Momentary High-Z Gate Driving (MHZGD) at Miller Plateau for IGBT Load Current Estimation from Gate Driver

To eliminate a load current (I
L
) sensor required to determine optimum gate driving parameters of a digital gate driver for IGBTs and to estimate I
L
from the gate driver, a momentary high-Z gate driving (MHZGD) method is proposed. In MHZGD, the output voltage (V
OUT
) of the gate driver is measured at Miller plateau when the gate driving current (I
G
) is zero for a short time (1 μs in this paper), and I
L
is estimated from the measured V
OUT
. MHZGD is suitable for the digital gate driver, because the I
L
estimation is not affected by I
G
, and has the advantage of not affecting the switching operation of IGBT. In the double pulse test of IGBT at 300 V, by using one-point calibration at I
L
= 20 A at 25 °C, the measured I
L
estimation errors of three IGBTs in the range from 5 A to 80 A are within + 7.7 % / − 7.0 % at 25 °C, 75 °C, and 125 °C, which suggests that MHZGD can estimate I
L
with acceptable error against IGBT and temperature variations.