CCS/TMS320F28069M: Selection of TBPHS for a three phase system in UPDOWN mode.

Sharat Yadav

Expert 1015 points

Part Number: TMS320F28069M

Tool/software: Code Composer Studio

I have just started with this F28069M MCU for inverter application, IN 180° mode of conduction of Inverter..

I am generating a ePWM using UPDOWN mode,
let PRD = 1125;
ePWMA as Master, SYNCOSEL at ctr=0;

TBPHS for B phase= 1/3 *(2*Period) = 750

TBPHS for C phase= 2/3 *(2*Period) = 1500, and this value gets more then the period. What are views regarding it.

How to decide value for phase C TBPHS. as it exceed the value of period.

over 7 years ago

0 Sean Bigley over 7 years ago

TI__Genius 17175 points

Is this for motor control inverter or digital power inverter? I'm not familiar with 180° mode of conduction for motor control inverters

Sean

0 Sharat Yadav over 7 years ago in reply to Sean Bigley

Expert 1015 points

for ref about 180° mode: https://nptel.ac.in/courses/108103009/module5/lec15/1.html

Its not related to motor control, I am just learning to implement various switching schemes for inverter from basics.

0 Brett Larimore over 7 years ago in reply to Sharat Yadav

TI__Guru 57255 points

Hi Zesto,

For synchronization in up-down count mode, please be aware there is a capability to synch while up-counting or down-counting.

So if you wanted TBPRD to be 1125 & have 120 degrees of phase between PWMs, you could:

set PWM1 to be the synchronization master
set PWM2's TBPHS to be 750 & to start up-counting after a synch (technically should be 748 to compensate for synchronization delay)
set PWM3's TBPHS to be 750 & to start down-counting after a synch (technically should be 752 to compensate for synchronization delay)

Note that setting TBPHS greater than TBPRD would make the PWM act in a way you wouldn't want after a synch - until the PWM counter would overflow (after which it would start to work between 0 and TBPRD again).

Thank you,
Brett

0 Sharat Yadav over 7 years ago in reply to Brett Larimore

Expert 1015 points

Thank you Brett for this Explanatory and Clear answer.

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CCS/TMS320F28069M: Selection of TBPHS for a three phase system in UPDOWN mode.