Recent Modular Multilevel Converter (MMC) topology allows for drastic improvements in power electronic conversion such as higher energy quality, lower power semiconductors electrical stress, ...decreased Electro-Magnetic Interferences (EMI), and reduced switching losses. MMC is widely used in High Voltage Direct-Current (HVDC) transmissions as it offers, theoretically, no voltage limit. However, its control electronic structure is not modular itself. Especially, the insulation voltage between the submodule gate drivers’ primaries and secondaries depends on the number of submodules. The converter voltage levels cannot be increased without designing all gate driver isolations again. To solve that issue, the novel concept of distributed galvanic insulation is introduced for multilevel converters. The submodule’s gate drivers are daisy-chained, which naturally reduces the insulation voltage to the submodule capacitor voltage, regardless of the number of submodules. The MMC becomes truly modular as the number of submodules can be increased without impacting on the previous control electronic circuit. Such an innovative control structure weakens the link between the main control unit and the gate drivers. This inherent structural problem can be solved through the use of Smart-Gate Drivers (SGD), as they are often equipped with fast and bidirectional communication channels, while highly increasing the converter reliability. The innovation proposed in that work is the involvement of smart gate drivers in the distributed galvanic insulation-based MMC control and monitoring. First, the numerous benefits of smart gate drivers are discussed. Then, an innovative Voltage Balancing Algorithm directly integrated on the chained gate drivers is proposed and detailed. It features a tunable parameter, offering a trade-off between accurate voltage balancing and execution time. The proposed embedded algorithm features a low execution time due to simultaneous voltage comparisons. Such an algorithm is executed by the gate drivers themselves, relieving the main control unit in an original decentralized control scheme. A simulation model of a multi-megawatts three-phase grid-tied MMC inverter is realized, allowing validation of the proposed algorithm. Matlab/Simulink logic blocs allow us to simulate a typical CPLD/FPGA component, often embedded on smart gate drivers. The converter with the proposed embedded algorithm is simulated in steady-state and during load impact. The controlled delay and slew rate inferred by the algorithm do not disturb the converter behavior, allowing its conceptual validation.
•Pediatric noninvasive group A Streptococcus (GAS) infections decreased during the early COVID-19 period.•From March 2022, an increase was observed, with levels above the pre-pandemic level.•This ...increase was observed before the surge of invasive GAS infections.•Surveillance of noninvasive GAS infections may help anticipate invasive infections.
We evaluated the burden of noninvasive group A Streptococcus (GAS) infections in ambulatory pediatrics before and during the COVID-19 pandemic in France.
We analyzed data from a national network of ambulatory pediatricians between 2018 and 2022. Clinicians evaluating children ≤15 years old for tonsillopharyngitis, perianal infections, paronychia/blistering dactylitis, and scarlet fever were invited to perform a rapid antigen detection test (RADT) for GAS. Monthly incidence of noninvasive GAS infections per 10,000 visits was modeled using time series analysis, considering two breakpoints: March 2020 (first national lockdown) and March 2022 (end of mandatory mask-wearing in schools).
Over the study period, 125 pediatricians recorded 271,084 infectious episodes. GAS-related illnesses represented 4.3% of all infections. In March 2020, the incidence of GAS diseases decreased by 84.5% (P <0.001), with no significant trend until March 2022. After March 2022, the incidence significantly increased (+23.8% per month, P <0.001), with similar patterns across all monitored GAS-related diseases.
By using routine clinical data and RADTs, we have monitored changes in the incidence of noninvasive GAS infections in ambulatory pediatrics. COVID-19 mitigation measures have had a major impact on the epidemiology of noninvasive GAS infections, but their relaxation was followed by a surge above baseline levels.
Wide-bandgap technology evolution compels the advancement of efficient pulse-width gate-driver devices. Integrated enhanced gate-driver planar transformers are a source of electromagnetic ...disturbances due to inter-winding capacitances, which serve as a route to common-mode (CM) currents. This paper will simulate, via ANSYS Q3D Extractor, the unforeseen parasitic effects of a pulse planar transformer integrated in a SiC MOSFET gate-driver card. Moreover, the pulse transformer will be ameliorated by adding distinctive shielding layers aiming to suppress CM noise effects and endure high dv/dt occurrences intending to validate experimental tests. The correlation between stray capacitance and dv/dt immunity results after shielding insertion will be reported.
