This paper investigates the trade-off between the AC current loop inductance and diode temperature balance in the electro-thermal design of a series double-diode (SDD) configuration for power device health monitoring. An SDD configuration with AC current injection allows online estimation of the on-state resistance without the need for current measurement. The design challenges arise from the high-frequency AC current injection, which requires minimizing the AC current loop inductance while maintaining thermal balance among the diodes. Experimental results demonstrate the impact of poor thermal or electrical design on measurement accuracy. The study emphasizes the need for an optimized electro-thermal design to achieve accurate monitoring and estimation of power device parameters.
