
do you have any circuit diagrams for a good smps dc/dc converter that i could use to charge a cap bank
Re: fast cap bank charger
DerAlbi, Fri Aug 03 2012, 07:16AM
Hi guys
I am currently thinking about designing a microcontroller based SMPS in fullbridge configuration. I try to get 600W out of 24V. Target voltage is about 400V. With this Voltage i use a stepdown topology to charge the Capacitor with constant _Power_, This should ease the controll of the fullbridge due to constant load operation and should charge any capbank in no time
But: building an efficient topology is very hard! I would like to utilize Zero Voltage Switching, however this is not easyly done with microcontroller since sensing the voltage transition is not easy.
if someone would love to help... this would be a goog community project
DerAlbi, Fri Aug 03 2012, 07:16AM
Hi guys
I am currently thinking about designing a microcontroller based SMPS in fullbridge configuration. I try to get 600W out of 24V. Target voltage is about 400V. With this Voltage i use a stepdown topology to charge the Capacitor with constant _Power_, This should ease the controll of the fullbridge due to constant load operation and should charge any capbank in no time
But: building an efficient topology is very hard! I would like to utilize Zero Voltage Switching, however this is not easyly done with microcontroller since sensing the voltage transition is not easy.
if someone would love to help... this would be a goog community project
Re: fast cap bank charger
Harry, Fri Aug 03 2012, 09:02AM
Try the ZVS (Mazzili) driver, it's very efficient and powerful. You'll have to wind your own transformer though round a ferrite core.
Harry, Fri Aug 03 2012, 09:02AM
Try the ZVS (Mazzili) driver, it's very efficient and powerful. You'll have to wind your own transformer though round a ferrite core.
Re: fast cap bank charger
Forty, Fri Aug 03 2012, 02:25PM
to answer your question: Yes. that should work.
rectified 240ac will give you a peak dc voltage of about 340v, so as long as your caps are rated higher than that you should be alright.
I couldn't find any dc-dc converters that gave 300+ volts(from a =< 24v input) at a decent power.
The mazilli circuit does make a powerful charger but it requires some sort of regulation and auto turn off (something I haven't quite found a reliable method for) if you don't want to watch the voltage and shut it off manually
Forty, Fri Aug 03 2012, 02:25PM
to answer your question: Yes. that should work.
rectified 240ac will give you a peak dc voltage of about 340v, so as long as your caps are rated higher than that you should be alright.
I couldn't find any dc-dc converters that gave 300+ volts(from a =< 24v input) at a decent power.
The mazilli circuit does make a powerful charger but it requires some sort of regulation and auto turn off (something I haven't quite found a reliable method for) if you don't want to watch the voltage and shut it off manually
Re: fast cap bank charger
blackgrunge, Fri Aug 03 2012, 03:40PM
To be honest, it's just not practical to charge off of a 12v or even 24v dc source. At 300w were talking about 12.5 amps @ 24v or 25amps @ 12v input and to build a non-commercial dc-dc converter at those sort of power levels is going to expensive and difficult to construct. Plus you have the problem of constructing heat sinks to dissipate the heat generated by the switching
I guess it boils down to how bad you want to charge off of a battery. There are commercial options out there (for instance at lowes) for a ~300w DC-AC converter that you could then rectify+mulitply (depending on need) the output of that.
If you're wanting a circuit schematic that charges a capacitor bank from a battery you're going to be hard pressed to find a cookie cutter example out there. What your wanting is a very unique application of a boost converter. You haven't really given us what voltage you want to charge your cap bank to so there's only a limited amount of help we can provide with such limited information.
blackgrunge, Fri Aug 03 2012, 03:40PM
To be honest, it's just not practical to charge off of a 12v or even 24v dc source. At 300w were talking about 12.5 amps @ 24v or 25amps @ 12v input and to build a non-commercial dc-dc converter at those sort of power levels is going to expensive and difficult to construct. Plus you have the problem of constructing heat sinks to dissipate the heat generated by the switching
I guess it boils down to how bad you want to charge off of a battery. There are commercial options out there (for instance at lowes) for a ~300w DC-AC converter that you could then rectify+mulitply (depending on need) the output of that.
