R<inf>dson</inf> behavior in various MOSFET families

Abstract

MOSFET are widely used for energy conversion and are must appropriated to photovoltaic systems up to 200VDC. Efficiency of these systems is very critical point. Efficiency of converters is mainly related to losses of its components and the MOSFET appears as one the main original. for the conversion of energy, it is very important to insure the higher efficiency as possible. In a first approach we studied MOSFET used in a switching mode. The losses in the transistor are directly linked to the R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dson</sub> value. As anterior studies have shown a linear dependence between the R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dson</sub> and the voltage supported by the transistor, we can predict a linear increasing of the losses for high output voltage. Our investigations clearly show that the MOSFET losses are greater than they would have to be, especially for high voltages, and our investigations on a large sample of transistors families clearly shows that this law have to be revisited. Indeed simulations show an increase much faster than expected of losses when voltage V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ds</sub> increases. After compiling data on many power MOSFETs family data sheets a new behavioral model, including the fast evolution of R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dson</sub> , for high voltage, has been purposed. This model includes two parameters to be adjusted to a given MOSFET family and which make possible the losses calculation of the concerned family.