Online Gate-Oxide Degradation Monitoring of SiC MOSFETs Based on Parasitic Capacitance Aging Characteristics

Gate-oxide degradation is a critical reliability issue that limits the widespread application of SiC MOSFETs. As an effective way to improve the reliability of SiC MOSFETs, the online monitoring of gate-oxide degradation can obtain real-time health information of the gate-oxide layer, thus providing data support for the lifetime prediction and periodic maintenance. This paper proposes an online monitoring method of the gate-oxide degradation based on aging characteristics of the input capacitance (Ciss), which extracts the aging characteristic parameter without affecting the normal operation of the converter. The relationship between Ciss, the extracted aging characteristic parameters and the gate-oxide degradation is systematically characterized. The extraction method and its associated circuit operating principle are explained in detail. Experimental results verify the effectiveness and accuracy of the proposed method on the aging parameter extraction and gate-oxide degradation evaluation.