eBay TB6560 Stepper Motor Driver Boards

[Mad Professor]

I am running PicoScope v6.3.4.0.

I have not had this scope long so I am still finding my way around the settings, so I am not 100% sure what you are after.

Bipolar Parallel:
True RMS Avg 120mv.
Peak to Peak Avg 1.15v

Bipolar Series:
True RMS Avg 80mv.
Peak to Peak Avg 30mv.

[irving2008]

I am running PicoScope v6.3.4.0.

I have not had this scope long so I am still finding my way around the settings, so I am not 100% sure what you are after.

Bipolar Parallel:
True RMS Avg 120mv.
Peak to Peak Avg 1.15v

Bipolar Series:
True RMS Avg 80mv.
Peak to Peak Avg 30mv.

1.15v peak over .33 ohm = 3.5A peak, RMS = .36A

80mV over .33ohm = 0.24A, but the peak looks low, sure it wasnt 300mV?

Can you post the waveforms?

[Mad Professor]

Sure I can save the waveforms, do you want them as screenshots or save the waveforms to an output file?

[irving2008]

Sure I can save the waveforms, do you want them as screenshots or save the waveforms to an output file?

I usually do screen capture or print as PDF.

Attached are 3 captures from my L297/L298 board using the same motor at 500, 750 and 900 steps/sec on a 36v supply, wired bipolar parallel (coil resistance = 3.2ohm).

This shows the A-enable signal (blue) and the sense voltage (red). The sense voltage is directly proportional to the current in the coil (x 2), so .5v = 1A. At 500stesp/sec the RMS voltage is 0.64v, a current of 1.3A RMS, the peak voltage being 0.9v equivalent to 1.8A. You can see that the current doesn't start to flow (indeed its negative slightly at the start of the cycle which is due to the back emf/collapsing field of the previous cycle) until 0.7mS into the cycle, it then ramps up due to the inductance of the coils (these being high inductance motors i.e. not very fast) until it finally gets to the current limit and the driver goes into chopping.

At 750stesp/sec the RMS current has dropped to about 1A, the peak still being 1.8A. This is because the initial start-up and ramp is a greater proportion of the cycle time.

At 900steps/sec the current never gets to the set limit before the cycle ends... this is the fastest the motor will go at this voltage and the power output wil be low, the RMS current here is about 0.5A.

To go faster with these motors needs about 70v...

Setting Vref using the scope like this is much more accurate than adjusting it statically or relying on the overall current consumption.

[Mad Professor]

This board is ment to be rated upto 36vdc, So I tried using my 36vdc 10A PSU.

I set the board to it's lowest current setting on the DIP switches to make sure I did not burn out or over heat my stepper motor, I am only testing X-Axis atm.

Powered up the board, and all the lights and the fan came on, Turned it all off and, when I next turned it back on, I was greated with a nice pop / bang, with sparks, and blue / white smoke.

Part of the Z-Axis TB6560AHQ had exploded, Oh Joy.

I have since looked at some of the datasheet for the Absolute Maximum Rating.

L7812CV - 35 Volts Absolute Maximum Rating.
L7805CV - 35 Volts Absolute Maximum Rating.
TB6560AHQ - 40 Volts Absolute Maximum Rating.

I will post a pic of the poor TB6560AHQ chip once I have uploaded it to my site.

[irving2008]

This board is ment to be rated upto 36vdc, So I tried using my 36vdc 10A PSU.

I set the board to it's lowest current setting on the DIP switches to make sure I did not burn out or over heat my stepper motor, I am only testing X-Axis atm.

Powered up the board, and all the lights and the fan came on, Turned it all off and, when I next turned it back on, I was greated with a nice pop / bang, with sparks, and blue / white smoke.

Part of the Z-Axis TB6560AHQ had exploded, Oh Joy.

I have since looked at some of the datasheet for the Absolute Maximum Rating.

L7812CV - 35 Volts Absolute Maximum Rating.
L7805CV - 35 Volts Absolute Maximum Rating.
TB6560AHQ - 40 Volts Absolute Maximum Rating.

I will post a pic of the poor TB6560AHQ chip once I have uploaded it to my site.

Can you turn down the power supply? Mine goes down to 32 and up to 40v. it could be that back-emf from the motor had damaged the chip by spiking the supply - I'd limit that board to a 30v supply if it has regulators on-board unless they have an additional dropping zener diode in series. On my board you can see spikes of 65v on deceleration, so I have a snubber (basically a 36v zener and a low ohm resistor) across the supply. Another solution, shown in the attached schematic uses a transistor to the same effect...

[Mad Professor]

Here is a pic of what is left of the chip.



My 36vdc PSU is not adjustable.

I now need to start looking at ways to limited the voltage and spikes.

I was looking at using a zener diode and Metal Oxide Varistor to deal with the spikes.

But I still have to look into it more.

[Tom]

Can you turn down the power supply? Mine goes down to 32 and up to 40v. it could be that back-emf from the motor had damaged the chip by spiking the supply - I'd limit that board to a 30v supply if it has regulators on-board unless they have an additional dropping zener diode in series. On my board you can see spikes of 65v on deceleration, so I have a snubber (basically a 36v zener and a low ohm resistor) across the supply. Another solution, shown in the attached schematic uses a transistor to the same effect...

Hi Irving,

That snubber circuit is very interesting... It's just what I need. I'm running one of those 50V power supplies that Kip found in "unregulated" mode at 43V. My drivers will smoke at 50V, so I'm nervous.
Can you point me towards any online material that would help size the components to dissipate the sort of spikes I'm likely to see?

Sorry to hijack! (maybe Irving's tip will save a few more driver boards... :)

Tom

[crossleymarko]

i know this is an old post, but ive just come accross it. ive been on cnczone and asked about a full kit for my first build.
i have been told.

Run far and fast from that controller. Search this site for TB6560 and you'll have all the info you need. Almost 500 posts in this threadalone.

so what do you think...

hope to get much info on ere. im in the uk myself.
:confused: