2000 watts server supply: DPS-2000BB (A)

Something like that.
But DimensionEngineering warned me that this kind of setup could damage the sabertooth (so maybe it could damage the MM as well) because the power generated by the DC motors is not sinked as there is no resistor in that case. Maybe the MM has a protection ?

Hum. Today I wired the second smolka to the sabertooth, and after testing 5 minutes with LFS, the PSU failed. Same problem appeared. As I wired the second smolka, I also removed one resistor to clamp voltage on second output, so I went back to 18 ohm instead of 9. I'll order some more 9 ohm and see what happens. I'll also put another diode on the + side.
Improving, but still far from perfect....
EDIT: added another diode and no issues after 10 mins. Will order 5 ohm as well, together with power diodes. Should find a working setup with all that !

@vthinsel any news about that?

Well, with 2 diodes it looks good. I havent ordered bigger ones, as I'm working on the rig diagrams. I hope that when amps go up nothing burns

Banana - to be in the habit like bsft Which diodes are you using for now? Sorry for asking again but I am a little bit confused

I'm currently using this one: http://www.farnell.com/datasheets/1661896.pdf
But I'll move to something more like this probably http://www.farnell.com/datasheets/1671171.pdf
This one looks nice also:
http://ixdev.ixys.com/DataSheet/96509.pdf
especially:

Applications
●Antiparallel diode for high frequency switching devices
● Anti saturation diode
● Snubber diode
● Free wheeling diode in converters and motor control circuits
● Rectifiers in switch mode power supplies (SMPS)
● Inductive heating and melting
● Uninterruptible power supplies (UPS)
● Ultrasonic cleaners and welders
Or cheaper : http://ixdev.ixys.com/DataSheet/8862df85-7186-49cc-b6cf-928c5a4a2498.pdf
​

@vthinsel, thank you for information.

So I will order a DSEI2X61-12B and will do a test this week end. As fa as I understood:

• the max current is 2 x 52 A, if more is requested no more current will be provided?
  
• probably generated power from the motors can't "go back" to the PSU?
• this diode is rather expensive

Just ordered a couple of 40A IXYS DH40-18A. Shoudl receive them middle of next week. Looks like it is cheaper to order two diodes instaed of a dual unit.
Yep, they are expensive, but should prevent current from going back to the PSU.
If more amps are requested, the diode will probably get hot and potentially be damaged. I'll put it on a heatsink, maybe on the sabertooth heatsink which will have a fan (the PSU fans flowing towards the sabertooth).

2 x 52A current should be enough also for my big winches IMO. I hope this experiment goes well. If not - one more expensive experience on the fail list for ticking off

Yep.
I got some quotations from a supplier in France. They are cheap : 9 euros if ordered by 10 (with a total minimum order amount of 150 euros).... too bad I do not build 10 sims

What I did find so far:
Reverse battery protection
Three possible solutions can be considered:
1. a Schottky diode Dconnected to VCCpin
2. an N-channel MOSFET connected to the GND pin (see Figure 32: Typical application circuit for DC to 20 kHz PWM operationshort circuit protection on page 20)
3. a P-channel MOSFET connected to the VCCpin The device sustains no more than -30A in reverse battery conditions because of the two body diodes of the power MOSFETs. Additionally, in reverse battery condition the I/Os of VNH2SP30-E are pulled down to the VCCline (approximately -1.5V).
-----

@vthinsel the diode is installed. Did some tests without the seat, only by moving the levers by hand, which is producing a quite heavy oscillation. The diode will be very warm...so befor I start the final test I sticked a cooler on it. I am waiting until the thermal adhesive is dried off. I wonder how it will work. Will it blow?

If it is just warm, then it's OK.
As long as it doesnt become hot. They can probably cope quite high temp.
I'll put mines on a decent radiator as well, with some fans. Should do the job. Goal is to validate that diodes avoid PSU shutdown. Then we can find better/bigger ones. I lso think of the ones you find in your real ca, that look very big...
r

loool. I hope you are wrong

OMG, first of all the PSU did not shut down after "Fuchsröhre" on Nords, I stopped the game immediately and did the temperature "finger test" - wtf the radiator was extremely hot! Ergo I need a fan as well...

Are you sure that you have the right diagnosis?

You are certainly correct that when the motors stop, they appear as a short circuit. Unfortunately these server/pc power supplies are heavily protected against such things.
You are also correct about a voltage being induced but not necessarily a reverse voltage, as this would blow up capacitors almost instantly. These problems are always sorted out
at the motor controller (MM/JRK). What you could do is add very large capacitors to the power supply to lessen the load put on the power supply, or a car battery.
Sometimes depending on the motor size and its current draw a capacitor nor a car battery will suffice as it is just the PSU doing what it is meant to do and shut down when an excessive load is applied.

Here is a bit of info scavenged from the interwebs (just pay attention to motor characteristics, as this is a section of an answer to a question posted "what are capacitors on motors used for"):

• • When motors with brushes are running normally, the motor brushes produce sparks, which cause noise "from DC to daylight". This has nothing to do with PWM -- it happens even when these motors are connected directly across a battery, without any PWM. If we did nothing, the cable running from the electronics board (or directly from the battery) to the motor would act like an antenna, radiating TV and other radio interference. One way people fix that problem is to attach small ceramic capacitors directly to the motor to absorb much of that noise.
    
    
  • When using PWM to drive the motor, when the transistors turn "on", the motor may pull a current spike / surge current -- the above noise-filtering capacitors make that current spike worse. When the transistors turn "off", the motor inductance may cause voltage spikes from the motor inductance -- the above noise-filtering capacitors help a little. More complex filters attached directly to the motor can help these two problems.
    
    
  • When a motor -- even a motor that doesn't have brushes -- is first turned on at a dead stop, and also when the robot hits an obstruction and stalls the motor, the motor pulls much higher currents than it does in normal operation -- currents that may last for several seconds. This high current may pull down the battery power rail enough to reset all the digital electronics in the system (or perhaps reset just some of the digital electronics, causing half-brain syndrome).
    
    One work-around has 2 parts:
    
    1. add large electrolytic capacitors directly across the battery (or across the battery input to the PWM motor driver, or across the battery input to the digital electronics, or often capacitors in all three locations) -- these capacitors work better at supplying high currents for a few milliseconds than the battery does.
    2. In the few milliseconds we have before the stalled motor pulls all the energy from those big capacitors and then pulls the power rails low enough to start resetting things, program the digital system to somehow recognize that the motor has stalled and kill the power to that motor. Then that motor no longer drags down the power rail, and the digital electronics and all the other motors continue to operate normally. ("soft-start", "current-limiting", "torque-limiting", etc. are more sophisticated forms of this idea). (Those big capacitors, also absorb some of the energy that comes out of the motor when the PWM turns "off", and later put that energy back into the motor when the PWM turns "on").

ok guys obviously I wasted 50 bucks...at "Döttinger Höhe" the winches stopped again. At least the PSU stops a little bit later, but it stops.

Now using one PSU for one winch - no issues.

Hi

I havent read the entire thread but this sounds an awful lot like the voltage is rising on the supply rail and is causing the psu to go into over voltage protect. Like Alexey posted.

Are you able to log the rail voltages? or maybe just log maximum voltage?

in my own experience it is imperative to use heavy and short wires to avoid induction.

Just for giggles try and put a heavy resistor across the psu 0v and +24v. 100w (5Ohm@24v) should be enough (re purposed space heater maybe ?) . If this does the trick i would recommend a braking resistor 3-400w and a control circuit as not to continuously draw power. .


Cheers
Daniel