Purpose -The paper aims to develop a CAD tool power electronics converters. Design/methodology/approach -Integration of knowledge base techniques with OOP paradigm. Using Visual Basis class builder, 15 classes were built to form the kernel of the tool's KB. Findings -A knowledge-based CAD tool was developed to ease the design of power electronics converters. It can be considered a learning aid tool too.Research limitations/implications -The knowledge base of developed tool can be expanded to accommodate large number of topologies. The GUI can be also ameliorated to a better look and interaction process. Practical implications -With proper enhancements, the purpose of the developed tool can be upgraded from educational one to industrial one. Originality/value -Beside the methodology, the new thing in the paper is the specificity of the application of the tool (i.e. in power electronics).