Design constraint on feedback gain vector of switching regulators for local stability

A discrete-time dynamic model of closed-loop switched mode electronic regulators is derived. No small-ripple approximations are required. The same model serves for both local and global stability study: by discarding the nonlinear terms (like products of small-signal perturbations in the converter state variables) and using the z-transform, a local stability criteria is formulated. Applying the condition that the eigenvalues of the z-domain characteristic matrix have to be situated inside the unit circle, a design constraint on the feedback gains is found. An example of a boost converter operating in continuous conduction mode with inductor current and output voltage feedback is presented