High-Ripple DC Link Capacitors for EV Chargers

Electric vehicle on-board chargers require compact, high-reliability DC link capacitors capable of handling elevated ripple currents and operating temperatures. TDK Corporation has introduced the B43655 and B43656 series to address these requirements in 400 V and 800 V battery architectures.

Design Focus: DC Link Stability in 800 V Platforms
In modern electric vehicles, the DC link capacitor stabilizes the intermediate circuit between rectifier and inverter stages within the on-board charger (OBC). As charging power levels increase and 800 V battery systems become more common, capacitor components must withstand higher voltages and ripple currents while maintaining thermal stability.

The B43655 series is rated at 475 V and 500 V, with capacitance values from 110 µF to 880 µF. These ratings align with the voltage margins required for 800 V battery architectures. The series supports ripple currents up to 3.29 A at +105 °C (120 Hz) and features typical ESR values as low as 100 mΩ at 120 Hz and +20 °C. Lower ESR reduces resistive losses and heat generation in high-frequency switching environments.

The B43656 series, rated at 450 V, is designed for higher current handling in demanding OBC topologies. It supports ripple currents up to 4.42 A at +105 °C (120 Hz), making it suitable for high-power charger configurations where ripple current density is a limiting factor.

Thermal Management and Mechanical Integration
Both capacitor series are optimized for base cooling and forced-air cooling operation. This configuration improves heat dissipation from the core winding to the mounting surface, extending service life under elevated ambient temperatures.

The specified useful life exceeds 3,000 hours at +105 °C, a standard endurance reference condition in automotive-grade passive components. Mechanical formats include compact snap-in designs with diameters from 22 mm to 35 mm and lengths between 25 mm and 60 mm, depending on capacitance and voltage class. Selected variants are available with tight length tolerances of ±0.5 mm, supporting automated assembly in high-volume production.

Each device incorporates a pressure relief mechanism integrated into the case wall to manage internal overpressure conditions.

Qualification and Automotive Compliance
Both series are qualified according to AEC-Q200 Rev. E, the stress test qualification standard for passive components in automotive applications. Materials are RoHS compliant.

The capacitors are also integrated into TDK’s web-based AlCap Useful Life Calculation Tool, allowing design engineers to estimate operational lifetime under application-specific thermal and electrical load conditions.

Electrical Performance Overview
At 120 Hz and +20 °C, typical ESR values range:

Ripple current ratings at 120 Hz and +105 °C:

Capacitance ranges:

Application Context
The primary application area is DC link stabilization in on-board chargers for electric vehicles. High CV (capacitance × voltage) density and compact dimensions make these components suitable for space-constrained power electronics assemblies where efficiency and thermal reliability are critical design parameters.

With increasing charging power levels and migration toward 800 V vehicle platforms, DC link capacitors must balance ripple current capability, thermal endurance, and volumetric efficiency. The B43655 and B43656 series are engineered to meet these electrical and mechanical constraints within automotive qualification requirements.

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