Current Limiting & Fault Ride-Through Patents: Leaders, Trends 2026
- Filings peaked in 2017 at 201 and have since declined, with 2026 sitting at 25 on a partial-year count — a field with a settled rather than expanding claim base.
- The top 5 assignees hold just 11.3% of all 4,438 records, and the top 10 only 18.8% — concentration exists but a long tail of single- and few-filing entrants still does most of the filing.
- Protection and power-conversion classes dominate jointly, with H02M, H02H and H02J each covering roughly a quarter of records, showing the technology is claimed as a systems problem, not a single-component one.
Filing growth compares 2021 (134 records) with 2024 (170) — 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 4,438 records in scope (CR5), not by the ranked leaders only.
What this patent landscape covers
Current limiting and fault ride-through are the mechanisms that keep a grid-forming converter within safe operating limits and still contributing to grid stability when a fault occurs nearby. The dataset behind this page spans 4,438 published records filed between 2015 and mid-2026, drawn from filings that combine converter-level current-limiting claims with protection coordination, negative-sequence current handling and transient-stability recovery behaviour. Publication lags filing by roughly 18 months, so the 2025 and 2026 counts in the trend chart understate actual filing activity for those years.
The picture that emerges is one of a mature, systems-oriented claim space rather than a single dominant component patent. Filing activity has already passed its peak, ownership is spread across a long tail of assignees, and the technical classes most heavily claimed are protection circuitry and power conversion rather than any one control algorithm.
Trend and technology composition
The filing trend and IPC composition below are drawn directly from the 4,438 records in scope. Because a single record can carry several IPC classes, the composition shares sum to well over 100% of the record total.
Filings rose to a 2017 peak, then declined
Annual filings reached 201 in 2017, the high point across the window, and by the 2022 midpoint had already fallen to 181. The 2026 figure of 25 is a partial-year count depressed further by publication lag, but the trajectory from 2017 onward is one of decline rather than growth, suggesting the core claim space around current limiting and fault ride-through was staked out early in this window.
Protection and conversion classes dominate jointly
H02M (power conversion) leads at 25.6% of the 4,438 records, closely followed by H02H (protective circuit arrangements) at 23.5% and H02J (power supply and grid systems) at 22.8%. The near-parity of these three classes shows that current limiting and fault ride-through are claimed across the conversion, protection and grid-integration layers together rather than being cornered by any single discipline; smaller shares in H05B, H01H, H03K, G05F and H02P mark adjacent, less-crowded territory.
Shares are the percentage of the 4,438 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Current Limiting and Fault Ride-Through in Grid-Forming Converters with Eureka
This page is one run against one query. Ask Eureka your own question about current limiting and fault ride-through in grid-forming converters and every answer comes back with the patent numbers behind it.
Try EurekaA representative claim: protection coordination under islanding
Fault current limiting control and protection coordination for a converter operating in islanding state
The filing sets an output current command limit (Imax) for the inner-loop dq current controller of a flexible DC transmission converter, tuned so that it sits at or just above the AC line's Section III overcurrent protection threshold. The bridge-arm overcurrent protection thresholds are set at or below the corresponding AC line thresholds, coordinating converter-level current limiting with grid-side protection so that the converter rides through a fault without tripping ahead of, or interfering with, upstream protection.Filed by NR Electric Co., Ltd, published 2019-08-22.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US7202576B1 | Uninterruptible power supply systems and enclosures | 1,053 |
| 2 | US5888198A | Electrosurgical system for resection and ablation of tissue in electrically conductive fluids | 655 |
| 3 | US20130214232A1 | Nonvolatile memory device using a varistor as a current limiter element | 528 |
| 4 | US5766153A | Methods and apparatus for surgical cutting | 527 |
| 5 | US6034322A | Solar cell assembly | 246 |
| 6 | US5465011A | Uninterruptible power supply with improved output regulation | 246 |
| 7 | WO2011057675A1 | Device and method to break the current of a power transmission or distribution line and current limiting arra… | 240 |
| 8 | US6657419B2 | Micro-solar insolation circuit | 240 |
| 9 | US6034493A | Brushless DC motor control | 233 |
| 10 | US20030094931A1 | Micro-solar insolation circuit | 223 |
Citation counts reflect influence within the searched corpus and skew toward older, more general records — several of the most-cited documents here come from adjacent fields such as uninterruptible power supplies and surgical systems rather than converter fault ride-through specifically, which is a reminder to weight citation rank against topical relevance rather than treat it as a technology ranking on its own.
Each row carries its publication number; clicking a row searches Eureka by that number.
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Browse MCP servers →What the numbers mean for a filing decision
Three patterns in the data matter more than the raw counts: where concentration sits, where the technology classes cluster, and where geographic filing activity is heaviest.
Leadership is real but thin
The leading assignee holds 141 records and the field's top 5 combined hold 11.3% of all 4,438 records in scope; the top 10 add up to only 18.8%. That leaves the large majority of filings spread across a long tail — useful context for freedom-to-operate work, since blocking positions are rarely held by a single player.
