Comparative Evaluation of Voltage Source Converters With Silicon Carbide Semiconductor Devices for High-Voltage Direct Current Transmission

Recent advancements in silicon carbide (SiC) power semiconductor technology enable developments in the high-power sector, e.g., high-voltage-direct-current (HVdc) converters for transmission, where today silicon (Si) devices are state-of-the-art. New submodule (SM) topologies for modular multilevel converters offer benefits in combination with these new SiC semiconductors. This article reviews developments in both fields, SiC power semiconductor devices and SM topologies, and evaluates their combined performance in relation to core requirements for HVdc converters: grid code compliance, reliability, and cost. A detailed comparison of SM topologies regarding their structural properties, design and control complexity, voltage capability, losses, and fault handling is given. Alternatives to state-of-the-art SMs with Si insulated-gate bipolar transistors (IGBTs) are proposed, and several promising design approaches are discussed. Most advantages can be gained from three technology features. First, SM bipolar capability enables dc fault handling and reduced the energy storage requirements. Second, SM topologies with parallel conduction paths in combination with SiC metal-oxide-semiconductor field-effect transistors offer reduced losses. Third, a higher SM voltage enabled by a higher blocking voltage of SiC devices results in a reduced converter complexity. For the latter, ultrahigh-voltage bipolar devices, such as SiC IGBTs and SiC gate turn-off thyristors, are envisioned.

Automated summary

The article reviews developments in silicon carbide (SiC) power semiconductor technology and submodule (SM) topologies for modular multilevel converters, evaluating their combined performance in high-voltage-direct-current (HVdc) converters based on core requirements. Various alternative design approaches to state-of-the-art SMs with Si insulated-gate bipolar transistors (IGBTs) are proposed, with a focus on leveraging advantages such as SM bipolar capability, reduced losses with SiC metal-oxide-semiconductor field-effect transistors, and higher SM voltage enabled by SiC devices. Potential future developments in ultrahigh-voltage bipolar devices like SiC IGBTs and SiC gate turn-off thyristors are also discussed.