Analysis And Optimization Of Switching Noise Of Fs IGBT

Insulated Gate Bipolar Transistor(IGBT)has the advantages of low on-voltage drop,high current density,high withstand voltage,fast switching speed and good thermal stability.It has been widely used in power electronic systems.Field Stop IGBT(FS-IGBT)has become the mainstream of current design development due to its low loss,but when it is used as a power switching device,it will generate large switching noise during high-speed switching,which seriously affects system performance.This thesis aims to solve the high switching noise problem of 1200V FS-IGBT.In this thesis,the system-level switching noise test is first carried out on the sample chip,and the switching noise of the original FS-IGBT chip in the system is found to be as high as 42 dB.Secondly,the generation process of FS-IGBT switching noise and the relationship between switching noise and device parameters are elaborated in combination with full-bridge inverter circuit.Again,after extensive testing and research,it is found that the high current spike and current of the FS-IGBT when zero current is on are not controlled by the gate resistor R_G,and the voltage overshoot generated when the large current is turned off which is the device level influence of the FS-IGBT's switching noise.Comibining the test results,theoretical and simulation analysis,all of these shows that increasing the device R_G and improving the negative capacitance can reduce current spikes and voltage overshoot.Finally,based on the mechanism research,three new structures of low switching noise FS-IGBT devices with deep floating P-layer structure,carrier storage layer structure and trench-type emitter structure are proposed.On the basis of ensuring other performance parameters of the FS-IGBT device,the current spike at the time of device turn-on and the voltage overshoot at the time of turn-off are reduced,thereby achieving effective control of switching noise.The test results of the current chip show that the designed switching noise suppression effect of the FS-IGBT device with carrier storage layer is the best,the switching noise in the system is as low as 39dB,the breakdown voltage is 1250V,and the conduction loss is 4.08mJ.The turn-off loss is 2.39mJ,the turn-on voltage drop is 1.518V,and the threshold voltage is 5V.All parameters meet the design specifications.