Multiple Points Measurement-Based Junction Temperature Estimation of IGBT Module

The junction temperature (
$T_{\text {j}}$
) estimation of IGBTs is critical for improving their reliability. To obtain
$T_{\text {j}}$
, the existing reference point temperature (RPT) measurement-based methods require the power loss information, which is difficult to obtain accurately in the real-time applications. Also, these methods utilize the thermal model of IGBT, which changes with aging, resulting in an error in
$T_{\text {j}}$
estimation. In this article, a
$T_{\text {j}}$
estimation technique is proposed, which utilizes the temperature of multiple leads/terminals of an IGBT module. Unlike the existing methods, the proposed technique does not require the information of power losses in the power semiconductor chips (PSCs). Instead, the power losses in the PSCs are additional outcome of the proposed technique. Also, even for a degraded IGBT module, the proposed technique provides an accurate
$T_{\text {j}}$
estimation. The proposed technique also has the capability of estimating
$T_{\text {j}}$
of multiple PSCs in an IGBT module simultaneously. A mathematical analysis of leads selection for the proposed technique is presented in this article. Furthermore, a comparative analysis is presented between the proposed and the conventional method for a degraded IGBT module. The simulation studies of the proposed technique are carried out in ANSYS ICEPAK software. The proposed technique is also validated on an experimental setup developed in the laboratory.