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PWM to H-bridge switching

The PWM is really the key.  Unless you need immediate and/or high-precision adjustments to the PWM duty cycle, the suggestions here about hardware-timed DO will likely be more sensible than the 8-counter idea I posted earlier.  (Not to mention the fact I'm not sure my 8-counter method will work).

-Kevin P.

CAUTION! New LabVIEW adopters -- it's too late for me, but you *can* save yourself. The new subscription policy for LabVIEW puts NI's hand in your wallet for the rest of your working life. Are you sure you're *that* dedicated to LabVIEW? (Summary of my reasons in this post, part of a voluminous thread of mostly complaints starting here).
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Message 11 of 17
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Thank you all for your help!  I will take all the suggestions into consideration and let you know how it goes!  Heh...I have 2 weeks to get this thing working...add an encoder...get it working again...and then drive it without the Halls...should be quite a challenge. 
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Message 12 of 17
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I forgot to mention that I am using a PCI-6024E board.  Can that example also work for the E searies boards?  I noticed it was for an M series...
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Message 13 of 17
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No, the E-series boards only support software-driven timing for digital I/O.  Seems awfully unlikely you could achieve sufficient timing reliability that way.

-Kevin P.

CAUTION! New LabVIEW adopters -- it's too late for me, but you *can* save yourself. The new subscription policy for LabVIEW puts NI's hand in your wallet for the rest of your working life. Are you sure you're *that* dedicated to LabVIEW? (Summary of my reasons in this post, part of a voluminous thread of mostly complaints starting here).
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The PCI-6601 is only a couter/timer card right?  I have one of those but that wouldn't work would it....
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Message 15 of 17
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No, the 6601 digital I/O only supports software timing.  You might be able to use it to test out the older idea I threw out there though -- using the Pause Trigger feature to support variable PWM.  If it works, then you'd have an additional option for moving forward on the project -- another 6601 would provide the additional 4 counters you'd need for a total of 8.

The best choice depends on your overall needs & budget.  If you don't need to vary the PWM freq and/or duty cycle on the fly, I'd think an M-series board would be most peoples' best choice because of its versatility.  Maybe consider the 6221 or 6251?

-Kevin P.

CAUTION! New LabVIEW adopters -- it's too late for me, but you *can* save yourself. The new subscription policy for LabVIEW puts NI's hand in your wallet for the rest of your working life. Are you sure you're *that* dedicated to LabVIEW? (Summary of my reasons in this post, part of a voluminous thread of mostly complaints starting here).
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Message 16 of 17
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High side switching is standard in a 3 phase H-Bridge

Only two are really active at one time mainly because you need a full path from one Hi and one low. This is typically a grounded phase operation;

 

The diagram from https://www.basilnetworks.com/article/hybrid/powerbridge.html explains the two out of three phases being used and the third is grounded.

 

To create a sine wave from pulses follow the PMBM web page https://www.basilnetworks.com/article/motors/brushlessmotors.html and set the the number of pulses from 0 to Pi for three phase points.

 

Sal Tuzzo

CTO Basil Networks

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Message 17 of 17
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