Resonant Converter Magnetics Patents: Leaders & White Space 2026
- Filing peaked in 2024 at 52 families, but the run-rate from 2022 to the most recent year is flat rather than climbing, and several previously active filers show zero output in the latest year tracked.
- H01F magnetics claims sit almost as thick as H02M power-conversion claims (248 vs 322 of 470 families), meaning transformer and inductor construction is claimed nearly as densely as the converter topology wrapped around it.
- The most-cited prior art is a decade or more old — one planar magnetic element patent from 1996 still carries 225 citations, so influence in this corpus is concentrated in older foundational filings rather than recent work.
What resonant converter magnetics patents actually cover
Resonant converter magnetics and passives sit at the intersection of two claim families: the resonant power-conversion topology (LLC converters, resonant DC-DC stages) and the magnetic component that stores and transfers energy inside it — planar transformers, integrated magnetics, resonant inductors. A single product design typically touches both, which is why H02M and H01F classifications co-occur across most of the 470 families in this dataset rather than sitting in separate silos.
Because publication lags filing by roughly 18 months, the most recent year in any trend line understates real filing activity; treat the last one to two years as a floor, not a ceiling.
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Filing trend and technology composition
Two views of the same 470-family dataset: how filing volume has moved year over year, and which IPC subclasses carry the claim weight.
A flat-to-declining trend after a 2024 peak
Annual filings moved from 30 in 2017 to a peak of 52 in 2024. The 2022 midpoint of 39 sits below that peak, and the count for the most recent year (5, partial) confirms the usual reporting lag rather than a real collapse — but the plateau between 2022 and 2024 is real and suggests the topology space is filling up.
Magnetics claims run almost as deep as converter claims
H02M (power conversion) leads with 322 of 470 records, but H01F (magnets, inductors and transformers) follows closely at 248 — a ratio that tells you construction details of the magnetic component are claimed nearly as heavily as the switching topology itself. H02J, H05K, H01G, H03K, B60L and H10D each account for a smaller slice, marking where resonant magnetics work touches grid supply, PCB integration, capacitor pairing, control logic, EV propulsion and semiconductor integration respectively.
Shares are the percentage of the 470 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Resonant Converter Magnetics and Passives with Eureka
This page is one run against one query. Ask Eureka your own question about resonant converter magnetics and passives and every answer comes back with the patent numbers behind it.
Try EurekaThe prior art anchoring this space
US20250292943A1 — Resonant Converter (Delta Electronics, 2025)
A resonant converter combining a circuit board, primary- and secondary-side circuits and a planar transformer, where the transformer's core column penetrates a through-hole in the board and vias connect sub-layer boards to windings formed around that hole as part of the transformer structure.Structural claim: the winding is realised as PCB routing around a board-integrated core, not a discrete wound component.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US20080055941A1 | Inverter | 254 |
| 2 | US6400579B2 | Lossless switching DC to DC converter with DC transformer | 248 |
| 3 | US5583474A | Planar magnetic element | 225 |
| 4 | WO2006001557A1 | Wireless charging pad and battery pack using radio frequency identification technology | 209 |
| 5 | US20160016479A1 | An integrated dual-output grid-to-vehicle (G2V) and vehicle-to-grid (V2G) onboard charger for plug-in electri… | 207 |
| 6 | US5132888A | Interleaved bridge converter | 176 |
| 7 | US6593841B1 | Planar magnetic element | 162 |
| 8 | US20180222333A1 | Integrated dual-output grid-to-vehicle (G2V) and vehicle-to-grid (V2G) onboard charger for plug-in electric v… | 154 |
| 9 | US6304460B1 | Switching DC-to-DC converter utilizing a soft switching technique | 151 |
| 10 | US20090303753A1 | Multi-Element Resonant Converters | 148 |
Citation counts inside a searched corpus favour older filings; read these as markers of influence on later work, not as a ranking of current relevance.
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Browse MCP servers →What the filing pattern signals for a design decision
Three things the numbers say about where to file next and where not to bother.
Growth has stalled, not accelerated
The rise from 30 filings in 2017 to a 2024 peak of 52 is gradual, and the midpoint year of 39 sits well under that peak — this is a maturing claim space, not one still opening up.
The transformer, not just the topology, is claimed territory
With H01F trailing H02M by only 74 records, integrated magnetics and planar transformer construction carry nearly the same claim density as the resonant converter circuit itself.
Foundational patents still anchor the field
The most-cited records in this corpus — a 1996 planar magnetic element patent and a 2002 lossless-switching DC-DC patent among them — predate most of the recent filing activity by well over a decade.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to resonant converter magnetics and passives, with the prior art for and against each one.
Who is filing, and where the activity has cooled
Recent-year momentum data shows several previously active assignees dropping to zero output in the latest tracked year, which changes who is worth watching versus who has moved on.
A historically active filer has gone quiet
Delta Electronics Inc. shows zero filings in the latest year with a -100% year-on-year change, despite being the assignee behind the representative 2025 planar-transformer filing in this dataset — a sign of a pause in disclosure rather than exit from the field.
