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关键词： Locally advanced cervical cancer   CT-based 3D-IGBT   Outcome   Bavazcizumab  

摘要： PurposeTo retrospectively review locally advanced cervical cancer (CC) cases treated with three-dimensional image-guided brachytherapy (3D-IGBT) and two-dimensional (2D)-*** and MethodsPatients with Stage IB-IVa CC who underwent intracavitary irradiation between 2007 and 2021 were divided into the 3D-IGBT and 2D-IGBT groups. Local control (LC), distant metastasis-free survival (DMFS), progression-free survival (PFS), overall survival (OS), and gastrointestinal toxicity (G3 or more) were investigated at 2/3 years ***-one patients in the 2D-IGBT group from 2007 to 2016 and 61 patients in the 3D-IGBT group from 2016-2021 were included in the study. The median follow-up period was 72.7 (4.6-183.9) months in the 2D-IGBT group and 30.0 (4.2-70.5) months in the 3D-IGBT group. The median age was 65.0 (40-93) years in the 2D-IGBT group and 60.0 (28-87) years in the 3D-IGBT group, but there was no difference in FIGO stage, histology, or tumor size between the groups. In treatment, the median A point dose was 56.1 (40.0-74.0) Gy in the 2D-IGBT group and 64.0 (52.0-76.8) Gy in the 3D-IGBT group (P < 0.0001), and the proportion of patients who underwent chemotherapy more than five times was 54.3% in the 2D-IGBT group and 80.8% in the 3D-IGBT group (P = 0.0004). The 2/3-year LC, DMFS, PFS, and OS rates were 87.3%/85.5%, 77.4%/65.0%, 69.9%/59.9%, and 87.9%/77.9% in the 2D-IGBT group, and 94.2%/94.2%, 81.8%/81.8%, 80.5%/80.5%, and 91.6%/83.0% in the 3D-IGBT group, respectively. A significant difference was observed in PFS (P = 0.02). There was no difference in gastrointestinal toxicity, but there were four intestinal perforations in the patients from the 3D-IGBT group, three of whom had a history of bevacizumab *** 2/3-year LC of the 3D-IGBT group was excellent and PFS also tended to improve. Care should be taken with concomitant use of bevacizumab after radiotherapy.

关键词： Insulated gate bipolar transistors   Current supplies   Magnetic circuits   Topology   Switches   Logic gates   Threshold voltage   Active region   high-precision   insulated-gate bipolar transistor (IGBT)   pulsed current supply  

摘要： A high-power and high-precision pulsed current supply of magnets was developed by using insulated-gate bipolar transistor (IGBT) modules in the active region. First, two basic circuit topologies including the series structure and parallel structure were compared in detail. With a wider current range, higher power efficiency, and reliability, the series structure was suitable for the application requirements. Thereafter, a new cascade feedback scheme in the IGBT driver was proposed to weaken the nonlinearity and time-varying of the system, and improve its dynamic responses. Accordingly, a fit average model was established based on the measured Bode diagrams of the quasi-linearization system. The control strategies of feedforward and feedback were both adopted to realize the high-precision and high-bandwidth current supply. Finally, the proposed current supply was experimentally verified and can meet the demands of the application with a pulsed output current of 200 A/10 ms and static precision of about 0.02 A.

关键词： Silicon carbide  

摘要： Power semiconductors process roughly 70 % of global energy, with a higher percentage expected as worldwide transport electrification, renewables and wide-band-gap (WBG) semiconductors are implemented, significantly affecting global energy savings. This manuscript evaluates the cumulative energy demand (CED) encompassing the manufacture and use-phase in a railway traction application of silicon (Si) and silicon carbide (SiC) power semiconductor modules. Realistic manufacturing data from a power semiconductor fab has been considered for 3.3 kV/450 A state-of-the-art Si and SiC LinPak modules. SiC devices presented around 2.6 – 3.8× higher CED per area than Si devices in the manufacturing phase. However, due to the considerably smaller SiC chip area per ampere required, a 1.1 – 1.6× lower grey energy than Si technology is estimated. For the first time, such analysis is based on specialized power semiconductor fab data for both technologies and provides a baseline for the life cycle energy assessment of power electronics systems. Besides, the use-phase energy losses were evaluated for a realistic railway application, considering an operational lifetime of 30 years. The module manufacturing energy is negligible compared to the use-phase stage. Furthermore, the SiC technology presented an estimated energy-saving potential of 24 MWh/lifetime per module compared to the Si device. © 2023 The Authors

