TMS320F280039C-Q1: Why the PWM pulse will lost in variable frequency control and variable phase control

Part Number: TMS320F280039C-Q1

Tool/software:

Hi team, 

I ask this for my customer, they use EPWM2 is the source of sync signal and the EPWM1 is slave. the configuration is show in this 

BspEpwm.c
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/**********************************************************************
Copyright 2022,valeo Corporation.
File Name: BspEpwm.c
Description: BspEpwm
Version: V1.0
Author: deyi.chen
Date: 2022-11-25
***********************************************************************/
/* header files ***************************************************************/
#include "include.h"
#include "sfo_v8.h"
/* local macro definitions ****************************************************/
#define myEPWM1_BASE EPWM1_BASE
#define myEPWM2_BASE EPWM2_BASE
#define myEPWM3_BASE EPWM3_BASE
#define myEPWM4_BASE EPWM4_BASE
/* local types definitions ****************************************************/
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

They use global load and they keep the EPWM1 frequency is 100kHz, the duty is 50%, and they change the phase of EPWM1.

they found if they decrease the lead phase of EPWM1, the first pulse of EPWM1 will lost(the EPWM will out a period high voltage). they do below test:

1. they change the lead phase from 91° to 85.887°, the output of EPWM1 is abnormal.

2.they change the lead phase from 85.887° to 91°, the output of EPWM1 is ok.

Could you give us some suggestion how to do next to find the reason? Could you help to check if the configuration is right? They want to use global load and sync the EPWM1 to EPWM2.

BRs

Shuqing

  • Hi Shuqing,

    Are there any waveforms that can be shared showing the results from the tests above?

    For test 1 and 2, the phase shift of EPWM 2 is changed correct? Can I please know the TBPRD value set and the phase value set in the phase registers along with the CMPA values when these tests are done?

    Best Regards,

    Marlyn