Null audio susceptibility of current-mode buck converters: small signal and large signal perspectives

Small signal modeling of sensorless current-mode (SCM) control for DC-DC converters reveals a method of achieving zero (null) audio susceptibility. Similar results are known for peak current-mode (PCM) control. The true line-to-output responses of such SCM and PCM "null"-designs are demonstrated to be nonzero for nonsmall signal disturbances. Definitions of large signal null audio susceptibility are proposed beyond the linearized small signal paradigm. Investigations of true large signal null audio susceptibility controllers are compared with the SCM method for buck converters.