bldc 7i39, current status?

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12 Jun 2011 20:35 - 12 Jun 2011 20:36 #10457 by jCandlish
jCandlish created the topic: bldc 7i39, current status?
There seems to be a dearth of motion control servos >200W.

What is the current status of the 7i39 integration? It looks like the best fit for my situation..

What else fills the need 200W<need<500W?

Thanx
jC
Last Edit: 12 Jun 2011 20:36 by jCandlish. Reason: grammar
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12 Jun 2011 22:59 #10458 by PCW
PCW replied the topic: Re:bldc 7i39, current status?
The 7I39 has a output power capability of about 250W but is only suitable for small (up to 80W or so ) servos. This is because a servo rated 200W continuous will need around 600 to 800 W of intermittent power, for up to minutes at a time.

We (mesa) dont currently have any mid range 3 phase drives (the next is the 8I20 which is overkill for such small motors), but there are many available, usually packaged with the motors and commonly using analog +-10V torque or velocity mode control.

The 7I39 and 8I20 are supported in the development branch of EMC (2.5)
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12 Jun 2011 23:13 - 12 Jun 2011 23:17 #10459 by jCandlish
jCandlish replied the topic: Re:bldc 7i39, current status?
Then why does Mesanet describe the product as "7I39 Dual 250W 3 Phase BLDC driver"?

Wouldn't 80W BLDC driver be more appropriate?

So we're running out of steam at <200W ...

If I want to replace my current 0.3Kw combined axis drive motor, what capacity will I need at the servo controllers?

It's stuff like this that make me wonder about the outcome of my project.

edit: I did not notice that the 8i20 incorporates hall effect feedback.

Cheers
_jC
Last Edit: 12 Jun 2011 23:17 by jCandlish.
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12 Jun 2011 23:25 #10460 by PCW
PCW replied the topic: Re:bldc 7i39, current status?
Perhaps 80W would be a better match to motor specifications. When we started making HBridges we rated them at maximum continuous output power (since they can be and are used for other things than motor drives), the 7I39 follows that rating scheme.

If you want the simplest guaranteed solution for a servo drive and you want brushless motors, purchase a standard servo motor/driver pair from AMC, Siemens, Danaher etc and use the analog torque or velocity control mode. Known to work well with EMC in 1000's of retrofits
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12 Jun 2011 23:28 #10461 by jCandlish
jCandlish replied the topic: Re:bldc 7i39, current status?
PCW wrote:

If you want the simplest guaranteed solution ...


Where's the fun (read learning) in that?
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13 Jun 2011 00:14 #10462 by jCandlish
jCandlish replied the topic: Re:bldc 7i39, current status?
Just to clarify.

When I look to a motor specificaiton like:

BLDC 313
48 Volt
8.70 Ampere
8 3000 1,0 Nm
3 Nm
1000 / 4000
2,08 Kg

Although the motor is advertized at 313W the Peak consumption is 417.6W.

Or
BLM57180-1000
Nennleistung / Nennspannung 180 W / 36 V DC
Nenndrehzahl 3000 rpm
Nennstrom / Spitzenstrom 6,7 A / 20,0 A
Nennmoment / Spitzenmoment 0,57 Nm / 1,71 Nm
Länge / Masse 140 mm / 1,25 kg
.
In this case the Peak current is > 3* nominal, so although the motor is rated 180W the nominal is 242W and Peak is 720W.

It makes just about as much sense to talk about a 2Kg NEMA 34 motor. I think that’s about what I need.

Does the 7133 integrate with the granite vsx-e?
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13 Jun 2011 03:01 #10464 by PCW
PCW replied the topic: Re:bldc 7i39, current status?
The 7I33 is a analog servo interface, Does the Granite drive accept analog +-10V control signals?
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13 Jun 2011 06:06 #10465 by jCandlish
jCandlish replied the topic: Re:bldc 7i39, current status?
The granite has PWM, Step/Dir, SPI and Analog command types directing Torque, Velocity or Position modes. The device does much that I would prefer to delegate to EMC2.



So it looks like interfacing is possible in a number of ways.

How to drive XYZA, servos read their corresponding axis' glass-scales (rs-422) and close that feedback loop is the question.

I had wanted all the hysteresis knobs in the same place.

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14 Jun 2011 09:50 #10480 by andypugh
andypugh replied the topic: Re:bldc 7i39, current status?
_jC wrote:

So it looks like interfacing is possible in a number of ways.


For your purposes the best approach is probably PWM-input velocity-control. That should integrate pretty well with glass-slide feedback (the Anilam machines, for example, used velocity amps and tachos and glass-slide feedback). You can do that with just a parallel port, or with a bare Mesa card.
(though you probably want some form of daughter-card as protection/breakout)

To answer a previous question: The 8i20 does not take Hall sensor signals, those go straight to EMC2 on GPIO lines, where the "bldc" component interprets them and sends direct current/angle commands to the 8i20.

I started writing a page to explain this, but didn't finish it.
wiki.linuxcnc.org/emcinfo.pl?BLDC
Time to create page: 0.073 seconds
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