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Run your analysis now →https://www.patsnap.com/resources/blog/rd-blog/resonant-converter-control-system-patent-landscape/ · Patsnap · data cut-off 2026-07-31 · downloaded from the live page
Power Electronics · Patent LandscapeResonant Converter Control System Patents: Filing Trends and Who Leads
- Filings have already peaked. Activity rose from 32 families in 2017 to a high of 76 in 2023, then eased off — this is a maturing claim space, not a rising one.
- Power conversion dominates the IPC mix. 573 of 633 families sit in H02M, with EV propulsion (B60L, 34) and lighting/heating circuits (H05B, 26) as the largest adjacent branches.
- Filing is concentrated but leaders are cooling. Several of the most active historical assignees show zero filings in the latest year, including one at -100% YoY — the leaderboard is not the same as the momentum board.
633
Published Records
26%
Top-5 Share of All Records
-43%
Filing Growth 2021→2024
US
Leading Jurisdiction
Filing growth compares 2021 (63 records) with 2024 (36) — a three-year span. 2024 is the most recent year we treat as complete: publication lags filing by roughly 18 months, so 2025 onwards are still filling in and any growth rate that ends there would understate the field. Top-5 share is the combined record count of the five largest assignees divided by all 633 records in scope (CR5), not by the ranked leaders only.
Published byPatsnap Research··7 min readSourced from Patsnap Eureka
Overview
What this landscape covers
This landscape tracks 633 patent families published between 2015 and mid-2026 that combine resonant power conversion — LLC converters, resonant DC-DC topologies — with a specific control layer: frequency modulation control, phase-shift control, or synchronous rectification control. The search deliberately pairs a converter topology term with a control-method term, so the corpus is narrower than "resonant converter" alone and is weighted toward claims that specify how switching, timing or rectification is managed rather than just the power stage.
Filing offices skew toward the United States (257) and Europe (119), with China (91), PCT filings (44) and Germany (33) forming the next tier. Because publication typically lags filing by around eighteen months, the falloff visible in 2025 and 2026 understates real filing activity in those years.
Filings by year, 2017–2026
Source: Patsnap Eureka. Assignee ranking and totals. Derived from a Patsnap search on Resonant Converter Control System covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish.Run this in Eureka MCP
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The data
Filing trend and technology composition
Two views of the same 633-family corpus: how filing volume has moved year over year, and how those families distribute across IPC subclasses.
A rise, a peak, then a pullback
Filings climbed from 32 in 2017 to a peak of 76 in 2023, roughly double the 2022 midpoint of 41. The post-2023 decline, read against the 18-month publication lag, suggests filing has plateaued rather than reversed outright.
H02M carries the claim density
H02M (power conversion) accounts for 573 of 633 records — nearly all of them. B60L (EV propulsion, 34) and H05B (electric heating and lighting circuits, 26) are the largest branches where resonant control claims cross into an application domain rather than staying purely at the converter-topology level.
Shares are the percentage of the 633 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Source: Patsnap Eureka. Filing trend and technology composition. Derived from a Patsnap search on Resonant Converter Control System covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish.
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Most-cited prior art and a recent representative filing
Representative recent filing
US20240022177A1 — Resonant converter and synchronous rectification control method thereof
ECOFLOW INC.
A synchronous rectification control method for a resonant converter includes: obtaining an output current of the resonant converter; obtaining a first parameter if the output current is greater than a first current threshold; obtaining a second parameter if the output current is less than a second current threshold, the first current threshold being greater than the second current threshold, and the first parameter being greater than the second parameter; establishing a first current hysteresis loop according to the first parameter and establishing a second current hysteresis loop according to the second parameter.Filed by ECOFLOW INC., published 2024-01-18 — illustrates current-threshold-based hysteresis control as an active filing pattern in synchronous rectification.
