FYI H-bridge thoughts

I've written up notes on building H-bridges (so far only the BJT section is populated). You can read about them here: http://www.mcmanis.com/chuck/robotics/tutorial/h-bridge /
Enjoy, --Chuck
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Hi Chuck,
A really good article you have written there. Thanks for sharing.
Peter http://robotics.pj-engineering.com

is
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Nice presentation, Chuck. Some comments:
AFAIK, the term "four quadrant" doesn't refer to the ability to control all four legs independently (though that is required for four quadrant control), but to the ability to control all four quadrants of the torque vs speed graph.
All your discussion of braking talks about using a short circuit. Braking using a short circuit dissipates energy using (only) the resistive losses of the motor, which might not be sufficient with some motors depending on the application. Regenerative braking by dumping energy back into the supply can be used to get more powerful braking - or did I miss where you discuss this? Regen using MOSFETS is cute, as when "on" they can sustain a considerable reverse current, meaning you don't need such powerful flywheel diodes and can avoid the diode losses.
Clifford.
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