High-Temperature DC Link Capacitors for Power Electronics

TDK Corporation has introduced the ModCap UHP (B25648A) series of DC link film capacitors designed for sustained high-current operation at hotspot temperatures up to +105 °C without derating, addressing key thermal and electrical challenges in power conversion systems used across renewable energy, energy storage, industrial drives and traction applications.

Extending DC Link Performance under Thermal Stress
The new ModCap UHP family is engineered to meet increasing demands in power electronics, particularly where silicon carbide (SiC) semiconductor-based inverters and converters operate at elevated switching frequencies and thermal loads. Traditional DC link capacitors often require derating of performance above ~+90 °C, reducing effective capacitance or lifetime under continuous thermal stress. By contrast, the ModCap UHP series maintains rated capacitance and current handling up to +105 °C, enabling higher sustained current density and longer operational life — specified at 200,000 hours at +105 °C.

This performance is achieved through use of a high-temperature dielectric material combined with a modular construction approach that also supports low equivalent series inductance (ESL ~8 nH), an important factor in minimizing parasitic effects at high switching speeds.

Electrical and Mechanical Characteristics
The ModCap UHP capacitors are offered with DC voltage ratings from 1350 V to 1800 V and capacitance values ranging from 470 µF to 880 µF, targeting power levels typical in medium- to high-power converter architectures. Rated current values at +75 °C span approximately 180 A to 205 A depending on model, with comparable surge current capabilities.

Designed in a cubic package (~205 × 90 × 170 mm), these capacitors can be integrated directly into DC link busbar structures, supporting compact layouts and reducing reliance on additional snubber components. The modular format also aligns with scalable converter designs in modular power converters.

Application Context and Technical Use Cases
DC link capacitors play a pivotal role in buffering energy and smoothing voltage in power conversion stages. Their performance directly affects converter efficiency, thermal management and system lifetime. The ModCap UHP series is positioned for systems where high current density and thermal resilience are essential, such as central inverters for solar and wind installations, battery energy storage systems (ESS), hydrogen electrolyzers, auxiliary traction drives and industrial motor drives built around wide-bandgap semiconductors.

By enabling continuous operation at higher hotspot temperatures without derating, designers can reduce the total number of parallel units required, cut DC link volume and potentially lower overall system cost while preserving reliability under sustained load.

Standards, Materials and Safety Considerations
Alongside thermal and electrical enhancements, the ModCap UHP series incorporates ISCC certified bio-circular BOPP dielectric film and meets recognized safety standards for housing materials (e.g., UL94 V-0 and EN 45545-2 HL3 R23), addressing sustainability and flammability requirements relevant to industrial and transportation sectors.

Competitive and Technical Positioning
Within the domain of high-performance DC link components, the ModCap UHP series extends the operating envelope beyond conventional polypropylene capacitors by combining elevated temperature tolerance with low ESL and modular integration — characteristics increasingly important in digital supply chain-driven power conversion designs that leverage advanced semiconductors for higher efficiency and power density.

Conclusion
TDK’s ModCap UHP capacitors provide an incremental yet technically significant advancement for high-current DC link applications, enabling continuous operation at elevated hotspot temperatures without derating and supporting the evolving performance demands of renewable energy, energy storage and industrial converter systems.

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