Here is an app note from Maxim describing the various SMPS regulator topologies for battery powered systems:
This tutorial presents an overview of regulator topologies for battery-powered equipment. The discussion covers linear regulators, charge pumps, buck and boost regulators, inverters, and flyback designs. The importance of peak current is explained, and schematics of each topology are shown.
The output polarity for the inverter should be the other way ?