Long-term reliability of a hard-switched boost power processing unit utilizing SiC power MOSFETs

Abstract

Silicon carbide (SiC) power devices have demonstrated many performance advantages over their silicon (Si) counterparts. As the inherent material limitations of Si devices are being swiftly realized, widebandgap (WBG) materials such as SiC have become increasingly attractive for high power applications. In particular, SiC power metal oxide semiconductor field effect transistors' (MOSFETs) high breakdown field tolerance, superior thermal conductivity and low-resistivity drift regions make these devices an excellent candidate for power dense, low loss, high frequency switching applications in extreme environment conditions. In this paper, a novel power processing unit (PPU) architecture is proposed utilizing commercially available 4H-SiC power MOSFETs from CREE Inc. A multiphase straight boost converter topology is implemented to supply up to 10 kW full-scale. High Temperature Gate Bias (HTGB) and High Temperature Reverse Bias (HTRB) characterization is performed to evaluate the long-term reliability of both the gate oxide and the body diode of the SiC components. Finally, susceptibility of the CREE SiC MOSFETs to damaging effects from heavy-ion radiation representative of the on-orbit galactic cosmic ray environment are explored. The results provide the baseline performance metrics of operation as well as demonstrate the feasibility of a hard-switched PPU in harsh environments.

Silicon-Carbide Power MOSFET Performance in High Efficiency Boost Power Processing Unit for Extreme Environments

“…Leveraging advanced component models and SPICE simulations, a normalized system efficiency is represented in Figure 9. Results from clamped inductive switching tests conclude negligible variation in switching energy for devices with increasing junction temperature and is assume constant [14]. However, due to the susceptibility to gate oxide leakage and on-state resistance drift at high temperature the conduction loss in the MOSFETs does not remain constant over the observed temperature range.…”

Radiation resistance of wide-bandgap semiconductor power transistors

“…The increase of R DS_ON in the dose range from 20 to 700 kGy is not so critical. Tenfold increase in R DS_ON causes only 5% decrease in efficiency of a power converter such as shown in work where the 1200 V SiC MOSFET was used as an active switch.…”

Trade-offs Between Gate Oxide Protection and Performance in SiC MOSFETs

“…Furthermore, the number of parts tested is also dependent on the acceleration factor and for obtaining the required failure metrics at stress values close to the nominal gate voltage required very large sample numbers [30]. Examples of lifetime calculations for SiC MOSFETs are available in [24,26,31]. In [31], accelerated gate stresses were performed at different temperatures and the data indicated that reducing the gate voltage from 20.588 V to 19.127 V improved the predicted lifetime of the gate oxide from 10 to 20 years for a temperature of operation of 150 °C.…”

“…Examples of lifetime calculations for SiC MOSFETs are available in [24,26,31]. In [31], accelerated gate stresses were performed at different temperatures and the data indicated that reducing the gate voltage from 20.588 V to 19.127 V improved the predicted lifetime of the gate oxide from 10 to 20 years for a temperature of operation of 150 °C. The studies in [24] used a previous generation of the device evaluated in this paper and from the lifetime projections, reducing the gate driver voltage 10% (from 20 V to 18 V) increases the lifetime approximately 3.6 times.…”