Simplifying the Calibration of On-State Voltage Drop for Online Junction Temperature Estimation in an Industrial Context

Abstract:
To industrialise Junction Temperature Estimation, self-calibration of the power devices should ideally be performed during converter routine test. This paper describes a key part of this process which removes the dependence on current of the measured on-state voltage. The method takes current and voltage measurements and reduces them to a set of “TSEP voltages” which depend only on temperature. It applies to IGBTs, diodes and MOSFETs, and is applicable to other current-dependent TSEPs. This allows a range of calibration procedures to be used to estimate the junction temperature in an operational converter. Results are analysed for both IGBTs and diodes, demonstrating the use of TSEP Distillation for simplifying the on-state voltage before calibration and for estimating temperature after calibration.