As AI data centers (AIDC) evolve toward higher power density and faster construction timelines, power supply systems are confronting new architectural challenges. Solid-state transformers (SST), one of the emerging power supply technology routes, are moving from technical research and prototype demonstrations toward engineering validation. Recently, at an international exchange exhibition themed around computing-power synergy held in Shanghai, Chen Zhiyuan, AIDC Solutions Director at Beijing Sifang Digital Intelligence Energy Technology Co., Ltd. (hereinafter referred to as "Sifang Digital Intelligence"), a subsidiary of Beijing Sifang Automation Co., Ltd. (hereinafter referred to as "Sifang Automation"), told a reporter that unlike their previous supporting role at data center exhibitions or new energy exhibitions, SSTs have now formally stepped into the spotlight and are drawing significant attention. Sifang Automation formally established Sifang Digital Intelligence this year, entering the new power supply market with SST products as its core focus. On October 28, a reporter visited Sifang Automation for on-site research to explore how this veteran power equipment enterprise will leverage new technological capabilities to seize market opportunities in the SST industry.
Deep technological accumulation
SSTs are also known as power electronic transformers. Unlike traditional line-frequency transformers that operate on the principle of electromagnetic induction, SSTs use power electronic devices as their core, achieving voltage level conversion and AC/DC form transformation through high-frequency switching. Their value lies not merely in replacing a single piece of equipment, but in providing new and more advantageous options for adjusting power supply system architecture. "The power supply chain of a traditional computing center includes multiple voltage levels and AC/DC conversion stages," Chen Zhiyuan told the reporter. In a typical scheme, medium-voltage AC enters the data center, goes through transformation, UPS (uninterruptible power supply) and subsequent distribution stages, and then undergoes multi-stage conversion by server power supplies to ultimately meet chip power supply requirements. As rack power continues to increase, traditional power supply architectures face new challenges in terms of equipment count, spatial layout, conversion stages, and construction timelines. An important technical direction for SSTs is to directly convert medium-voltage AC into DC voltage suitable for high-power racks, thereby reducing some intermediate conversion stages. Using an 800-volt DC power supply architecture for next-generation high-power racks as an example, Chen Zhiyuan explained that, provided the system solution is properly matched, SSTs are expected to simplify the power supply chain, improve space utilization, and reduce some equipment and connection stages. "Concentrating all problems into a single SST device to solve means that if the SST can be delivered, the project can be delivered. At the same time, system efficiency can be improved by 3% to 5% compared with traditional solutions, and the footprint can be reduced by more than 50%."
The catalyst for this technology route moving from a laboratory concept to an industry focal point comes from the AIDC construction boom. Meanwhile, a leading enterprise has explicitly positioned SSTs as the ultimate power supply solution for data centers. Against this backdrop, in the first half of this year, multiple power equipment companies including Sifang Automation successively launched SST products; Sifang Automation also specifically established subsidiary Sifang Digital Intelligence to handle SST industrialization. Discussing the core purpose of establishing Sifang Digital Intelligence, a relevant person in charge at Sifang Automation told the reporter that Sifang Digital Intelligence focuses on the hottest global AI data center architecture transformation, though the company's main energy is currently still devoted to advancing SSTs from the laboratory to engineering and from customized products to mass-produced standardized products. "This kind of engineering-oriented approach requires deep technological accumulation, and Sifang Automation's accumulation in the SST field did not begin this year," the person in charge said. Sifang Automation has participated in the development of new power electronic equipment for the two major grid operators (State Grid and China Southern Power Grid) since 2015, landing a large number of projects in DC transmission and DC distribution network fields. The company's earlier layout in power electronic transformers, power routers, and other previous-generation products also accumulated a complete technology chain and engineering experience for the current Digital Intelligence Solid-State Transformer 1.0, which was mass-produced upon release.
Computing-power synergy puts products to the test
The reporter noted that although SST market enthusiasm continues to rise, after multiple companies concentrated on product launches in the first half of this year, few followers have emerged. "The technical threshold determines that there will not be too many participants in the SST race," Chen Zhiyuan believes. SSTs involve multiple areas including high-frequency isolation magnetic components, wide-bandgap semiconductor devices, power electronic topology, control and protection, thermal management, and system coordination, requiring a balance among power density, efficiency, reliability, cost, and manufacturability — it is a system-level engineering endeavor. "The real threshold is not making each technical module separately, but integrating them into a product that can operate stably over the long term, is easy to maintain, and can be mass-produced," Chen Zhiyuan said. The R&D cycle for related products is affected by factors such as a company's existing technological foundation, target power level, product architecture, and certification scope, so progress may vary considerably among different companies. In Chen Zhiyuan's view, SST industrialization needs to cross multiple stages: the first stage is completing prototype and key function validation; the second stage is conducting system-level testing, reliability verification, and certifications required by target markets; the third stage is entering customer site testing and small-batch delivery; the fourth stage is gradually expanding delivery scale based on operational data, supply chain capability, and manufacturing consistency. "Judgments at each stage should be based on actual test results, certification progress, customer validation, and delivery records, rather than being measured solely by product launches or project intentions."
