Inverting vs. Non-inverting Buck-boost transfer functions

Discussion in 'General Electronics Chat' started by WayTooLate, Apr 18, 2010.

  1. WayTooLate

    Thread Starter New Member

    Mar 15, 2010
    I am trying to derive transfer functions for a non-inverting, full-bridge buck-boost (4 single quadrant switches) in CCM using the Fundamental of Power Electronics (2nd) book as a resource.

    Using the small signal equivalent model of an inverting buck-boost, the book derives the line-to-output (Gvg(s)) and the control-to-output (Gvd(s)) transfer functions.

    Which for example, Gvg(s) = (-D/D') *(R || 1/sC) / (sL/D'^2) + (R || 1/sC).

    Now my question: Are the non-inverting model's transfer functions the same as the inverting models (ALL of them) except for the change from negative to positive? It seems the main components of the transfer functions are the passive component values and input & output voltages.

    *I am deriving these equations to add voltage control or current control to the non-inverting model. T.F.s for current control also include Gid(s) and Gig(s). (all duty cycle controlled gains)
  2. buckysparks

    New Member

    Mar 30, 2010
    yes, I believe the transfer functions are the same. Since the 4 switch buck boost has two switches on at the same time, the circuit model can be simplified to the two switch equivalent.