At 19:00 onthe evening of June 12, 2023, the Heng Ai Jing Cheng team successfully held the11th paper reading activity of this academic year. This event was held in theacademic conference center.Fivesecond-year graduate students reported on relevant literature according totheir respective research directions. Mr. Li Ming was the instructor of this paperreading, and some graduate students participated in the Paper reading activityconference.

Fig.1   Photoof the paper reading activity

First, ZhangQian gave a report. The topic of the paper was " Dynamic IGBTThree-dimensional Thermal Network Model Considering Base Solder Degradation andThermal Coupling Between IGBT Chips ". The report first introduced theIGBT temperature identification method and its thermal network model. On thisbasis, the influencing factors affecting the thermal behavior of the IGBTmodule were studied, Based on FEM, the thermal performance of IGBT modulesunder different substrate solder degradation and the thermal coupling effectbetween chips were studied, and the corresponding thermal network modelparameters were extracted. Then, the IGBT dynamic three-dimensional thermalnetwork model considering substrate solder degradation and thermal couplingbetween chips was presented. Finally, the accuracy of the proposed model wasverified by finite element simulation and experiment. In the teacher's commentstage, Mr. Li Ming conducted in-depth research and discussion with Zhang Qianon the "dynamic" meaning of the thermal network model mentioned inthe article, thus leading to one of Mr. Li Ming's thoughts on this article: thehigher the order of the thermal network model, the more complicated the modelestablishment. Can we use neural network algorithm to estimate parameters fromthe perspective of data to reduce the complexity of the model? This alsoprovided a reference for Zhang Qian's future work.

Fig.2   ZhangQian read the paper

Next, HanTianxia launched a report. The topic of the paper was " A real-timedigital twin approach on three-phase power converters applied to conditionmonitoring ". First of all, he gave a brief background introduction todigital twins and state detection, and also analyzed the key points anddifficulties of the current digital twin monitoring methods for powerelectronic converters. The following was a focus on the construction of thedigital twin model in this paper, and realized an interconnection with theactual physical system through particle swarm optimization algorithm andgenetic algorithm, and constantly iteratively estimated the health state offilter inductance and filter capacitance. What was the difference between theconstructed digital twin model and the traditional identification method basedon physical model proposed by Mr. Li Ming? Han Tianxia said that the statemonitoring method of the digital twin concept focused on the digital modelingof all aspects of the physical system, including the modeling of the maincircuit, control and modulation, to achieve a complete virtual image. Inaddition, whether the grid-connected mode and island mode of the inverter hadan impact on the identification of inductors and capacitors needed to befurther studied by Han Tianxia, this work needed to wait for more in-depthresearch.

Fig.3   HanTianxia read the paper

Then, Wang Zeao gave a report, The topic of the paperwas " Dynamic probability modeling of photovoltaic strings and itsapplication in fault diagnosis ". The report focused on the faultdiagnosis technology of photovoltaic modules, and the advantages anddisadvantages of different traditional fault diagnosis methods were compared,and the output indicators of different clusters were probabilistic statistics.Two characteristic parameters were extracted from the probability model asindicators to identify anomalies, which could represent the photovoltaiccluster model with differences between probabilities. The test results ofactual running data showed that the model can effectively identify differentabnormal situations. Mr. Li Ming pointed out that the randomness of outputindicators of different sets of strings had a great impact on fault diagnosis.He suggested Wang Zeao to consider model building with multi-dimensional data,which would be more practical.

Fig.4   WangZeao read the paper

Finally, Wu Jijun gave a report, The topic of thepaper was " Open-Circuit Fault Diagnosis and Tolerant Control for 2/3-LevelDAB Converters ". He introduced the previous open-circuit fault diagnosismethods and fault-tolerant methods for DAB, analyzed the limitations of thecurrent methods, led to a fault diagnosis method based on waveform conversionthought, and proposed the "By-pass complementary switch tube (CBS)"method on the basis of the existing open-circuit fault analysis of 2/3-LevelDAB switch tubes. Under the condition that the original topology of 2/3-LevelDAB was not changed, it still had a certain carrying capacity after anopen-circuit fault occurs. Mr. Li Ming affirmed Wu Jijun's report and asked whythis paper studied 2/3 level instead of 3/3 level, and Wu Jijun said that hewas studying 3/3 level.

Fig.5   Wu Jijun read the paper

The paperreading activity was beneficial for students in different research directionsto conduct academic exchanges, enabled students to understand their unfamiliarresearch directions, and inspired students to think about scientific research.I would like to thank the Hengai Jingcheng Team for organizing the paperreading activity, and I hoped that the students can cherish the opportunity toread the paper. Finally, I would like to thank Mr. Li Ming for his meticulousguidance on this paper reading activity. He gave a lot of thinking about the report,which had benefited the students a lot and made this activity more flexible andinteresting. The paper reading event ended successfully with applause.

Editor: Han Tianxia | Photographer: Han Tianxia