measure current drawn while using pulse width modulator?

Sep 25, 2014
73
I have a motor hooked up to a pulse width modulator. How would I measure current draw at partial duty? At 100%, it's easy enough. I don't have an oscilloscope, so I can't determine the pulse width at a given setting. If I am at a duty percentage less than 100%, and I take a current reading, how would I interpret the results? I have an analog meter, btw. I imagine the current reading on the meter would be a good approximation of what I'm actually drawing, or would it? Thanks.

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,510
The analog meter should give you something approaching the average current. If you multiply that by the inverse of the duty cycle you'll get the peak current.

This can be confirmed by replacing the motor with a resistor and ensuring that the average current measured by your meter is proportional to the duty cycle.

Sep 25, 2014
73
thanks

Minder

Apr 24, 2015
3,478
The current waveform does not generally represent the voltage waveform, it is a mean level saw tooth in nature.

M.

Replies
1
Views
1K
Replies
7
Views
1K
Replies
7
Views
1K
Replies
9
Views
3K
Replies
3
Views
2K