pid

Hi vinod,

Download controlSuite... This app includes a bunch of helpful examples and blocks for digital power conversion developers.

http://www.ti.com/ww/en/embedded/controlsuite/index.html?DCMP=mcu_controlsuite&HQS=Other+OT+controlsuite

However PID is a poor solution for most DC-DC topologies try 2P2Z instead. Believe me I made the experience by myself recently!

Best regards

Andreas

Hi Andreas

while this is slightly off-topic I'd like to ask you if you can you elaborate on this:

andreas von kaenel said:

However PID is a poor solution for most DC-DC topologies try 2P2Z instead. Believe me I made the experience by myself recently!

I've mostly worked with drives and AC/DC converters and I've never had any difficulty stabilizing control loops with classical (or slightly modified) PID controllers.

How do you tune 2P2Z? More specifically is there a procedure to tune 2P2Z experimentally similar to PID tunning method (see: http://www.scribd.com/doc/24892385/PID-Without-Phd)?

Best regards

Mitja

Vinod,

You can take the 2p2z controller and use it as a PID.  All you need is to set the higher pole of the 2p2z controller to fp2 = fs/pi and the lower pole to fp1 = 0. Here, fs is the sampling loop frequency where you implement this 2p2z controller.

Also, digital control of DC-DC controller allows you to use either complex zeros, or real zeros, in your 2p2z controller depending on what type of output capacitors you used, ceramic or electrolytic.

For ceramic only design, the output filter has a very high Q and the ESR zero is at very high freq. In this case using a complex zero compensation you can adjust the compensator Q to conteract the effect of filter Q and get good transient response. For, designs with electrolytic output caps, where the ESR is much higher and the filter Q is lower, you can use real zeros in your compensation to get better transient response.

For detail on this you can download TI application report SLUA416. The compensation with real and complex zeros, discussed in that application report, was implemented in a different TI device. But you can use the same procedure and implement the same thing in TMS320F28035 device.

Regards,

Shamim