3P3Z controller coefficient

Thank you so much for your quick reply..

All this data are really helpful for me.

I also gone through this  document sprabe7a.pdf(Digital Peak Current Mode Control With Slope
Compensation Using the TMS320F2803x)  . I am new to MATLAB that's why i have some doubt related this concept.In this design example they selected 15KHz as crossover frequency for 200 KHz PWM switching period .How this is selected ? 

My application PWM frequency is 25 KHz . for this how much crossover frequency required?

Sameer,

From memory, the cross-over frequency in the appnote was chosen to compensate the loop with a digital 2P2Z controller.  The plant phase lag increases quickly at higher frequencies (see fig. 6) so with the additional lag from digital delay and reconstruction, compensation would have been more challenging.

For digital loop compensation, a rule-of-thumb is to aim for a cross-over of about 1/10th of the switching frequency.  In this example, we used something a little lower than that, but not too far off.

Regards,

Richard

Thank you so much...

Hello,

After trying i am stucked  because my 3P3Z loop  does not give the correct output voltage .Below  is the my application details please notify me if there is wrong in any calculation or selection process of SFRA and 3P3Z coefficient.

Application:Buck converter using voltage mode control

code:C:\ti\controlSUITE\libs\app_libs\SFRA\v1_10_00_00\examples\DPSWrkShpKit_SFRA_F28035

Input Voltage:12 volt

output voltage :any voltage less than the  input voltage .

switching frequency:25KHz

Here is the Copy of 8686.C2000_DPS_Workshop_R2.xlsxcoefficient calculation  of 3P3Z  i have derived coefficient from this document  Presentation_-_Mr._Ali_Shirsavar.pdf page no. 31,33

for this example i have selected the followinf SFRA data and 3P3Z coefficient.

    cntl3p3z_coeff1.Coeff_A1=_IQ24(-0.212433857);                             
    cntl3p3z_coeff1.Coeff_A2=_IQ24(0.992719045);                             
    cntl3p3z_coeff1.Coeff_A3=_IQ24(0.219714811);                             
    cntl3p3z_coeff1.Coeff_B0=_IQ24(0.600155167); 
    cntl3p3z_coeff1.Coeff_B1=_IQ24(-0.20928543);  
    cntl3p3z_coeff1.Coeff_B2=_IQ24(-0.536513646);
    cntl3p3z_coeff1.Coeff_B3=_IQ24(0.272926952);  
    cntl3p3z_coeff1.IMin=_IQ24(-0.1);                                        
    cntl3p3z_coeff1.Max=_IQ24(0.9);                                         
    cntl3p3z_coeff1.Min=_IQ24(0.0);   

#define SFRA_ISR_FREQ 25000   //200000
#define SFRA_FREQ_START 100        //100
#define SFRA_FREQ_LENGTH 100   // 100
//SFRA step Multiply = 10^(1/No of steps per decade(40))
#define FREQ_STEP_MULTIPLY (float)1.059253

    //SFRA Object Initialization
    //Specify the injection amplitude
    SFRA1.amplitude=_IQ26(0.01);            //_IQ26(0.01);0.00009
    //Specify the length of SFRA
    SFRA1.Vec_Length=SFRA_FREQ_LENGTH;
    //Specify the SFRA ISR Frequency
    SFRA1.ISR_Freq=SFRA_ISR_FREQ;
    //Specify the Start Frequency of the SFRA analysis
    SFRA1.Freq_Start=SFRA_FREQ_START;
    //Specify the Frequency Step
    SFRA1.Freq_Step=FREQ_STEP_MULTIPLY;
    //Assign array location to Pointers in the SFRA object
    SFRA1.FreqVect=FreqVect;
    SFRA1.GH_MagVect=OL_MagVect;
    SFRA1.GH_PhaseVect=OL_PhaseVect;
    SFRA1.H_MagVect=Plant_MagVect;
    SFRA1.H_PhaseVect=Plant_PhaseVect;

if i am wrong please correct me ..

And  one another question is related SFRA GUI and CompDesigner GUI.

Can i use SFRA csv file located at :\ti\controlSUITE\libs\app_libs\SFRA\v1_10_00_00\GUI  for my example as it is for the calculation of 3P3Z coefficient using CompDesigner GUI.

Thank you for quick reply..

I am using my development board for buck converter and i am unable to connect  SFRA GUI .

could you please tell me the switch position for GPIO 34 and TDO pin or any schematic for reference

Sameer,

Please can you clarify which board?  There are several buck converter boards and I want to be sure we are talking about the same one.  Can you give me a part number?

Regards,

Richard

Now my buck converter working...

Thank you so much for your response.

Now i want to develop boost converter using type III compensator and SFRA lib. so can you please provide documents or material related to boost converter pole zero calculation.

Thanks in advance...