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CCS/TMS320F28027: TMS320F28027:HVPSFB how to design 2P2Z controller

user5277039
Intellectual 640 points
Part Number: TMS320F28027
Other Parts Discussed in Thread: SFRA, CONTROLSUITE

Tool/software: Code Composer Studio

I want to design 2P2Z controller  for my design refer to HVPSFB project and document 「Digital Loop Exemplified」(SLUA622).

Now I have a analog design like Figure2.

This analog compensation is GE (written in page4).

I can select 2pole p0 ,p1 and 2zero z0 z1 like figure3.

I want to change this analog design to digital.

But, in document 「Digital Loop Exemplified」 page13

Gc(s) have 2zero wz1,wz2 and 1pole wp2.

How can I design compensation like figure3?

  • 0
    TI__Mastermind 27200 points

    The report was not prepared by the C2000 group and I regret I have been unable to reach the author for comment.

    The application report describes (in section 3) analogue compensation using a type 3 compensator. After discretization, this will lead to a third order control law. For some reason the author of this paper has chosen to use a second order transfer function as his starting point for his discrete time calculations, so you cannot just 'plug-in' the poles and zeros you have selected in section 3.

    I don't have a more suitable paper to recommend, however you can apply the same (Tustin) transformation used in the report to find the 3P3Z coefficients you need. The equations will be more complicated than those shown on p.14, but the method is the same.  Start with the equation at the bottom of p.4, and make the substitution for 's' at the bottom of p.13.  The rest is algebra.

    There is a video on the discrete time conversion which you may find helpful, here:
    www.youtube.com/watch

    I hope this helps. 

    Regards,

    Richard

  • 0 in reply to Richard Poley
    Intellectual 640 points

    Thank you for your reply.

    It is difficult to design type 3 compensator. to degital, isn't it?

    Accrding to 「HVPSFB_User's Guide」page 31,

    「From the GUI environment the voltage loop can also be tuned using two poles (fp1, fp2), two zeroes (fz1, fz2) and gain (Kdc).」

    But I check GUI sourse code,the source don't  reflect fp1.

    So,how should the 2P2Z value be decided?

    I understand that I decide the value by experiment.

    But I'm scared to become unstable by the 2P2Z value desided first.

  • 0 in reply to user5277039
    TI__Mastermind 27200 points

    In general, I think most designers would use Matlab or some similar tool to find the discrete coefficients.  The video I referenced demonstrates how this is done using Matlab.  TI has the SFRA and Compensation Designer which do a similar job, at least for some power topologies, and companies such as Biricha have their own tools.  The choice is really down to the designers preference and what tools they have access to. 

    If you have not already done so, it might be worthwhile downloading the C2000 controlSUITE package, which contains details of a HV PSFB development kit, including the design calculations.  The solution uses a 2P2Z compensator for VMC.

    I hope this helps.

    Regards,

    Richard