If you're wanting a circuit schematic that charges a capacitor bank from a battery you're going to be hard pressed to find a cookie cutter example out there. What your wanting is a very unique application of a boost converter. You haven't really given us what voltage you want to charge your cap bank to so there's only a limited amount of help we can provide with such limited information.
Re: fast cap bank charger
ConKbot of Doom, Fri Aug 03 2012, 09:00PM
On candlepowerforums, Ive seen someone steal the ~300VDC bus from an inverter to power a ballast that required a similar DC voltage to run a short arc (maybe UHP) bulb off of a battery.
It all depends on the inverter though. Some push/pull a modified sine wave at 12v right into a chunky transformer, some use a DC/DC to get an appropriate bus voltage and output the 120/240VAC directly from the AC line. (PWMed and filtered for pure sine, stepped and minimal filtering for modified sine)
ConKbot of Doom, Fri Aug 03 2012, 09:00PM
On candlepowerforums, Ive seen someone steal the ~300VDC bus from an inverter to power a ballast that required a similar DC voltage to run a short arc (maybe UHP) bulb off of a battery.
It all depends on the inverter though. Some push/pull a modified sine wave at 12v right into a chunky transformer, some use a DC/DC to get an appropriate bus voltage and output the 120/240VAC directly from the AC line. (PWMed and filtered for pure sine, stepped and minimal filtering for modified sine)
Re: fast cap bank charger
josh1234, Sun Aug 05 2012, 03:54PM
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
josh1234, Sun Aug 05 2012, 03:54PM
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
Re: fast cap bank charger
MArked One, Sun Aug 05 2012, 08:35PM
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
MArked One, Sun Aug 05 2012, 08:35PM
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
Re: fast cap bank charger
brandon3055, Sun Aug 05 2012, 10:45PM
You can get small 150w inverters really cheap and they are basically gust an smps with a dc-ac converter on the output
brandon3055, Sun Aug 05 2012, 10:45PM
You can get small 150w inverters really cheap and they are basically gust an smps with a dc-ac converter on the output
Re: fast cap bank charger
Pieznice29, Wed Aug 08 2012, 07:48PM
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.
Pieznice29, Wed Aug 08 2012, 07:48PM
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.
Re: fast cap bank charger
Dr. ISOTOP, Wed Aug 08 2012, 11:44PM
Or you could rectify the output directly for a plug-and-play solution.
Dr. ISOTOP, Wed Aug 08 2012, 11:44PM
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.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.
Or you could rectify the output directly for a plug-and-play solution.
Re: fast cap bank charger
josh1234, Thu Aug 09 2012, 12:43PM
but i was thinking about using an inverter so i can run it of a battery so it will be portable
josh1234, Thu Aug 09 2012, 12:43PM
but i was thinking about using an inverter so i can run it of a battery so it will be portable
Re: fast cap bank charger
brandon3055, Fri Aug 10 2012, 03:04AM
Have a look at some of these
brandon3055, Fri Aug 10 2012, 03:04AM
Have a look at some of these
Re: fast cap bank charger
jpoopdog, Sun Nov 04 2012, 11:33PM
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.
jpoopdog, Sun Nov 04 2012, 11:33PM
josh1234 wrote ...
but i was thinking about using an inverter so i can run it of a battery so it will be portable
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.
Re: fast cap bank charger
josh1234, Tue Nov 06 2012, 04:00PM
the cap bank is 5000uf at 400v
josh1234, Tue Nov 06 2012, 04:00PM
the cap bank is 5000uf at 400v
Re: fast cap bank charger
vk2fro, Fri Nov 16 2012, 09:18AM
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.
vk2fro, Fri Nov 16 2012, 09:18AM
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.
Re: fast cap bank charger
Ash Small, Tue Nov 20 2012, 06:17PM
For a cheap and simple solution, I'd try a cheap £10 150W inverter with a Villard doubler on the output, one diode and one capacitor.
It can't get any simpler than that.
Ash Small, Tue Nov 20 2012, 06:17PM
For a cheap and simple solution, I'd try a cheap £10 150W inverter with a Villard doubler on the output, one diode and one capacitor.
It can't get any simpler than that.
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