TMS320F28379D: PWM Counter synchronization running from two CPU.

Anoop kumar N

Part Number: TMS320F28379D

Hello Experts,

I'm using F28379D for one of my projects. I have a 3PH to DC active rectifier, followed by a dc-to-dc PSFB stage. The active rectifier is running from cpu1 for that ePWM1, ePWM2 and ePWM3 are used. The rectifier output is 750VDC and have 200uF capacitor is there, which forms the input to the PSFB. For PSFB ePWM4 and ePWM5 are selected and which is running from cpu2 using the following command.

DevCfgRegs.CPUSEL0.bit.EPWM4 = 0x01
DevCfgRegs.CPUSEL0.bit.EPWM5 = 0x01

Now for the time being both converters are running independently from both cpu and haven't any communication between them.

Qn. 1. Is it necessary / if there is any advantage, if the counters of these converters to be synchronized ?

Qn 2. How to do this synchronization for the pwms running in two cpus ?

over 2 years ago

0 Ryan Ma over 2 years ago

TI__Mastermind 25716 points

Hi Anoop,

Anoop kumar N said:
Qn. 1. Is it necessary / if there is any advantage, if the counters of these converters to be synchronized ?

I do not know the answer to this but let me verify what are the advantages if there are any when counters are synchronized to an expert on this application.

Anoop kumar N said:
Qn 2. How to do this synchronization for the pwms running in two cpus ?

Yes, achieving synchronization between two cores by setting GBCLKSYNC instead of TBCLKSYNC. This will start time base counter of the EPWM modules at the same time regardless of the core they are assigned to.

Best,

Ryan Ma

0 Anoop kumar N over 2 years ago in reply to Ryan Ma

Intellectual 998 points

Thank you ryan !

0 Ryan Ma over 2 years ago in reply to Anoop kumar N

TI__Mastermind 25716 points

Hi Anoop,

I will follow up question 1 tomorrow by end of day,

Best,

Ryan Ma

0 Anoop kumar N over 2 years ago in reply to Ryan Ma

Intellectual 998 points

ok ryan..! Thanks in advance

0 Uttam Reddy Pailla over 2 years ago in reply to Anoop kumar N

TI__Expert 6020 points

Hi Anoop,

The ePWMs have synchronization signals that can be used. Also when the clock is started with the below call the PWMs all start together.

//
// Release the ePWM modules together
//
SysCtl_enablePeripheral(SYSCTL_PERIPH_CLK_TBCLKSYNC);

**Can you ellaborate on why do you want to achieve counter synchronization from topology point of view? Is it something you want to have PWMs with the same start point or something else?

Best,

Uttam

0 Anoop kumar N over 2 years ago in reply to Uttam Reddy Pailla

Intellectual 998 points

When i simulated the two converters with common DC link Capacitor, i found that ripple current demand is lesser when counters of two converters are synchronized..!

0 Ryan Ma over 2 years ago in reply to Anoop kumar N

TI__Mastermind 25716 points

Hi Anoop,

Synchronization sounds like a good plan!

If you have any more questions about the PWM, you can create another thread. For now I believe we can close this thread.

Best,

Ryan Ma

0 Anoop kumar N over 2 years ago in reply to Ryan Ma

Intellectual 998 points

Yes, Thank you Ryan for ur suppor

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TMS320F28379D: PWM Counter synchronization running from two CPU.