Design And Thermal Analysis Of IGCT Driver Circuit Board

Integrated Gate Commutated Thyristor is the integration of GCT and its driver circuit through PCB(Printed Circuit Board),which has advantages of low loss,high blocking voltage and high switching frequency for the special structure.PCB is used as the connecting body of the driving circuit and GCT,its structure directly affects the performance and reliability of IGCT.Therefore,researching PCB layout of IGCT is very important.This thesis study mainly the controlling of the parasitic inductance and the enhancing of heat dissipation capability of the circuit board.The extraction method of parasitic inductance and the heat dissipation characteristics of the circuit board were studied by Q3 D Extractor and thermal analysis Flotherm software respectively.Based on this,the design scheme of universal type IGCT is put forward.The main research contents are as follows:Firstly,the extracting method of the parasitic inductance of PCB was studied.The effect factors that the parasitic inductance are analyzed,and the different layout and wiring of the GCT turn-off circuit are analyzed contrastively.And the scheme is determined,some measures,such as,using multilayer wiring and surface mount package devices,the connection of GCT area and the MOS of turn-off circuit covered by copper etc,are adopted,which makes the parasitic inductance of GCT turn-off circuit drop to 8.8057 nH.Secondly,heat dissipation characteristics of the PCB are studied.the power loss of the device is estimated,the PCB modeling and thermal simulation are done by Flotherm software.The influences of copper layer thickness and thermal through hole on PCB heat dissipation was analyzed.By increasing the thickness of the copper layer and adding heat through the hole,the temperature of PCB was significantly decreased under natural cooling condition.Moreover,the overall thermal simulation of IGCT is completed by adding a simple GCT model in PCB.The influences of the loss of GCT on PCB heat dissipation is analyzed,and the design scheme of adding external forced cooling heat sink is presented.Thirdly,according to layout and routing rules of the turn-off circuit,combined with theIGCT's heat dissipation characteristics,the design scheme of complete PCB is proposed.In accordance with package structure of general type IGCT,the layout and the wiring of driver circuit board has completed.PCB is divided into four layers to route,in the order from top to bottom are power signal layer,signal layer,and two ground plane layers.The research results can provide the basic ideas for the PCB design of IGCT,and has a certain practical value.