关键词： Thermal network   Thermal interface material   IGBT module   Junction temperature calculation   FEM simulation  

摘要： Thermal interface materials (TIMs), as important materials for heat dissipation of insulated gate bipolar transistor (IGBT) modules, degrade under long-term thermal cycling, resulting in elevated junction temperatures and threatening the safe operation of IGBT modules. In consideration of the thermal coupling effect in IGBT modules, this paper proposes a three-dimensional thermal network model characterizing the TIM degradation. An IGBT module with the TIM is adopted to establish the finite element method (FEM) model, in which the TIM layer is divided into regular areas. The thermal network is established by simulating the heat transfer paths. The thermal impedance in each path is extracted according to the heat flow through its area considering the TIM degradation. Thereby, the impact of thermal coupling and TIM degradation on junction temperature of IGBT modules could be characterized. Furthermore, the proposed thermal network is verified by simulation from calculation accuracy of junction temperature and TIM temperature. & COPY;2023 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://***/licenses/by-nc-nd/4.0/).

关键词： Insulated gate bipolar transistor (IGBT) module   Stray inductance of main circuit   Numerical simulation   Bonding wires fault   Multi-physical fields coupling   Mine-used inverter  

摘要： The insulated gate bipolar transistor (IGBT) module is subjected to unbalanced electric-thermal stress for a long time due to its own turn-on and turn-off, the fluctuation of processing power and the change of external operating environment, resulting in fatigue failure. And there is a strong coupling effect between its electrical, temperature and mechanical properties. At the same time, the fatigue failure of IGBT module is also the result of multi-physical field coupling. This paper reveals the influence mechanism of main circuit stray inductance on the electric-thermal-stress coupling characteristics of high power IGBT module bonding wires fault in the context of mine-used inverter application. First, the inverter main circuit topology model considering stray inductance is constructed, and the loss value of the power chip is obtained based on extracting the busbar stray inductance and establishing the IGBT module behavior model, and the validity of the results is verified. Secondly, the package structure model of IGBT module is established and the failure analysis boundary conditions are determined, and then the joint circuit-finite element method is used to reveal the operation behavior characteristics of IGBT module under the combined action of multi-physical fields. Finally, the influence of main circuit stray inductance on the multi-physical field coupling characteristics of IGBT module and its change law are compared and analyzed under the bonding wires fault condition to study the causes of fatigue failure of IGBT module.

关键词： Insulated gate bipolar transistors (IGBT)  

摘要： This paper aims to clarify the effect of asymmetric gate inductance Lg and emitter inductance Le inside power modules with two parallel-connected IGBTs on switching characteristics when a three-step digital gate driver is employed. Five types of IGBT modules with different Lg and Le were fabricated to implement double pulse tests by conventional gate driving and digital gate driving with three-step vectors. Under the conventional gate driving, the asymmetric Le introduced an imbalanced current during on-stage, and the asymmetric Lg introduced gate voltage spike Vg_spike and an imbalanced current during the turn-off interval. Large Lg introduced large Vg_spike. From the miller plateau in the turn-off, the current started to concentrate on the IGBT whose Lg is small. In the turn-on interval, the asymmetric Le made current share in two IGBTs become imbalanced, and the occurred large Vg_spike is positively corresponding to the difference of emitter current Ie flowing through two IGBTs. Under digital gate driving, it was found that the tradeoff between switching loss and voltage/current overshoots can be improved. And, the difference of Eoff between two IGBT chips, which results from asymmetric Le mainly, could be decreased more than that in conventional gate driving. In the turn-on interval, the large Vg_spike can be suppressed by a small vector number at the second step, and the difference of turn-on loss Eon could be also decreased. According to the above switching characteristics, the design considerations of power modules with parallel-connected IGBTs were proposed as the digital gate driver is applied. © 2023

关键词： Insulated gate bipolar transistors   Thermal management   Thermal stresses   Temperature measurement   Stress   Junctions   Inductance   Converters   heat stress   insulated gate bipolar transistors (IGBTs)   power semiconductor devices   reliability   thermal management  

摘要： The reliability of power electronic devices and converters is closely related to thermal stress. However, the research on insulated gate bipolar transistor (IGBT) heat balance in the converter is still insufficient. To address this problem, a novel thermal management method for enhancing the consistency of IGBT heat stress in a converter is proposed in this article. A converter-level method based on the bus voltage ringing is utilized for the IGBT junction temperature monitoring. The IGBT power loss can be controlled by modulating the switching frequency, thus IGBT temperature can be adjusted to improve the IGBT thermal consistency of the converter. The validity of the proposed method is verified by experiments with unbalanced load and unbalanced thermal impedance for a three-phase inverter. Besides, the transient process and steady-state performance with asynchronous switching frequency are demonstrated. The method proposed can enhance the thermal consistency effectively and be promising for improving the reliability of the converter with little effect on the performance.

