Series connection of IGBTs

Series connection of IGBTs
Effective factors for voltage sharing:
device characteristics
driver
static
dynamic
∆ICES, ∆Tj
∆Tj, ∆Vgeth, ∆tdon, ∆tdoff, ∆Qrr
-
∆Lwire , ∆ton, ∆toff
Recommendations:
use devices of one production lot (smallest parameter deviations guaranteed)
symmetrical design of gate driver (minimize deviations of delays)
symmetrical cooling conditions (identical heat-sink temperature and flow rate
below the series connected devices)
use parallel resistors with IR ≈ 5..10 x I CESmax to enforce static voltage sharing
use RC snubber to equalize voltage rate of rise
Dr. Schütze SM PD
Series connection of IGBTs
Snubber circuit:
parallel resistor for
static voltage sharing
CG-clamping
RC snubber for
dynamic voltage sharing
Dr. Schütze SM PD
Alternative: use of 3- or multi-level circuit configurations