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Where are the office hours?  This thread?  A chat?  A video?  

Hi Jut,

The office hours will take place in this thread.   Just come back on the designated date/time and post your question in the thread and one of our C2000 Experts will answer it for you in real-time! 

Mark your calendar!

August 21 – 11am -12pm  CST

August 22 – 3pm -4pm CST

August 23 -  9am – 10am CST

Thanks!

Hi everyone,

Welcome to C2000 Office Hours! I just want to let you know we will be on hand for the next hour to answer any questions you may have.

Thanks.

Patrick

Hi,

I have some questions about the software phase locked loop (SPLL) module from the solar application library in ControlSUITE:

I tried it on the Development Kit, and the sine output of the SPLL was able to lock the phase of its AC input.   The problem is that the value of the angle ' theta[0]' was only between 0 to 1 , instead of between 0 to 2pi.

My AC input is 60Hz, and the spll is triggered at 20K Hz

I modified the code to   spll_obj->theta[0]=spll_obj->theta[1]+(spll_obj->wo*(0.00000795));

according to the posting  " About the Solar Liberary Function of C2000™ Solar Inverter Development Kits "

What is the meaing of   ( spll_obj->wo*(0.00000795) )   ?

If Wo= 2*pi*f,   and  0.00000795 is calculated by delta_t / (2*pi), then the formula above becomes   '  frequency * delta_t '   or delta_t / period '  ?

Hi Frank,

I am initially not clear on the answer to this question; however, I have directly forwarded this question to the team who developed the library and development kit. Hopefully we can get an answer for you here soon.

Patrick

Thank you.

Actually, I have more questions related to this SPLL module. Can I post all my questions here?

Frank,

Definitely, feel free to post your remaining questions here. We will work to get you answers in addition to your original posting.

Thanks,
Patrick

I'm having trouble with the HVBLDC_Sensorless example code on the TMS320F28035 microcontroller.

I have selected build level 1, set the enable bit, and when I pause the debugger, I get a value between 0 and 5 on the MOD6_CNT output variable.

But when I try to measure the PWM outputs, I get nothing. I tried one of the other PWM examples, and I got the expected result on the oscilloscope. So nothing should be wrong with the hardware itself.

Any ideas why it doesn't work on the motor control code? Is there some setting I'm missing?

In the posting  "About the Solar Liberary Function of C2000™ Solar Inverter Development Kits",

Manish Bhardwaj, a TI expert, said the SPLL module in the solar library was designed to handle input frequency changes from 57Hz to 63Hz if the grid voltage was 60Hz.

My first question is :

why is it from 57Hz and 63Hz ? Is this based on any industry stardard ?

My second question is :

How can I modified this SPLL module, so that it will still perform well for larger input frequency changes, i.e. 54Hz to 66Hz ?

Gard,

Could you provide more information? Which development kit are you using?

Patrick

Gard,

Do you happen to have the motor connected?  I believe that the instructions don't have you connect the motor until Incremental Build 2.

The motor control software that you are using has protection via internal comparators peripherals and trip zone peripherals.  I believe that the software doesn't expect a motor to be connected and is tripping quickly because things are not as the hardware expects.


Thank you,
Brett

I don't know if I'm too late now. But I'm using the "C2000 Microcontrollers Development Tools" and the newest free version of Code Composer Studio.

I also have not connected the motor yet. I'm measuring the output on the PWM without connecting it to anything. 

In the posting  "About the Solar Liberary Function of C2000™ Solar Inverter Development Kits",

Manish Bhardwaj, a TI expert, said the SPLL module in the solar library was designed to handle input frequency changes from 57Hz to 63Hz if the grid voltage was 60Hz.

My first question is :

why is it from 57Hz and 63Hz ? Is this based on any industry stardard ?

My second question is :

How can I modified this SPLL module, so that it will still perform well for larger input frequency changes, i.e. 54Hz to 66Hz ?

The frequency range mentioned is typical of what a PV inverter manufacture will specify. In a traditional grid infrastructure the frequency is quite stable. The PLL module can work for larger range of frequency if you use adaptive notch filters and use update the center frequency adaptively.  If you experiment you will find the PLL locks for  54 to 66 Hz as well, but you may get more error in your phase lock.

I'm trying to generate a sine wave on CCS v4.0 using C28335 as my target. The C code is below :

# include <math.h>

int x;
float k[360];

#define PI 3.1415926

void main(void)
{
        while(1)
           {

              for(x=0; x<360; x++)
                {

                      k[x] = (float)sin(x*(2*PI)/360);

              }

       }
}

but the numbers I get after execution seem to me like random numbers. Sometimes I get the right values till, say, 120 and then all values are set to 0. And rarely I get all the values right! 

My stack size is 400.

Could anyone tell what the problem is?

Thank you.