PRBS duty Cycle

[preet_singh]

Dear all

   i am working on system identification. i want to add prbs with PWM pulses on analog output for the purpose of digital control. please help me.

thanks

gurpreet

[James_McN]

Hi Preet,

What is the control variable, the analog output or do you mean you are generating PWM signals over the analog output?

If you have the SysID toolkit there is a PRBS generator to give you the sequence, if you control the system through PWM then this should then become a sequence of pulse widths which you write to your PWM generation code.

If you are using analog output though you will need some extra logic to take the pulse widths and generate a PWM style signal over the analog output though as there doesn't tend to be a native way of doing this, this will depend on the hardware your using.

Cheers,

James

[preet_singh]

thanks for reply

 actually my problem is that i have to generte the pulses with rep rate 1 to 100 Hz and pulse width of 1ms to 20 msand during that pulse width i have to apply the PWM pulses to the switch of buck converter and i am working on sysstem identification i need to add prbs with pwm for the determination of system transfer function and then controller to get the stable output. can you help me to get some idea. i am totally blank to start with it. as i have worked on papper  with algo.

thanks

[James_McN]

I would focus on getting the PWM generation working first but the exact steps will depend on what hardware you are using, do you have a DAQ card or RIO device?

[preet_singh]

it is pCI 6221

[James_McN]

That is a DAQ card which uses the NI DAQmx driver.

I would start by looking at http://www.ni.com/white-paper/2991/en/ and the DAQmx help to get the PWM generation running first.

Cheers,

James

[preet_singh]

dear i have generated PWM on analog output now i want mixing of PRBS with PWM

[migsdigs]

Hi

Did you manage to solve this? I am dealing with a similar problem.

Thanks