# Is there a way to get a vfd to run at lower voltage



## flyn_brian (Oct 21, 2012)

I ask this because I have put the cart before the horse and bought a 3 phase drive before I bought the motor. I believe the control portion of a drive runs at a much lower voltage. So why wouldn't it be possible to trick the controller into thinking its running at the voltage required, while in effect running it at the voltage needed by the motor. I know that industrial drives are so far advance that I think it make economical sense to use them.


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## Tesseract (Sep 27, 2008)

flyn_brian said:


> I...So why wouldn't it be possible to trick the controller into thinking its running at the voltage required, while in effect running it at the voltage needed by the motor. I know that industrial drives are so far advance that I think it make economical sense to use them.


Because any type of vector control scheme (FOC, DTC, whatevuh) needs to know the DC link voltage to calculate the correct on time for each switch.

As for your second assertion, industrial drives are not designed to be used in the high vibration/extreme environment of an EV so, caveat emptor.


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## flyn_brian (Oct 21, 2012)

Tesseract said:


> Because any type of vector control scheme (FOC, DTC, whatevuh) needs to know the DC link voltage to calculate the correct on time for each switch.
> 
> As for your second assertion, industrial drives are not designed to be used in the high vibration/extreme environment of an EV so, caveat emptor.


I have worked in an Industrial environment where temperatures far exceed ambient temperatures. And as far as vibration is concerned some of the machinery I was hired to install/maintain/program had to have footing/bases that would be poured 4 feet deep and filled with re-bar to accept the vibrations that the machinery its self had created. I realize that an ev vehicle controller in many cases is filled with an epoxy. One reason is because of vibration and another is to not let out the "secret" circuit. I'm not debating the vibration issue. My cause of posting is to get an answer. I simply would like to get a drive to work at a lower voltage. And that is my reason for posting.


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## Siwastaja (Aug 1, 2012)

What is exactly your voltage? Many VFDs do work with decreased voltage within some limits. Just note that you lose power at high rpms. The field weakening (decreasing torque, constant power) region comes earlier at lower rpm, the lower the voltage is. You may need to modify or rewind the motor.


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## flyn_brian (Oct 21, 2012)

The motor in question is an Azure Dynamics AC24LS motorhttp://www.azuredynamics.com/products/force-drive/documents/AC24_DMOC445ProductSheet.pdf
while the drive is an ABB ACS601-0006-4-000B1200801 http://96.61.63.50/techlib/ABB/ABB_ACS-600_AC_Drives.pdf


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## PStechPaul (May 1, 2012)

I found more information on the ABB website:

http://www05.abb.com/global/scot/sc...3ec4cd/$File/en_600MD_SystemDescription_3.pdf

http://www.motorsanddrives.com/docs/s60104.pdf

http://www05.abb.com/global/scot/sc...56def0049196e/$File/EN_600stdprg_FWmanual.pdf

The last document indicates that the DC bus undervoltage trip is set at 0.65 times the minimum AC voltage, which is 380 for 400 and 500 volt units, or 334 VDC (although I calculate 247 VDC). My 230 VAC drive works on 200-400 VDC) This is probably limited by hardware, such as a voltage divider, and there will also be some kind of DC-DC converter to supply the main logic voltage, including the fan, which appears to be 24 VDC. To use the drive at lower voltage, you MIGHT be able to feed it with an external 24 VDC source, and change the voltage divider for the DC bus voltage you want to use. 

Of course this means getting deep into the drive electronics, and without a schematic, it will be mostly hit or miss, with a chance of destroying something or creating an unsafe condition. You may have some luck contacting an ABB representative or an AC drive repair service. 

Good luck!


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## zaxxon (Jul 11, 2009)

flyn_brian said:


> The motor in question is an Azure Dynamics AC24LS motorhttp://www.azuredynamics.com/products/force-drive/documents/AC24_DMOC445ProductSheet.pdf
> while the drive is an ABB ACS601-0006-4-000B1200801 http://96.61.63.50/techlib/ABB/ABB_ACS-600_AC_Drives.pdf





flyn_brian said:


> I ask this because I have put the cart before the horse and bought a 3 phase drive before I bought the motor. I believe the control portion of a drive runs at a much lower voltage. So why wouldn't it be possible to trick the controller into thinking its running at the voltage required, while in effect running it at the voltage needed by the motor. I know that industrial drives are so far advance that I think it make economical sense to use them.


