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Post by Mitch on Sept 7, 2015 8:34:08 GMT
Update: I was able to work on this again tonight for a little bit, so far I'm pretty happy with the results. I'll post my entire VFD settings compared to defaults at some point when I'm done making adjustments. I figured out what the crackling noise is - the AMC1280 is sending a small voltage (300-400 mV) to the VFD at rest. (I think something like this is probably normal for AC motor and the feedback sensors we use) I believe there are three ways to deal with this, - Compensate for the voltage:
If 0-10V correlates to 0-60Hz then there are 10,000mV in 60Hz. I've adjusted for about 300 mV noise by setting A013 to 3%. This means if 0 V is equal to 0 Hz, now anything below 300mV equals 0Hz.
- Adjust the minimum frequency:
I observed the commanded freq at 300mV was flickering at a peak of 0.75Hz, but the motor wasn't moving (hence the noise). I adjusted the min freq. B082 from the default of 0.5 Hz to 1 Hz.
- Adjust the min motor speed in Fabi's software:
I don't know what this adjustment does in terms of altering the 0-10V signal, or if it also does other things. The way the description is written I'm not really sure what it does. I've left it set at 1.
I'm hesitant to increase the minimum frequency much more, I'm thinking it will kick too hard during small movement commands. I didn't increase the oversample for sensors as I already had it set to 16. It's now quiet in most static positions, including the hold position using Ians software. -Mitch |
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Post by vicpopo on Sept 7, 2015 9:37:17 GMT
Hi ,
Great progress !
For the noise it can come from the inverter PWM frequency.I don't know what is the ground setup? 8kHz ?
If you have several PWM frequencies choose the higher it will reduce the noise .
The only thing to know is so high is the PWM frequency it wil reduce a little bit the torque available! Don't know how many !
For the min speed you would prefer the best result even it it kicks .You can reduce it with the xsim sequence setup.
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Post by Mitch on Sept 7, 2015 16:35:29 GMT
Hi , Great progress ! For the noise it can come from the inverter PWM frequency.I don't know what is the ground setup? 8kHz ? If you have several PWM frequencies choose the higher it will reduce the noise . The only thing to know is so high is the PWM frequency it wil reduce a little bit the torque available! Don't know how many ! For the min speed you would prefer the best result even it it kicks .You can reduce it with the xsim sequence setup. Thanks! Oh, it's not the VFD carrier noise, it's electrical crackling like the motor trying to drive but not being supplied enough hz to do so. |
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Post by vicpopo on Sept 7, 2015 17:45:19 GMT
The noise I was talking about which is linked to the pwm frequency is listenable on the motor also .Not only on the vfd.
If you have a parameter for the pwm frequencies try the highest value and give a try !
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Post by Mitch on Sept 7, 2015 18:21:19 GMT
I get what you're saying. I've got B083 set at 12. It turns out I don't mind that high pitched sound at all! From the videos, it comes through much louder and annoying than reality.
That's not the problem though, it's a different sound- like an electrical crackle coming from the motor. Im sure it's because the motor is being commanded to a set point, either through noise in the signal or deliberately, but not being given sufficient freq by the VFD to start moving. So it kind of whines and crackles. Those previous adjustments to start adding hz after 3% mV min is reached, and to start at 1 hz, made a big difference to the crackle noise when the platform should be at rest.
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Post by vicpopo on Sept 7, 2015 19:45:47 GMT
Ok I stop boring you with this :-) , it was just to share some experience which can help also another members !
Will keep tuned to your thread !
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Post by riton39 on Sept 8, 2015 17:43:53 GMT
it is not easy to help and above all it is not my native language ..
I see that it works, the problem was the wiring of the engine?
strange.
you had a notice which indicated the possibility of the cabler in Delta?
normally, the good operation, for a three-phase motor is in Delta, I fear that this is not correct ....
you should try to understand what went wrong.
assistance, the seller questions might help to understand?
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Post by Mitch on Sept 9, 2015 1:12:36 GMT
Hi Riton, I understand what you're saying. Motor connection is now in Wye. The motor label shows only two types of connection, low and high voltage, both appear to be Wye. My motor label (attached). Same T#'s and colors as iron horse. My delta wiring was like the attached image (written). The same as Thanos blog. motionsim.blogspot.ca/2013/07/close-up-photos-of-6dof-platform-and.html#moreAttachments:
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Post by clyevo on Sept 9, 2015 1:57:02 GMT
Some motors are solely design to be wired in wye (star) connection. It has something to do with the less number of windings of the stator. But you can confirm with the motor supplier.
