Research And Optimization Of Short-circuit Robustness In FS-IGBT

Insulated Gate Bipolar Transistor(IGBT)has the advantages of small on-state voltage drop,high current density,high breakdown voltage,fast switching speed and good thermal stability.It has been widely used in power electronics,especially in motor drive system.Field Stop IGBT(FS-IGBT)gradually gains its dominant position in the motor drive system with its lower on-voltage drop,but the three-phase bridge inverter circuit in motor drive application places high demands on its short circuit robustness.At present,there are not many research on FS-IGBT short-circuit type?,?and?.Therefore,the research of FS-IGBT short circuit robustness is of great significance.Firstly,different test platforms are introduced in this thesis according to different types of short circuit.Secondly,the mass research data shows that the failure of the FS-IGBT in short-circuit type?and?is caused by high load voltage and largre gate resistance,but this situation will not happen in short-circuit type?.Thirdly,the theoretical and simulation analysis show that the potential difference between the two sides of the gate oxide is too large,which can lead to the gate oxide breakdown,will cause the device failure.During the short circuit,the equivalent doping concentration of the IGBT drift region is changed by a large number of free carriers,causing a spike electric field at the junction of the N-buffer/N-drift and a severe dynamic avalanche,which will result in device failure.On the basis of theoretical research,a scheme with floating P amplification inside the N-buffer and another one are proposed to improve the short circuit robustness.The short circuit robustness is improved in the new schemes without compromising other parameters of the FS-IGBT.Finally,the short-circuit withstand time of the two new FS-IGBT device under the load voltage of 400V exceeds 10?s,the breakdown voltage exceeds 650V,and the conduction voltage drop is less than 1.8V at the current density of 100A/cm~2,all of the parameters meet the design specification.