TB6600 + general drive and driver matching question

[CNCStudent]

Jazcnc thanks very much for the very informative post I've learnt a lot

Next daft question does anyone know what the actual difference is between the leadshine em806 drives and it's predecessor the am882 and also the dm870?

The first two appear to be the same (hence is there a diff paying extra for the new one when the old one is still being sold new) and the dm870 appears to not offer sensorless stall detection although that is only above 300 rpm which for a direct drive application is a bit fast in my plasma application. Is it worth it is there anything else different?

Thanks again for your time and hope you have a happy christmas

Jonathan is current not consistent. Input must equal total output? But measuring the input would be smoother than measuring just one of the channels

[Neale]

I asked about the AM882/EM806 difference a week or so ago. The answer is that the AM882 is an older version, now obsoleted by the EM806 which is in some unknown way "better" - but I'm not sure quite why or how! Zapp only have one of the AM882s left and as it's the same price as the newer model, it might be there for a while (unless someone needs a replacement, maybe). Don't know about the DM870.
As far as current is concerned, are there some measurement problems given that the output is generally PWM and this might not correctly read on a digital meter? Just thinking out loud. Ditto power measurements - need to take phase difference between voltage and current into account with a highly inductive load.

[JAZZCNC]

Jazcnc thanks very much for the very informative post I've learnt a lot

Next daft question does anyone know what the actual difference is between the leadshine em806 drives and it's predecessor the am882 and also the dm870?

The first two appear to be the same (hence is there a diff paying extra for the new one when the old one is still being sold new) and the dm870 appears to not offer sensorless stall detection although that is only above 300 rpm which for a direct drive application is a bit fast in my plasma application. Is it worth it is there anything else different?

I've used all three series. The EM806 appears to give slightly smoother motors at lower speeds and gives slightly more torque at higher speeds so can tune motors that little bit more aggresive. The case is slightly larger and gives better cooling but Basicly the EM series are the same as AM series but with tweaked software. Put it this way the difference is that if I couldn't get the EM and only had the AM I'd take them. If I had the choice and was £5-10 difference I'd take the EM every time.

The DM series on the other hand don't have stall detect and the software isn't has advanced and it shows in the motor smoothness at slower speeds. I also noticed that the motors get hotter compared to AM/EM so don't think they manage the amps/resonance the same. Compared to the EM/AM I wasn't so impressed. Still very good drives but not quite as good.! On a lesser note the DM are also limted to 7A motors so no use for larger 34's.

[Jonathan]

Jonathan is current not consistent. Input must equal total output? But measuring the input would be smoother than measuring just one of the channels

The formula you need to recall is power=voltage*current. I said in the previous post that the output power fro the motor driver must be roughly equal to the input power. In reality there are losses in the driver, but if we assume they're small then we can equate the input and output power to get ..
Now do you see why the input current, ., is lower than the output?

Here's an example of the same concept with a different stepper driver - in this case a 2m542 driver with a 3Nm motor from CNC4you connected to a lab PSU:



Current is on the left, voltage on the right.

[CNCStudent]

Thanks for taking the time to wire up a stepper & drive to a lab power supply Jonathan. I thought that the Power In = Power Out (V*I[in] = V*I[out]) only applied to transformers and voltage doubler circuits, given the stepper is acting as a chopper circuit, and no voltage change is taking place [albeit the stepper coil is an inductor].

separate AM882 question ->

seems you can get 3 variants of the AM882 drive, the AM882 (which has a datasheet from Leadshine), an AM882H, which seems to be above to take AC + DC and at a slightly higher voltage, and a AM882-DK (which is apparently a dedicated drive for an engraving machine).

The AM882H seems to have a fan as well, anyone got any experience of these (as I can't find an English language PDF) are they the same as the AM882, but with a heatsink mounted fan, and has a listed supply voltage of 18-70 VAC & 24-100VDC, with the supply terminals listed as "AC"

seems the AM882H can be had for ~£48

Any comments / experience would be very much appreciated.

Thanks again for your time,