I only aware of this because thanos mentioned something about this wye only motor in the motor section forum in AC motor FAQ.
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Post by tronicgr on Sept 9, 2015 14:48:32 GMT
Some motors are solely design to be wired in wye (star) connection. It has something to do with the less number of windings of the stator. But you can confirm with the motor supplier. I only aware of this because thanos mentioned something about this wye only motor in the motor section forum in AC motor FAQ. That is true. I have two motors that can be connected only in wye connection, with no access to the individual windings in their connection panels. Usually the ones that can be wired to delta, offer 6 connectors or more. Thanks Thanos |
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Post by Mitch on Sept 9, 2015 14:51:39 GMT
I think delta wiring could have worked for my motors - but the appropriate VFD settings were unknown to me - it was causing over current errors and autotune could not complete.
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Post by clyevo on Sept 10, 2015 3:33:28 GMT
I think delta wiring could have worked for my motors - but the appropriate VFD settings were unknown to me - it was causing over current errors and autotune could not complete. could it be that the current are way higher than your inputed parameters resulting in fail. I imagine delta wiring is like parallel circuit which means current running through is higher and thus the stator need higher resistance winding. Wye wiring is like series circuit in which the stator resistance is added up contributing to lower current running through it. Usually motor has different parameters for wye and delta, for example 220v is delta, 380v is wye (like my motor). So if your motor parameter 230v is for wye, it should be lower voltage for delta which you need to ask your motor supplier for that info. If say your motor is suppose to be wired in wye according to the nameplate at 230v then you are running it at the 0.55 watts as it suppose to. If you wire it in delta with the same voltage (230v), you will have more power, maybe 3 times more, because 3 times more current running through at same voltage. 0.55w x 3  This will damage/burn the windings. |
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Post by Mitch on Oct 6, 2015 3:11:10 GMT
Just a quick update - haven't had a chance to work on this much lately. It is working, I've set up Ian's software and played with it quite a bit. I was tuning PID but I haven't had a chunk of time to dedicate to finishing tuning.
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Post by paulg100 on Jul 27, 2016 12:48:37 GMT
Hi MitchAre you still working on this? I have exacly the same problem as you, the crackling at very low frequency, as you say its like the motor dosent have enough power to start moving to set point. I thought it may need a more aggresive (P) but this dosent seem to help. Raising A013 and B082 does help tame the problem but is it making your sim less smooth? It would be nice to know exactly what is causing this issue rather than capping the start frequency/volts and loosing performance in the sim. In my case im sure ive eliminated it as an EMI problem as my sensor readings at rest have been measured with an Oscope and it looks good. my motors are also wired in delta. Maybe the motors are not as good as the iron horse ones (quite possible as mine were cheaper from china) I will post some pics vids of the issue at the weekend. |
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Post by paulg100 on Jul 27, 2016 20:42:49 GMT
OK more testing and I can confirm that upping A013(start volts) and B082(start frequency) whilst alleviating the problem seriously degrades the motion so this is not the answer.
You can see by putting BFF in manual mode. with A013 at 0 and B082 at 0.5 (both fac default) the slider needs to move by about 2% before the motors try to move. In your example Mitch, With an increased value of A013:3 and B082 0.1 there is a huge dead band between moving the slider and the motor trying to move, about 15% !!.
The result is the motor kicking in late and causing snapping/notchy movement.
With B082 at 0.01 the motion is 1:1 with the slider and buttery smooth but the jitter is mental on my system. (even 0.5 is not workable for me)
TIP FOR THOSE WITHOUT THE JITTER ISSUE: Set A013:0 (default) and get B082 as low as you can without jitter, the lower the start frequency the smoother the motion.
I'm no nearer to finding the solution but ive made allot of progress in the past week in finding what it isn't!
I have enough info to make some good videos now to show the problem (will do this weekend) and hopefully we can get to the bottom of things. I'm almost certain the solution lies with the VFD settings and motor combination
as opposed to emi or software settings.
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This will damage/burn the windings. 
