IGBT Total Loss

Formula

Description

IGBT total power loss consists of conduction loss and switching loss. Unlike MOSFETs, which have a resistive on-state (I²R), IGBTs have a nearly constant saturation voltage Vce(sat) of 1-3 V, making conduction loss proportional to V × I rather than I². Switching loss is characterized by energy per switching event (Eon + Eoff from the datasheet), multiplied by the switching frequency. IGBTs are preferred over MOSFETs for voltages above 400-600 V and frequencies below 20-50 kHz, where their lower conduction loss compensates for their higher switching loss.

Variables

• V_ce — Collector-emitter saturation voltage (V)
• I_c — Collector current (A)
• D — Duty cycle (0 to 1)
• E_sw — Total switching energy per cycle, Eon + Eoff (J)
• f — Switching frequency (Hz)

Practical Notes

Vce(sat) increases with temperature (positive temperature coefficient), which aids parallel operation. Switching energy depends on bus voltage, current, gate resistance, and temperature — use datasheet curves at your operating conditions. For sinusoidal modulation (motor drives), average conduction loss = Vce × Ic × (1/(2π) + D/(8)) and requires integration over the fundamental cycle.