SuperJunction cascode, a configuration to break the silicon switching frequency limit

This paper evaluates the SuperJunction MOSFET in cascode configuration with a low-voltage silicon MOSFET. The structure combines the good switching performance provided by the cascode configuration with advantages of the silicon technology as the robustness, the maturity and the low-cost. The objective of this paper is to elucidate and to demonstrate the reduction of switching losses of SuperJunction MOSFETs in cascode configuration with respect to their standalone counterparts (directly driven). A detailed simulation analysis of power loss contributions is carried out under hard-switching operation. Eventually, experimental evidence is provided by using a boost converter (100 V-to-400 V) in continuous conduction mode for a wide range of switching frequency (100 kHz-to-400 kHz) and output power (180W-to-500W).This work has been supported by the Spanish Government under Project MINECO-13-DPI2013-47176-C2-2-R, MINECO-15-DPI2014-56358-JIN, the scholarship FPU14/03268 and the Principality of Asturias under the grants “Severo Ochoa” BP14-140 and by the Project FC-15- GRUPIN14-143 and by European Regional Development Fund (ERDF) grants

Analytical switching loss model for superjunction MOSFET with capacitive nonlinearities and displacement currents for DC-DC power converters

A new analytical model is presented in this study to predict power losses and waveforms of high-voltage silicon superjunction MOSFET during hard-switching operation. This model depends on datasheet parameters of the semiconductors, as well as the parasitics obtained from the printed circuit board characterization. It is important to note that it also includes original features accounting for strong capacitive nonlinearities and displacement currents. Moreover, these features demand unusual extraction of electrical characteristics from regular datasheets. A detailed analysis on how to obtain this electrical characteristic is included in this study. Finally, the high accuracy of the model is validated with experimental measurements in a double-pulse buck converter setup by using commercial SJ MOSFET, as well as advanced device prototypes under development.This work was supported by the Asturian Gobernment through the grant Beca Predoctoral “Severo Ochoa” BP14–140. This work was also supported by the project E2 SG, cofunded by grants from Belgium, Italy, Austria, Germany, Spain, The Netherlands, Portugal, Slovakia, The U.K., and the ECSEL

High-accuracy modelling of ZVS energy loss in advanced power transistors

IEEE Applied Power Electronics Conference and Exposition (APEC) (33th, 2018, San Antonio, Texas

Maize meal fortification and its impact on maize porridge quality

Food fortification involves adding essential vitamins and minerals to foods to prevent micronutrient malnutrition and birth defects and thus improve overall health. Although maize meal is an important staple food in many African countries, only 30% of the industrially milled maize meal on the continent is fortified so the potential for better health is still enormous. A major drawback for maize meal fortification however is that it may provoke sensory (colour, taste) changes in the cooked maize porridge leading to rejection by the population. To get insight in the mechanisms driving this food quality issue, the impact of fortification premixes and some of its components (Fe and Zn fortificants) on porridge quality was studied for maize meal stored up to 10 weeks. Furthermore, the interaction with type of maize meal (super or special), type of water (demi or tap water) and type of cooking pot (stainless steel and aluminum) was investigated. Porridges were produced with a standardized cooking trial. Porridge colour was measured with a colorimeter (L*a*b*) and a rheometer was used to perform pasting experiments on the maize meal. It was found that Fe and Zn fortificants, did not impact porridge colour when demi water was used for porridge production. When applying tap water for porridge production, colour changes were observed for all Fe fortificants (ferrous sulphate, ferrous fumarate, NaFeEDTA)