Etude des circuits de commande assurant la compatibilité électromagnétique des variateurs de lumière utilisant des interrupteurs à grille isolée : application aux MBS

摘要

Insulated Gate devices are more and more often used in AC operated light dimmer. These devices allow to ensure EMC compliance of the systems through waveform shaping. Hence the bulky and expensive main filter generally used for this purpose could be removed. The aim of this work was to study different driving method used to reduce emitted EMI while keeping reasonable power losses. A new behavioural model of the MBS during turn-on over resistive load is first introduced. This model allows to study the influence of the device's electrical parameters on the switching waveforms. It could be similarly used to predict the emitted EMI by circuit simulation. Then we focus on the driving circuit used to design EMC compliant MBS based light dimmer. We introduce a new optimisation method for classical R-C drive. Performances of such driving circuit are analysed through simulations and measurements. The main drawback of such methods is theirs over sensitivity to device's electrical parameters variations. This led us to define a new kind of insulated gate devices driving circuit allowing to obtain low-emission switching waveform in a simple and reliable manner. The new driving method, based on a gate current drive, is introduced and its performances are investigated. It shows reduced sensitivity to electrical parameters variations compared to more classical driving methods. Moreover this solution could be implemented using a monolithic integrated circuit. This driving circuit has been used to design 500W EMC-free light dimmer based on MBS devices. The maximum overall dissipation of the system is reduced to 3.5W thus achieving an efficiency of 99.3%.