Temperature Dependence Of Conversion Efficiency Research Articles

Temperature Dependence of Dynamic Performance Characterization of 1.2-kV SiC Power mosfets Compared With Si IGBTs for Wide Temperature Applications

Due to the superior material properties, SiC mosfet is a promising candidate switching device for high power density and high efficiency power conversion system. The robustness of switching device under extreme temperature condition becomes a crucial factor to ensure power conversion system safely and continuously operating. In this paper, the temperature dependence of dynamic performance of 1.2-kV 4H-SiC power mosfet s is systematically characterized over such wide temperature range of 90–493 K and compared with 1.2-kV Si IGBT by a layout optimized double pulse tester (DPT). The degradation of dynamic on -resistance related interface traps is analyzed specially and the energy loss caused by degradation is quantified at cryogenic temperatures. Besides, to validate the performance of SiC mosfet under safely and continuously operating conditions for cryogenic temperature application, a hard switched non-isolated dc–dc buck converter is designed and tested to estimate temperature dependence of conversion efficiency under temperature range of 90–290 K. Moreover, the further characterizations are conducted with gate resistance range of 2–20 Ω, load current range of 3–30 A, and converter output current of 5–22.5 A under different switching frequency (up to 150 kHz) to validate high power and high frequency application potential of SiC mosfet .

Up-conversion fluorescence of Er 3+ — and Yb 3+-doped TeO 2-based oxide glass and single crystals

Luminescence, decay times and up-conversion luminescence of Er 3+-and Yb 3+-doped TeO 2 oxide glasses and nonlinear single crystals are measured at temperatures down to 12 K. Green up-conversion luminescence of TeO 2:Er 3+ glasses and crystals from the 4S 3 2 → 4I 15 2 transition show quadratic and nearly biquadratic dependence on incident power of 800 nm laser diodes, respectively. Up-conversion mechanisms are discussed by considering the temperature-dependence of conversion efficiency, the presence of two sites and the nonlinear optical properties of TeO 2 crystal.