TDK’s High-Current DC-Link Capacitors Operate at 105 °C Without Derating
Designed for high current density in power electronics, the new ModCap UHP series combines a high-temperature dielectric with a modular form, enabling a 200,000-hour lifetime in high temperatures.
TDK Corporation has released the ModCap UHP series of DC-link capacitors for high-temperature operation in power electronics. The B25648A capacitor line operates continuously at hotspot temperatures up to 105 °C without requiring current derating, addressing a limitation present in previous ModCap generations that required derating above 90 °C.
TDK’s ModCap UHP (B25648A) series of DC link capacitors supports high-temperature operation up to 105 °C. Image used courtesy of TDK Corporation
Thermal Performance and Lifetime Extension
The ModCap UHP series achieves its temperature capability through a new high-temperature dielectric material combined with TDK’s modular capacitor design. At 105 °C operation, the series maintains a rated lifetime of 200,000 hours while supporting a 20% higher current density than prior generations. This thermal performance directly impacts power density in converter designs, particularly those using silicon carbide semiconductors that operate at higher switching frequencies and temperatures.
The capacitors are rated for DC voltages from 1350 V to 1800 V with capacitance values ranging from 470 µF to 880 µF. The equivalent series inductance is 8 nH, which TDK indicates reduces the need for additional snubber capacitors in fast-switching applications. The cubic housing design measures 205 mm x 90 mm x 170 mm and facilitates busbar integration in compact converter layouts.
TDK’s web-based thermal simulation tool, CAP Thermal, enables users to identify hotspot areas. Image used courtesy of TDK Corporation
Material and Safety Specifications
The dielectric film used in the ModCap UHP series is ISCC-certified bio-circular BOPP material. The housing complies with UL94 V-0 flammability standards and meets EN 45545-2 HL3 R23 requirements for railway applications. TDK has submitted the series for UL recognition, though certification remains pending.
Three initial part numbers are available with varying voltage and capacitance combinations. The B25648A1887K003 provides 880 µF at 1350 V with a rated current of 205 A at 75 °C. The B25648A1647K003 offers 640 µF at 1600 V with 190 A rated current, while the B25648A1477K003 delivers 470 µF at 1800 V with 180 A rated current. Surge current ratings range from 150 kA to 205 kA, depending on the model.
The ModCap UHP series is compatible with TDK’s Capacitor Life and Rating Application (CLARA), a web-based, search-oriented simulation tool. Image used courtesy of TDK Corporation
Design Resources and Target Applications
TDK supports the ModCap series with several engineering tools, including a SPICE library for circuit simulation, the web-based Capacitor Life and Rating Application (CLARA) for lifetime calculation, and CAP Thermal for thermal modeling. These tools allow designers to evaluate capacitor performance under specific operating conditions during the design phase.
The ModCap UHP series targets applications in renewable energy systems, including solar inverters, wind power converters, electrolyzer systems, energy storage systems, and industrial motor drives. The railway sector represents another key application area, particularly for auxiliary power converters in traction systems.
The capacitors’ high-temperature operation without derating makes them suitable for installations where ambient conditions or thermal management constraints previously limited capacitor selection. The combination of extended lifetime, higher current density, and compatibility with SiC switching devices positions the series for use in designs prioritizing power density and reliability in demanding thermal environments.