Highest-cited records in this corpus
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US6246599B1 | Constant frequency resonant inverters with a pair of resonant inductors | 196 |
| 2 | US20210155100A1 | Vehicle on-board charger for bi-directional charging of low/high voltage batteries | 182 |
| 3 | US6326740B1 | High frequency electronic ballast for multiple lamp independent operation | 141 |
| 4 | US6961253B1 | Drive circuits for synchronous rectifiers | 114 |
| 5 | US20080247194A1 | Resonant converter system and controlling method thereof having relatively better efficiency | 112 |
| 6 | US5262930A | Zero-voltage transition PWM converters | 111 |
| 7 | US20120250360A1 | LLC controller with programmable fractional burst frequency | 106 |
| 8 | US5486752A | Zero-current transition PWM converters | 95 |
| 9 | US20120262954A1 | Off line resonant converter with merged line rectification and power factor correction | 92 |
| 10 | WO2019199964A1 | Vehicle on-board charger for BI-directional charging of low/high voltage batteries | 87 |
Citation counts favour older filings inside any searched corpus — treat these as markers of foundational influence, not of what matters commercially today.
Each row carries its publication number; clicking a row searches Eureka by that number.
Source: Patsnap Eureka. Citation counts and representative records. Derived from a Patsnap search on Resonant Converter Control System covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish.Run this in Eureka MCP
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What the numbers say about this field
Three read-throughs from the filing trend, the IPC mix, and the most-cited prior art.
Filing trend
76 in 2023
peak year
The growth phase is behind, not ahead
From 32 families in 2017 to a peak of 76 in 2023, this corpus grew for roughly six years before flattening. A 2022 midpoint of 41 against a 2023 peak of 76 shows the acceleration happened late, then stalled — consistent with a technology whose core control methods are now well staked out.
Filing trend, 2017–2023
Technology mix
573 of 633
families in H02M
Claim density sits almost entirely in the power-conversion subclass
H02M alone accounts for 90% of this corpus. The remaining branches — EV propulsion, lighting/heating, protective circuits, magnetics and amplifiers — are all an order of magnitude smaller, meaning most freedom to operate outside pure power-conversion claims is still in application-specific integration rather than the converter core.
IPC subclass distribution
Prior art
196 citations
top-cited record
Foundational patents predate the current control-method wave
The most-cited record, US6246599B1 on constant-frequency resonant inverters, sits well ahead of any filing in this corpus by citation count. High citation counts here mark foundational influence on the field, not current filing activity — several top-cited records are ballast and rectifier drive patents from the 2000s.
Most-cited records
Eureka AI Agent
Looking for what nobody has claimed yet?
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to resonant converter control system, with the prior art for and against each one.
Source: Patsnap Eureka. Co-assignee relationships and derived observations. Derived from a Patsnap search on Resonant Converter Control System covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish.Run this in Eureka MCP
Players
Who is filing, and where the field is moving
Filing volume and recent-year momentum tell different stories here: several assignees with the deepest historical portfolios show no filings in the latest year, while smaller or newer entrants are still active.
Momentum shift
-100% YoY
for one major historical filer
Established filers are pulling back
Multiple assignees with substantial historical filing — including major Chinese and Japanese electronics manufacturers — show zero filings in the most recent year, with one down -100% year over year. This does not necessarily mean exit; it may reflect the publication lag or a shift to filing under different subsidiaries.
Recent-year momentum by assignee
Collaboration
9 pairs
co-assignee relationships
Co-filing is rare and concentrated
Only 9 co-assignee pairs appear across the corpus, and the strongest pair recurs across multiple filings. This is a field where most patents are filed by a single corporate assignee rather than through joint development arrangements.
Co-assignee pairs
Recent filer
2024-01-18
representative filing date
New entrants are still filing on synchronous rectification
The representative record from ECOFLOW INC., published in January 2024, claims current-threshold-based hysteresis control for synchronous rectification — evidence that this specific control sub-area remains active even as overall filing volume has cooled from its 2023 peak.
