High-Temperature DC-Link Capacitors for Automotive and Industrial Power Electronics

The B3271xP series of metallized polypropylene (MKP) film capacitors provides high thermal robustness for the next generation of power electronics. These components are specifically engineered for the automotive data ecosystem and industrial applications where compact design requirements lead to elevated internal ambient temperatures.

Thermal Performance and Electrical Stability
Operating conditions in modern xEV traction inverters and industrial frequency converters often exceed the limits of standard film capacitors. The B3271xP series addresses this by supporting a maximum operating temperature of 125 °C. A key technical differentiator is the component's ability to maintain its full rated power up to 105 °C; derating only becomes necessary for temperatures exceeding this threshold.

The series spans a capacitance range from 0.47 µF to 110 µF and is available for rated DC voltages of 600 V, 900 V, and 1200 V. By utilizing a polypropylene dielectric, the capacitors achieve low equivalent series resistance (ESR) values, which minimizes internal self-heating during high ripple current loads. Typical ESR values reach down to the single-digit milliohm range at 10 kHz, facilitating efficient power conversion in a digital supply chain.

Mechanical Design and Application Integration
To ensure mechanical stability in demanding environments, the capacitors are housed in flame-retardant plastic cases sealed with epoxy resin, meeting the UL 94 V-0 safety standard. They are available in three standard lead spacings: 27.5 mm, 37.5 mm, and 52.5 mm. While 2-pin versions are standard, 4-pin configurations are available upon request to provide additional vibration resistance and lower inductance for high-frequency switching.

Primary application areas include:

The integration of these capacitors into power modules is supported by comprehensive SPICE model libraries and the web-based "Capacitor Life And Rating Application" (CLARA) tool. This allows engineers to simulate service life and electrical performance under specific load profiles accurately.

Standards and Reliability
The B3271xP series complies with the AEC-Q200E reliability standard, making it suitable for automotive platforms. Furthermore, the construction is recognized under UL 810, ensuring global compliance for industrial safety. The self-healing properties of the MKP dielectric further enhance system uptime by allowing the capacitor to recover from local dielectric breakdowns without catastrophic failure.

Objective Comparison
When compared to the existing B3277*H series from the same manufacturer, which is rated for 105 °C with a 1000-hour Temperature, Humidity, and Bias (THB) test, the B3271xP series offers a 20 °C increase in peak operating temperature. While standard MKP capacitors typically require voltage derating starting at 85 °C, this new series maintains voltage stability up to 105 °C, providing a broader operational window for high-density power stages.

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