Reliability prediction in power electronic converters is of paramount importance for converter manufacturers and operators. Conventional approaches employ generic data provided handbooks random chance failure probability within useful lifetime. However, the wear-out failures affect long-term performance converters. Therefore, this article proposes a comprehensive approach estimating reliability lifetime period. Moreover, based on structural concept. The proposed can quickly predict behavior...

One of the future challenges in modular multilevel converters (MMCs) is how to size key components with compromised costs and design margins, while fulfilling specific reliability targets. It demands better thermal modeling compared state-of-the-arts terms both accuracy simplicity. Different from two-level power converters, MMCs have inherent dc-bias arm currents device conduction time affected by operational parameters. A time-wise for devices is, therefore, an iteration process...

This article proposes a mission profile-based reliability prediction method for modular multilevel converters (MMCs). It includes key modeling steps, such as long-term profile, analytical power loss models, system-level and component-level thermal modeling, lifetime Monte Carlo analysis, redundancy analysis. Thermal couplings uneven stresses among submodules are considered. A case study of 15-kVA down-scale MMC has been used to demonstrate the proposed validate theoretical The outcomes serve...

Scope Premature ovarian insufficiency (POI) is a common female infertility problem, with its pathogenesis remains unknown. The NOD‐like receptor family pyrin domain‐containing 3 (NLRP3)‐mediated pyroptosis has been proposed as possible mechanism in POI. This study investigates the therapeutic effect of α‐ketoglutarate (AKG) on reserve function POI rats and further explores potential molecular mechanisms. Methods results are caused by administration cyclophosphamide (CTX) to determine whether...

Power cycling in semiconductor modules contributes to repetitive thermal-mechanical stresses, which return accumulate as fatigue on the devices, and challenge lifetime. Typically, lifetime models are expressed number-of-cycles, within device can operate without failures under predefined conditions. In these models, thermal stresses (e.g., junction temperature variations) commonly considered. However, of power devices involves cross-disciplinary knowledge. As a result, prediction is affected...

This letter proposes a method for the condition monitoring of submodule (SM) capacitors in modular multilevel converters (MMCs) without additional circuitry or computationally heavy algorithm. The proposed leverages discharging curve SM connection with parallel bleeding resistors. It is independent MMC control and modulation schemes. Moreover, it potentially does not require thermal load-related calibration capacitor degradation monitoring. principle, case study, proof concept are presented.

This letter proposes a new submodule capacitor condition monitoring method for modular multilevel converters (MMCs) based on the dc-side start-up procedure. During this process, MMC can be simplified into an RC charging circuit, and capacitance estimated by investigating its relationship with phase current voltage. Several practical issues related to implementation, advantages, limitations of proposed are presented as well. In order validate method, series experiments different capacitances...

This letter proposes an artificial intelligence-aided thermal model for power electronic devices/systems considering cross-coupling effects. Since multiple heat sources can be applied simultaneously in the system, proposed method is able to characterize parameters more conveniently compared existing methods where only single source allowed at a time. By employing simultaneous cooling curves, linear-to-logarithmic data re-sampling, and differentiated losses, neural network-based trained with...

Background Pinus massoniana is an important timber species with high ecological and economic value in southern China a pioneer for the reforestation of barren mountains. The structure function existing Masson pine ecosystem have been seriously affected by worsening habitats under current climate change. Its suitable habitat likely to change greatly near future. Methods To estimate potential geographic distribution P. its response change, Maxent model was selected simulate potentially...

This study aimed to summarize the major health problems among Chinese workers, strategies and measures for occupational hazards control, network organizations of administration, achievements current challenges in China. The situation was found be still serious Enterprises with were widely distributed, exposed population cases diseases numerous, risks being transferred from city countryside developed areas developing ones. New emerging coexisted traditional hazards. Besides, a lack services...

Reliability modeling of power electronic converters is paramount importance for optimal design, control and operation based systems. Suitable topology selection, converter components sizing, proper strategy adoption in a single unit together with multi-converter systems require to predict the reliability within its useful life wear-out phases. This paper proposes prediction approach hardware random failures period. The methodology exemplified single-phase PV inverter predicted during...

This letter proposes a novel capacitor condition monitoring method for modular multilevel converters (MMCs) based on reference submodules (SMs). It significantly enhances the accuracy by making full use of SM voltage sensor measurement range. Accuracy comparison between existing and proposed is conducted to quantify improvement accuracy. Moreover, its operation principle practical implementation considerations are presented. Finally, three-phase MMC platform built experimentally verify...

