Summary

Jason Sachs examines DC-link decoupling for H-bridges, explaining why electrolytic capacitors alone are insufficient to control switching transients and ensure reliable operation. The article presents capacitor selection (ESR/ESL), parallel decoupling strategies, PCB layout guidance, snubber options, and practical measurement techniques to harden H-bridge designs.

Key Takeaways

• Calculate required DC-link capacitance and consider ripple current, transient energy, and derating when specifying capacitors.
• Use parallel decoupling (electrolytic + low-ESR/low-ESL ceramics or film) and select parts by ESR/ESL, not just capacitance.
• Optimize PCB layout to minimize loop inductance and current return paths to reduce voltage overshoot and EMI.
• Design and apply snubbers, RC/RCD networks, or damping to control ringing and protect switching devices.
• Verify designs with proper scope probes and current measurements and iterate component placement and values based on measured transients.

Who Should Read This

Embedded hardware engineers and firmware developers working on motor drives or power converters who want practical guidance to design reliable DC-link decoupling and avoid failures from electrolytic-only solutions.

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