Part Number:TMS320F28032
Tool/software: Code Composer Studio
HI,
I'M a FAE in TI, now my customer has a question.
The background is, they are trying to achieve interleave buck with TMS320F28032, buck worked in DCM mode, frequency change, and the on time Ton was constant. EPWM1A and EPWM2A was 180 degree shift, EPWM2 is slave. the problem is the EPWM2A may increase suddenly, the waveform was shown.
the yellow wave is EPWM1A, the blue one is EPWM2A, the green one is the current which was driven by EPWM2A.
the Ton was constant, set the counter of EPWM1A give a Synchronous signal to EPWM2A when CTR=0; the EPWM2A enable the PHASE LOAD function, after receiving the Synchronous signal, set the value of CTR equal to the value of TBPHS(0.5*Ts). the 2 EPWM are both adding counter mode, CTR=0 output high, CTR=CMPA, output low.
Question: At the last rising edge of EPWM1A, the value of TBPHS was loaded into CTR of EPWM2, but at this moment, the value of EPWM2 CTR is less than CPMA, so the output is still high. the value of TBPHS was bigger than CMPA, so the CTR change from less than CMPA to bigger than CMPA, so it can't be equal to CMPA, so the output of EPMA is still high,.
we have 3 questions:
1.is the analysis correct?
2.when use 28032 EPWM module to achieve interleave buck in frequency change mode, is there any limitations?
3.how can we solve these problems.
Thank you very mucn