Discontinuous PWM for Online Condition Monitoring of SiC Power Modules

This article presents the utilization of DPWM for the online condition monitoring of SiC power MOSFET switching at high switching frequencies in a three-phase inverter prototype. Due to the settling time imposed by the monitoring system, accurate measurements require low switching frequency and high modulation indexes when monitoring. To overcome these limitations, a DPWM strategy is proposed. This way, the monitored device does not switch during a certain time, and hence, the accuracy of the measurements is not compromised. The effect of the alteration of the modulation is analyzed in terms of power losses and current ripple, comparing the traditional with the proposed modulation. Moreover, online monitoring results performed in a SiC-based inverter prototype in different operating points are presented. An RDS-based thermal model is presented in order to estimate online the junction temperature.

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