Characterisation of insulated gate bipolar transistors for resonant power conversion

This thesis presents a comprehensive analysis of the IGBTs, antiparallel diodes and IGBT power modules in resonant switching conditions using experimental results, PSpice simulation results, Medici mixed mode simulation results and mathematical models. A simplified sinusoidal analysis of the series and parallel resonant converters is carried out with particular attention given to power switch behaviour. Resonant converter behaviour under various operating conditions and parameters is investigated in order to develop a complete understanding before power switch characterisation. Furthermore stresses on the power switch and the resonant tank under extreme conditions are determined. Three identically rated IGBTs representing the complete range of IGBT variants available today are selected for the ZCS and ZVS characterisation. Experimental results are obtained from two application circuits which produce practical resonant conditions. Test instrumcnlation includes a highly accurate Lecroy power measure system. PSpice results are obtained using an accurate IGBT model based on the Kraus model while 2-D mixed mode simulations are used to study the internal carrier dynamics under resonant switching. A comprehensive analysis and modelling of the IGBT conduction and switching losses in ZCS and ZVS is carried out. Mathematical models are developed giving careful consideration to all the significant features and dependant parameters, namely collector current, switching frequency and case temperature. Model refinement and validation is carried out using the device characterisation results obtained above. The refined model can be made available in a manufacturer's datasheet either as characteristic equations or characteristic curves. A detailed study of the parasitic effects on IGBT power modules in hard switching and resonant switching conditions is presented. For resonant switching characterisation of the IGBT power module a test rig accommodating four different resonant inverter topologies is designed and built. Parasitic inductance effects due to each IGBT terminal is analysed individually in order to identify the effects clearly. Current sharing imbalances in paralleled IGBTs within power modules are comprehensively analysed. The findings and tools resulting from this research will be useful for various sectors in the power electronics industry. The IGBT and power diode characterisations as well as the power loss models will assist the power device designers in the development of optimised devices for future applications. Power device selection for resonant applications will be made accurate and easier by including the characteristic curves or equations within published datasheets. Furthermore optimisation of the parasitics in the power modules will be made possible for specific applications. This work can ultimately lead to the availability of application specific IGBTs and IGBT power modules for resonant switching applications.EThOS - Electronic Theses Online ServiceGBUnited Kingdo