Solid-State Transformer

The industry's path to advancing solid-state transformers is mostly to pilot them first in closed or controllable scenarios such as data centers, ships, and railway traction, and then promote them to distribution grids after accumulating operational data.

Solid-state transformers can complete voltage compensation and reactive power regulation at the millisecond level, and support direct DC power supply, reducing losses from multi-stage AC-DC conversion.

Large-scale deployment of solid-state transformers still faces practical tests such as cost, reliability, and large-scale manufacturing.

Solid-state transformers contain a large number of power electronic devices, and the lifespan of their electrolytic capacitors and semiconductor modules is significantly shorter than that of traditional iron-core windings, making long-term maintenance-free operation a core challenge.

Currently, high-voltage devices such as SiC are costly, and the unit cost of high-power solid-state transformers remains significantly higher than that of traditional solutions.

Solid-State Transformers replace the traditional iron-core and copper-winding structure with power electronic devices, achieving voltage conversion through semiconductor switches and high-frequency conversion technology.

Solid-state transformers first rectify power-frequency AC into DC, then invert it into high-frequency AC through high-frequency semiconductor switches (such as IGBT and SiC devices), and finally convert it to the target voltage; with higher frequency, magnetic components can be greatly reduced in size at the same power.

Solid-state transformers have bidirectional power flow capability and can connect to both DC (such as photovoltaics, energy storage, and data center DC buses) and AC systems.

The value of the SST lies in its ability to produce the 800 VDC bus required by servers directly from utility AC, eliminating the losses and footprint brought by the multi-stage AC-DC-AC-DC conversion in traditional architectures.

In programmable power systems such as SSTs, protection logic is partly implemented in software, and the system may switch among AC, DC, and energy storage modes, changing the fault current path accordingly, which significantly increases the difficulty of protection coordination.

Solid-state transformers (SSTs) use power semiconductors (such as SiC and GaN devices) to perform power conversion at high frequency, rectifying AC to DC and then inverting it to the required AC or DC form, featuring small size, active controllability, and multi-port output.

If solid-state transformers are deployed at scale, they could theoretically alleviate the transformer supply bottleneck and bring greater controllability to the grid.