In terms of testing cycles, taking North America as an example, UL certification requires 3 to 5 months and must pass all content in one attempt, while customer on-site data testing requires another 3 to 6 months; the two parts can proceed in parallel, with an overall verification cycle of about half a year. This means that products delivered in the second quarter of next year will not actually be put into project use until around the end of next year. "The industry's general judgment is that SSTs will achieve large-scale application in 2028," Chen Zhiyuan said. This timeline is fully aligned with the pace of market demand. It is expected that after Nvidia releases megawatt-level or 600-kilowatt racks in early 2027 and achieves mass delivery, traditional solutions and first-stage and second-stage DC retrofit solutions will be unable to support power supply for such high-power racks, and only then will rigid demand for SSTs truly be unleashed.
SST applications in China are also advancing in parallel. A relevant technical staff member at Sifang Automation told the reporter that the driving force in the North American market comes from rigid demand on the user side — data centers are being built quickly, equipment manufacturing cannot keep up, and long delivery cycles have become a prominent pain point, while SSTs can significantly shorten project cycles. The logic in the domestic market is different, coming more from the need for strong coupling between computing power and the energy side against the backdrop of large-scale new energy development; policy directions such as green power direct connection and computing-power synergy provide another development path for SSTs. "Both markets are key directions the company is advancing," the technical staff member said. "Domestic green power direct connection and computing-power synergy projects are often at the hundred-megawatt or even gigawatt level, testing whether dozens or even hundreds of SSTs can maintain coordinated operation, placing higher demands on control strategies, dynamic response, power distribution, and protection coordination," the technical staff member said. If the response characteristics among devices are inconsistent, problems such as circulating currents, efficiency degradation, or protection actions may occur. Therefore, system-level simulation, hardware-in-the-loop testing, parallel system verification, and on-site operational data are important bases for evaluating whether SSTs can be applied on a large scale.
Application boundaries will continue to broaden
AIDC power supply is currently the most closely watched application scenario for SSTs, but in Chen Zhiyuan's view, considering a longer time scale, the upgrading of new distribution systems may also create broad application space. "Over the next 5 to 10 years, with the increase of distributed new energy, energy storage, charging facilities, and adjustable loads, distribution networks are gradually showing characteristics of bidirectional interaction between sources and loads and the coexistence of AC and DC equipment. The multi-port, multi-voltage-level, and AC/DC conversion capabilities of SSTs provide new technology route options for some complex scenarios." The application of SSTs in solar-storage-charging is another scenario worth watching. Chen Zhiyuan said that megawatt-level flash charging successively released by several leading companies places higher demands on the power conversion efficiency, equipment footprint, power regulation, and grid adaptability of power supply systems. SSTs can reduce some intermediate conversion stages and integrate systematically with DC buses, energy storage, and charging equipment. With the superposition of multiple advantages, SSTs offer significant economic advantages compared with traditional solutions. In scenarios involving the coordination of solar, wind, and energy storage, SSTs can undertake functions such as voltage conversion, AC/DC conversion, and multi-port energy management according to system design. For example, in a suitable DC architecture, solar, energy storage batteries, and DC loads can exchange energy through a DC bus, reducing some conversion stages. Microgrids are also an important application direction for SSTs. Traditional microgrids require multi-stage converter and transformer equipment; when connecting AC/DC sources and loads at multiple voltage levels, they face problems such as many stages, large footprint, and complex coordination, and control commands must be transmitted level by level, whereas SSTs have unique advantages in AC/DC integrated scenarios. Chen Zhiyuan believes that as technology matures and costs decline, the application boundaries of SSTs will continue to broaden. The technical staff member said that overall, companies along the domestic SST industry chain have continued to make progress in high-frequency isolation transformers, control systems, and complete machine integration, and some segments already possess strong domestic supply capabilities. Although power semiconductor devices such as silicon carbide still require comprehensive consideration of performance, cost, supply cycle, and long-term reliability, with the vigorous development of the domestic semiconductor industry, the localization of related devices is expected to be just around the corner. From entering DC distribution network technology R&D in 2015, to establishing Sifang Digital Intelligence this year and launching the Digital Intelligence Solid-State Transformer 1.0 product, to targeting small-batch delivery next year and large-scale application thereafter, Sifang Automation's pace in the SST race is clear. The relevant person in charge at the company told the reporter that the company places great emphasis on technology R&D investment and has long adhered to the philosophy of driving the market through technology; SSTs are precisely the continuation of this philosophy in a new race.
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