TMS320F28027F: whether this processor suits my application or not

Annapurna,

This processor should have no difficulty handling the control loops for both parts of the system.  

Both buck and boost use a basic controller structure involving an ADC read module, a controller module, and a PWM driver module, connected in series.  All these are available in the digital power library for the F28027 in controlSUITE.  The benchmarks are given in the supporting documentation, from which we can expect approximate cycle count to be about 14 + 44 + 12 = 70 cycles.  Assuming the lowest spec F28027F (40MHz), this will take 1.75us per loop.

Your 70kHz ISR period is 14.285us, so the boost control consumes 12.25% of CPU bandwidth.  Similarly, your 100kHz buck control consumes 17.5% of CPU bandwidth, so the combined CPU loading is just under 30%.  A 60MHz processor would be loaded by about 20%.  You will have other code too, but it seems a comfortable loading just based on the control loop requirements.

I recommend you start by looking at the DP library for this device.  If controlSUITE is installed in the default directory on your machine, the library will be at path:

C:\ti\controlSUITE\libs\app_libs\digital_power\f2802x_v3.5

There are examples of the buck and boost converters in the "BOOSTXL_BUCKCONV" and "SolarExplorer" application kits respectively.

You may like to take a look at the 1-day digital power training materials for an introduction of how to use DP library:

http://processors.wiki.ti.com/index.php/C2000_DPSWorkshop

I hope this helps.

Regards,

Richard