Articles de revues : « DV/dt control »

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R, Mini, Manjiri Joshi, B. Hariram Satheesh et Dinesh M.N. « Active LC Clamp dv/dt Filter for Voltage Reflection due to Long Cable in Induction Motor Drives ». International Journal of Electrical and Computer Engineering (IJECE) 6, n^o 4 (1 août 2016) : 1456. http://dx.doi.org/10.11591/ijece.v6i4.9156.

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<p class="JESAbstract">This paper presents an active LC clamped dv/dt filter to mitigate the over voltages appearing across the motor terminals. The over voltages at motor terminal is due to voltage reflection effect of long motor cable connected between high frequency PWM inverter having high dv/dt switching waveforms and ac motor drives. The voltage reflection due to fast switching transients can be reduced by increasing the rise time and fall time of inverter output voltage pulses. The most commonly available mitigating technique is a passive dv/dt filter between inverter and cable. Since, size, cost and losses of passive LC dv/dt filter is more, an active dv/dt filtering technique is used to reduce over voltage at motor terminals. Active LC clamp filtering technique used here consists of a small LC filter designed for a single motor cable length which can be used for any lengths of cable up to 1000m only by changing the active control of the PWM pulses to achieve the desired voltage slope during voltage transition period. The basic principle of active dv/dt filer used here is to charge and discharge the capacitor in the filter with modified PWM pulses to increase the rise time and fall time of output voltage pulses without any extra devices to handle the transient response of the LC filter. Detailed investigation is carried out by simulation using MATLAB-Simulink software with active control of common LC clamp dv/dt filter suitable for various cable lengths ranging from 100 m to 1000 m. Comparative analysis is done with active dv/dt filter designed with a common LC clamp filter and active LC clamp dv/dt filter designed for various cable lengths and also with diode clamped passive dv/dt filter. The results proves the effectiveness of the active common LC dv/dt filter to mitigate the over voltages at motor terminal for cable lengths up to 1000m.</p>

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R, Mini, Manjiri Joshi, B. Hariram Satheesh et Dinesh M.N. « Active LC Clamp dv/dt Filter for Voltage Reflection due to Long Cable in Induction Motor Drives ». International Journal of Electrical and Computer Engineering (IJECE) 6, n^o 4 (1 août 2016) : 1456. http://dx.doi.org/10.11591/ijece.v6i4.pp1456-1469.

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<p class="JESAbstract">This paper presents an active LC clamped dv/dt filter to mitigate the over voltages appearing across the motor terminals. The over voltages at motor terminal is due to voltage reflection effect of long motor cable connected between high frequency PWM inverter having high dv/dt switching waveforms and ac motor drives. The voltage reflection due to fast switching transients can be reduced by increasing the rise time and fall time of inverter output voltage pulses. The most commonly available mitigating technique is a passive dv/dt filter between inverter and cable. Since, size, cost and losses of passive LC dv/dt filter is more, an active dv/dt filtering technique is used to reduce over voltage at motor terminals. Active LC clamp filtering technique used here consists of a small LC filter designed for a single motor cable length which can be used for any lengths of cable up to 1000m only by changing the active control of the PWM pulses to achieve the desired voltage slope during voltage transition period. The basic principle of active dv/dt filer used here is to charge and discharge the capacitor in the filter with modified PWM pulses to increase the rise time and fall time of output voltage pulses without any extra devices to handle the transient response of the LC filter. Detailed investigation is carried out by simulation using MATLAB-Simulink software with active control of common LC clamp dv/dt filter suitable for various cable lengths ranging from 100 m to 1000 m. Comparative analysis is done with active dv/dt filter designed with a common LC clamp filter and active LC clamp dv/dt filter designed for various cable lengths and also with diode clamped passive dv/dt filter. The results proves the effectiveness of the active common LC dv/dt filter to mitigate the over voltages at motor terminal for cable lengths up to 1000m.</p>

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Shihong Park et T. M. Jahns. « Flexible dv/dt and di/dt control method for insulated gate power switches ». IEEE Transactions on Industry Applications 39, n^o 3 (mai 2003) : 657–64. http://dx.doi.org/10.1109/tia.2003.810654.

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TANRIVERDİ, OSMAN, et DENİZ YILDIRIM. « Independent closed loop control of di/dt and dv/dt for high power IGBTs ». Turkish Journal of Electrical Engineering and Computer Sciences 30, n^o 3 (1 janvier 2022) : 487–501. http://dx.doi.org/10.55730/1300-0632.3793.

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Zhang, Yingying. « Investigation and Improvement of Switching Characteristics of SiC Optically Controlled Transistor ». Journal of Physics : Conference Series 2331, n^o 1 (1 août 2022) : 012006. http://dx.doi.org/10.1088/1742-6596/2331/1/012006.

