Solid-State Transformer Protection Patents: Who Leads 2026
- Filing has already peaked. 2017 recorded the high point at 3 families, and the midpoint year of 2022 sits below that at 2 — this is a flat-to-declining filing curve, not an emerging one.
- China dominates the filing venue. 11 of 13 records were filed in China against 2 in the United States, meaning most of the enforceable claim scope sits under Chinese examination practice.
- The field is thin enough to map by hand. Only 13 patent families exist across the entire search window, with just 10 co-assignee pairs — this is a small, legible landscape rather than a crowded one.
A narrow, China-heavy field built on DC fault ride-through
Solid-state transformer (SST) protection and relaying sits at the intersection of power conversion topology and fault-handling circuitry. The dataset covers 13 patent families published between 2015 and 2026, concentrated in H02M power conversion architectures, with a smaller but consistent overlay of H02H protective circuitry and H02J grid-supply integration. Most filings describe modular multilevel converter (MMC) based four-port or DC-DC topologies where fault ride-through is designed into the converter stage itself rather than added as a separate protection layer.
Filing activity peaked in 2017 and has not returned to that level since, with the 2022 midpoint showing only two families. Combined with a filing base dominated by Chinese receiving offices, the picture is of a technology area explored early by a handful of Chinese universities and grid-equipment makers, with limited fresh entrants since. Publication lags filing by roughly 18 months, so any 2025-2026 activity is understated in these counts.
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Filing trend and technology composition
Two views of the same 13-family dataset: how filing activity moved year over year, and which IPC subclasses the claims actually sit in.
Flat-to-declining filing since the 2017 peak
Filings rose to 3 in 2017, the high point of the series, then settled to lower levels; the 2022 midpoint value of 2 confirms the trend has not resumed growth. With the most recent year always undercounted due to publication lag, the honest read is a mature, low-volume filing pattern rather than a technology in early ramp.
Power conversion carries the claim weight
H02M (power conversion) appears in 12 of 13 records, meaning nearly every filing anchors its claims in converter topology. H02J (grid supply systems) appears in 7 and H02H (protective circuit arrangements) in 6, showing that protection and grid-integration claims are usually layered on top of a converter-topology base claim rather than filed as standalone protection patents.
Shares are the percentage of the 13 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Solid-State Transformer Protection and Relaying with Eureka
This page is one run against one query. Ask Eureka your own question about solid-state transformer protection and relaying and every answer comes back with the patent numbers behind it.
Try EurekaThe most-cited records in this space
Four-port power electronic transformer based on hybrid modular multilevel converter
Discloses a four-port power electronic transformer built on a hybrid modular multilevel converter (MMC), with DC/DC converters and an inverter arranged so that the MMC module and the front stage of the connected DC/DC circuit jointly handle DC fault ride-through. The design reduces the number of devices needed compared with prior power electronic transformers by having the MMC module regulate DC voltage while the DC/DC stage manages the remaining fault-handling function.Filed by Southeast University, published 2018-03-29 — the highest-cited record in this dataset at 73 citations.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US20180091037A1 | Four-port power electronic transformer based on hybrid modular multilevel converter | 73 |
| 2 | CN107968572A | 一种具有故障穿越能力的直流固态变压器及其控制方法 | 25 |
| 3 | CN107947221A | 一种电力电子变压器直流故障穿越方法 | 22 |
| 4 | CN112311238A | 一种具备直流短路故障保护能力的新型直流电力电子变压器 | 7 |
| 5 | CN116131325A | 一种用于远距离海上风电场直流汇集外送的固态变压器 | 5 |
| 6 | CN110336470A | 电力电子变压器系统、变压器及其故障穿越控制方法 | 5 |
| 7 | CN115940649A | 基于MMC子模块桥臂复用的SST拓扑及故障穿越方法 | 3 |
| 8 | CN111224534A | 一种混合MMC型多端口固态变压器的直流故障穿越控制方法 | 2 |
| 9 | US9960666B2 | Four-port power electronic transformer based on hybrid modular multilevel converter | 1 |
Citation counts reflect influence inside the searched corpus and skew toward older publications; they are not a measure of current commercial relevance.
Patent titles are shown in the language they were filed in, not translated, so that each record stays verifiable against the original filing — a translated title will not match in Eureka or in any national register. Publication numbers are shown where the record carries one (9 of 9 rows); clicking a row searches Eureka by that number.
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Browse MCP servers →What the numbers say about where this field stands
Three readings of the dataset that matter for a filing or freedom-to-operate decision.
The growth phase already happened
The series peaks at 3 families in 2017 and the 2022 midpoint sits at only 2, below peak. That is a declining-to-flat trajectory, not an accelerating one — new entrants filing now are joining a field that already had its highest-density year.
Examination and enforceability concentrate in China
Eleven of thirteen records were filed with a Chinese receiving office against two in the United States. Anyone assessing freedom-to-operate for a China-manufactured or China-deployed SST needs to weight Chinese prior art heavily; US coverage in this exact claim space is comparatively thin.
