In this dataset, it is a filing that combines bidirectional DC-DC converter topology language with claim-level efficiency terms such as soft switching, loss reduction or efficiency optimisation, classified under core power-conversion IPC codes (H02M3/335, H02M3/158, H02M1/00). This excludes converters described only in general terms without an efficiency-specific claim element. The distinction matters because a topology claim and an efficiency-mechanism claim can sit in the same family but face different prior art.

The trend shows 84 filings in 2017 climbing to 121 in 2023, but the 2022 figure of 94 was already close to that peak, meaning the growth had largely flattened a year earlier. This pattern is typical of a claim space where the core circuit topologies are already well covered and later filings are refinements rather than new territory. It does not mean interest has stopped — publication lag of roughly 18 months means 2025 and 2026 figures are still filling in.

H02M, since it covers 1,773 of the 1,774 families in this dataset and is effectively the entire corpus. H02J (power supply and grid systems, 269 records) and B60L (electric vehicle propulsion, 110 records) are the next largest pools and worth a secondary pass, especially for claims framed around a specific application rather than the converter circuit itself. Smaller pools such as H01F, H03K, H01L and H05B are thin enough that a targeted search there may surface less-crowded claim language.