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Abstract Aiming to the switching characteristics of SiC optically controlled transistor, SiC NPN optically controlled transistor was investigated through Silvaco TCAD. The results show that under 4500V bias voltage, the turn-on and turn-off dV/dt of the SiC transistor are 428.5V/ns and 23.9V/ns, respectively. And the tailing problem in the turn-off process is obvious. In order to improve the switching characteristics of SiC optically controlled transistor, the minority carrier lifetime in base layer is regional controlled. The simulation results indicate that, by using minority carrier lifetime control technology, the turn-off time and turn-off dV/dt are improved by about 28.2% and 39.3%, respectively. Meanwhile, turn-on time and turn-on dV/dt are only degenerated by about 3.6% and 3.4%, respectively. The overall level of switching characteristics of SiC optically controlled transistor are improved.

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Shu, Lu, Junming Zhang, Fangzheng Peng et Zhiqian Chen. « Active Current Source IGBT Gate Drive With Closed-Loop di/dt and dv/dt Control ». IEEE Transactions on Power Electronics 32, n^o 5 (mai 2017) : 3787–96. http://dx.doi.org/10.1109/tpel.2016.2587340.

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Roubertou, S., R. Ehlinger et J. P. Chante. « Study on dv/dt Susceptibility of a MCT Under Low Control Voltage ». EPE Journal 8, n^o 3-4 (septembre 1999) : 11–13. http://dx.doi.org/10.1080/09398368.1998.11463428.

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Idir, Nadir, Robert Bausiere et Jean Jacques Franchaud. « Active gate voltage control of turn-on di/dt and turn-off dv/dt in insulated gate transistors ». IEEE Transactions on Power Electronics 21, n^o 4 (juillet 2006) : 849–55. http://dx.doi.org/10.1109/tpel.2007.876895.

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Bau, Plinio, Marc Cousineau, Bernardo Cougo, Frederic Richardeau et Nicolas Rouger. « CMOS Active Gate Driver for Closed-Loop dv/dt Control of GaN Transistors ». IEEE Transactions on Power Electronics 35, n^o 12 (décembre 2020) : 13322–32. http://dx.doi.org/10.1109/tpel.2020.2995531.

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Makki, Loreine, Marc Anthony Mannah, Christophe Batard, Nicolas Ginot et Julien Weckbrodt. « Investigating the Shielding Effect of Pulse Transformer Operation in Isolated Gate Drivers for SiC MOSFETs ». Energies 14, n^o 13 (27 juin 2021) : 3866. http://dx.doi.org/10.3390/en14133866.

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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.

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Riazmontazer, Hossein, et Sudip K. Mazumder. « Optically Switched-Drive-Based Unified Independent dv/dt and di/dt Control for Turn-Off Transition of Power MOSFETs ». IEEE Transactions on Power Electronics 30, n^o 4 (avril 2015) : 2338–49. http://dx.doi.org/10.1109/tpel.2014.2327014.

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Lyu, Gang, Yuru Wang, Jin Wei, Zheyang Zheng et Kevin J. Chen. « Dv/Dt-Control of 1200-V Normally-off SiC-JFET/GaN-HEMT Cascode Device ». IEEE Transactions on Power Electronics 36, n^o 3 (mars 2021) : 3312–22. http://dx.doi.org/10.1109/tpel.2020.3015211.

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Meng, Wuji, Fanghua Zhang, Zirui Fu et Guangdong Dong. « High dv/dt Noise Modeling and Reduction on Control Circuits of GaN-Based Full Bridge Inverters ». IEEE Transactions on Power Electronics 34, n^o 12 (décembre 2019) : 12246–61. http://dx.doi.org/10.1109/tpel.2019.2903818.

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Broderick, Tom L., Jackie Sennott, Joseph Morrissey et Paul Standley. « Treadmill Running Induces a Detrimental Metabolic Adaptation in the Diabetic Mouse ». Clinical & ; Investigative Medicine 30, n^o 3 (1 juin 2007) : 34. http://dx.doi.org/10.25011/cim.v30i3.1732.

