In 1831, British scientist Michael Faraday discovered the phenomenon of electromagnetic induction, laying the theoretical foundation for the birth of the transformer. During the 1880s-amidst the "War of Currents" between alternating current (AC) and direct current (DC)-the transformer emerged as the pivotal device enabling AC to achieve long-distance power transmission and ultimately triumph. In 1884, the "secondary generator"-invented by Frenchman Lucien Gaulard and Englishman John Dixon Gibbs-illuminated a street in Turin, Italy; this marked the earliest prototype of a practical transformer.
The practical realization of the modern transformer is credited to William Stanley, an engineer at Westinghouse, who in 1885 invented a transformer utilizing a closed, E-shaped laminated iron core and constructed the first complete AC power transmission system. Over the century that followed, transformer technology underwent continuous evolution: core materials advanced from ordinary steel sheets to silicon steel and amorphous alloys; insulation and cooling media evolved from mineral oil to eco-friendly plant-based oils; and structural designs expanded from the singular oil-immersed type to encompass various forms, such as dry-type and fully sealed units.
Entering the 21st century, traditional transformers have faced new challenges regarding response speed, power density, and intelligent control in order to meet emerging demands-such as high-density power supply for AI data centers, the grid integration of new energy sources, and fast charging for electric vehicles. Consequently, Solid-State Transformers (SSTs)-centered on semiconductor devices such as Silicon Carbide (SiC) and Gallium Nitride (GaN)-have begun to emerge. By leveraging high-frequency power electronic conversion technologies, SSTs achieve higher efficiency, a more compact footprint, and flexible control over voltage, frequency, and power factor. In 2023, China XD Group commissioned a 2.4 MW-class Solid-State Transformer for a data center participating in China's "Eastern Data, Western Computing" initiative.
Looking ahead, transformers are evolving from passive "power conversion devices" into active "nodes" within the smart grid. Through the integration of sensors, edge computing, and digital twin technologies, they will be capable of self-sensing their operational status, self-diagnosing faults, and engaging in intelligent interactions with the power grid. In terms of materials, amorphous alloys and nanocrystalline soft magnetic materials are poised to find even wider application.
