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Topic: Low voltage Stepper Drivers bypass (Read 701 times) previous topic - next topic

zobom

Hello gentleman...

I'm studing a way to bypass a low cost stepper driver voltage limitation, maybe some of you may had the same issue.

Can one use a custom Mosfets H-bridge to on the +A/-A/+B/-B end to drive the bipolar stepper with approximately the same waveform but using different voltage?

Example:

A L298 with 12v output and 0.25A that passes through this second H-bridge that uses 200v 10amp mosfets? The arduino would be used with a current sensing circuit on the supply voltage to control the current flow.

This can be done this way?

Thank you in advance.

zobom

Ok, i know what i want... It was a Stepper Gate Driver without the FET's... The DRV8711 will do the trick.

This is from TI, they have a ready design example called TIDA-01227

http://www.ti.com/lit/df/tidrqe9/tidrqe9.pdf

DRV8711 diagram

http://www.ti.com/general/docs/datasheetdiagram.tsp?genericPartNumber=DRV8711&diagramId=SLVSC40G

MarkT

#2
Dec 05, 2017, 06:27 pm Last Edit: Dec 05, 2017, 06:28 pm by MarkT
No, you just use the right MOSFET drivers with the output devices.  There are a lot of high-low drivers that
are rated to 200V or even 600V...

However once you are starting to work at high voltage and power levels there are a lot of pitfalls and
its ever so easy to pop MOSFETs (they typically explode, so wearing eye-protection is essential!).

IGBTs are more robust for high voltage, but need extra free-wheel diodes (if not built-in to the package,
IGBTs don't have a body diode as part of their geometry, so its a separate die).

MOSFET/IGBT gate driving is best the province of gate driver chips designed for the purpose, not a cobbled together
small slow H-bridge.

The L298 uses darlingtons so it cannot even pull a gate to 0V for hard turn off, let alone do it in 250ns or
whatever switching window you need for sensible switching losses in a high power H-bridge.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

Robin2

H-bridge that uses 200v 10amp mosfets?
Just out of curiosity, why would it be necessary to drive a stepper motor with 200v?

...R
Two or three hours spent thinking and reading documentation solves most programming problems.

MarkT

[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

Robin2

For 5000 rpm?
Would that be possible?

However I was really hoping to find out what the OP is planning to do.

...R
Two or three hours spent thinking and reading documentation solves most programming problems.

MarkT

Don't know if its possible, but you need lots of voltage to overcome inductive and motional back-EMF to
run a stepper motor quickly with torque.  You do get increased losses as the voltage and switching speed
goes up, and eventually that limits performance.

I've driven a NEMA17 at 2400rpm from 24V, but with very little torque available at that speed.  80V systems
are fairly common for CNC.

Proper stepper driver chips aren't commonly available for very high voltage, so a separate index controller and
explicit MOSFET H-bridges are used with current feedback in hardware I'd imagine for bespoke high voltage
controllers.  Most integrated stepper driver chips are around 30 to 50V I think.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

Robin2

Don't know if its possible
Still waiting for a response from the OP. My guess is that you know a great deal more about this stuff :)

...R
Two or three hours spent thinking and reading documentation solves most programming problems.

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