关键词： Harmonics   insulated gate bipolar transistor (IGBT)   induction melting furnace (IMF)   inverter   power quality  

摘要： A dynamic load profile is experienced by the power topology to which the induction melting furnace (IMF) is coupled when an iron scrap is being melted in the furnace. This load profile necessitates continuous correction in silicon-controlled rectifier (SCR)-based front-end converter as well as adjustment in the switching frequency of an inverter in a conventional 12-pulse SCR current source inverter (CSI-SCR) design. This correction on both sides of the converter results in harmonics and interharmonics, which gets injected into the supply line current, degrading the distribution grid's power quality. The line current total harmonic distortion (THD) is observed to be around 16%-19.5% which is beyond the permissible limit (< 12%) as per IEEE 519-2014 standard. This article investigates the dynamic load profile of the IMF system based on simulation and extensive practical field data from existing running IMF. In this article, LLC resonant insulated gate bipolar transistor (IGBT) inverter is proposed for an iron scrap melting application. In the proposed topology, in which the practical load profile of the furnace is taken into account, the front-end converter is an uncontrolled diode rectifier, and the power to the furnace load is controlled by a combination of phase shift modulation (PSM) and frequency control of the IGBT inverter. A prototype model of 100 kW is designed, fabricated, and tested in the field to validate the concept. The proposed topology reduced the line current THD from 19.5% to 11.6%, meeting the required standard. In addition, the system efficiency has improved by 2.05%.

关键词： Wire  

摘要： This paper presents a new detection method of bond wire lift-off in Insulated Gate Bipolar Transistor (IGBT) power module. The bond wire lift-off is a major failure mode in power cycle degradation of the IGBT module, and many monitoring methods have been proposed and demonstrated for safety operation of power electronics systems in the previous works. In this study, we focus on the gate voltage waveform as an indicator to detect wire-lift for a simple and straightforward detection method. Due to the increase in parasitic inductance caused by bond wire lift-off, the turn-off switching waveform becomes modulated. The digital gate control (DGC) was employed to control the switching behavior to obtain precision for low-noise and high-performance. Furthermore, the DGC 2-step vector control (2-sVC) can enhance the sensitivity of bond wire lift-off failure detection by gate voltage waveform change. As feature quantities, the gate voltage spike peak, its amplitude and the timing shift were measured at various operating conditions. The DGC obtained larger feature quantities compared with conventional gate control. In particular, high-current conditions were found to be more favorable for achieving high sensitivity due to the high die/dt. From these results, the DGC is effective to achieve both the high sensitivity to detect bond wire lift-off by gate voltage waveform and maintaining the best switching performance. © 2023 The Authors

关键词： Pulse power source   silicon carbide (SiC)-insulated-gate bipolar transistor (IGBT)   surge current test   thermal simulation  

摘要： To develop a high-power and small-size pulse power source, the mechanism of maximum-current limitation for a 10-kV silicon carbide (SiC)-insulated-gate bipolar transistor (IGBT) device during a millisecond-short pulse was investigated. One method of measuring the maximum current is the surge current test. Although some of a Si-IGBT module's surge current capability was reported, there have been no reports for a SiC-IGBT module. We fabricated a single-chip 10-kV SiC-IGBT module consisting of our 10-kV SiC-IGBT chip and conducted a surge current test using the module. After the test, the module failed by a short between its collector and emitter. From the results of the failed chip observation and thermal simulation, we concluded that the cause of failure was the melting of the aluminum electrode or bonded wires on the SiC-IGBT device, which was caused by the increasing temperature on the top side of the device. The estimated current limit calculated by the equation of semiconductor theory was almost consistent with the surge current test result. The determined parameter for the current limit was the bulk mobility of the SiC device, which decreases with increasing temperature. To suppress the increasing temperature on the surface of the SiC-IGBT device, a structure of the module with a Cu plate added on the top side of the device was simulated. The simulated result indicated that the structure can decrease the temperature on the surface of the device and increase the current limit.