# AC VFD 30hp and a 10HP motor workable system?



## Tesseract (Sep 27, 2008)

You haven't really given us any of the important details to answer your essential question, _is this doable?_

Practically speaking, it isn't simply because a VFD expecting a 480VAC input will need a 480 x sqrt(2) volt DC input to generate maximum output. That's a 680V battery pack. The downside here is obvious, but the potential upside is that it will only take 10-20 A/hr capacity batteries to get a usable 30-40mi of range.

Of course, this all pre-supposes that the ABB inverter can run on *DC*... Theoretically it can, because all inverters rectify the incoming AC, anyway, but many inverters use a small 50/60Hz transformer to power themselves. Now, there are ways to get around this but at some point you just gotta draw the line and say this is way more trouble than it's worth, especially if you don't have a clue (no offense intended, btw, we are all clueless about most things, after all).


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## frodus (Apr 12, 2008)

Also, DC and AC motors are rated continuous output. See if you can find the peak Hp of the motor anywhere, or from the manufacturer.

Tesserect is right though, you're gonna need WAY more than 480VDC to run that, and thats assuming you can tap into the DC-Bus (DC-Link). Some VFD's allow this, so you can attach a brake resistor and do dynamic braking if the voltage spikes on regen/braking. I don't know if you can just tap the bus and run it though.

480V is a lot of voltage, but Tesserect is right again, you don't need much Ah capacity to go far.


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## Chris Sandberg (Sep 13, 2008)

Hello Group, 
Thanks for the responses guys It sounds like this is more than a simple modification to the VFD. And 680vdc is way to big and one hell of a lot of 12vdc batteries for any EV. So I think I will go back to designing my conversion in straight DC and a safe voltage. If anyone thinks this still might work let me know but for now this idea is Dead.
TX Chris


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## frodus (Apr 12, 2008)

Chris Sandberg said:


> Hello Group,
> Thanks for the responses guys It sounds like this is more than a simple modification to the VFD. And 680vdc is way to big and one hell of a lot of 12vdc batteries for any EV. So I think I will go back to designing my conversion in straight DC and a safe voltage. If anyone thinks this still might work let me know but for now this idea is Dead.
> TX Chris


650 isn't impossible, just use small batteries.... like the ones I originally used (SLA 1116 by Power Patrol, 18Ah 12V), they're 13lbs. That'd only be 7-800lbs.


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## Chris Sandberg (Sep 13, 2008)

Hello Frodus, 
So you are saying that the vfd is usable I just need to work on the DC buss connection and it is their at 500V and the rectifier is connected to a fairly large transformer say the size of a grapefruit Florida size lol. I am not the sharpest pencil in the jar but as an electrician I get the basic ideas. Maybe this plan isn't dead yet I will try and get as much info on the VFD and start looking into the DC connection. What else could I be looking at on the controller side of things? TX for the battery idea I will check on that tonight after supper. I will talk to you soon.
TX Chris a newbie / beginner


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## frodus (Apr 12, 2008)

well, we can't know if you can use DC straight into the VFR, you have to do some research on that VFD, maybe contact the manufacturer and see if they'll help you with this application.


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## akbnkb (Feb 2, 2009)

Tesseract said:


> You haven't really given us any of the important details to answer your essential question, _is this doable?_
> 
> Practically speaking, it isn't simply because a VFD expecting a 480VAC input will need a 480 x sqrt(2) volt DC input to generate maximum output. That's a 680V battery pack. The downside here is obvious, but the potential upside is that it will only take 10-20 A/hr capacity batteries to get a usable 30-40mi of range.
> 
> Of course, this all pre-supposes that the ABB inverter can run on *DC*... Theoretically it can, because all inverters rectify the incoming AC, anyway, but many inverters use a small 50/60Hz transformer to power themselves. Now, there are ways to get around this but at some point you just gotta draw the line and say this is way more trouble than it's worth, especially if you don't have a clue (no offense intended, btw, we are all clueless about most things, after all).


Well i have some good news to add to this. I own a AB powerflex 70 E Frame and it is rated at 50 HP peak. With this VFD, it can be set up to run along side others of the same make with a common DC power supply. So some can run off DC input. this model also has regen braking. It will also off 240-480 VAC so if i remember right this will take an input of 280-715 VDC (dont quote me on that, its close but off the top of my head) i got this unit not working so im trying to fix it. nothing is burn just dead. i put 240 ac in and the bridge rectifier does its job turning it in dc, the IGBT is good i just dont have any control power. this model feeds off the DC buss for control power it runs through a 24 VDC regulator for the control power. When i first opened the cover i was shocked at how simple AB made this. I mean it has at most 20-25 components. i would highly recomend others to check this unit out. also if anyone may have some info on the control power on this i could use the help. im fairly new with this kind of trouble shooting.


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## Wattmotion (Sep 10, 2008)

akbnkb said:


> Well i have some good news to add to this. I own a AB powerflex 70 E Frame and it is rated at 50 HP peak. With this VFD, it can be set up to run along side others of the same make with a common DC power supply. So some can run off DC input. this model also has regen braking. It will also off 240-480 VAC so if i remember right this will take an input of 280-715 VDC (dont quote me on that, its close but off the top of my head) i got this unit not working so im trying to fix it. nothing is burn just dead. .


Did you ever have any luck with this? I am in the process of stripping the front end of a GE /FUJI 30 Hp drive to run a 10 HP motor as well. According to the spec's, this drive will continue to run down to 197 volt DC (230 volt input drive) which is very doable as far as battery pack size.


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## Batterypoweredtoad (Feb 5, 2008)

3 prius packs in series would get you over 600V. Wouldn't be much capacity though. I guess you could use the headway 10ah batteries.


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## aeroscott (Jan 5, 2008)

check out thread allen bradley 98kva in controllers last post 4/15/10 .


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## Salty9 (Jul 13, 2009)

Check this video. 

http://www.youtube.com/user/etischer

This URL would be good reading for anyone considering building an EV. It is very well documented.

http://etischer.com/awdev/


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