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Background: Regular exercise is generally recommended for the treatment of type 2 diabetes. Exercise reduces body weight, increases insulin sensitivity, and improves glycemic control. The present study was designed to determine the impact of voluntary wheel and forced treadmill running on the metabolic state in the db/db mouse, a model of type 2 diabetes. Our hypothesis is that exercise training improves the metabolic status such that a reduction in body weight, blood glucose and insulin are observed, resulting in improved insulin sensitivity. Methods: Male diabetic db/db mice were assigned to sedentary (DS), voluntary wheel running (DV), and treadmill running (DT) running groups for 12 weeks. Nondiabetic heterozygote littermates served as control (CN). Results: After 12 weeks of training, DV and DT mice ran a total of 4.24 ± 0.18 km and 11.8 km, respectively. Data are expressed as mean ± SEM for 10-12 mice in each group. * P < 0.05 vs CN, † P < 0.05 vs DS *** Table in Full Text PDF. *** Conclusions: Voluntary exercise training is beneficial in reducing body weight and blood glucose in the db/db mouse, but this effect is minor. Forced treadmill running, however, did not improve body weight, blood glucose and the hyperinsulinemic state remained. These results suggest that forced treadmill exercise training may actually worsen the metabolic state in this model of diabetes.

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Fu, Lan Fang, He Xu Sun et Yan Cai Zhu. « Sample Time Staggered One-Cycle Control Based on Three-Phase H-Bridge Cascade VSI ». Advanced Materials Research 516-517 (mai 2012) : 1822–26. http://dx.doi.org/10.4028/www.scientific.net/amr.516-517.1822.

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The One-Cycle Control(OCC) technique not only provides fast dynamic response, but also can admirably suppress the perturbation yielded by dc source and eliminate the undesired harmonic contents.The cascade H-bridge VSI has very low dv/dt and distortion in the voltage output waveform.Sample time staggered one-cycle control（STS-OCC） based on three-phase H-bridge cascade VSI is proposed. It yields all of the advantages of the OCC and cascade VSI.The results of the simulation and analysis show that the STS-OCC technology has high equivalent work frequency, little switching loss and quick dynamic response speed, which means it is fit for the cascaded multilevel inverter.

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Chaikhy, Hamid, Mouna Es-saadi et Mohamed Khafallah. « Assessment of field oriented induction machine control strategy using new generation of inverters in BB36000 locomotive ». International Journal of Power Electronics and Drive Systems (IJPEDS) 13, n^o 3 (1 septembre 2022) : 1295. http://dx.doi.org/10.11591/ijpeds.v13.i3.pp1295-1304.

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Due to their excellent characteristics; Reaching high voltage inverters by using lower voltage switches, reduced output current distortion, dv/dt, and switching losses decrease, efficiency rise, multilevel inverters are an interesting alternative to the two-level inverters especially in traction applications. Many studies compared both topologies, but this work compare performances of Field oriented control strategy using two levels and neutral point piloted three levels inverter supplied by space pulse width modulation. Based on real parameters, this work shows that this efficient multilevel inverter reduces current distortion and torque ripples in a manner to reduces the size and cost of all railway traction systems chosen for this work

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Miserocchi, G., et D. Negrini. « Contribution of Starling and lymphatic flows to pleural liquid exchanges in anesthetized rabbits ». Journal of Applied Physiology 61, n^o 1 (1 juillet 1986) : 325–30. http://dx.doi.org/10.1152/jappl.1986.61.1.325.

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We studied the time course of volume and protein reabsorption of a 2-ml hydrothorax using whole (WP) or diluted (DP) homologous plasma injected into the right pleural cavity in anesthetized spontaneously breathing supine rabbits. Animals were killed at 5 (WP, n = 4; DP, n = 3), 36 (WP, n = 3; DP, n = 4), 55 (WP, n = 4), 90 (WP, n = 8; DP, n = 4), and 150 (WP, n = 4; DP, n = 5) min after the injection. The volume and protein content of the pleural liquid in control conditions (n = 12) amounted to 0.35 +/- 0.015 (SE) ml/kg and 1.8 +/- 0.27 g/100 ml, respectively, which are not significantly different at 90 min (n = 7). Pleural liquid volume decreased at a similar rate during WP or DP reabsorption according to the equation V = 0.84 +/- 0.05 X e-0.02t, with net reabsorptive flow expressed as dV/dt. The globulin quantity (Q) of the pleural liquid for WP and DP, respectively, decreased according to the equations Qwp = 1 + 1.5 X e-0.04t and Qdp = 0.7 + 0.6 X e-0.03t. Assuming a major lymphatic globulin clearance and no filtration into the cavity, we obtained lymph flow using the equation VL = dQ/dt X l/C where dQ/dt is calculated from the equations for Qwp and Qdp and C represents globulin concentration. The Starling flow (Vs) was then calculated by the equation Vs = dV/dt-VL. With increasing time, lymph flow was found to decrease progressively and was not significantly different from net flow with DP, which implied a Starling flow value of zero. During WP reabsorption, lymph flow initially exceeded the net flow, with the difference disappearing at approximately 60 min; accordingly, Starling filtration flow decreased progressively, becoming zero at the same time.

