This paper proposes a new methodology, Power Block Geometry (PBG), for the presentation of power electronics topologies that process ac voltage. PBG's strategy uses formal methods based on a geometrical representation with particular rules and defines a universe with axioms and conjectures to establish a formation law. It allows power electronics configurations observed in the technical literature to be obtained by just following PBG's proposed rules, taking a systematic approach and using the familiar concept of connection blocks. Such an approach provides the formal outline needed for a comprehensive didactic presentation.