Performance of Parallel Connected SiC MOSFETs under Short Circuits Conditions

Abstract

This paper investigates the impact of parameter variation between parallel connected SiC MOSFETs on short circuit (SC) performance. SC tests are performed on parallel connected devices with different switching rates, junction temperatures and threshold voltages (VTH). The results show that VTH variation is the most critical factor affecting reduced robustness of parallel devices under SC. The SC current conducted per device is shown to increase under parallel connection compared to single device measurements. VTH shift from bias–temperature–instability (BTI) is known to occur in SiC MOSFETs, hence this paper combines BTI and SC tests. The results show that a positive VGS stress on the gate before the SC measurement reduces the peak SC current by a magnitude that is proportional to VGS stress time. Repeating the measurements at elevated temperatures reduces the time dependency of the VTH shift, thereby indicating thermal acceleration of negative charge trapping. VTH recovery is also observed using SC measurements. Similar measurements are performed on Si IGBTs with no observable impact of VGS stress on SC measurements. In conclusion, a test methodology for investigating the impact of BTI on SC characteristics is presented along with key results showing the electrothermal dynamics of parallel devices under SC conditions.

Simulations and Measurements of Failure Modes in SiC Cascode JFETs under Short Circuit Conditions

“…The DUT is a 650 V/31 A SiC Cascode JFET from UnitedSiC with datasheet reference UJ3C065080K3S and the control IGBT is a 1200 V/1000 A IGBT from Infineon with datasheet reference FF1000R17IE4. A DSP is used to control the gate drivers of the IGBT and the SiC Cascode JFET in a non-destructive short circuit [21,22]. The IGBT is turned ON before the DUT and turned-OFF after the DUT thereby ensuring the DUT is disconnected from the power supply, after the defined short circuit test duration, as shown in Fig.…”

Electrothermal Ruggedness of High Voltage SiC Merged-PiN-Schottky Diodes Under Inductive Avalanche & Surge Current Stress

“…For Surge Current measurements [17]- [19], the C4D20120A SiC JBS diode is replaced by a 1200V/26A SiC JBS diode with reference C4D20120H while the DSI30-12A Silicon PiN diode is replaced by a 1200V/30A Silicon PiN diode with reference DSEP30-12B. The Surge current testing board and the typical current and voltage waveforms in a single surge current event [20] is shown in Fig.…”

Electrothermal Modelling and Measurements of Parallel-Connected V_THMismatched SiC MOSFETs under Inductive Load Switching

“…This paper investigates the impact of VTH variation on several parallel (up to 8 -self-imposed limit -the range can be extended to 10s of devices) SiC MOSFETs. The role of parameter variation in the short circuit performance of parallel devices has been investigated in [1,2,3] and unclamped inductive switching [4,5]. Due to the inherent variability of VTH in SiC MOSFETs, it is essential to select devices with minimal VTH variation to avoid unbalanced current sharing and unsynchronised switching between devices [6].…”