Новое поколение монолитных GaN-транзисторов преодолело барьер в 5 кВ для средневольтовых сетей

A breakthrough for the bidirectional switch By exceeding a blocking voltage of 5 kV while keeping conduction loss and reliability in check, a new generation of monolithic GaN bidirectional switches promise efficient, more compact medium-voltage AC power conversion. BY YUAN QIN FROM UNIVERSITY OF SCIENCE AND TECHNOLOGY OF CHINA, MING XIAO FROM XIDIAN UNIVERSITY, KAI CHENG FROM ENKRIS SEMICONDUCTOR, AND YUHAO ZHANG FROM THE UNIVERSITY OF HONG KONG With minimal fanfare, power electronics is becoming the enabling layer for a number of converging transitions: electrified transport and industry, the build-out of renewable generation and storage, and the expansion of energy-intensive digital infrastructure. For all these cases, higher efficiency and a higher power density are no longer optional – instead, they directly translate into smaller passive components, simplified thermal management and a lower lifetime cost. The introduction of wide-bandgap semiconductors has already shifted the landscape, with GaN’s success story told through unidirectional HEMTs, powering compact, high-frequency converters from 30 V to 400 V. But many of the next frontiers for GaN are inherently AC-facing, so switches will have to handle current reversal and bipolar off-state voltages. While it is workable to implement that bidirectional capability with anti-series devices, that solution scales poorly as voltage rises: chip area grows, parasitic capacitances stack, and gate-drive and layout complexity multiply. A better approach is to attack this problem at its root, using a monolithic bidirectional switch. This form of switch shares the high-voltage region inside one device, and preserves efficiency while simplifying the circuit. Taking the performance of these switches to a new realm, by delivering a hike in the voltage-handling capability, is our team from University of Science and Technology of China, Xidian University, Enkris Semiconductor and the University of Hong Kong. Our breakthrough promises to open the door to the deployment of this device in medium-voltage AC applications. Motivation for our efforts has come from considering three questions: Why does bidirectional switching matter in real converters? Why do monolithic implementations offer such a strong advantage? And how is it possible to reach a high voltage with a bidirectional switch? Why bidirectional? The applications most in need of a bidirectional switch are those that involve a converter having to connect and disconnect an AC node efficiently. Matrix converters and current-source inverters are classic examples. In these circuits, the switch must handle current in both directions, as the load current and the instantaneous line voltage are not necessarily aligned. In addition, the same device must often sustain positive and negative blocking voltages, as switching states change over a line cycle. Bidirectional switches are also valuable in solid-state transformers. They are a critical component in Nvidia’s next-generation 800 V power delivery architecture in AI data centres, as well as in medium-voltage motor drives, and emerging AC distribution and protection concepts, where fast, controllable bidirectional elements can replace bulky passive components. For all these examples there tends to be a common economic driver: if a bidirectional function can be implemented with fewer devices, the overall system can be smaller, faster and more efficient.