LG Innotek and Jeonju University co-file consistently
LG Innotek and the Jeonju University Industry-Academic Cooperation Foundation share 18 filings, the strongest co-assignee pair in the dataset by a wide margin over the next pairings at 2 filings each.
Filing is concentrated in the US and Europe
United States receiving-office filings (207) outnumber EPO (88), WIPO/PCT (46), China (30), Austria (18) and Germany (16) combined at nearly the same level as all of them added together.
| Assignee | Recent year | YoY |
|---|---|---|
| Delta Electronics, Inc. | 0 | -100% |
| Taida Electronic Co., Ltd. | 0 | -100% |
| LG Innotek Co., Ltd. | 0 | — |
| Jeonju University Industry-Academic Cooperation Foundation | 0 | — |
| Taida International Holdings Limited | 0 | — |
| Virginia Tech Intellectual Properties, Inc. | 0 | — |
| 10644137 Canada Inc. | 0 | -100% |
| CUK SLOBODAN | 0 | — |
Where to take this analysis
The dataset points to specific follow-up questions rather than a single conclusion.
Check freedom-to-operate on winding geometry
With H01F claims running nearly as dense as H02M, a design review that only checks converter topology claims misses half the exposure.
Run a claims search in EurekaTrack the Delta Electronics filing gap
A -100% YoY drop from a historically active assignee, paired with a live 2025 filing, suggests undisclosed applications are likely still in the pipeline.
Set up assignee monitoring in EurekaMap the LG Innotek / Jeonju University pairing
An 18-filing co-assignee relationship this concentrated usually traces back to a specific lab or license arrangement worth identifying by name.
Explore co-assignee networks in EurekaCommon questions about resonant converter magnetics patents
This category covers patents claiming either the resonant power-conversion topology — LLC converters and resonant DC-DC stages — or the magnetic components inside them, such as planar transformers, integrated magnetics and resonant inductors. In practice most filings claim elements of both, since the magnetic component's construction (winding layout, core geometry) is usually inseparable from how the resonant circuit performs. The dataset behind this page pulls 470 patent families filed between 2015 and mid-2026 that match both concepts.
Filing volume rose from 30 in 2017 to a peak of 52 in 2024, but the 2022 midpoint of 39 sits well below that peak, indicating the growth curve has flattened rather than accelerated. The apparent drop in the most recent year is partly an artefact of the roughly 18-month lag between filing and publication, so it should not be read as a sudden collapse. Taken together, the pattern looks like a maturing claim space rather than an emerging one.
Delta Electronics is one of the more visible filers, evidenced by a 2025 planar-transformer filing (US20250292943A1), though its most recent year shows zero new filings and a -100% year-on-year change. LG Innotek co-files heavily with Jeonju University's Industry-Academic Cooperation Foundation, the strongest co-assignee pairing in the dataset at 18 shared filings. Several other named assignees also show zero output in the latest tracked year, which likely reflects publication lag rather than a full exit from the space.
The smaller IPC subclasses in this dataset — H01G (capacitors, 19 records), H03K (pulse and logic circuits, 17), and H10D (semiconductor devices, 15) — sit far thinner than the H02M and H01F core, suggesting under-claimed intersections such as capacitor-integrated resonant tanks or semiconductor-magnetics co-packaging. PCB-embedded winding structures, illustrated by the representative 2025 Delta Electronics filing, are also a comparatively recent construction approach with room for further claims. Thermal management specific to resonant inductors is another area that does not show up as a dominant IPC cluster on its own.
Citation counts inside any patent search corpus accumulate over time, so older filings such as the 1996 planar magnetic element patent (225 citations) or the 2002 lossless-switching DC-DC patent (248 citations) have simply had more years to be cited by later work. This is a signal of foundational influence, not of current commercial relevance. Recent filings, including 2024-2025 activity, have not yet had time to accumulate comparable citation counts even if they represent the current state of the art.
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Disclaimer. This page is generated from Patsnap Eureka data drawn from a limited snapshot of global patent and scientific-literature records, and is provided for general information and reference only.
Patent data carries inherent limitations: recent filings (typically the most recent 18–24 months) are under-counted due to standard publication lag; counts may be reported at either a patent-family or a patent-record basis and are not always directly comparable; classification, applicant-name, and citation data may contain errors, duplicates, or omissions; and the underlying search query defines and constrains the scope shown. As a result, the analysis may be incomplete or inaccurate and may not reflect the full technology landscape.
Nothing on this page constitutes an exhaustive prior-art, novelty, freedom-to-operate, or validity search, nor does it constitute legal, financial, investment, or professional advice, and it should not be relied upon as such. Any patent, commercial, or strategic decision should be verified independently and reviewed with qualified patent, legal, and domain professionals. Patsnap makes no warranties, express or implied, as to the accuracy, completeness, or fitness for any particular purpose of the information presented.
Machine translation. Assignee and organisation names originally recorded in Chinese, Japanese or Korean have been rendered into English by an AI translation step so that the tables stay readable. These renderings are best-effort and may not match a company’s registered English name; the original name is what the underlying patent record carries, and it is what any Eureka query launched from this page uses.