(1) Background: While goat milk formula (GMF) is an alternative to cow milk formula (CMF), infants’ preferences for one over the other have not been formally assessed. Specifically, our aim in this ...study was to determine whether infants experience fewer feeding behavior problems with whole milk-based GMF than with conventional whey-based CMF. (2) Methods: This was a multicenter, double-blind, randomized controlled trial with two-arm parallel assignment conducted in six pediatricians’ offices in or near Paris, France, between June 2018 and 31 December 2021. Overall, 64 healthy infants (≤4 months old), predominantly formula-fed, were randomly assigned to either the whole milk-based GMF (n = 33) or whey-based CMF (n = 31) arm. Parents completed the Baby Eating Behavior Questionnaire (BEBQ) and the modified QUALIN questionnaire to evaluate infant feeding behavior and quality of life (psychomotor and socioemotional development), respectively, at inclusion (1 to 5 days before milk delivery) and the final visit (day 28 ± 3 after milk delivery). Informed consent was obtained for all recruited patients, and an ethical committee approved the study. (3) Results: Changes in BEBQ Enjoyment of Food and Slowness in Eating subscale scores from inclusion to final visit did not differ between arms. However, there were significant improvements in subscale scores for Food Responsiveness (GMF: 0.15 ± 1; CMF: −0.48 ± 0.81; p = 0.010) and General Appetite (GMF: 0.26 ± 1.2; CMF: −0.48 ± 0.88; p = 0.012), and modified QUALIN (GMF: 4.6 ± 9.4; CMF: −0.40 ± 7.6; p = 0.03) scores in favor of the GMF group. (4) Conclusions: In this double-blind, randomized controlled trial, GMF-fed infants exhibited a greater general appetite than CMF-fed infants, possibly due to differences in the composition of these formulas (i.e., protein and lipid profiles). In addition, GMF-fed infants enjoyed a better quality of life. There was no difference in food enjoyment between groups. These findings suggest that whole-milk-based GMF could be an attractive alternative to whey-based CMF. Clinical trial registration: NCT03488758 (clinicaltrials.gov).
In industrial applications, a feedback loop is used in order to transmit control and diagnostic informations from the motor back to the inverter. The implementation of such feedback loop requires the ...use of extra cabling between both sides and that may have length exceeding few hundred meters. In this paper, the motor feeder cable is used for data transmission instead of the separated extra cable by using the power line communication (PLC) technology. However, beside the fact that feeder cables are not designed for data transmission, they are also polluted by the inverter's outcome. Therefore, PLC modems developed for domestic applications may not be suitable. The aim of this study is to underline the possibility of communicating in such an environment. Limitations and difficulties that obstruct transmission are revealed. Also, possible solutions are discussed such as the use of a pulsewidth modulation filter in mean to overcome those limitations.
Naso-pharyngeal RT-PCR is the gold standard for the diagnosis of COVID-19, but there is a need for rapid and reliable tests. Some validation studies have used frozen aliquots mainly from adults. The ...aim of this real-life study was to test the performance of a SARS-CoV-2 rapid antigen test (SC2-RAT) in children. Symptomatic patients aged 0 to 17 years were recruited in the emergency department of the University Hospital of Creteil and in primary care pediatric practices from October 10, 2020 for 7 weeks. Each enrolled child had a SARS-CoV-2 RT-PCR test and a SC2-RAT from two distinct nasopharyngeal swabs. Among the 308 patients (mean SD age 4.9 5.3 years), fever was the main symptom (73.4%), with no difference between COVID-19–negative and –positive groups. The prevalence of COVID-19 was 10.7% (95% CI 7.5–14.7). On the whole cohort, the sensitivity and specificity of the SC2-RAT compared to RT-PCR was 87.9% (95% CI 71.8–96.6) and 98.5% (95% CI 96.3–99.6). Considering samples with cycle threshold >25, the sensibility was lower: 63.6% (95% CI 30.8–89.1) and the specificity 99.6% (95% CI 98.0–100.0). The mean delay to obtain an SC2-RAT result was <15 min but was 3.2 h (SD 5.5) for an RT-PCR result. Contact with a COVID-19–positive person was more frequent for COVID-19–positive than –negative patients (
n
= 21, 61.6%, vs.
n
= 64, 24.6%;
p
< 0.01). In real life, SC2-RAT seems reliable for symptomatic children, allowing to detect contagious children.
