TMS320F28035: current consideration in ramp sine generation

Ashok Jogani

Part Number: TMS320F28035

Hi,

I have generated sine using ramp library as below:

/***init***/
#define GRID_FREQ 50
#define INV_FREQ 12800.0

RAMPGEN_IQ rgen1;

RAMPGEN_IQ_init(&rgen1);
rgen1.Freq = _IQ24(GRID_FREQ);
rgen1.StepAngleMax = _IQ24(1.0/INV_FREQ);

/****Int_ISR()*****/
//Read ADC of current on ISR
inv_meas_cur_inst = ((int32)((int32) IINV_FB << 12) - offset_GridCurrent) << 1;

RAMPGEN_IQ_MACRO(rgen1);
IntSineRampgen = _IQsinPU(rgen1.Out);
duty_inv_pu=_IQ24mpy(IntSineRampgen,InvModIndex);

duty_inv_pu= (duty_inv_pu>_IQ24(1.0))?_IQ24(1.0):duty_inv_pu;
duty_inv_pu= (duty_inv_pu<_IQ24(-1.0))?_IQ24(-1.0):duty_inv_pu;
duty_inv = _IQ24mpy((long)(INV_PWM_PERIOD),_IQ24abs(duty_inv_pu));

I have take CT input on ADC for current measurement.
I want to add current input to my output sine so It can balance voltage using current input.
Please guide me how can i add current input on ramp sine.

Thanks,

over 5 years ago

0 Santosh Jha over 5 years ago

TI__Guru 50611 points

As this is duplicate thread. We are closing this thread. Please refer to

e2e.ti.com/.../954623

0 Ashok Jogani over 5 years ago in reply to Santosh Jha

Prodigy 90 points

Hi Santosh,

Can you please verify link of thread(954623) that you mentioned?

I can not see repeated threads. As this thread also has a ID 954623 and thread ID 954623 that you have mentioned is same.

Please correct me if i am wrong.

Thanks

0 Santosh Jha over 5 years ago in reply to Ashok Jogani

TI__Guru 50611 points

Ashok,

I could not find the thread, sincere apology for that. Let me assign it to the subject matter expert to this thread.

Due to short work-week in India, lot of folks are taking OFF, so please expect delay in response. I will be watching the thread.

0 Shanty over 5 years ago in reply to Santosh Jha

TI__Expert 5410 points

I dont think I fully understand your question. What limitations are you facing it while adding it in your code?

-Shantanu

0 Ashok Jogani over 5 years ago in reply to Shanty

Prodigy 90 points

Hi Shantanu,

I want to add "inv_meas_cur_inst" in to "duty_inv_pu" as i mentioned in above source.

How can i add current in ramp generation?

Can i add directly like below:

duty_inv_pu = duty_inv_pu + inv_meas_cur_inst;

Thanks,

Jignesh Patel

0 Shanty over 5 years ago in reply to Ashok Jogani

TI__Expert 5410 points

Jignesh,

Yes, that addition should work. Are you seeing wrong results?

-Shantanu

0 Ashok Jogani over 5 years ago in reply to Shanty

Prodigy 90 points

Hi Shantanu,

I have added a following equation :

duty_inv_pu = duty_inv_pu + (inv_meas_cur_inst/2.2);

2.2 is required to divide to calibration at 1 Amp load.

I am facing the issue of non-linearity on the above equation. This means using 2.2 it balance load to 230V on 1 Amp load but when I am giving 20 Amp load using above equation it increases/balance voltage up to 270V.

I am facing an issue to not get the linearity using the above equation on 1 Amp load to 20 Amp load.

Thank you.

0 Shanty over 5 years ago in reply to Ashok Jogani

TI__Expert 5410 points

Hi Ashok,

I see that the definition of duty_inv_pu is non linear in the region [-1, -1]. Could this result in the non linearity of duty_inv ?

0 Ashok Jogani over 5 years ago in reply to Shanty

Prodigy 90 points

Hi Shantanu,

Yes it give the same none linearity in duty_inv.

It also give none linearity in output voltage.

Thanks

0 Shanty over 5 years ago in reply to Ashok Jogani

TI__Expert 5410 points

Ashok,

I don't think I understand the issue here. Are you facing an issue with the result from IQMath? Or is it an issue with the algorithm you are using? Can you share your data and expected data and point out the area where the problem is occuring?

-Shantanu

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TMS320F28035: current consideration in ramp sine generation