ePWM Synchronization Question

Frank H Zhang

Expert 1515 points

Other Parts Discussed in Thread: TMS320F28035

Hi,

I was the ePWM document ' TMS320x2802x, 2803x Piccolo Enhanced Pulse Width Modulator (ePWM) Module ' (TMS320F28035)

------ Literature Number: SPRUGE9E
------ December 2008–Revised March 2011

On page 95,

Figure 67. 3-Phase Interleaved DC/DC Converter Waveforms

I don't understand why the pulse width of EPWM2A/B and EPWM3A/B become shorter and shorter.

Thank you,

Frank

over 14 years ago

0 Frank H Zhang over 14 years ago

Expert 1515 points

Hi,

Can somebody just let me know whether It should be like that, or I misunderstood something here?

Thank you,

Frank

0 Daniel Chang over 14 years ago in reply to Frank H Zhang

TI__Expert 4120 points

Frank,

That is not being done on purpose to show the effects of interleaving. Perhaps the creater wanted to show that the duty for each phase can be independent. Just assume that the three phases are being controlled independently and that each PWM module generates its own waveforms but only the settings for PMW1 are shown.

The focus of that diagram is on the phase shift and not the PWM duty values.

Regards,
Daniel

0 Frank H Zhang over 14 years ago in reply to Daniel Chang

Expert 1515 points

Hi Daniel,

Thanks for your reply.

I know what you mean. The focus is on the phase shift.

But, I was also reading the code snippet associated with that diagram (the following page), and it made me start questioning my understanding of EPwm module.

Overall, I think it is kind of misleading.

Thank you,

Frank

0 Daniel Chang over 14 years ago in reply to Frank H Zhang

TI__Expert 4120 points

Frank,

I agree. Based on the code snippet, the three modules should generate identical PWM duty values. I will ask to have this entered to be changed.

Regards,
Daniel

0 Frank H Zhang over 14 years ago in reply to Daniel Chang

Expert 1515 points

Thanks.

Frank

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ePWM Synchronization Question