From: Nick Wernicke on
I am trying to simulate a current mode dc/dc converter as described by Dr Ray Ridley. (http://www.ridleyengineering.com/downloads/curr.pdf page 9)

This requires a special transfer function as part of the control loop that has only zeros:
He(s)=1+s/a+s^2/b, where a and b are constants. Unfortunately, the makers of simulink have seen fit to bar such usefulness from the built in transfer functions.

How can I add this block to my control loop?