F28335 - aPWM cont-up-down mode.

Lusi Castro

Other Parts Discussed in Thread: TMS320F28335

I´m trying to generate PWM for a seven-level inverter using TMS320F28335.

We need 18 pulses to control the inverter, and combining the ePWM and aPWM (eCAP) modules we can achieve a partial solution.

The gating pulses are not centered, because the ePWM and aPWM are in count-up mode, which generates a worst harmonic distortion than in count-up-down mode (centered pulse).

Anybody knows how to emulate the cont-up-down mode using the aPWM (eCAP) cont-up mode?

thanks,

Gustavo Castro

over 15 years ago

0 Arefeen over 15 years ago

Genius 5170 points

I don't think this can be done as all PWM blocks are hardware based. Have you considered running multiple devices in sync using syncin and synco feature?

0 Lusi Castro over 15 years ago in reply to Arefeen

Prodigy 30 points

I´ve considered, but it would be better if I use only one device, costs problems...

0 Arefeen over 15 years ago in reply to Lusi Castro

Genius 5170 points

Okay, I understand .... I was thinking the total system cost which requires so many power devices (IGBT/MOSFET etc.) may not be affected by the cost of an additional controller.

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F28335 - aPWM cont-up-down mode.