By DFT computations, we proposed Cu 5 @MoS 2 —an anchored cluster on defective MoS —as a promising catalyst for CO -to-ethylene conversion. With distinctive square-like sites, demonstrates remarkable activity and selectivity, particularly in alkaline conditions.

Various methods have been presented in the past to emulate electrical behavior of modular multilevel converters (MMCs). To meet demands for reliability aspect study MMCs, this paper proposes a viable setup thermal and investigate its feasibility testing model validation power modules MMC. The proposed mission profile emulator has three distinctive features: 1) capable emulating measuring stresses modules; 2) implementing practical switching as full-scale MMC; 3) having significantly reduced...

Current frequency allocation scheme results in poor spectrum utility. In some bands, the may not be fully utilized either on geographical or at temporal level. addition, hot spot business resources become short supply. Many papers discuss new management policies, and focus is dynamic access (DSA) technology based cognitive radio. However, mobility handoff are challenges for wireless networks. Little research addresses these fields now. this paper, we concepts of mobility/handoff probability...

Thermal transient measurement based on source-drain voltage is a standard method to characterize thermal properties of silicon semiconductors but doubtful be directly applied carbide (SiC) devices. To evaluate its feasibility and limitations, this paper conducts comprehensive investigation into accuracy, resolution, stability towards yielding the structure information SiC MOSFET using as temperature sensitive electrical parameter. The whole characterization process involves two main...

The reliability aspect study of Modular Multilevel Converter (MMC) is great interest in industry applications, such as offshore wind. Lifetime prediction key components an important tool to design MMC with fulfilled specifications. While many efforts have been made the lifetime IGBT modules renewable energy applications by considering long-term varying operation conditions (i.e., mission profile), justifications using associated profiles are still missed. This paper investigates impact...

This paper aims to provide a guideline with respect reproducible thermal transient measurement for SiC MOSFETs. Although the based on source-drain voltage is widely applied method characterizing properties of MOSFETs, approach developed silicon-based devices may not be directly applicable devices. Therefore, this investigates MOSFETs using as temperature-sensitive electrical parameter. A comprehensive investigation its linearity, sensitivity, and stability toward yielding structure-property...

The effects of simulated acid rain (SAR) on the photosynthetic performance subtropical coniferous species have not been thoroughly investigated. In this study, we treated two species, Pinus massoniana (PM) and Cunninghamia lanceolata (CL), with four gradients SAR then analyzed their activities through measurements gas exchange, prompt fluorescence (PF), delayed (DF), modulated reflection at 820 nm (MR820). Gas exchange analysis indicated that decrease in net rate (Pn) PM CL was unrelated to...

In the reliability evaluation of power electronic systems, one challenges is to model thermal profiles across multiple time scales, i.e., from switching cycles at nano-or micro-seconds annual or even longer-time mission profiles. Without consideration dissimilarity behaviors under different a single usually leads either considerable modeling errors heavy computational burden. Based on frequency response impedances, this paper proposes novel and simplified analyze with scales. It enables...

To evaluate the reliability of power electronic systems, it is necessary to estimate junction temperatures devices under periodic loss profiles due fundamental-frequency current. However, a large number long-term evaluation (e.g., 1 year) are challenging compute quickly. On other hand, in order improve computational efficiency, unvalidated simplified thermal analysis methods may impair confidence outcome. Therefore, this paper proposes an analytical model for semiconductors with compromise...

One of the next challenges for modular multilevel converters (MMCs) is how to size critical components their limits with reduced design margins, while at same time fulfilling reliability target. To do it confidently, better thermal modeling quantitative uncertainty analysis necessary support decision-making during product stage. Regarding conversion long-term mission profiles into evaluation, this paper proposes a computationally efficient method insulated-gate bipolar transistor modules in...

A large gate metal height technique is proposed to enhance breakdown voltage in GaN channel and AlGaN high-electron-mobility-transistors (HEMTs). For HEMTs with gate–drain spacing L GD = 2.5 μm, the V BR increases from 518 582 by increasing h 0.2 μm 0.4 μm. 7 953 1310 0.8 1.6 The enhancement results increase of sidewall capacitance depletion region extension. Al Ga 0.6 N HEMT 1535 1763 resulting a high average electric field 2.51 MV/cm. Simulation analysis indicate that an effective method...

Traditional information retrieval systems lack a uniform semantic description for information, so it is hard users to find more relevant and realize the share in resource. There are many challenging tasks retrieval, such as how make managed resource have machine understandable meaning what really need searching by means of domain knowledge. A framework intelligent retrieve based on Web proposed this paper through researching Semantic analyzing feature traditional retrievals Web. The design...