CCS/TIDM-1007: How to use the DCL_runPI_C1() function?

Watermelon and Noodles

Prodigy 40 points

Part Number: TIDM-1007

Tool/software: Code Composer Studio

Hi, expert

Please look at the DCL_runPI_C1() function used in TIDM-1007.

The discription of this function is:

extern float32_t DCL_runPI_C1(DCL_PI *p, float32_t rk, float32_t yk);

//! \brief Executes an inline series form PI controller on the FPU32
//! \param[in] p Pointer to the DCL_PI structure
//! \param[in] rk The controller set-point reference
//! \param[in] yk The measured feedback value
//! \return The control effort
//!

But, this function is cited by:

gi_out=GI_RUN(&gi, ac_cur_sensed, ac_cur_ref_inst);

My question is, why here the parameters of rk and yk seems are reversed? Anything is wrong?

Hope your reply. Thanks.

over 6 years ago

0 Manish Bhardwaj over 6 years ago

TI__Mastermind 43730 points

Nothing is wrong, see how the controller as designed Fig 9,

http://www.ti.com/lit/ug/tidud61b/tidud61b.pdf

and the sign around the compensator is reversed of what typically is, hence the inversion when running the DCL routine,

0 Watermelon and Noodles over 6 years ago in reply to Manish Bhardwaj

Prodigy 40 points

Hi, Manish

Thanks for reply.

But, I think a positive feedback loop can not be controlled stablilty? There must be another negative sign.

And, finially I found, it is hiden in the 'Duty' parameter you set, because you used the upside MOSFET duty as the controller output, which equals to 1-D of the boost switching MOSFET.

This solved my pulzze. Thanks!

0 Manish Bhardwaj over 6 years ago in reply to Watermelon and Noodles

TI__Mastermind 43730 points

I try to see it more intuitively,

We define the D in the section before, and the relation of that D with the current is negative,

That is to increase current you need to reduce D,

To decrease current you need to increase D,

Which is an opposite relation to conventional control loop.

However, I am glad you are comfortable with the implementation now,

-Manish

C2000™︎ microcontrollers

C2000 microcontrollers forum

CCS/TIDM-1007: How to use the DCL_runPI_C1() function?