add predefined topologies: buck, boost, buck-boost

Author: gituser789

CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - add parasitic capacitors to MOSFET components
 - add topologies: LLC, PSFB, DAB
 - add CHANGELOG.md
+- add topologies: buck, boost, buck-boost
 
 ### Changed
 - update reamde: update getting started section, add changelog to readme