Running a servo motor at 0-1/3 speed

[H.O]

I'd say that, generally speaking, it does need the hall sensors for commutation and the encoder for position feedback. Some encoders have commutation "tracks" on them basically replacing the hall sensors and some drives can run sensorless using wake & shake at start up to determine the commutation angle.

[thm_w]

All commercial servo motors I've seen have both hall sensors and encoder. Its definitely not needed, you can do without the hall sensing, but just makes life a lot simpler. Hall sensors are incredibly cheap and reliable.

I made my own differential/se boards but they should be somewhat commonly available https://cnc4pc.com/c46-differential-ended-converter.html

Again, still no mention of model numbers of the motor driver though to know what it is capable of.

[Postal2]

.... it does need the hall sensors for commutation ....

Here is:
https://www.allegromicro.com/en/products/sense/switches-and-latches/dual-hall-effect-latches/a1230

[Simon]

I suspect that what I call hall sensors are in fact just different tracks in the encoder disk to give 1 pulse per phase per electrical cycle as they too are +/- 400mV.

[Simon]

All commercial servo motors I've seen have both hall sensors and encoder. Its definitely not needed, you can do without the hall sensing, but just makes life a lot simpler. Hall sensors are incredibly cheap and reliable.

I made my own differential/se boards but they should be somewhat commonly available https://cnc4pc.com/c46-differential-ended-converter.html

Again, still no mention of model numbers of the motor driver though to know what it is capable of.

It was just a case of getting something quick, I'm going to knock my own up for the future along with some other adapter boards I had already done some work on.

The driver I am looking at is an escon2 from Maxon, the motor is a delta line 80SV-48VDC, knock yourself out  .

When I used a delta-line controller on a similar motor it did a calibration at start up. The motor was moved backwards and forwards by a small amount. I don't know if it was "searching" for the "hall" sensor pulse or simply getting the rotor to line up with the stator field.

[Postal2]

... it did a calibration at start up. The motor was moved backwards and forwards by a small amount. ...

Shouldn't do that. What if it's a shredder and you put your finger in it?

[Simon]

... it did a calibration at start up. The motor was moved backwards and forwards by a small amount. ...

Shouldn't do that. What if it's a shredder and you put your finger in it?

You should never put your finger in a shredder, particularly when you have just turned it on. By start up I mean when the motor driver DS402 states were changed through 3 different levels from completely disabled to getting ready to power up and move if asked to.

[Postal2]

Well, if the "Tesla" also twitches when turned on, then fine.

[thm_w]

It is crazy the power density that is available now, says board is 20g and has 1800W motor capacity. And yeah it supports brushless mode and absolute encoder only FOC, so definitely no actual requirement for hall sensors.

It is derated above 25C, -0.5A/C but I'm sure you've looked at that. Otherwise its well within spec.

https://www.maxongroup.com/medias/sys_master/root/9255271268382/ESCON2-Feature-Comparison-Chart-En.pdf
https://www.maxongroup.com/medias/sys_master/root/9255271399454/ESCON2-Module-60-30-Hardware-Reference-En.pdf

[Simon]

Well This guy, I've dealt with him before. I suspect that he knows more about the CAN Open programming than the actual electronics.

[Simon]

And yes it is one compact unit, but there are tradeoffs. The Delta-Line controller does 40A and is not much bigger but has more stuff and does not require a board to plug into and the CAN bus is isolated which maxon see no need for. On balance I went with this one as either way I have to put it in a box so having an on board molex connector that requires a custom loom to another internal connector is not what I wanted. With the maxon PCB mount option I do save space although they always recommend putting low value output chokes which means that the space claim is not as small as it first appears although the inductors do fit under the controller board but still as a two board solution it is still no what it first seems. But this way works for me which is why I am using it as the CAN Open is not available until later which means that I have to design in a whole load of stuff to deal with their IO.

Sending Analogue signals, in fact any non isolated signal to a motor drive gives me the hibigeebees. At least with it not having a cable to the main board it's less likely to have weird stuff happen.

[Simon]

Well it ran just fine.