Question AASD-15A at 110v. Performance loss?

So, given that the AC servo drivers are very similar to 3-phase AC inverter speed controllers used in industrial motor control applications, they are pretty forgiving when it comes to the kind of juice you feed them. The caveat is what you can get out of them with less than ideal input.

I currently have my drivers using 110v, and have heard that there is no trade-off for doing this. However, when using the AASD-15A drivers JOG mode, and stepping through the speeds at 100 step increments, there is a notable and audible change in frequency only up to about 2300 RPM. The motor and driver are supposedly rated for 3000 RPM, but it doesn't seems like it is going over 2300 RPM. Is this a common side effect that has been found when running these units at 110v 60hz, and will this have any real-world performance impacts if so?

Just thought I would ask before adding a step-up converter to the mix, only to find that there is some other factor at play.

I know this is an older thread but can confirm that when running on 120v (pn083 = 100), they are maxing out at 2000 rpm in my case. I'm using Thanos recommended parameters otherwise.

I switched to using 240v as a test with pn083=200, I get 3000 rpm with the same settings. I'm guessing there is another parameter that needs to be tweaked but I cannot find it in my searches.

Thought this might save others some time when googling like I have been the last couple of days.

Here is a speed/torque diagram of a 750W servo motor. It's not the AASD brand but a SanyoDenki motor but that doesn't matter much, they all behave very similarly.

For a permanent magnet synchronous motor speed is nearly proportional to voltage and toque is proportional to current. So if you run the driver at half the voltage that effectively cuts your max speed in half. (1500 instead of 3000RPM rated speed) But the rated speed and torque are not a hard limit. The motor can run above the rated speed (field weakening operation) but at lower torque. The motor can also run above the rated toque but only for a short time. Otherwise it would overheat.
Feeding the driver with 3 phases provides more power reserve because the DC bus voltage is more stable especially under heavy load (instaneous zone).

Running at 115V instead of 230V effectively changes the scale of the X axis. Max torque starts to drop at 1500RPM. You may be able to run it at 2000RPM but at reduced torque capability.

I'm not an Electrical (or Mechanical) Engineer so please forgive me.

I'm not talking about torque at the moment. The units have far more torque than I need anyway.

Ignoring 3 phase AC benefits which we don't have (except for industrial buildings) around here. 240 and 120 both have the ability to provide 750w easily within standard household circuits. 120v will just use more amperage. Roughly 6 vs. 3.

If the controller is rated to run at 110v, which it says it is in their manual, it seems reasonable to believe they would have put a disclaimer somewhere stating the limitation on RPM/torque if it was a hard limit. Since it hits 2000 rpm on the nose and not 1 rpm more, I'm very skeptical this is a setting (or hard limitation in software) and not a random artifact of the voltage difference potential. My service isn't perfectly 120v anyway so that would be a heck of a coincidence.

I'm not trying to espouse theories I don't know enough about. I'm just trying to look for a hard answer to a seemingly unanswered issue of why 120v nets 2000 RPM while 240v nets full 3000 RPM. I see many instances of people using these things at 120v blindly believing all the hype that there is no trade off yet there sure appears to be one.

If I have to use 240v, so be it. If I don't have to, I would rather stick to 120v to allow me autonomy to move the thing around a typical residential building without a step-up transformer.

What disadvantages do you think the normal user of SFX100 or SFX150 should have? You will never reach 2000rpm with these systems!

You can only reach this speed with a gear ratio with the small stroke that most platforms have.

You're really turning a triviality into a drama here. Let's do the math: 2000rpm with the often used 1605 spindles would be 33 revolutions per second, at 5mm pitch this would be 166mm in one second without any acceleration or braking. You don't want anywhere near that in your Simrig.

I don't appreciate your response. It seems unnecessarily aggressive and combative. I'm in no way attempting to create drama. I went out of my way to write a paragraph on how I'm NOT trying to create "drama" in not so many words.

I'm merely trying to find a solution to a newly found (to me) limitation of the aasd-15a on 120v. If you have knowledge here, please, help. Otherwise, your opinion of if I need 3000 rpm is irrelevant.

I have an SRT 80 setup at 220mm stroke with a dedicated surge axis so I'm in a different world although similar to sfx. More importantly, I don't have interest in faster motion for my heave, pitch, roll axis. I initially found the issue when my dedicated surge axis was clearly lagging behind motion and noticed 2000rpm on the screen. I'm working on it right now at 3000 rpm and it feels much better. So, there are, in my humble opinion, cases where 3000 rpm are perfectly reasonable on MY sim rig.

The easiest and cheapest way would be to use a spindle with a higher pitch. Especially for Surge, a 5mm pitch is not necessary or may be too little, but this depends on many factors, above all on the software, i.e. max acceleration, filter and crash detection. With the latter, you would get exactly the problem you describe.


I myself have now switched from 220v to 100v with 190mm stroke from Surge and even 370mm stroke for TL with 5mm spindle pitch and don't have these problems.

I fully realize that this is not an answer you want to hear, but it is no less true.

Agree to disagree. This is off topic. I really only want to discuss aasd-15a functioning at 3000 rpm and 120v, not whether or not you agree with my rig design or reasons for achieving said speeds.

It's simple physics. It doesn't care if you agree or disagree. A switch mode power supply with a wide range input can deliver it's rated output power from 100 to 240V input because the switch mode voltage converter is designed for it.

The servo drive doesn't have a transformer so it can only down-convert the voltage. The motor has a rated voltage of 200V which means that the back EMF is slightly below that at the rated speed, let's say roughly 150V at 3000RPM. So the voltage output of the driver has to be higher than the back EMF of the motor which is ~0,05V per RPM or 75V at 1500RPM. Otherwise it can't drive current through the motor. So the limit for 100 to 120V supply is around 2000RPM.

And no, the drive won't deliver anything near the 750W at 120V supply. Same torque half the speed gives half the power or 375W.

BTW, I just found this on AliExpress. This servo is available in two versions, 110 and 220V. So there should be no power loss at 110V. It seem's a bit different from the well known AASD15 drive. It has a 17 bit digital encoder which is better than the AASD incremental encoder. But parameter settings and pin assignment of the CN1 connector may be different which means a bit of extra work.

I think he will not respond, because it's not the answer he wants to hear

No, I just got busy with other things and didn't get on the forum. Not sure why you find the need to be rude to me though. Just trying to have an honest discussion. Your rig is looking great BTW.

Thanks for the link and explanation Aerosmith. I've just resolved to stay on 220v and my rig is working well for me.