Epidemiological surveillance of nasopharyngeal pneumococcal carriage is important for monitoring serotype distribution and antibiotic resistance, particularly before and after the implementation of ...pneumococcal conjugate vaccines (PCVs). With a prospective surveillance study in France, we aimed to analyze the dynamics of pneumococcal carriage, antibiotic susceptibility and serotype distribution in children aged 6 to 24 months who had acute otitis media between 2001 and 2022 with a focus on the late PCV13 period from May 2014 to July 2022. Trends were analyzed with segmented linear regression with autoregressive error. For the 17,136 children enrolled, overall pneumococcal carriage was stable during the study. During the late PCV13 period, the five most frequent serotypes were all non-PCV13 serotypes: 15B/C (14.3%), 23B (11.0%), 11A (9.6%), 15A (7.4%) and 35B (6.5%). During the same period, we observed a rebound of penicillin non-susceptibility (+0.15% per month, 95% confidence interval, +0.08 to 0.22,
< 0.001). Five serotypes accounted for 64.4% of the penicillin non-susceptible strains: 11A (17.5%), 35B (14.9%), 15A (13.9%), 15B/C (9.9%) and 19F (8.2%); non-PCV13/PCV15 accounted for <1%, and non-PCV15/PCV20 accounted for 28%. The next generation PCVs, particularly PCV20, may disrupt nasopharyngeal carriage and contribute to decreasing the rate of antibiotic resistance among pneumococci.
BackgroundSeveral studies indicated that children seem to be less frequently infected with SARS-CoV-2 and are potentially less contagious than adults. To examine the spread of SARS-CoV-2, we combined ...both Reverse transcription-PCR testing and serology in children in the most affected region in France, Paris, during the COVID-19 epidemic.MethodsFrom 14 April 2020 to 12 May 2020, we conducted a cross-sectional, prospective, multicentre study. Healthy controls and pauci-symptomatic children from birth to age 15 years were enrolled by 27 ambulatory paediatricians. A nasopharyngeal swab was taken for detection of SARS-CoV-2 by Reverse transcription-PCR and a microsample of blood for micromethod serology.ResultsAmong the 605 children, 322 (53.2%) were asymptomatic and 283 (46.8%) were symptomatic. Reverse transcription-PCR and serology results were positive for 11 (1.8%) and 65 (10.7%) children, respectively, with no significant difference between asymptomatic and pauci-symptomatic children. Only three children were Reverse transcription-PCR-positive without any antibody response detected. The frequency of Reverse transcription-PCR SARS-CoV-2 positivity was significantly higher for children with positive than negative serology results (12.3% vs 0.6%, p<0.001). Contact with a person with confirmed COVID-19 increased the odds of Reverse transcription-PCR positivity (OR 7.8, 95% CI 1.5 to 40.7) and serology positivity (OR 15.1, 95% CI 6.6 to 34.6).ConclusionIn an area heavily affected by COVID-19, after the peak of the first epidemic wave and during the lockdown, the rate of children with Reverse transcription-PCR SARS-CoV-2 positivity was very low (1.8%), but that of serology positivity was higher (10.7%). Most children with positive Reverse transcription-PCR results also had positive serology results.Trial registration numberNCT04318431.
Silicon Carbide (SiC) power transistors are more and more used in electric energy conversion systems. SiC power semiconductors devices, such as SiC metal-oxide-semiconductor field-effect transistor ( ...mosfet ) can operate at higher frequency and higher temperature compared to Silicon power mosfet or insulated-gate bipolar transistor. However, the maturity of the SiC technology is moderate compared to the well-known Silicon-based power semiconductor devices. Recent research works on reliability of SiC power mosfet identified gate leakage currents as an ageing indicator. The monitoring of ageing indicators during normal operation may definitely help to predict damages and simplify the maintenance on the energy conversion systems. Due to the low amplitude of gate leakage currents, its direct measurement is difficult even under laboratory conditions and requires an offline characterization. This article presents a new method for estimating the gate leakage current using the gate drive circuit. The proposed method takes advantage of the internal structure of the typical gate drivers used to command SiC power mosfet s.
The control of mosfet or IGBT transistors is carried out by a dedicated circuit called « driver », which is located as close as possible to the power module. It transmits switch- on and switch- off ...orders coming from the control unit and ensures the integrity of the component through safety functions. It also provides a galvanic isolation essential to guarantee the effective functioning of the system and the users' safety. Switching times of SiC mosfet are faster than Si IGBT, and SiC mosfet can also work under a greater dc voltage than Si mosfet . This involves the presence of higher dv/dt in the converter. In this paper, a communication function is studied to be integrated into the new generations of drivers for SiC mosfet . The interest of the implementation of a communication system in a driver is presented. Currently available solutions on the market to provide isolation to communication channels are debated. The theoretical development of a solution called « CAN-ISO » is detailed and experimental results under a high peak voltage of 2 kV and a high dv/dt equal to <inline-formula><tex-math notation="LaTeX">{\text{125}}\;{\text{kV}}/{\mu}{\text{s}}</tex-math> </inline-formula> are presented.
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