Help tune

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madius
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Help tune

Post by madius »

hi everyone,

I have my car running, I am very happy and grateful for the help of this forum and all of you.
I am in the tuning stage and I would like to understand well how the different parameters work.

It's an ACIM of 15Kw, 200V, 2 pole pairs.
My battery bank now it's 150V.

According to what I read in the wiki tutorial, parameter list and different forum posts, I understand the following:

150V / 1,41 = 106V
fweak = (106V / 200V) * 50Hz = 26Hz is it not too low?
So, the V/Hz function is like that?
Image

fslipmin = 50-2*1460/60=1.33Hz is it correct?

fslipmax = 2 * fslipmin good point for start right?

I cant understand what does fconst and fslipconstmax.

thanks
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catphish
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Re: Help tune

Post by catphish »

I will try to answer this, but you're probably not going to love the answer.

Lets start with the basics. If your ACIM is designed for 200V AC at 50Hz, that roughly equates to 282V DC at 50Hz.
You only have 150V, so your fweak should be 150 / 282 * 50 = 26.6Hz. Looks like you calculated this correctly :)

Next, you will need some boost. This can be calculated from the DC resistance of the motor and your desired peak current, but it's probably easier done by trial and error. Start at boost=0 and increase in small increments until the motor actually works, and then continue to increase until torque is roughly consistent from a standstill up to 25Hz. More boost = more current and torque at 0RPM. You'll probably find you need to increase it into the 4-digits range (1000+) but start low and be cautious with it.

I'm not aware of any way to calculate slip, but as a starting point, I would suggest using the rated slip as fslipmin, which is probably around 3% of 50Hz (fslipmin=1.5) and fslipmax to be double that (fslipmax=3).

fslipconstmax is a higher slip value to be used at speeds above fweak, and fconst is that frequency at which that higher maximum slip should be reached. For example: if you set fweak=26, fconst=50, fslipmax=3, fslipconstmax=5, then what will happen is you will get a slip of 3Hz up to 26Hz, but then this will increase proportionally from 3Hz at 26Hz up to 5Hz at 50Hz. This helps to overcome back EMF and produce more torque at higher speed.

I hope this all makes sense. Ultimately, there are very approximate starting points, and you will likely wish to push the motor a lot harder than its rated values.
chentron
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Re: Help tune

Post by chentron »

Your comment has been of great help to me. Understanding what each parameter is with just the wiki description is very difficult for someone who is not familiar with those terms. Furthermore, the explanation interrelating each of the parameters is sensational. I think it would be very helpful if you could also comment something about the ampmin, sincosofs, sinecurve parameters.

catphish wrote: Wed Mar 08, 2023 12:09 am I will try to answer this, but you're probably not going to love the answer.

Lets start with the basics. If your ACIM is designed for 200V AC at 50Hz, that roughly equates to 282V DC at 50Hz.
You only have 150V, so your fweak should be 150 / 282 * 50 = 26.6Hz. Looks like you calculated this correctly :)

Next, you will need some boost. This can be calculated from the DC resistance of the motor and your desired peak current, but it's probably easier done by trial and error. Start at boost=0 and increase in small increments until the motor actually works, and then continue to increase until torque is roughly consistent from a standstill up to 25Hz. More boost = more current and torque at 0RPM. You'll probably find you need to increase it into the 4-digits range (1000+) but start low and be cautious with it.

I'm not aware of any way to calculate slip, but as a starting point, I would suggest using the rated slip as fslipmin, which is probably around 3% of 50Hz (fslipmin=1.5) and fslipmax to be double that (fslipmax=3).

fslipconstmax is a higher slip value to be used at speeds above fweak, and fconst is that frequency at which that higher maximum slip should be reached. For example: if you set fweak=26, fconst=50, fslipmax=3, fslipconstmax=5, then what will happen is you will get a slip of 3Hz up to 26Hz, but then this will increase proportionally from 3Hz at 26Hz up to 5Hz at 50Hz. This helps to overcome back EMF and produce more torque at higher speed.

I hope this all makes sense. Ultimately, there are very approximate starting points, and you will likely wish to push the motor a lot harder than its rated values.
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