I have been trying to implement a phase shift modulator using the PWM_PSFB_VMC_SR digital power library module. I needed to modify the block slightly to allow for a positive and negative phase shift. +/- 90 degrees of phase shift was adequate for my purposes, so my plan was to offset the ePWM1 channel by 90 degrees to allow the ePWM2 channels to shift relative to that. I made the following code modifications in the PWM_PSFB_VMS_SR_CNF file to implement the phase offset:
(*ePWM[n]).TBCTL.bit.PRDLD = TB_IMMEDIATE; // set Immediate load
(*ePWM[n]).TBPRD = period;
(*ePWM[n]).CMPA.half.CMPA = (period)/4;
(*ePWM[n]).CMPB = (3*period)/4; // Fix duty at 50%
(*ePWM[n]).TBPHS.half.TBPHS = 0;
(*ePWM[n]).TBCTR = 0;
(*ePWM[n]).TBCTL.bit.CTRMODE = TB_COUNT_UP;
(*ePWM[n]).TBCTL.bit.PHSEN = TB_DISABLE;
(*ePWM[n]).TBCTL.bit.SYNCOSEL = TB_CTR_ZERO; //used to sync EPWM(n+1) "down-stream"
(*ePWM[n]).TBCTL.bit.HSPCLKDIV = TB_DIV1;
(*ePWM[n]).TBCTL.bit.CLKDIV = TB_DIV1;
(*ePWM[n]).AQCTLA.bit.CAU = AQ_SET;
(*ePWM[n]).AQCTLA.bit.CBU = AQ_CLEAR;
When I run the code however I get a phase shift of +90 degrees with the TBPHS register on the ePWM2 channel is programmed to zero, 180 degrees of phase shift when the TBPHS register is programmed to half of the max phase shift, and 270 degrees when the TBPHS register is programmed fully (180 degree phase shift). My first thoughts are that the offset on the master ePWM channel is not working properly or I've made a mistake in implementing the phase offset by using the CMPA and CMPB registers.
