  AC power cycling tests allow the most realistic reliability assessment by
applying close to real stress to the device or module under test to meet
functional safety standards, which is highly critical for traction
applications. This paper presents a comprehensive guideline and shares critical
know-how to develop a 120 KVA AC power cycling test setup for high-power
Silicon Carbide (SiC) modules. As of today, traction applications can not
generate an early warning signal for drivers to replace critical components on
time. For this purpose, the suitable precursors for all dominant failure
mechanisms are discussed, and the corresponding condition monitoring tools are
proposed to monitor the device aging on power converters. These condition
monitoring tools are integrated into the built-in desaturation protection
circuit of the electric vehicle (EV) gate driver for low-cost, practical
implementation. The on-resistance of all twelve switches is monitored online as
a temperature-sensitive electrical parameter (TSEP) to measure the junction
temperature of the devices. To avoid heavy processing load in the
microcontroller, the out-of-order equivalent time sampling technique is
developed for data sampling, which leads to a measurement error of less than
1.5%. In addition, the design considerations regarding common mode noise and
aging effect on DESAT protection are investigated, and experimental findings
are presented.
