The phrase "in a non-steady system" in a converter title is doing real work. US10916991B2, granted to Mainspring Energy on February 9, 2021, is a DC-DC converter patent, but claim 1 binds it to a context where the input is not a steady DC bus — it is the pulsing output of a reciprocating generator.
The CPC tags confirm the coupling. Alongside the converter classes (H02M 3/06, H02M 3/1582) sit H02K 7/1884 (generator coupled to a reciprocating engine), F02B 71/04 (free-piston engines), and H02P 9/04 (generator control). This is a power-electronics claim that only makes sense attached to Mainspring's linear-generator engine. The converter is the interface between a non-steady source and a usable DC output.
Claim construction matters here because the "non-steady" limitation both narrows and strengthens the patent. A general DC-DC converter claim would drown in prior art; a converter claim specifically adapted to manage a reciprocating generator's variable output is novel precisely because the context is unusual. The fence is small but well-defended.
Why a grid-IP desk cares: Mainspring's linear generator is pitched as a flexible, fuel-agnostic distributed-generation asset. The power electronics that turn its non-steady output into grid-usable power are core IP. This patent is a piece of the moat around the architecture, not a standalone converter business.
The caution, as always: claim 1 fences off a converter-for-this-generator, not converters generally, and not the generator itself. Anyone building steady-state converters is untouched. The patent's value is entirely a function of the engine it serves.