may be better if altered to:Efficiency in this case is measured as wattage. If you have a SMPS with 90% efficiency, and it converts 12VDC to 5VDC at 10 Amps, the 12V side will be pulling approximately 4.6 Amps. The 10% (5 watts) not accounted for will show up as waste heat. While being slightly noisier, this type of regulator run much cooler than their linear counterparts.
I know, I know, now you can say I am being nit-picky.Efficiency in this case is measured as wattage. If you have a SMPS with 90% efficiency, and it converts 12VDC to 5VDC at 10 Amps, the 12V side will be pulling approximately 4.6 Amps. The 10% (5 watts) not accounted for will show up as waste heat. While being slightly noisier, this type of regulator runs much cooler than its linear counterparts.
It is a bidirectional controller. If you have a 50% PWM signal, the motor will turn in neither direction, two directions being balanced. 0% is full rotation in one direction, and 100% is full rotation in the other direction. Motors, being basically inductive, will reject the high frequency components and respond to the low frequency component, much like speakers. It is simplified, but the base concept is valid.
This picture does not appear correct to me.
If you create a path through the MOSFETs that drives a motor in one direction using a PWM signal, you do not want the reverse direction to be activated during the resting portion of the PWM.
Actually the point I'm trying to make is the symmetry of the triangle wave doesn't matter. I lifted this image from a thread that is currently dormant.Bill_M,
I haven't mentioned it yet but I think you deserve high praise for taking the time to compile this treatise on PWM. Next to LEDs and Microcontrollers, I think PWM is a frequent topic of post here in the forum.
http://forum.allaboutcircuits.com/attachment.php?attachmentid=15652&d=1264596237
In the post linked to above, you show a comparator with a potentiometer and several representative outputs. The two lower output plots are indicative of different settings of the potentimeter. I wonder if it would be a good idea to note on each, the setting of the potentiometer that yielded the output.
hgmjr
Probably. If you have a better thought how to draw it, sketch it up as ugly as you like and I'll pretty it up. My thought is a 12 V power supply would do the job, top gets 0V, bottom gets 12V. Other side gets opposite.Bill_M,
Do you suppose anyone is going to quibble over the fact that the two high-side MOSFET devices in your H-bridge (in the motor driver illustration) requires a high-side driver to switch properly?
hgmjr
P.S. This is not a quibble.
I thought of that too. They keep drumming that they want to reduce the bandwidth, which left its mark. I'll redraw it and see if it looks better.I think it would be helpful if the diagram showing the sinusoid to PWM waveform would benefit from being enlarged. This would provide greater resolution of the resulting PWM signal. I think it would make the concept clearer to those encountering PWM for the first time.
hgmjr
Not a problem. This is the kind of feedback I'm hoping for.From a grammatical persective, I think that the last sentence in the following paragraph.
may be better if altered to:
I know, I know, now you can say I am being nit-picky.
hgmjr
I'm reviewing the AAC book for any sections on PWM, and can't find anything. Anyone else see something I'm missing?[/QUOTE
I aded <section> </section> tags around the text. All else looked good
Thanks, Bill for your fine work.
for the record the new or updated files at ibiblio are :
dcdrive.sml contrib.sml 4300[34567].png 43003.png 43004.png 43005.png 43006.png 43007.png