Electrical And Thermal Analysis And Applications Of Power Semiconductor Modules

Power semiconductor devices are the core components of power electronics converters.In this dissertation,the influences of package design and circuit parameters on the stray inductance,thermal management,and switching characteristics are analyzed,and improvements are made to module package design and circuit applications.First,the demands for power semiconductors in the emerging applications of power electronics converters are summarized.According to the scope of this dissertation,the key issues of power semiconductor modules are introduced,including the low-inductance design of power modules,power module thermal management design,press-pack packaging of power semiconductors,and the switching oscillation problem of hybrid power modules.IGBT modules adopting the traditional packaging structure are still the mainstream products.This dissertation studies the influence of module layout on the stray inductances and the thermal coupling between the chips.Currently,finite element analysis(FEA)is used in extracting module stray inductances,which makes the design process complicated and time-consuming.In this dissertation,simplified evaluation methods are established for the module stray inductances and the thermal dissipation of the chips.The methods are used for the layout designs of half-bridge and T-type three-level IGBT modules.The finite element simulation results and test results on the manufactured samples verify the effectiveness of the evaluation methods.The module samples are used in a multi-source emergency power supply system.It is verified that the modules can operate steadily in the continuous operation tests.Press-pack power devices have attracted much attention in high power applications.A press-pack packaging method suitable for SiC MOSFET is proposed in this disseration.There are two challenges in realizing press-pack packaging on SiC MOSFETs:SiC MOSFET chips are smaller than Si IGBTs with smaller contact area,thus the pressure contact methods for IGBTs may not be plausible on SiC MOSFETs;SiC MOSFETs are sensitive to package parasitics,thus the press-pack structure for SiC MOSFETs should meet the requirement of low stray inductance.In this dissertation solutions are proposed to deal with the aforementioned challenges.Press pins are used to realize pressure contact on SiC MOSFET.Micro-channel heatsinks are designed to meet the requirements of press-pack SiC MOSFET.Based on the proposed press-pack packaging structure,the influence of layout design on the stray inductances and current sharing between the paralleled chips are studied.Samples are manufactured according to the designs and experiments are conducted to verify the performances.To experimentally measure the dynamic current sharing between the paralleled chips in the press-pack SiC MOSFET,a current measurement method is studied based on PCB Rogowski coil and integration circuits.The current measurement results verify a good dynamic current balancing between the paralleled chips in the press-pack SiC MOSFET.Hybrid power modules are constituted by Si IGBTs and SiC Schottky barrier diodes(SiC SBDs)as free-wheeling diodes.By substituting Si diodes with SiC SBDs,IGBT turn-on loss and diode reverse recovery loss can be largely reduced.However,when the IGBT is turning on high-frequency oscillations are caused by the parasitic capacitances of the SiC SBDs and the loop stray inductances.In this dissertation,theoretical models are established to study the influence of gate drive and circuit parasitics on the turn-on oscillation.A damping circuit method is proposed to suppress the oscillation.Theoretical models are used to determine the optimized parameter selection of the damping circuit,and experimental tests are conducted to verify the effectiveness of the oscillation damping method.An active gate driving method is studied as well to suppress the turn-on current overshoot of the hybrid module.The experimental results verify that combining active gate driving and damping circuit methods,the turn-on current overshoot and oscillation of the hybrid module can be suppressed simultaneously without causing large increases in the switching losses.The hybrid modules are used in the grid-side converter of a wind power generation system based on doubly-fed induction generator(DFIG).The converter efficiencies under different operating conditions are analyzed and experimentally tested.A summary of this dissertation at last.The main contributions of this dissertation are summarized,and the future works are presented.