State plane analysis is often applied to resonant converter, bi-directional dual-active-bridge, trajectory control and some other soft-switching topologies. It is used to reduce complicated tank waveforms to geometry and get an accurate soft-switching timing.  When properly normalized, the tank waveforms are described by segments of circles, lines, and/or other simple figures in the state plane. Determination of converter steady-state characteristics is often a matter of piecing together these segments, then solving a few triangles or other figures.

For detailed tutorial information, please check out the link below:

Introduction to State Plane Analysis Basics

If you have any questions on this, don’t hesitate to contact me through 466288351@qq.com