In practice, operational chip temperature and thermal
swing of power modules varies with thermal design and
operation mode [7]. Consequently, achieving accurate online
thermal stress measurement and monitoring is
paramount to improve reliability in MW high power
conversion systems. Most on-line chip temperature
measurement methods focus on the IGBT rather than P-i-N
diodes. Conventional IGBT chip temperature measurement
methods can be divided into the optical method, the physical
contact method, and the TSEP method. The TSEP method is
the only way to implement fast measurement on packaged
IGBT modules within a 100µs [8]. From the insightful
overview of the TSEP extraction methods, it will be
concluded that most TSEP methods cannot directly be
employed to evaluate high power P-i-N diodes. The
electrical parameters of diode reverse recovery are strongly
correlated with diode chip temperature. This study aims to
explore the interaction between P-i-N diode chip temperature
and reverse recovery current. Then the maximum recovery
current rate di/dt is chosen as a TSEP to extract the
temperature of the high power P-i-N diode chips