Output voltage from mains driver?

[A_Camera]

Hi!
I’m looking at 2 different drivers for a 8,2Nm Nema 34 stepper.
Options are the Leadshine Am882 or DM2282.

I calculated the maximum stepper voltage to 66V. (8 wire, 4,2mH, 6,4 A in Bipolar parallel.)
The PSU that I would build for it would give about 75V, I guess it won’t hurt but... (Writing this made me see that the DM2282 seem to be the better choice all things considered.)

One question remain. I haven’t really got what the output voltage to the stepper would be using the Leadshine DM2282 mains driver??

Hej!

I don't know the DM2282 and can't give you more than what I have just recently measured on my system, which uses the DQ542MA drivers, which are fake Leadshine analogue 4.2A drivers for my 3A NEMA 23 steppers.

In fact, I made three short YT movies also.



The first one is what is measured on the input. My DIY PSU (toroidal transformer based) gives about 43VDC without load. This voltage drops a bit when the drivers are enabled and the motors are running. The current measured on the input to the drivers is not really true because I don't think that those cheap meters can cope with the fast changes, but it gives an indication of the behaviour.

The second video is about voltages on the Z motor coils.



Note that the voltage is AC, if measured with a DMM it is important to set it to AC otherwise the reading will be false and totally off and unrealistic. Note also that my DMMs are accurate enough between each, and the differences you see in the voltage between the two DMMs are real differences. I think it is caused by the driver not being properly calibrated and balanced on both outputs. I don't know is all my drivers would demonstrate similar errors, but on this one there is definitely a difference between the coil voltages. If the differences matter or not... well, I have no idea. Perhaps I will redo this measurement just to see if there is a difference between drivers, because due to a f...up during the next video I killed the driver and had to swap it with a new one.

The third video is about measuring the voltage and the current AND the AC frequency of one coil of the Z axis.



It was here I realized that an ordinary DMM can not be used for the measurements. Especially the current measurements are wrong. My DMM has a frequency response of 400 Hz and that's not enough because the frequency is well above that, so the current is totally wrong, especially when the stepper is moving. After measuring the current and making the first part of this vid, I wanted to measure the frequency, so I hooked up the left DMM for frequency measurement. The only thing is that I forgot the twist the switch to Hz, and forgot to move the probe from the 10A input of the DMM to the Hz input, which meant the motor coil was shorted by the shunt and that instantly killed my driver. I have several, so no big deal, but pretty annoying. Will have to fix the fried one later, but for now I just swapped it out.

So, back to your question, the voltage over the stepper coils should be the same as the DC voltage input to the drivers. That is what I measure. The only difference is that the drivers are driven by DC and the output to the steppers is measured AC. I think if you measured yours you would come to the same conclusions. The frequency may be different for your drivers, but the behaviour should be the same or very similar as my three videos show.

BTW, if you decide to measure be careful. Use my post for learning and not making the same stupid mistake I did, because that might fry your driver, just like I fried mine.

Regarding the DM2282, the manual says "theoretical output voltage of 80~220VAC" and that it has a "motor auto-identification and parameter auto configuration feature" which should take care of the output voltage for you.

The Am882 needs DC power supply and the way I interpret the manual that you have to be more careful with that one. I think the output voltage will be the same as the input voltage, according to my measurements on my driver.

I am not sure which one I'd chose, but probably the DM2282 because that does not require a rectified input voltage and can use the AC directly from the transformer.