Parameter Correction Method of Vce(on)-based Junction Temperature Estimation Model Based on Bonding Wire Fatigue

The junction temperature (
T
_j
) obtained by the
V
_ce(on)
-based junction temperature estimation model under high current, the accuracy of which depends on the output characteristics curve of the IGBT modules. However, there is a significant increase in the conduction voltage drop
V
_ce(on)
throughout the fatigue degradation process. As a result, substantial errors occur in the
T
_j
obtained through the traditional
V
_ce(on)
-based junction temperature estimation model. Under high current, lifting-off of bonding wires emerges as the primary fatigue mode. In this article, therefore, the crack propagation behavior at the bonding nodes is thoroughly analyzed based on the bonding wire lift-off fatigue mechanism, and an equivalent resistance degradation model is established. Ultimately, a
V
_ce(on)
-based
T
_j
estimation model that considers the degradation is selected before correcting the output characteristic curve of the fatigue-degraded modules. This model effectively considers the offset in the curve caused by the degradation, thus realizing online
T
_j
monitoring after long-term fatigue. An experimental system has been set up, demonstrating that the error between the
T
_j
obtained from the corrected model and the actual
T
_j
does not exceed 2%. The method proposed in this paper can diminish the error by more than 30% compared to the uncorrected model.