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Old 12-09-2014, 03:59 PM   #1411 (permalink)
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Quote:
Originally Posted by P-hack View Post
one thing that does occur to me, in lieu of a boost converter (and maybe this is what is in your matlab) is to repeatedly reverse the polarity of the battery pack itself via full bridge a-la square wave when feeding the inverter bus. Extra losses but 1/2 the batteries for a given bus voltage.
That would reassemble a line voltage doubler (I use them to operate 3ph equipment from a single phase supply).

And you don't need a full bridge, just two diodes on one phase with neutral being the center point and each diode charging a series capacitor.

I posted a improved version of that on #1407, along with the capacitor ripple waveform. Just remember that using diodes its not possible to regenerate back to the source (Battery)

Using the circuit on #1407 one could technically triple the output as well. Just add another capacitor/diode/IGBT

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Old 12-09-2014, 04:16 PM   #1412 (permalink)
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Still, i'd like to salvage a few of these and a half bridge igbt for buck-boost
(or just figure out how to make a nice high power inductor)
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Old 12-09-2014, 06:09 PM   #1413 (permalink)
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What frequency did toyota use with the boost/buck converter? I was planning on adding an extra IGBT along with an inductor. I've wound my own before, but it was extremely annoying as it was a toroid, and I had no special equipment. I'd like to figure it out with a copper sheet and maybe some kapton tape or nomex. If the materials are under $400, it would be better than what's available commercially, as far as I know.
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Old 12-09-2014, 06:39 PM   #1414 (permalink)
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hobbit says 20khz
http://techno-fandom.org/~hobbit/cars/ginv/VH.html

from what I can see, one gen 2 inductor is good for ~25kw.
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Old 12-10-2014, 02:17 PM   #1415 (permalink)
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also interesting to read:
http://www.mouser.com/pdfDocs/Cree-Power_Article_4.pdf

SIC mosfets, small switching power, 100khz, small inductors, you might need a better CPU though (arm? st?). Will cloudstash some notes here if you don't mind.

per 5kw
C2M0080120D mosfet $15
C4d10120d diode $11
400uh Fe-Si-Al AWG12*1*55Ts OD:63 x HT:26 $12 (Kool M?)
looks like 132nh/t^2 @ 100khz, so maybe a 0077616A7 core?
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Old 12-10-2014, 04:32 PM   #1416 (permalink)
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It is true that running at a higher switching frequency allows you to reduce the inductor size.

Some years ago, I made a 1kW boost converter for a lithium battery charger. At the time, Infineon made an excellent control IC that was made specifically for a MPPT, high power factor, high efficiency boost converter. At the time I used a SiC diode, but SiC Mosfets weren't available.

They had excellent app notes regarding inductor sizing and the frequency relationship.

The DS pic would be quite capable of doing this. I don't see why an ARM or ST controller is necessarily better.

It may be possible to use a stand-alone controller with simple controls that could be administered by the main motor controller.

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Old 12-10-2014, 04:51 PM   #1417 (permalink)
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I was going to try a dsPIC that's 70 MIPs, and has 14 or 16 PWM channels I believe, and can do 8 simultaneous A/D conversions. It's designed for driving 2 ACIMs or PMSMs. 512k of program flash and 56k of data memory I think. It's the dspic33ep series, which has a bunch to choose from. I just wasn't thrilled with using a 3.3v micro.
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Old 12-10-2014, 05:37 PM   #1418 (permalink)
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Quote:
Originally Posted by MPaulHolmes View Post
I was going to try a dsPIC that's 70 MIPs, and has 14 or 16 PWM channels I believe, and can do 8 simultaneous A/D conversions. It's designed for driving 2 ACIMs or PMSMs. 512k of program flash and 56k of data memory I think. It's the dspic33ep series, which has a bunch to choose from. I just wasn't thrilled with using a 3.3v micro.
I use everything at 3.3V, makes no difference whatsoever.

I was digging F & T website and I've come across this. Not sure if they sell them tough:





Looks like a clean addition to the inverter!
Elko-Bnke - FTCap Fischer & Tausche Capacitors Group

Here's a different type, same company:

http://www.ftcap.de/index.php/fischerlink-archiv.html
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Old 12-10-2014, 06:04 PM   #1419 (permalink)
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Quote:
Originally Posted by e*clipse View Post
It is true that running at a higher switching frequency allows you to reduce the inductor size.

Some years ago, I made a 1kW boost converter for a lithium battery charger. At the time, Infineon made an excellent control IC that was made specifically for a MPPT, high power factor, high efficiency boost converter. At the time I used a SiC diode, but SiC Mosfets weren't available.

They had excellent app notes regarding inductor sizing and the frequency relationship.

The DS pic would be quite capable of doing this. I don't see why an ARM or ST controller is necessarily better.

It may be possible to use a stand-alone controller with simple controls that could be administered by the main motor controller.

- E*clipse

I'm sure these SiC mosfets are not the most affordable thing. I've looked into a few in the past and they were only available in TO-247 and similar, with a significantly higher price than a comparable IGBT.

The other issue is finding a core that can withstand such high frequencies. Has anyone done some research on that? It appears most are only available to OEM's with a MOQ of a few 1000's
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Old 12-10-2014, 06:18 PM   #1420 (permalink)
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I have spent several thousand dollars on massively paralleled TO-247 package based controller failures. haha. That's why I'm taking a few year break and only using those chassis mount components until I heal emotionally.

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