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Advanced Energy Unveils 800 VDC Converters for AI Data Centers

35 d ago

The electrical infrastructure is shifting toward inverter-based resources (IBRs) such as solar photovoltaics, wind turbines, and battery energy storage systems (BESS). Traditional synchronous generators provide kinetic energy buffers, resist rate-of-change-of-frequency (RoCoF) events, and inject high fault currents. Grid-following (GFL) inverters, which rely on a low-impedance voltage source, were adequate when synchronous generators dominated. However, growing IBR adoption leads to low short-circuit ratios, high RoCoF, and voltage instability. Grid-forming (GFM) inverters address these challenges by operating as controlled AC voltage sources behind virtual impedance, providing synthetic inertia and stabilizing weak grids. GFM operation stresses semiconductors through transient overcurrent, safe operating area limits, and thermal changes. During faults, current spikes can exceed device ratings, risking latch-up or thermal runaway. Current-limiting controls in GFM inverters may cause voltage collapse or hinder fault detection, while higher fault-current injection increases losses and device stress. Asymmetrical faults and advanced control strategies like finite set model predictive control alter loss distribution and switching frequencies. Power device selection involves trade-offs among cost, efficiency, power density, control bandwidth, and ruggedness. Silicon IGBTs dominate high-power utility-scale GFM systems due to low cost and short-circuit ruggedness (up to 10 µs withstand), but their limited switching frequency (1–5 kHz) requires large filters. Silicon MOSFETs are unsuitable for high-voltage AC stages due to high on-resistance. SiC MOSFETs offer higher switching frequencies (15–50 kHz), lower losses, and better thermal conductivity, enabling smaller filters and wider control bandwidth. However, they have shorter short-circuit withstand times (1–3 µs), demanding fast protection. Gallium Nitride (GaN) HEMTs are limited to low-voltage applications (<650 V) and not yet viable for high-power GFM inverters. No single device is ideal; choice depends on inverter size, efficiency, cooling, and fault-ride-through requirements.