SiC/GaN power semiconductor devices: a theoretical comparison and experimental evaluation under different switching conditions

The conduction and switching losses of SiC and GaN power transistors are compared in this paper. Voltage rating of commercial GaN power transistors is less than 650V while that of SiC power transistors is less than 1200V. The paper begins with a theoretical analysis that examines how the characteristics of a 1200V SiC-MOSFET change if device design is re-optimised for 600V blocking voltage. Afterwards, a range of commercial devices (1200V SiC-JFET, 1200V SiC-MOSFET, 650V SiC-MOSFET and 650V GaN-HEMT) with the same current rating are characterised experimentally and their conduction losses, inter-electrode capacitances and switching energy Esw are compared, where it is shown that GaN-HEMT has smaller ON-state resistance, inter-electrode capacitance values and Esw than SiC devices. Finally, in order to reduce device Esw, a zero voltage switching circuit is used to evaluate all the devices, where device only produces turn-OFF switching losses and it is shown that GaN-HEMT has less switching losses than SiC device in this soft switching mode. It is also shown in the paper that 1200V SiC-MOSFET has smaller conduction and switching losses than 650V SiC-MOSFET

National records of 3000 European bee and hoverfly species: A contribution to pollinator conservation

Pollinators play a crucial role in ecosystems globally, ensuring the seed production of most flowering plants. They are threatened by global changes and knowledge of their distribution at the national and continental levels is needed to implement efficient conservation actions, but this knowledge is still fragmented and/or difficult to access. As a step forward, we provide an updated list of around 3000 European bee and hoverfly species, reflecting their current distributional status at the national level (in the form of present, absent, regionally extinct, possibly extinct or non-native). This work was attainable by incorporating both published and unpublished data, as well as knowledge from a large set of taxonomists and ecologists in both groups. After providing the first National species lists for bees and hoverflies for many countries, we examine the current distributional patterns of these species and designate the countries with highest levels of species richness. We also show that many species are recorded in a single European country, highlighting the importance of articulating European and national conservation strategies. Finally, we discuss how the data provided here can be combined with future trait and Red List data to implement research that will further advance pollinator conservation