Hi,
I want to implement phase shifted carrier wave PWM on TMS320F28835. I am using this PWM pulses (12 nos.) to three phase NPC Inverter (DC-AC Converter). Currently I am comparing three sine reference waves with two 20kHz carrier waves (one in positive half and one in negative half). Here, Positive half of each sine reference wave is comparing with the carrier wave (triangular wave) in positive half, and negative half of each sine wave is comparing with the carrier wave in negative half.
Now, I want to compare first sine reference wave (R-phase) with one PAIR of carrier wave (one in +ve half n one in -ve half), next reference wave (Y-Phase) with another pair of carrier wave, which is 120 degree apart from the earlier carrier wave and next sine reference (B-Phase) eith another pair of carrier wave, which is 240 drgree (OR -120 degree) apart from the first sine wave. So that I need 6 carrier waves on the place of 2, which I am using currently.
I want to know that, how I can give this 120 degree phase shift to 20kHZ carrier wave, using inbuit ePWM module of F28335.
Thank you!
You can use both methods:
i) phase shifted carrier or
ii) phase shifted modulating signal
in TMS320F28335 DSP.
Everything you need to know about TMS320F28335 including the tutorial and the solution are available at the link below:
http://www.ti.com/lit/zip/ssqc019.
If you generate another two sine wave functions in your algorithm, you can compare these two functions with same triangular carrier waves. Then you can generate your 120 and 240 degrees phase shifted signals. Actually I think you do not need to use two carrier wave for generating positive and negative signals. Only one wave is enough I think.
Hello Yusuf,
Yea, I am using one carrier wave only to generate two pulse trains. Earlier explanation is to get theoretical background of the problem.
I have generated three sine waves in my algorithm. and i cant use same carrier wave to compare with all the three sine waves. I want one carrier wave for each sine wave. and those carrier wave should be 120 deg apart from each other.(This itself would rule out the possibility to use one carrier wave for all three sine waves)
Thanks for your comment Yusuf
Check attached link
Here you will get manual for ePWM
register required to be modified for phase shifted carrier is "TBPHS"
Go to section 3.8 Controlling a 3-Phase Interleaved DC/DC Converter a small example is given there
This will solve your problem
Thank you
www.ti.com/lit/ug/spru791f/spru791f.pdf
You can use both methods:
i) phase shifted carrier or
ii) phase shifted modulating signal
in TMS320F28335 DSP.
Everything you need to know about TMS320F28335 including the tutorial and the solution are available at the link below:
http://www.ti.com/lit/zip/ssqc019.
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