Representative record
Recent-year momentum by assignee
| Assignee | Recent year | YoY |
|---|---|---|
| Delta Electronics (Shanghai) Management Co., Ltd. | 1 | — |
| Delta Electronics, Inc. | 0 | -100% |
| Raytheon Company | 0 | — |
| Murata Manufacturing Co., Ltd. | 0 | — |
| Huawei Technologies Co., Ltd. | 0 | — |
| Delta International Holding Ltd. | 0 | — |
| ALEXSAVA HLDG | 0 | — |
| Silergy Semiconductor Technology (Hangzhou) Co., Ltd. | 0 | — |
Source: Patsnap Eureka. Assignee-level momentum. Derived from a Patsnap search on Resonant Converter Control System covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish.Run this in Eureka MCP
What's next
Where to take this analysis
The dataset points to specific next steps depending on whether the goal is freedom-to-operate, portfolio strategy, or tracking a competitor.
Check the under-claimed branches before filing
H02H protective circuits, H01F magnetics, and H03F amplifiers each carry single-digit-to-low-double-digit family counts against 573 in H02M. Run a targeted search in Patsnap Eureka against your specific control method before assuming the space is occupied.
Explore in EurekaWatch the momentum, not just the leaderboard
Several top historical assignees show zero recent filings. Set up ongoing monitoring in Patsnap Eureka to catch whether that reflects publication lag or an actual strategic pullback.
Set up monitoringTrace the citation network around the top-cited records
US6246599B1 and US6961253B1 anchor much of the downstream citation activity in this corpus. Mapping who cites them in Patsnap Eureka clarifies which current filers are building directly on that foundational art.
Map citationsSource: Patsnap Eureka. Forward-looking reading of the same dataset. Derived from a Patsnap search on Resonant Converter Control System covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish.Run this in Eureka MCP
FAQ
Common questions on resonant converter control patents
This landscape identifies 633 patent families published between 2015 and mid-2026 that combine a resonant converter topology (LLC converter, resonant DC-DC) with a specific control method such as frequency modulation, phase-shift, or synchronous rectification control. Using families rather than raw document counts avoids overstating activity from continuations or multi-jurisdiction refiling of the same invention. The true count for very recent years is understated because publication typically lags filing by around eighteen months.
No — filings rose from 32 in 2017 to a peak of 76 in 2023, then declined, with the 2022 midpoint of 41 showing the growth was concentrated in the final few years before the peak. The recent-year drop should be read cautiously given the roughly 18-month publication lag, but the shape overall points to a maturing rather than expanding claim space. Several previously active assignees show no filings in the latest tracked year, reinforcing that read.
H02M, the power conversion subclass, covers 573 of the 633 families in this corpus — roughly 90%. The next largest branches are H02J (power supply and grid systems, 91), B60L (electric vehicle propulsion, 34) and H05B (electric heating and lighting circuits, 26). Anyone filing outside H02M is filing into a much thinner prior-art base, for better or worse.
US20240022177A1, filed by ECOFLOW INC. and published in January 2024, claims a synchronous rectification control method that establishes two current hysteresis loops with different parameters depending on whether the converter's output current is above a first threshold or below a second, lower threshold. This is a threshold-and-hysteresis approach to adapting rectification behaviour to load conditions, not a frequency-modulation or phase-shift scheme. It is one useful representative example of where current filing activity sits within the synchronous rectification control branch, though it should not be read as covering the whole sub-area.
Filing is concentrated among a handful of large electronics and automotive-electronics manufacturers with substantial historical portfolios in this space, but the leaderboard should not be confused with current momentum. Several of the most prolific historical filers, including major Chinese and Japanese manufacturers, show zero filings in the most recent tracked year, with one showing a -100% year-over-year change. That divergence matters more for competitive tracking than raw cumulative rank does.
Answers are grounded in the same dataset. Derived from a Patsnap search on Resonant Converter Control System covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish.Run this in Eureka MCP
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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.