DC to DC Boost Converter - 12V to 96V at >9 amps

#12

Joined Nov 30, 2010
18,223
I never mentioned weight as one of the problems since it was not listed as a requirement.
True, but my mind sees, "180 amps" and goes straight to, "That's a minimum wire size of 00 AWG."
Quite an inductor!

Then I thought about the transformer (that won't be required for this circuit) and went off the track.
Sorry. My bad.
 

Papabravo

Joined Feb 24, 2006
17,292
True, but my mind sees, "180 amps" and goes straight to, "That's a minimum wire size of 00 AWG."
Quite an inductor!

Then I thought about the transformer (that won't be required for this circuit) and went off the track.
Sorry. My bad.
No need for apologies, I wasn't trying to state a conclusion. My only purpose was to get the OP/TS to think about the implications of his requirements.

[RANT ALERT]
Many people who want circuits to do voltage conversion start off by engaging in magical thinking. The first precept of magical thinking is that there is no cost to doing anything they can imagine. When we try to confront them with the inevitable consequences of their fantasies we get excoriated for being negative or opinionated. If we choose to ignore the request we get whiny pleas for attention because nobody will respond. Why do we do what we do? We do it because maybe, just maybe there is the occasional individual who is actually interesed in making an effort and learning some useful "skilz".
[/RANT ALERT]

Maybe one of these days I'll start to work on my atrocious spelling habits. NOT!
 

#12

Joined Nov 30, 2010
18,223
Your spelling doesn't trigger my spell checker. o_O

Meanwhile, I feel obligated to post these, "mea culpas" rather than let the public record at AAC suggest that I posted bad information and I still think I'm right.
I am wrong often enough, but I'm not too arrogant to learn or too vain to admit my mistakes.
 

tcmtech

Joined Nov 4, 2013
2,867
True, but my mind sees, "180 amps" and goes straight to, "That's a minimum wire size of 00 AWG."
Quite an inductor!
Not necessarily. If you ever look at a huge industrial SMPS or other similar such HF based power supply systems you will they they use considerably smaller gauges in their inductors and transformers despite carrying that high of currents.

Its pretty common to find devices pushing 200 - 300 amps through 2 - 4 ga copper or even aluminum in magnetic circuits without problems.
 

#12

Joined Nov 30, 2010
18,223
All I have to go on is the NEC...so I tried 90C for temperature and guessed. Finding the REAL size needed requires knowing how hot it's going to get in the windings and what's the best temperature wire you can buy.
 

#12

Joined Nov 30, 2010
18,223
"Skilz" must be a midwestern colloquialism.;)
Maybe the quotation marks hid it from the spell checker.
No, it's showing up as, "wrong" right now.
Oh well. I don't really care. I can understand what you mean. That's all that counts.
 

Papabravo

Joined Feb 24, 2006
17,292
Actually I know how to spell pretty well, but I was feeling a bit "smart alecky".

"Don't write naughty words on wall if you can't spell"
-- Ton Lehrer

 

tcmtech

Joined Nov 4, 2013
2,867
All I have to go on is the NEC...
Unfortunately the NEC coding is only good for residential and commercial power systems and does not apply to the actual inner workings of most every device that may be connected to them. :p

Just look at automotive wiring for a good example of where its totally legal to run 30 - 40+ amps though a 12 gauge or even 14 ga wire and to pull 400 - 500 amps through a 4 ga wire for a starter motor that gets its power from a DC solenoid that has the equivalent to a butter knife blade laying on its side for contacts. :eek:
 

Brownout

Joined Jan 10, 2012
2,390
my mind sees, "180 amps" and goes straight to, "That's a minimum wire size of 00 AWG."
Quite an inductor!
I wouldn't put too much faith in the 180 Amps figure. That would only be peak current and made lower by good design. Average current would be closer to the 90 Amps from earlier calculations, which would probably require 16Ga or so wire. The gauge would depend on wire resistance, length ( which would be pretty short ) and heat transfer, which could be aided with forced air cooling.

A more serious, or at least as serious, concern would be saturation of the core. Having a core physically large enough to avoid saturation and conduct excess heat would probably be the dominant determinant of core size. However, ferrite cores aren't heavy.
 
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Thread Starter

danielb33

Joined Aug 20, 2012
105
I will have to look into that! I would have lots of ripple but that might work.

I am negotiating 48V motors. I think we will run into too many issues with 96V after further investigation.

One solution is the LT3784 - parallel converter option. Up to 12 phases. Reliable and efficient. Additionally, the FAE from LT come over and inspect simulations, PCB layout, components selection, etc. Good way for a short time to market. This should handle 48V at 18A no problem, assuming good PCB layout w/ low L. Those boost converters take some serious current spikes.
 

Brownout

Joined Jan 10, 2012
2,390
Ripple may or may not be a problem. You might find that you don't need much filtering if you run it past the motor manufacturer.
 

tcmtech

Joined Nov 4, 2013
2,867
If you have to ask me what I am asking relating to cost analysis justification for over complicating a simple concept of powering a ~1 hp motor form a 12 DC power source I am pretty sure I am done with this thread. :(
 

ronv

Joined Nov 12, 2008
3,770
The other thing to consider is the stall current at start up. It will be much higher than the run current.
The only advantage of the higher voltage motor is that the IR losses are lower. But you will throw all that away with the drops in the converters.
Do you have a couple of motors that you are comparing? Maybe you could share that information.
 

Thread Starter

danielb33

Joined Aug 20, 2012
105
I thought I mentioned earlier. The end product is for the USARMY, Ford, Chevy, and RAM trucks. http://ezylift.com/ I did the design for the Polaris/John Deer/Bobcat vehicles. This is fine with 12V in 12V to motor. But replacing the hydraulic actuators with DC actuators on the trucks means more heat --> we needs higher motor efficiency. The cost of electronics will still be cheaper than using hydraulics.
 

tcmtech

Joined Nov 4, 2013
2,867
But replacing the hydraulic actuators with DC actuators on the trucks means more heat --> we needs higher motor efficiency. The cost of electronics will still be cheaper than using hydraulics.
Wait a minute angin. This does not add up either.:confused:
If you are getting more heat that means less overall system efficiency meaning that your linear actuator motors doing the work directly are less mechanically efficient than what the single motor and hydraulic pump with cylinders are already running at.

Now here's the thing I have worked with all sorts of electric motors and hydraulic systems and on the simple power VS efficiency for linear force a simple off the shelf hydraulic power pack and a cylinder will walk all over any electric linear actuator in terms of efficiency, robustness, service life and cost for equal work done.

Then to add to that any decent brand of DC electric motor regardless of size input will come in multiple voltages in the same frame size. IE a commercial 90 - 180 VDC motor and a 12 volt DC motor of identical speed and mechanical power come inexactly the same package and have exactly the same average efficiency.

See for yourself.https://motorsandcontrol.com/products/baldor-motors/dc-motors/?p=3

12 volt = 84%, 180 volt = 84%

Also looking at your linked websites for the EZ lift systems electrical/energy efficiency is not a concern let alone a valid selling point. Durability and service life are.
BTW looking at the prices for these things cost competitiveness is apparently is not much of a factor in there either. :rolleyes:
 
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