Protection claims ride on converter-topology claims
H02M appears in 12 of 13 records, H02J in 7, H02H in 6. Very few filings claim fault protection as a standalone mechanism; most bundle it into a converter or grid-interface architecture claim, which shapes how a competing claim needs to be drafted to avoid overlap.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to solid-state transformer protection and relaying, with the prior art for and against each one.
Who is filing, and how connected are they
With only 13 families and 10 co-assignee pairs, this field is small enough that collaboration patterns are visible directly rather than inferred statistically.
A small set of Chinese universities and grid entities
Filers include university research groups (Southeast University, Zhejiang University, Nanjing Normal University, North China Electric Power University) alongside grid-equipment entities such as Xuji Electric and its Xi'an subsidiary. No single assignee dominates a 13-family set of this size.
Filings cluster around university-institute pairings
The strongest pairings link a university or research institute to a state grid entity — Xi'an Xuji Power Electronics with Xuji Electric, and with the China Electric Power Research Institute; Nanjing Normal University with NARI Group. These look like joint research programs rather than open licensing arrangements.
No assignee is actively filing right now
Every assignee tracked for recent-year momentum — including Xi'an Xuji Power Electronics, Zhejiang University, Southeast University and North China Electric Power University — shows zero filings in the latest year. Combined with the flat filing trend, this points to a dormant rather than a contested field at present.
| Assignee | Recent year | YoY |
|---|---|---|
| Xi'an Xuji Power Electronics Technology Co., Ltd. | 0 | — |
| Zhejiang University | 0 | — |
| Nanjing Normal University | 0 | — |
| Nanjing Institute of Technology | 0 | — |
| North China Electric Power University | 0 | — |
| Southeast University | 0 | — |
| Xuji Electric Co., Ltd. | 0 | — |
| Xi'an Jiaotong University | 0 | — |
Where to take this analysis
The dataset points to specific next steps depending on whether the goal is freedom-to-operate, portfolio strategy, or identifying open claim space.
Check freedom-to-operate against Chinese filings
With 11 of 13 families filed in China, a freedom-to-operate review that only searches US and EPO prior art will miss most of the relevant claim scope in this space.
Run a freedom-to-operate search in EurekaMap the converter-topology base claims before drafting
Because protection claims are usually layered onto converter-topology claims rather than filed standalone, a new filing needs to be checked against the H02M base architecture, not just the H02H protection layer.
Explore claim structures in EurekaTrack whether filing resumes post-2022
The flat-to-declining trend since 2017 could reverse as offshore wind and DC-collection applications mature; watching for new entrants outside the current Chinese university cluster would be an early signal.
Set up monitoring in EurekaCommon questions about this landscape
This dataset identifies 13 patent families published between 2015 and 2026 that combine solid-state transformer or power electronic transformer terminology with fault protection, DC protection or fault ride-through claims under IPC classes H02M, H02H and H02M1/32. That is a small field by patent-landscape standards, which means individual filings carry more weight in freedom-to-operate analysis than they would in a denser area. Because publication lags filing by around 18 months, the true 2025-2026 count is likely higher than currently visible.
Eleven of the thirteen records in this dataset were filed with a Chinese receiving office, against two in the United States. This reflects where the underlying research and deployment activity is concentrated: several Chinese universities and state grid-affiliated companies are active in solid-state transformer development for grid and offshore wind applications. Anyone assessing risk or opportunity in this space should treat Chinese prior art as the primary body to search, not a secondary one.
Not currently. Filing peaked at 3 families in 2017, and the 2022 midpoint value of 2 families is below that peak, indicating a flat-to-declining trend rather than growth. Every assignee tracked for recent-year momentum shows zero filings in the latest year. This does not necessarily mean interest has disappeared — publication lag means the most recent one to two years are always undercounted — but on the visible evidence this is a mature, low-activity field rather than an emerging one.
US20180091037A1, filed by Southeast University and published in 2018, describes a four-port power electronic transformer built on a hybrid modular multilevel converter (MMC) architecture. Its distinguishing feature is that the MMC module and the front stage of a connected DC/DC circuit jointly perform DC fault ride-through, reducing the total device count compared with earlier power electronic transformer designs. It is the most-cited record in this dataset at 73 citations, making it a reference point that later filings in this space are likely to cite or design around.
The clearest gaps sit outside the dominant H02M converter-topology claims: standalone DC-side relay coordination, multi-port fault isolation sequencing, protection coordination across cascaded H-bridge stages, and fault ride-through specific to offshore wind DC collection networks all appear thinly represented relative to the converter-topology filings that dominate the dataset. A first claim in one of these branches would need to avoid restating the MMC or DC/DC base architecture already claimed in the highest-cited records and instead focus narrowly on the coordination or sequencing logic itself.
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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.