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Topic: MegaMoto High-Current motor shield (Read 3037 times) previous topic - next topic

RobotPower

Hi All,

I've recently been working on a high-current motor control shield.  I'm using the Infineon BTN7960B half-bridge chips.

This unit is designed for about 12A continuous current at up to 28V for each half-bridge chip.  

Each shield can control 1x 12A motor fwd-rev in H-bridge mode, 2x 12A motors in half-bridge mode (fwd only) or 1 large fwd-only motor 25A in parallel half-bridge mode.  Very flexible. 2 shields could run one large 25A motor fwd-rev in parallel half-bridge mode.

Any of the three timers on the Nano can be selected as the PWM source for the power FETs.  So for example  the PWMA source can come from OC2A (D3) and PWMB from OC2B (D11) using jumpers.

These power FETs also have a current sensor output.  This can be fed into the Analog pins.  The sensors from both chips can be either connected to an analog input pin or connected in parallel to a single input.  This uses a single pin to read out the current from both chips in H-bridge mode as only the high-side of the half-bridge generates an output voltage.

Since the Mega168/328 have 6x PWM outputs, up to three motors can easily be controlled by stacking three of these up. OR 6 motors in half-bridge mode or 2 brushless 3-phase motors or...

Impressions and comments welcome.  Will be posting code and images for this soon.

/me


RobotPower



Graynomad

I don't know much about these drivers but this looks pretty nice to me.

If you're going to make it a product you might like to ass it to http://shieldlist.org.

______
Rob

Rob Gray aka the GRAYnomad www.robgray.com

Fonyat

Hello...

I'm working on a low-cost, let's say, "educational" motor shield, to play around with low power motors and learn the basics on driving theory.

The fact is I'm stuck with a feature you seem to have sucessfully implemented on your shield: the ability to work with 2 independent drive circuits as a single paralleled one! As you said on your post, this adds a lot of flexibility to the shield...

Could you, please, point me some directions for research?
I'm not sure about the kind of logic I'll need, a simple IC indication would be a great start!!

Here is my project on Instructables.com:
http://www.instructables.com/id/Arduino-Dual-L293B-Motor-Drive-Shield-work-in-pro/


Thanks in advance,
Rodrigo Fonyat

P.S.: Congratulations for your shield... looks REALLY cool!


mowcius

Quote
might like to ass it

Hehe


Nice shield idea though.


Mowcius

Graynomad

Oops, well the D is right next to the S  :-[

______
Rob
Rob Gray aka the GRAYnomad www.robgray.com

mowcius

Quote
Oops, well the D is right next to the S

Indeed it is.

Gave me a laugh though :)

RobotPower

@Rodrigo:  I've never liked the L29x series chips even though a lot of people do.  What we did was to put in jumpers to allow the h-bridge inputs to be connected in parallel to a single Arduino pin.  The outputs will follow similarly and can be ganged together for increased current.  IIRC these are DMOS chips so they can be safely paralleled.

In other news testing is going well.  Working on a couple of sketches to demonstrate these.  Will convert to a library when everything has been tested.

Will add to shieldlist.org when it is ready for general consumption.

/me

RobotPower

Power testing today.  No problemo at 12A+ continuous.  Almost no heating at that current level.  Peak tested was over 40A but the power chips went into shutdown so I couldn't measure it accurately.  34A peak tested where I could measure it.  Friction burns on the hands from grabbing that wheel to put a load on the motor :o

Action shot:



Double stacked shot:



/me

RobotPower

P.S. I really really like these BTN7960B power chips.  They work soooo much better than those horrible VNH3SP30 chips that others use (*cough*Pololu*cough*).

/me

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