implementation of phase shifted carrier wave PWM on TMS320F28335

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!


---------------------------------------
Posted through http://www.DSPRelated.com