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Can We generate asymmetrical PWM in plecs and embedded code by TI F28379?

0 votes
Can We generate asymmetrical PWM in plecs and embedded code by TI F28379 for space vector modulation?

For example: My switching signal is not symmetrical PWM as attached image.
asked Jun 1, 2023 by Le Nam Pham (14 points)
Do you want the duty cycle to be modulated?
Yes, I want to modulate an asymmetric PWM

2 Answers

0 votes

I'm assuming your graphic shows the switching sequence within one switching cycle.

In this case, assuming a sawtooth carrier waveform, you would will need two compare values as inputs for each PWM channel, similar to CA and CB in the following graphic from the 28379 technical reference manual. 

While one can build a modulator to do this in a PLECS simulation, currently this type of modulation scheme isn't supported in by Plexim's TI C2000 Target Support Package.


answered Jun 5, 2023 by Bryan Lieblick (1,949 points)
Thank you for your comment. I saw this picture in TI C2000 manual. But as you said, this type of modulation scheme isn't supported in PLECS
0 votes
If I understood you correctly than I am sending you my solution for this problem. I have also needed asymmetric PWM to control BLDC motor by controlling duty cycle of every signal leaving the PWM block (Picture_01).

Up here you have the inside of PWM, next picture will show you inside of "PWM_test" because there everything is happening (Picture_02).

And here is inside of "Pulse Generator" added in "PWM_test" (Picture_03). Parameters such as f_pwm and duty are being changed in Simulation Parameters. I recommend value for parameter duty to be 0.0001 so then by increasing value "duty" on the input you will be decreasing width of signal, and by decreasing value "duty" on the input you will be increasing width of signal. I am recommending you this way, because that worked for me, maybe you will do it by yourself. Once again I made this PWM custom for my BLDC drive system.
answered Jun 6, 2023 by Sova (16 points)