PWM signal with variable duty cycle

Chris

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Jul 27, 2010, 1:23:05 AM7/27/10

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Hi,
I'm trying to generate a PWM signal with a duty cycle that increases with time. I'm using the Simscape Controlled PWM Voltage block. Is it possible to have a block parameter vary with time? Or is there a different block that might accomplish the same goal?
Thanks,
Chris

Jean Baptiste Lanfrey

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Jul 27, 2010, 4:46:29 AM7/27/10

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Hi Chris,
Depending on the version you are using there are several ways to do it.
You can use built-in blocks (physical signals from simscape foundation
library) and for instance compare a triangle carrier with an input signal
that will determine the duty cycle.
You can also use the simscape language to build you own PWM generator with
either a time varying duty cycle defined in the ssc file
(http://www.mathworks.com/access/helpdesk/help/toolbox/physmod/simscape/ref/time.html)
or as an input to your block.
HTH
Jean-Baptiste

"Chris " <christophe...@samsung.com> a écrit dans le message de news:
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Chris

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Jul 28, 2010, 1:15:27 AM7/28/10

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Hi Jean-Baptiste,

Thanks for your reply. So far, I've been trying to generate the signal using built-in blocks (I'm not familiar enough with Simulink/PWM to try to build the generator myself). I'm a bit confused by the other method you suggest. I want the duty cycle to increase 10% every .1 seconds, so I created this signal using a ramp and rounding function. Can I input this as a parameter for another block? I don't really understand what you mean by "compare a triangle carrier with an input signal." Sorry for my simulink incompetence....

Thanks again!

"Jean Baptiste Lanfrey" <jlan...@mathworks.com> wrote in message <i2m6d7$4ie$1...@fred.mathworks.com>...

> Hi Chris,
> Depending on the version you are using there are several ways to do it.
> You can use built-in blocks (physical signals from simscape foundation
> library) and for instance compare a triangle carrier with an input signal
> that will determine the duty cycle.
> You can also use the simscape language to build you own PWM generator with
> either a time varying duty cycle defined in the ssc file
> (http://www.mathworks.com/access/helpdesk/help/toolbox/physmod/simscape/ref/time.html)
> or as an input to your block.
> HTH
> Jean-Baptiste
>
>

> "Chris " <christophe...@samsung.com> a crit dans le message de news:

Jean Baptiste Lanfrey

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Jul 28, 2010, 3:47:21 AM7/28/10

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Hi Chris,
you can definetly do it and it is not that complicated.
The method I was proposing is a simple one that is using a few built-in
blocks (a triangle source, a comparator and a duty cycle input).

Have a look there : http://en.wikipedia.org/wiki/Pulse-width_modulation. It
explains the simplest method to generate a PWM.

Once you've built this simple model, just connect a ramp (slope 10%/0.1s) to
the duty cycle input and you're done.

Jean-Baptiste

"Chris " <christophe...@samsung.com> a écrit dans le message de news:
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Chris

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Jul 29, 2010, 12:45:20 AM7/29/10

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Yeah, I got it to work thanks. I actually had that wikipedia page bookmarked from about a month ago but didn't realize that it could be so helpful.

Thanks again for your help!

"Jean Baptiste Lanfrey" <jlan...@mathworks.com> wrote in message <i2onac$4f8$1...@fred.mathworks.com>...

Menaka seeni

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Aug 27, 2010, 6:38:04 AM8/27/10

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hi chris,
i am also seraching for variable pulse width(duty cycle) for regular interval of time.
ouput freq=50hz.switching freq=5khz.duty cycle is vary from time to time.
Is it possible to have a block parameter vary with time?how can i proceed to get that?
thanks,
harithaa

"Chris " <christophe...@samsung.com> wrote in message <i2r110$lbo$1...@fred.mathworks.com>...

Hossein

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Dec 8, 2011, 9:13:08 AM12/8/11

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Hi Jean-Baptiste
would you please upload the link ...
thanks
"Chris" wrote in message <i2oedf$coc$1...@fred.mathworks.com>...

kamilu sanusi

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Apr 8, 2014, 12:54:07 PM4/8/14

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please im trying to create PWM controled block for Z source inverter where i can control the duty cycle the sooth through state, and can not do it. please assist me with a model block for this.
Thank u
Sanusi Kamilu