Author Topic: Measuring space vector PMW signal with oscilloscope  (Read 868 times)

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Offline mike bubaTopic starter

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Measuring space vector PMW signal with oscilloscope
« on: July 07, 2018, 11:43:49 am »
Hi!
Is it possible to measure space vector PWM signal and "freeze" them, but with Sweep = Auto/Normal? How to set up the oscilloscope to do that? I have Rigol DS1054... For not I have to press Single button every time (or Sweep = Single) if I want to "freeze" picture?
If I am measuring dc/dc converter pulses there is no problem (signal is not moving even with Sweep = Auto/Normal). But for this signal, the width of the pulse is not constant and changes.
 

Offline JS

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Re: Measuring space vector PMW signal with oscilloscope
« Reply #1 on: July 07, 2018, 02:08:19 pm »
I'm not sure what you are asking, if the signal is changing the picture should be changing while using auto or normal triggering, and make a single snapshot with single trigger. The only thibg I can suggest if you want to stop an auto or normal display to look at it for a while isbto press the stop button. There's also the optional record mode in the 1054z, when you can capture a lot of snapshots and look at them later.

JS

If I don't know how it works, I prefer not to turn it on.
 

Offline rstofer

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Re: Measuring space vector PMW signal with oscilloscope
« Reply #2 on: July 07, 2018, 03:55:23 pm »
There should be no problem triggering on the rising edge of the signal.  That part should be easy.  What isn't easy is triggering on the beginning of the pattern.  Perhaps the pulse width is a minimum, rising to a maximum and diminishing to a minimum and you want to trigger at the beginning of the cycle.

I don't know how you are timing your PWM but if I were doing something like that with a microcontroller, I would generate a trigger pulse with one of the IO pins.

Chapter 5 (page 5-8) in the User Manual talks about triggering on a pulse of a certain minimum width.  So, presumably, you can trigger on the wide pulse in the sequence and then move the image around to get the first pulse on the left edge.

In fact, spend some quality time with Chapter 5.  The DS1054Z, like most DSOs, has an enormous number of trigger options.
 


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