Double MOSFET switching for reducing radiated emission on the wires to power electronic equipment

Abstract

By reducing the RF emission from power electronic equipments, the electromagnetic environment will be improved, which is a big concern when the number of power electronic equipment around us increases, for example in vehicles. In this thesis a circuit made of double MOSFET’s have been developed to switch a load in such a manner the RF emissions are reduced. The designed circuit for switching a load with two MOSFET's is made up of some different major parts. An integrator and an RCD-snubber together with a diode configuration are affecting the rise- and fall-time for the signals to the load so the sum of the two output signals becomes constant. A PD-regulator act as feedback to the MOSFET that acting as a slave in order to ensure that the rise and fall signals are as much as possible in synchronism. The evaluation of the practical circuit shows that it is possible to lower the RF emission compared to switching with one MOSFET. However, for the case of a load having a low resistance and a substantial inductance, the result was less accurate.