Activity has cooled since 2017
Annual filings peaked at 201 in 2017 and had already eased to 181 by the 2022 midpoint. The decline predates the most recent, publication-lag-affected years, indicating that the slowdown is a real trend and not just an artefact of recent filings not yet being published.
Three classes carry the claim load evenly
Power conversion (H02M), protective circuitry (H02H) and grid systems (H02J) sit within three points of each other, all above 22% of records. No single discipline owns this technology; a strong filing strategy has to account for prior art across all three layers at once.
US and China lead receiving offices
The United States receives the most filings at 1,211, with China close behind at 961, then Japan at 600 and the EPO at 536. The United Kingdom and PCT route each account for a smaller but non-trivial share, worth checking for regional freedom-to-operate before committing to a single jurisdiction.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to current limiting and fault ride-through in grid-forming converters, with the prior art for and against each one.
Who is filing, and where momentum has gone
Ownership of this claim space is led by large electrical-equipment and grid-operator groups, but no single assignee comes close to a dominant share, and recent-year filing momentum has slowed across the board.
A diversified electrical-equipment leader
The top-ranked assignee holds 141 of the 4,438 records in scope, well ahead of fifth place at 78 and tenth place at 57 — a real but not overwhelming lead over the rest of the ranked field.
Recent-year filing has slowed sharply
Several of the most active historical filers, including grid-operator and converter-protection specialists, show latest-year filings at zero or down as much as 88-100% year on year. This mirrors the overall 2017-to-2026 decline rather than signalling any single company's retreat.
Co-filing is concentrated in one partnership
Of the 10 co-assignee pairs identified in the dataset, the strongest links two affiliated converter-protection engineering entities at 77 shared records, far ahead of the next pairs at 16 and 13. Most assignees in the ranking otherwise file independently.
| Assignee | Recent year | YoY |
|---|---|---|
| State Grid Corporation of China | 1 | -88% |
| Mitsubishi Electric Corporation | 0 | — |
| Toshiba Corporation | 0 | — |
| NR Electric Co., Ltd | 0 | -100% |
| NR Engineering Co., Ltd | 0 | -100% |
| General Electric Technology GmbH | 0 | — |
| ABB Technology Ltd | 0 | — |
| General Electric Company | 0 | — |
Where to take this analysis
The dataset points to specific follow-up work depending on whether the goal is freedom-to-operate, white-space filing, or competitive tracking.
Map claims against the three dominant IPC classes
Because H02M, H02H and H02J each cover close to a quarter of records, a freedom-to-operate review needs to clear all three layers rather than treating conversion and protection prior art separately.
Explore IPC-level prior art in Eureka →Test claim language against the long tail
With the top 10 assignees holding only 18.8% of records, a new filing is more likely to run into a single-country individual filer than a repeat blocking assignee — worth checking claim scope against that tail directly.
Run a claim-scope check in Eureka →Watch for a rebound in filing activity
Filing has declined from its 2017 peak through the most recent, lag-affected years; tracking whether momentum stabilises or continues down will change how defensively a new entrant needs to file.
Set up filing-trend alerts in Eureka →Common questions about this patent landscape
The leading assignee in this dataset holds 141 of the 4,438 records in scope, ahead of fifth place at 78 and tenth place at 57. The top 5 assignees combined hold 11.3% of all records, and the top 10 combined hold 18.8%, so while there is a clear leader, no single company or small group controls the field. The remaining filings are spread across a long tail of the ranked assignees, many with only a handful of records each.
Filing activity peaked in 2017 at 201 records and has declined since, with the 2022 midpoint already down to 181. By 2026 the count sits at 25, though that figure is a partial year affected by the roughly 18-month lag between filing and publication, so the true 2025-2026 level will be somewhat higher once all filings publish. Even accounting for that lag, the multi-year trend from 2017 onward points to a cooling rather than an expanding claim space.
Three IPC subclasses dominate: H02M (power conversion) at 25.6% of the 4,438 records, H02H (protective circuit arrangements) at 23.5%, and H02J (power supply and grid systems) at 22.8%. Because records can carry multiple IPC classes, these shares add up to more than 100%, reflecting that most filings claim across the conversion, protection and grid-integration layers simultaneously rather than confining themselves to one. Smaller but notable activity also appears in H05B, H01H, H03K, G05F and H02P.
The United States receives the most filings among the tracked offices at 1,211 records, followed by China at 961, Japan at 600, and the European Patent Office at 536. The United Kingdom and the WIPO PCT route account for smaller totals at 220 and 218 respectively. Anyone assessing freedom-to-operate should prioritise US and Chinese prior art first given the filing volumes, but should not ignore Japan and Europe given their still-substantial counts.
US20190260201A1, filed by NR Electric Co., Ltd, claims a method for coordinating a converter's inner-loop current limit with upstream AC line overcurrent protection thresholds during islanded operation, specifically setting the converter's output current command limit at or just above the AC line's Section III protection threshold. It is a coordination method rather than a single-component patent, so it constrains specific threshold-setting relationships between converter and grid protection rather than current limiting or fault ride-through broadly. Filings that use different threshold-coordination logic, or that address non-islanded fault scenarios, are likely to sit outside its narrow claim scope, though a formal clearance review of the granted claims is still advisable before relying on that reading.
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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.