TIDM-1007: Current sharing between phases

user3969749

Prodigy 90 points

Part Number: TIDM-1007

Dear all,

I just built the TIDM-1007 mother board,

and I figured it can be evaluated both in DC and AC.

I wonder, does the provided source code guarantee appropriate current sharing between phases ?

or any other mechanism I may have missed ?

otherwise, how much current imbalance should I expect ?

I do not see any material on that particular aspect in the test results section of the TIDM-1007 design guide.

Any insight will be greatly appreciated, thanks.

over 3 years ago

0 Manish Bhardwaj over 3 years ago

TI__Mastermind 43730 points

Hi, We do not have test data on balancing, this was something we wanted to get to but we did not have time to do.

-Manish

0 user3969749 over 3 years ago in reply to Manish Bhardwaj

Prodigy 90 points

Hi Manish,

thank you for your feedback,

could you somehow elaborate on this topic ?

since there is one single current loop, should I expect unacceptable imbalance, if I stick with the provided source code ?

Thank you

0 Manish Bhardwaj over 3 years ago in reply to user3969749

TI__Mastermind 43730 points

We did not observe significant current imbalance, unfortunately, I am not able to pull my lab notes on this topic.

We do provide all three-phase current measurements in case that is a critical aspect in your system to adjust the duty to bring things in balance.

0 user3969749 over 3 years ago in reply to Manish Bhardwaj

Prodigy 90 points

Alright, thank you,

lastly, for my information, and as I am not able to check at the moment : would you say that the F280049 MCU is capable of running three current loops for Fsw=100kHz ?

0 Manish Bhardwaj over 3 years ago in reply to user3969749

TI__Mastermind 43730 points

The majority of the cycles on the TIDM-1007 are used in state machine for the PWM to manage the zero crossing transitions.

An additional control loop takes ~50 cycles average which at 100kHz and only considering the usage of C28x will take ~5 MIPS, looking at the UG we report 43% usage for the control loop, with advanced options it can take upto 60% of the 100Mhz core, and in addition you have the CLA running at 100MHz.

So even with advanced options you have > 120MIPS free and he F280049 can certainly do three more loops.

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TIDM-1007: Current sharing between phases