 
Yes, you can lower the input voltage where the Unit will turn on and operate. 
Before attempting this please read what others have tried and the issues they ran into trying to use Industrial VFD. Generally you need to modify the unit in two places: 

You will need to determine where the high voltage input sense resistor string is and shunt some of the series divider resistors. Look for series string of larger surface mount resistors connected to the input link capacitor. You may see similar strings of resistors monitoring the three output. Only modify the input monitoring string. 

You also will likely need to find the Auxiliary power supply’s start-up resistor for the PWM converter controller microchip. Look for a large resistor or string of resistors off the link capacitor that connects to the microchips power input pins. You will need to lower this resistor value until its starts at your lower input voltage.


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## flyn_brian (Oct 21, 2012)

Thanks for the reply's. Although I am not an electronics genius. I'm not a stranger to working on them. I have opened the drive and have made some determinations as to what some of the components are. I have cleaned and reassembled the drive. I'm now at the point where I need to take it to work and just hook it up to 480VAC and let it set and allow the capacitors to season themselves for a few hours. As I have no idea how long the drive has sat dormant. After which time, I will hook it to a small motor and program it and test it out. If everything is ok then I will take it back home and pull it apart and begin the task of actually figuring out all the components as well as possibly making a schematic. As far as I see it, I will have plenty of time because lithium polymer batteries aren't going to be cheap. Any and all help and opinions are appreciated.


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## gunnarhs (Apr 24, 2012)

flyn_brian said:


> I ask this because I have put the cart before the horse and bought a 3 phase drive before I bought the motor. I believe the control portion of a drive runs at a much lower voltage. So why wouldn't it be possible to trick the controller into thinking its running at the voltage required, while in effect running it at the voltage needed by the motor. I know that industrial drives are so far advance that I think it make economical sense to use them.


If you are running in V/f- mode this is no problem usually. Most standard inverters are able to ramp up voltage and frequency for a fixed torque (speed control). 
Be aware though that the maximal frequency is limited by the voltage in case of little load AND torque in case of a load. 
The problem of most standard-inverters is that the V/f must be set constant all the time so you can not start with high torque / low speed (high V/f - prportion) and end with high speed/low torque (low V/f proportion) as you would have wished for an EV.

If running in FOC-mode most standard inverters limit the lower voltage to protect inverter from high currents which could be a problem for this case you have here.

So my advice is to get a different motor if you are going to keep the inverter (or vica verse)

PS: The specs I was looking at showed a operational DC-voltage of 100 - 400 for motor AC24 in wye but your ABB is a 480V AC, my comment is made on that assumption. The 240V AC would suit much better of course


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## flyn_brian (Oct 21, 2012)

gunnarhs said:


> If you are running in V/f- mode this is no problem usually. Most standard inverters are able to ramp up voltage and frequency for a fixed torque (speed control).
> Be aware though that the maximal frequency is limited by the voltage in case of little load AND torque in case of a load.
> The problem of most standard-inverters is that the V/f must be set constant all the time so you can not start with high torque / low speed (high V/f - prportion) and end with high speed/low torque (low V/f proportion) as you would have wished for an EV.
> 
> ...


I have also considered using a 220VAC drive. In fact I already have one. The only problem is I planned on using it for my lathe.


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## PStechPaul (May 1, 2012)

Sackville said:


> dont have much idea regarding this as never used this stuff anytime its better to contact the moderator of the site for this query..


Actually, no. The moderator might know the answer, and certainly can add his/her input to the discussion, but the idea of a forum is to encourage everyone to add their individual knowledge and experience, or ask specific questions to improve the valuable content of the thread. A forum such as this is an important resource because it brings together talent and expertise from around the world and is a virtual encyclopedia of information.


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## flyn_brian (Oct 21, 2012)

PStechPaul said:


> Actually, no. The moderator might know the answer, and certainly can add his/her input to the discussion, but the idea of a forum is to encourage everyone to add their individual knowledge and experience, or ask specific questions to improve the valuable content of the thread. A forum such as this is an important resource because it brings together talent and expertise from around the world and is a virtual encyclopedia of information.


I could not have said it better myself. Thank you.


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## Salty9 (Jul 13, 2009)

Have you checked http://etischer.com/awdev/


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