| 1. |
- Asoodar, Mohsen, et al.
(författare)
-
Accurate Condition Monitoring of Semiconductor Devices in Cascaded H-Bridge Modular Multilevel Converters
- 2023
-
Ingår i: IEEE transactions on power electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 0885-8993 .- 1941-0107. ; 38:3, s. 3870-3884
-
Tidskriftsartikel (refereegranskat)abstract
- This article presents an online condition monitoring (CM) scheme for semiconductors used in modular multilevel converters (MMCs) that comprise cascaded H-bridge submodules. The CM algorithm is based on detecting changes in the ON-state resistance of the semiconductors over time. The proposed method is shown to successfully perform a curve tracing of semiconductors in MMCs while the semiconductor junction remains at a temperature that is readily measurable and undergoes minute changes during the measurement process. The ON-state resistance value is estimated from the measured ON-state voltage drop of the semiconductors and the measured arm current. Measuring the ON-state resistance at known temperatures allows for separating temperature-dependent variations of the ON-state resistance from age-dependent variations of this parameter. Suitable methods for reducing the effect of noise on the curve-traced data are proposed, and a recursive least square estimator is used to extract the optimum ON-state resistance from the traced v(CE) - i
|
|
| 2. |
- Asoodar, Mohsen, et al.
(författare)
-
Online Health Monitoring of DC-Link Capacitors in Modular Multilevel Converters for FACTS and HVDC Applications
- 2021
-
Ingår i: IEEE transactions on power electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 0885-8993 .- 1941-0107. ; 36:12, s. 13489-13503
-
Tidskriftsartikel (refereegranskat)abstract
- This article presents an online health monitoring scheme for dc capacitors in modular multilevel converters (MMCs). The health monitoring algorithm is based on detecting changes in the dc capacitance value over time. The proposed algorithm only utilizes measurements that are typically available in flexible alternating current transmission systems and high-voltage direct current applications. Hence, in the proposed estimation method, no additional sensors are used. The estimation scheme considers the presence of noise in voltage and current measurements, and utilizes a recursive least square estimator in conjunction with a special low-pass filter to minimize the estimation errors. Simulation results of a hardware replica, as well as experimental results on a low-power MMC prototype show that the proposed scheme can identify the dc-link capacitance value with a maximum error of 1%.
|
|
| 3. |
- Asoodar, Mohsen, et al.
(författare)
-
Temperature Considerations for Online Health Monitoring of DC-Link Capacitors in Modular Multilevel Converters
- 2021
-
Ingår i: 2021 23rd European Conference on Power Electronics and Applications, EPE 2021 ECCE Europe. - : Institute of Electrical and Electronics Engineers Inc..
-
Konferensbidrag (refereegranskat)abstract
- In this paper, the effect of temperature on online heath monitoring of dc capacitors in modular multilevel converters (MMCs) is studied. The submodule capacitance value is considered as the main indicator of health. Both self heating and ambient temperature are considered as sources of temperature variation. The study is conducted on a single phase MMC with full-bridge submodules. However, a similar analysis can be used for half-bridge MMCs and multiphase MMCs as well. The thermal behaviour of the capacitors is explained analytically and simulated using a simplified Cauer model. The effect of temperature on the estimated capacitance values is shown, and a method for reducing this effect is proposed. The results are verified using simulations in MATLAB/Simulink.
|
|
| 4. |
- Danielsson, Mats, Professor, et al.
(författare)
-
Edge-on photon-counting detector
- 2021
-
Patent (populärvet., debatt m.m.)abstract
- An edge-on photon-counting detector includes at least one detector module having a respective edge facing incident X-rays. The at least one detector module includes a semiconductor substrate. The edge-on photon-counting detector also includes a plurality of active integrated pixels arranged in the semiconductor substrate.
|
|
| 5. |
- Gong, H., et al.
(författare)
-
Admittance-Dissipativity Analysis and Shaping of Dual-Sequence Current Control for VSCs
- 2022
-
Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 2168-6777 .- 2168-6785. ; 10:1, s. 324-335
-
Tidskriftsartikel (refereegranskat)abstract
- This paper analyzes the admittance-dissipativity of dual-sequence current control for grid-connected voltage-source converters (VSCs). The output admittance model of dual-sequence current control is first developed in the stationary reference frame by using complex vectors. Impacts of digital filters used within current control and voltage-feedforward (VFF) control loops, and of the delay compensation at the fundamental frequency, are then evaluated. It is found that the cascaded use of sequence-decomposition filter (SDF) and the low-pass filter (LPF) in the VFF control loop adds a non-dissipative region in the output admittance, and the fundamental-frequency delay-compensation further worsens the dissipativity. An analytical design method for the LPF is then developed to mitigate the non-dissipative region, which lowers the instability risks and improves the stability robustness of dual-sequence current control under different grid conditions. Lastly, simulations and experimental results corroborate theoretical analyses.
|
|
| 6. |
- Liegnell, Rasmus, et al.
(författare)
-
Elevated plasma lactate levels via exogenous lactate infusion do not alter resistance exercise-induced signaling or protein synthesis in human skeletal muscle.
