Partial Discharge Measurement and Analysis in High Voltage IGBT Modules Under DC Voltage

Insulation performance of high voltage IGBT modules is one of the key attributes in power system applications.However,the existing standards of IGBT devices and research on the evaluation of insulation performance of high voltage IGBT modules are insufficient;for example,partial discharge resistance under DC voltage blocking condition is not considered.In this paper,a new test was proposed to allow the measurement of partial discharges in all the components of IGBT modules under DC voltage.The topology of the measuring circuit is arranged in the polarity discrimination way to exclude the interference,and the voltage and discharge current waveforms during the partial discharge process are measured by the wideband time domain measurement technique.According to the proposed test,the discharge phenomenon of the IGBT modules below the rating voltage were detected.A comprehensive waveform analysis on the voltage and discharge current was performed,and the influence of the applied voltage on the waveform parameters was obtained.The waveform parameters are influenced by the applied voltage and insulation structure,which enables the discrimination of the causes of the observed partial discharge in the IGBT module under DC voltage by the waveform analysis technique.Based on the waveform analysis technique,the types and causes of the observed partial discharges were discussed and inferred,and the correctness of the inference was further verified by observation.The proposed test and waveform analysis technique provide the possibility to evaluate and distinguish partial discharges in the high voltage IGBT module under DC voltage,which may be helpful to insulation performance evaluation and insulation defect diagnosis in high voltage IGBT module.

Fabrication of 4H-SiC n-channel IGBTs with ultra high blocking voltage

Owing to the conductivity modulation of silicon carbide（Si C） bipolar devices, n-channel insulated gate bipolar transistors（n-IGBTs） have a significant advantage over metal oxide semiconductor field effect transistors（MOSFETs） in ultra high voltage（UHV） applications. In this paper, backside grinding and laser annealing process were carried out to fabricate 4 H-Si C n-IGBTs. The thickness of a drift layer was 120 μm, which was designed for a blocking voltage of 13 k V. The n-IGBTs carried a collector current density of 24 A/cm^2 at a power dissipation of300 W/cm^2 when the gate voltage was 20 V, with a differential specific on-resistance of 140 mΩ·cm^2.

Design and optimization of linearly graded-doping junction termination extension for 3.3-kV-class IGBTs

A linearly graded-doping junction termination extension （LG-JTE） for 3.3-kV-class insulated gate bipo- lar transistors （IGBTs） was proposed and experimentally investigated. Unlike conventional multi-implantation uti- lizing more than one photolithography step, a single mask with injection window widths varied linearly away fi＇om the main junction to the edge was implemented in this proposed structure. Based on the simulation results, IGBTs with LG4TE structures were successfully fabricated on the domestic process platform. The fabricated devices exhibited a 3.7 kV forward-blocking voltage, which is close to the theoretical value of an ideal parallel plane case. This is the first success in fabrication 3.3-kV-class 1GBT in a domestic application.

Backside optimization for improving avalanche breakdown behavior of 4.5 kV IGBT

The static avalanche breakdown behavior of 4.5 kV high-voltage IGBT is studied by theory analysis and experiment. The avalanche breakdown behaviors of the 4.5 kV IGBTs with different backside structures are investigated and compared by using the curve tracer. The results show that the snap back behavior of the breakdown waveform is related to the bipolar PNP gain, which leads to the deterioration of the breakdown voltage. There are two ways to optimize the backside structure, one is increasing the implant dose of the N^＋ buffer layer, the other is decreasing the implant dose of the P^＋ collector layer. It is found that the optimized structure is effective in suppressing the snap back behavior and improving the breakdown characteristic of high voltage IGBT.

A simulation study on a novel trench SJ IGBT

An overall analysis of the trench superjunction insulated gate bipolar transistor（SJ IGBT） is presented and a detailed comparison between a trench SJ IGBT and a trench field stop IGBT is made by simulating with Sentaurus TC AD.More specifically,simulation results show that the trench SJ IGBT exhibits a breakdown voltage that is raised by 100 V while the on-state voltage is reduced by 0.2 V.Atthe same time,the turn-off loss is decreased by 50%.The effect of charge imbalance on the static and dynamic characteristics of the trench SJ IGBT is studied, and the trade-off between parameters and their sensitivity versus charge imbalance is discussed.