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Discussion Starter #1
Hello,
I am not sure if anyone is interested in this, but I am in the process of building a 10kW Bi-directional buck-boost converter (48V - 500V).

This will be used as a battery pack simulator (replacing my large stack of AGM batteries, which are retired from my truck)... I repair motor controllers and battery chargers ( http://www.wolftronix.com/EV.htm ), so a large variable voltage bi-directional buck-boost converter is useful to me. ;)

The bi-directional buck-boost converter is based on a Prius inductor and parts from a Solectria UMOC440 that had an exploded logic board (5V regulator failed and exposed all logic parts to 12V).

Lots of pics:
http://www.wolftronix.com/buckBoost/index.htm

Videos:
http://www.youtube.com/playlist?list=PLQdu_G7xyFIT2YItJQL1JZujxFJl6LOWL

If I could aquire a few Prius inductors, I have always wanted to build a large poly phase bi-directional buck-boost converter and hook it up to a bank of ultra/super caps. Then have a large portion of acceleration and regen go into the cap bank, instead of the battery pack. ;)
 

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Hello,
I am not sure if anyone is interested in this, but I am in the process of building a 10kW Bi-directional buck-boost converter (48V - 500V).

This will be used as a battery pack simulator (replacing my large stack of AGM batteries, which are retired from my truck)... I repair motor controllers and battery chargers ( http://www.wolftronix.com/EV.htm ), so a large variable voltage bi-directional buck-boost converter is useful to me. ;)

The bi-directional buck-boost converter is based on a Prius inductor and parts from a Solectria UMOC440 that had an exploded logic board (5V regulator failed and exposed all logic parts to 12V).

Lots of pics:
http://www.wolftronix.com/buckBoost/index.htm

Videos:
http://www.youtube.com/playlist?list=PLQdu_G7xyFIT2YItJQL1JZujxFJl6LOWL

If I could aquire a few Prius inductors, I have always wanted to build a large poly phase bi-directional buck-boost converter and hook it up to a bank of ultra/super caps. Then have a large portion of acceleration and regen go into the cap bank, instead of the battery pack. ;)
I like your idea of a polyphase converter, would you isolate the motor windings from each other? If so would you really need THE Inductors? ;)
I did some experiments on a similar topology and quite few others involving capacitors but it became difficult mainly due to lack of equipment and (lack of) programming skills.
I did find that PWM was one of the least efficient ways to control a motor, but the easiest under varying torque load and rpm conditions.

I will keep an eye on what you are up to with great interest.

also if your batteries internal resistances are climbing use a capacitor discharge or inductive kickback circuit, you may be surprised how well these can restore lead acids and nicads and they are easy to make from spare parts. My preference for lead was with discharging a decent size capacitor charged to about twice the battery voltage or slightly under across the battery using a mosfet and a comparator - works great with a solar panel even under moonlight! there are lots of circuits available from the pseudoscience crowd.
 

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Discussion Starter #6
I like your idea of a polyphase converter, would you isolate the motor windings from each other? If so would you really need THE Inductors? ;)
The poly phase was because the Prius inductor can only handle around 85kW peak, so with 2 or more inductors you can increase the peak and continuous power.

Ideally the power converter should be able to provide peak power for 30 seconds (or how ever long it takes to get up to highway speed), and receive regen power to go from highway speed to a stop.

Then the battery pack only ever sees the 15kW or so it takes to maintain highway speed. ;)

Same with the stop and go city driving, ideally, the super/ultra caps provide a buffer for the battery pack.

This is the type of capacitor module I am thinking of:
http://www.maxwell.com/images/documents/hq_48v_ds10162013.pdf
They show up on eBay every once in a while, sometimes inside large UPS systems that have been pulled from service, (you have to look at the pics, most salvage sellers assume they are a battery).


However what you are proposing is what the Solectria (Brusa) AMC2XX motor controllers did:
http://www.wolftronix.com/amc230_514/images/IMG_2825.jpg

Note the 6 inductors (3 in front, 3 in back), split between the motor phases, they implemented the bi-directional buck-boost converter in the motor controller.

The battery stack voltage is 216V and the motor runs around 150V... So they would run in buck mode while accelerating, and then boost mode during regen.

That AMC230 was in sad shape, here is the repair log (I have been told it is a good read), for those that are interested:
http://www.wolftronix.com/amc230_514/index.html

Thanks,
Wolf
 

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Discussion Starter #8
I was actually suggesting that you could use the inductance of the winding in the motor, instead of using a separate one.
A bi-directional buck-boost converter is not a motor controller...

It just converts one voltage to another, and allows boost in one direction and buck in the other direction.

i.e. in the Prius it is used to take 200V battery stack and boost it to the 600V that the motor controller works at, and during regen it takes in the 600V and bucks it down to 200V to charge the battery pack.

