Turn-On Delay Based Online Junction Temperature Monitoring for Silicon Carbide Power Modules With a 70 ps Resolution Time-Digital Converter Circuit

Temperature-sensitive electrical parameters (TSEPs) based junction temperature monitoring schemes have received significant attention due to their non-invasive, integrability, and capability for online detection. However, due to the low temperature-sensitivity of electrical parameters for silicon carbide (SiC) MOSFETs, existing monitoring schemes rely on complex signal conditioning circuits to convert/amplify the low-temperature-sensitivity signals to large-value signals that are detectable, which may however increase the complexity of the monitoring system or introduce amplified noises. In contrast, this article proposes a time-digital converter (TDC) circuit that can be deployed using on-chip hardware resources of FPGA to replace the complex signal conditioning circuits in existing schemes. This circuit has a picosecond (ps) - level resolution for pulse width monitoring, which can directly capture the low-temperature-sensitivity turn-on delay time (Ton-delay) of SiC MOSFETs to estimate the junction temperature. Finally, the proposed TDC circuit and a TSEPs extraction circuit are integrated into an active gate driver of a SiC power module, achieving a pulse width monitoring resolution of 70ps and a temperature monitoring accuracy of 0.598°C based on theTon-delay.