- 2020
-
Ingår i: American Journal of Physiology. Endocrinology and Metabolism. - : American Physiological Society. - 0193-1849 .- 1522-1555. ; 319, s. E792-E804
-
Tidskriftsartikel (refereegranskat)abstract
- Lactate has been implicated as a potential signaling molecule. In myotubes, lactate incubation increases mTORC1- and ERK-signaling and induces hypertrophy, indicating that lactate could be a mediator of muscle adaptations to resistance exercise. However, the potential signaling properties of lactate, at rest or with exercise, have not been explored in human tissue. In a cross-over design study, 8 men and 8 women performed one-legged resistance exercise while receiving venous infusion of saline or sodium lactate. Blood was sampled repeatedly, and muscle biopsies were collected at rest and at 0, 90,180 min and 24 h after exercise. The primary outcomes examined were intracellular signaling, fractional protein synthesis rate (FSR), and blood/muscle levels of lactate and pH. Post-exercise blood lactate concentrations were 130% higher in the Lactate trial (3.0 vs 7.0 mmol×l-1, p<0.001) whereas muscle levels were only marginally higher (27 vs 32 mmol×kg-1 d.w., p=0.003) compared to the Saline-trial. Post-exercise blood pH was higher in the Lactate-trial (7.34 vs 7.44, p<0.001), with no differences in intramuscular pH. Exercise increased the phosphorylation of mTORS2448 (~40%), S6K1T389 (~3-fold), and p44T202/T204 (~80%) during recovery, without any differences between trials. FSR over the 24-h recovery period did not differ between the Saline (0.067 %/h) and Lactate (0.062 %/h) trials. This study does not support the hypothesis that blood lactate levels can modulate anabolic signaling in contracted human muscle. Further in vivo research investigating the impact of exercised versus rested muscle and the role of intramuscular lactate is needed to elucidate its potential signaling properties.
|
|
| 7. |
- Zhang, Hongyang, et al.
(författare)
-
Loop-at-a-Time Stability Analysis for Grid-Connected Voltage-Source Converters
- 2021
-
Ingår i: IEEE Journal of Emerging and Selected Topics in Power Electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 2168-6777 .- 2168-6785. ; 9:5, s. 5807-5821
-
Tidskriftsartikel (refereegranskat)abstract
- The instability phenomena caused by converter–grid interactions can be prevented by designing controllers with adequate stability margins. Yet, the multiple-input–multiple-output (MIMO) dynamics of grid-connected voltage-source converters (VSCs) complicate the stability analysis for the controller design. To tackle this challenge, this article presents a loop-at-a-time stability analysis for grid-connected VSCs, which not only shows close correlations with the generalized Nyquist criterion for MIMO systems but also enables to quantify the stability margins of individual closed loops. Moreover, the interactions between the closed loops can be analyzed. Test cases with numerical sensitivity analysis, simulations, and field measurements of a converter validate the theory.
|
|
| 8. |
- Zhou, K., et al.
(författare)
-
An overlooked subset of Cx3cr1(wt/wt) microglia in the Cx3cr1(CreER-Eyfp/wt) mouse has a repopulation advantage over Cx3cr1(CreER-Eyfp/wt) microglia following microglial depletion
- 2022
-
Ingår i: Journal of Neuroinflammation. - : Springer Science and Business Media LLC. - 1742-2094. ; 19:1
-
Tidskriftsartikel (refereegranskat)abstract
- Background Fluorescent reporter labeling and promoter-driven Cre-recombinant technologies have facilitated cellular investigations of physiological and pathological processes, including the widespread use of the Cx3cr1(CreER-Eyfp/wt) mouse strain for studies of microglia. Methods Immunohistochemistry, Flow Cytometry, RNA sequencing and whole-genome sequencing were used to identify the subpopulation of microglia in Cx3cr1(CreER-Eyfp/wt) mouse brains. Genetically mediated microglia depletion using Cx3cr1(CreER-Eyfp/wt)Rosa26(DTA/wt) mice and CSF1 receptor inhibitor PLX3397 were used to deplete microglia. Primary microglia proliferation and migration assay were used for in vitro studies. Results We unexpectedly identified a subpopulation of microglia devoid of genetic modification, exhibiting higher Cx3cr1 and CX3CR1 expression than Cx3cr1(CreER-Eyfp/wt)Cre(+)Eyfp(+) microglia in Cx3cr1(CreER-Eyfp/wt) mouse brains, thus termed Cx3cr1(high)Cre(-)Eyfp(-) microglia. This subpopulation constituted less than 1% of all microglia under homeostatic conditions, but after Cre-driven DTA-mediated microglial depletion, Cx3cr1(high)Cre(-)Eyfp(-) microglia escaped depletion and proliferated extensively, eventually occupying one-third of the total microglial pool. We further demonstrated that the Cx3cr1(high)Cre(-)Eyfp(-) microglia had lost their genetic heterozygosity and become homozygous for wild-type Cx3cr1. Therefore, Cx3cr1(high)Cre(-)Eyfp(-) microglia are Cx3cr1(wt/wt)Cre(-)Eyfp(-). Finally, we demonstrated that CX3CL1-CX3CR1 signaling regulates microglial repopulation both in vivo and in vitro. Conclusions Our results raise a cautionary note regarding the use of Cx3cr1(CreER-Eyfp/wt) mouse strains, particularly when interpreting the results of fate mapping, and microglial depletion and repopulation studies.
|
|