A motor controller (inverter) still drives the motor.

[Battery] <--> [bi-directional buck-boost] <--> [Motor Controller] <--> [Motor]

Hope that helps,
Wolf
 

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I know a boost converter is not a controller,

I was suggesting that if you were connecting the two together why make it a separate system? use the inductances already in the motor.

a boost converter controller

do you comprehend what im getting at?
 

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Discussion Starter #10
I know a boost converter is not a controller,

I was suggesting that if you were connecting the two together why make it a separate system? use the inductances already in the motor.

a boost converter controller

do you comprehend what im getting at?
No, I don't think I comprehend what you are suggesting...

Perhaps a schematic would help me understand your concept.

Thanks,
Wolf
 

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Sure, this is one of them, there are many ways to do the same thing that achieve different current or voltage on the inductor (read that as time to discharge time to charge in motor applications)

The difficulty is that it only works at one speed, at least without switching capacitors around, and also it does not give true 3 phase as you are driving each coil separately not as a pair. so the torque it provides is not like the norm. which is good in some respects and not others as you can quite easily see.

Also the circuit is single sided.
 

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The poly phase was because the Prius inductor can only handle around 85kW peak...
Is that max dc-dc power at inductor saturation? Prius boost converter is rated at about 22KW max. I am also looking at Prius inductors to build 100KWp 150V to 400V buck-boost converter using maybe 3 coils and half bridges with common cap bank. But those inductors are kind of hard to find.
 

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Discussion Starter #13
Is that max dc-dc power at inductor saturation? Prius boost converter is rated at about 22KW max. I am also looking at Prius inductors to build 100KWp 150V to 400V buck-boost converter using maybe 3 coils and half bridges with common cap bank. But those inductors are kind of hard to find.
The inductor I used is from a 2nd generation Prius, it should be able to run 250A RMS peak... How I came up with the numbers at the 21 minute mark:
http://youtu.be/O8CSRCnCm3M

Power density will depend on what your lower voltage is...
i.e. 340V to 500V boost, would be 85kW...

So assuming 250A * 150V = 37.5kW Then three inductors would be able to operate 100kW peak.

Finding the saturation current is a bit more tricky...
In this video I measured the inductance to be 371uH:
http://youtu.be/CKiQwzH4n-E

Given the inductance, resistance of the coil, battery and IGBT Vsat, and knowing max conduction time is 600uS (60% at 1khz), you could calculate the peak inductor current in the Prius... And then assume saturation is a few percent above that.

Or you could measure it... But you would need to find a resistive load that can handle 300+ amps... And then hope that it does not fail, cause of all that energy stored in the inductor will make some serious high voltage arcs. :D

Or, you could be like me and guess Saturation current is probably around 300A. ;)

Either way, three inductors looks fine... Two inductors would probably saturate... Unless you upped to 200V on the input.

Hope that helps,
Wolf
 

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Any tips or hints where to find such Prius inductors for a project here.
I just found your interesting thread regarding the converter.

Some time before a company which I knew cleared their stock and I reserved several inductors (more than 20 pieces) for 100kW+ which should go to waste.
Unfortunately some employee there didn't recognize the reservation and all the parts were recycled before I could pick them up :-((

As I don't know the Prius hardware in detail, perhaps some details where those parts are included would be fine.
I assume its a combined inverter DC boost unit ?
 

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So I can assume that ALL Prius inverters include such coil ?
As I said I am not familiar with the Prius hardware and if there are different models which might be with or without the boost converter due to different battery configs or whatever.
 

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Discussion Starter #17
So I can assume that ALL Prius inverters include such coil ?
As I said I am not familiar with the Prius hardware and if there are different models which might be with or without the boost converter due to different battery configs or whatever.
I know the Gen2 2003–2009 Prius have one, because that is how I got mine...

If you search for "prius inverter teardown"

You can find some internal pics of the inverter:
http://techno-fandom.org/~hobbit/cars/ginv/561unit.jpg
The inductor is in the upper right, next to the three phase motor connection.

Hope that helps,
Wolf
 

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Thank you very much for your information.
Maybe I will have a look at the market and find such an inverter.
But first I will calculate if the inductor fits.
I already build such an buck/boost for battery testing but with much lower voltages.
It was able to test the very old SAFT NiCads on 4 parallel channels with charging and discharging.
 

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Discussion Starter #19
Thank you very much for your information.
Maybe I will have a look at the market and find such an inverter.
But first I will calculate if the inductor fits.
I already build such an buck/boost for battery testing but with much lower voltages.
It was able to test the very old SAFT NiCads on 4 parallel channels with charging and discharging.
No problem. :)

I will finish mine, after I get my truck running on Lithium, Spring is almost here!
 
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