A Robust Online Junction Temperature Calibration Method for Power Semiconductors in Traction Inverter Application

Thermo-sensitive electrical parameters (TSEPs) are widely used for estimating the junction temperature of power semiconductors, with the prerequisite that the relationship model between junction temperature and TSEPs is precalibrated. This article proposes an innovative online calibration scheme for power semiconductors in traction inverters, utilizing the inverter dc-link discharge operation mode after system shutdown. It is promising for transportation applications like electric vehicles (EVs) as the required operation mode is intrinsic and frequent. By exploiting the low dynamics in the discharge, the challenges in junction temperature acquisition are addressed and the measurement requirements for TSEPs and associated operation conditions are significantly reduced. The disturbances from parasitic parameters are attenuated as well, enabling calibration accuracy comparable to offline calibration. Compared to existing online calibration schemes, the proposed method outperforms in practicality, complexity, and accuracy, allowing robust calibration in traction applications. The on-state saturation voltage of insulated-gate bipolar transistor (IGBT) devices is used as a typical TSEP for the case study, and proof-of-concept experiments are performed on an automotive traction inverter prototype.