TB6600 stepper shutting down

Hello to all,

My problem is the following:

I use a TB6600 driver to power a Nema23 Stepper (version).

For very long (days) runs, everything worked okay. However, once, I had the TB6600 shutting down: there is a green and blue light. The blue light, labelled D7 I believe, usually clics. When the 'shutdown' happens, the blue light is lit continuously.

After checking all connections again and again, rebooting everything multiple times, magically the problem was solved.

Everything worked correctly for a few weeks, and now the problem comes again.

It is very strange indeed: I have already used the motor to maximum power, and did so for very long periods of time, without a problem.

I have attached a video of the problem.

Between the runs of a bout a minute of my experiment, I restart the driver as it has been crashing at times.

It is crucial for me that the driver doesn't crash, as otherwise my experiment is not correct.

Any ideas will be greatly appreciated :slight_smile:

Please post a link to the datasheet for the stepper motor driver that you are using. I think the TB6600 is theoretically good for 4 amps but your motor needs 4.2 amps and maybe the driver is just overloaded?. Also, perhaps the driver can't really provide even 4 amps?

...R

You state you are running "have already used the motor to maximum power"

Any motor and its driver have a MAXIMUM rating but beyond that there is usually a "duty cycle"
It may be that you are exceeding the duty cycle.

That gives you two options.

  1. Reduce the maximum load.
  2. Reduce your present duty cycle.

There is also another factor which is cooling.
Almost all motors and drivers required some form of cooling.
Again they will be mentioned in the specifications and you should not exceed those temperatures unless there is adequate cooling.

I took a look at the video and was horrified to see the way the motor was applied to your project.
Such an arrangement should use slide bearings and adequate lubrication.
You may also want to consider a servo for that application rather than force the motor to use a limited range of motion for long periods as it may be that you are overheating a specific set of winding within the motor.

Try rotating it 90 degrees and see if the problem still persists and if it does not then you have almost certainly placed a set of winding at risk.

Before answering your comments, the real question for me is: why does this fail now, as it did not for very long periods of time (under the same conditions). As the conditions are similar, I doubt it has something to do, say, with overheating.

Please post a link to the datasheet for the stepper motor driver that you are using

Here it is

Also, perhaps the driver can't really provide even 4 amps?

The driver is rated for max 3.5A with 4A peaks.

  1. Reduce the maximum load.
  2. Reduce your present duty cycle.

I am not sure about what you mean regarding the duty cycle. If you speak about the length of my runs (say, 1 min), I can't really change that, as the physics is dependant on that unfortunately (same goes with the load).

There is also another factor which is cooling.

I actually bought and plugged in a computer fan on top of the driver (not visible in the video). The motor is not very hot, though warm.

Such an arrangement should use slide bearings and adequate lubrication.

I know, I didn't build it myself. I'm a theoretical physicist, and it's not really my choice or pleasure to do this experiment to be honest. I have to do it because the experimental team decided to flip on us. However, the setup is quite smooth and there isn't much friction. The external load is much, much greater.

Another note about overheating is that I left the whole set up cool for ~ 30 mins, with no changes to the problem. The motor + driver were cold.

You may also want to consider a servo

I agree, but I couldn't find servos at a moderate price tag with this kind of speed + torque. (Torque at least 3 Nm, with at least a pulsation omega of 40 (/s), ideally more for both).

comrad_dau:
The driver is rated for max 3.5A with 4A peaks.

That seems to be the explanation of your problem. The motor needs 4.2 amps and for that I would choose a driver that can deliver 5 or 6 amps. Using electronic equipment close to its max limit is never a good idea.

...R

That seems to be the explanation of your problem. The motor needs 4.2 amps and for that I would choose a driver that can deliver 5 or 6 amps. Using electronic equipment close to its max limit is never a good idea.

I agree, but, again, I find it really strange that everything was fine for days and now it doesn’t work. Do you think the driver might have burned? It still works for about thirty seconds normally.

I bought new drivers under your impulsion.

comrad_dau:
I agree, but, again, I find it really strange that everything was fine for days and now it doesn't work. Do you think the driver might have burned? It still works for about thirty seconds normally.

I know nothing about failure modes and the internal effects of stress so I can't comment beyond saying that sounds plausible.

...R

"STRESSED" components can appear to work but have a much shorter time frame between overheat or other failures. Whilst the driver may appear OK a single stressed component inside the driver may be at the tipping point for failure.

The only way to know that is to replace the driver and the motor as a unit and see if the failure points are further apart.
If that is the case one or the other was the cause.

Re inserting a single original item eg motor back into the setup may cause the the failure to re-appear in which case you would suspect the motor.

If the motor does not bring back early failure then the driver could be considered the cause.

As for duty cycles Robin partially covers it in the max amps scenario but motors and drivers each have thier own duty cycle and you must consider the item with the lowest duty cycle as the weak link in any setup.

You cannot simply run one item at its maximum capacity for extended periods of time.
That could cause one or the other item to fail either completely or partially.

Yours seems to be a partial failure.

Some light reading on stepper duty cycle

The TB6600 output FETs have a resistance of 0.4 ohms (worst case 0.6 ohms), and as two are involved the
power dissipation for 4A is between 12W and 19W. Without water cooling I can easily see the chip overheating
and shutting down at these power levels, depending on airflow and ambient temperature.

The chip senses its own temperature and shuts down automatically when too hot.

However it wll be much more reliable run cooler than this, such as by adding a fan to its heatsink.