Ranking Power Losses in Converters

Lesson notes

Key points

• Gate drive loss: Charging the gate takes Qg times Vgs times frequency, usually tiny, so it sits in C.
• Inductor core loss: Hysteresis and eddy currents rise with frequency, but good ferrite keeps them moderate.
• Diode reverse recovery: Stored charge causes a current spike at turn-off, heating both the diode and the switch.
• Conduction loss: I squared times on-resistance heats the switch every on-period, dominant at high current.
• Switching loss: Voltage and current overlap at every transition, and this loss grows directly with switching frequency.

Takeaway: Higher frequency shrinks inductors but multiplies switching loss.