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Marzoughi, Alinaghi, Rolando Burgos et Dushan Boroyevich. « Active Gate-Driver With dv/dt Controller for Dynamic Voltage Balancing in Series-Connected SiC MOSFETs ». IEEE Transactions on Industrial Electronics 66, n^o 4 (avril 2019) : 2488–98. http://dx.doi.org/10.1109/tie.2018.2842753.

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Zhang, Shao Rong, Zhi Li et Ai Jun Zhu. « FPGA-Based High Precision and Low EMI Switching Power Supply Design ». Applied Mechanics and Materials 496-500 (janvier 2014) : 1442–47. http://dx.doi.org/10.4028/www.scientific.net/amm.496-500.1442.

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We analyze the reasons why DC-DC switching power supply generates the electromagnetic interference (EMI), and through the FPGA control the digital-to-analog converter (DAC) to output the pulse width modulation (PWM) signal with high precision and slew rate controlled, the slew rates of the voltage and current of external N-channel MOSFET are controlled. So, dv/dt and di/dt can be decreased in the circuit; and the ripple noise and EMI of switching power supply are reduced vastly in this way. Experimental results show that the ripple noise of switching power supply could be reduced by 80% and EMI reduced 15dBμV. The experiment has proved that we can cut down the ripple noise and EMI of switching power supply by lessening the slew rates of the voltage and current of MOSFET switching tube.

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Beye, Mamadou Lamine, Thilini Wickramasinghe, Jean François Mogniotte, Luong Viêt Phung, Nadir Idir, Hassan Maher et Bruno Allard. « Active Gate Driver and Management of the Switching Speed of GaN Transistors during Turn-On and Turn-Off ». Electronics 10, n^o 2 (7 janvier 2021) : 106. http://dx.doi.org/10.3390/electronics10020106.

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The paper investigates the management of drain voltage and current slew rates (i.e., dv/dt and di/dt) of high-speed GaN-based power switches during the transitions. An active gate voltage control (AGVC) is considered for improving the safe operation of a switching cell. In an application of open-loop AGVC, the switching speeds vary significantly with the operating point of the GaN HEMT on either or both current and temperature. A closed-loop AGVC is proposed to operate the switches at a constant speed over different operating points. In order to evaluate the reduction in the electromagnetic disturbances, the common mode currents in the system were compared using the active and a standard gate voltage control (SGVC). The closed-loop analysis carried out in this paper has shown that discrete component-based design can introduce limitations to fully resolve the problem of high switching speeds. To ensure effective control of the switching operations, a response time fewer than 10 ns is required for this uncomplex closed-loop technique despite an increase in switching losses.

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Beye, Mamadou Lamine, Thilini Wickramasinghe, Jean François Mogniotte, Luong Viêt Phung, Nadir Idir, Hassan Maher et Bruno Allard. « Active Gate Driver and Management of the Switching Speed of GaN Transistors during Turn-On and Turn-Off ». Electronics 10, n^o 2 (7 janvier 2021) : 106. http://dx.doi.org/10.3390/electronics10020106.

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The paper investigates the management of drain voltage and current slew rates (i.e., dv/dt and di/dt) of high-speed GaN-based power switches during the transitions. An active gate voltage control (AGVC) is considered for improving the safe operation of a switching cell. In an application of open-loop AGVC, the switching speeds vary significantly with the operating point of the GaN HEMT on either or both current and temperature. A closed-loop AGVC is proposed to operate the switches at a constant speed over different operating points. In order to evaluate the reduction in the electromagnetic disturbances, the common mode currents in the system were compared using the active and a standard gate voltage control (SGVC). The closed-loop analysis carried out in this paper has shown that discrete component-based design can introduce limitations to fully resolve the problem of high switching speeds. To ensure effective control of the switching operations, a response time fewer than 10 ns is required for this uncomplex closed-loop technique despite an increase in switching losses.

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Kawaguchi, O., Y. Goto, S. Futaki, Y. Ohgoshi, H. Yaku, K. Hata, T. Takasago, A. Saeki et H. Suga. « Ejecting deactivation does not affect O2 consumption-pressure-volume area relation in dog hearts ». American Journal of Physiology-Heart and Circulatory Physiology 265, n^o 3 (1 septembre 1993) : H934—H942. http://dx.doi.org/10.1152/ajpheart.1993.265.3.h934.

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We studied the effects of ejection velocity and resistive properties of the left ventricle (LV) on myocardial oxygen consumption (VO2) in 13 excised cross-circulated dog hearts. Increases in peak ejection velocity (-dV/dt) from 4.0 +/- 1.3 (SD) end-diastolic volume (EDV)/s to 12.7 +/- 5.3 EDV/s with constant EDV and end-systolic volume (velocity run) induced systolic pressure deficit. This decreased pressure-volume area (PVA; a measure of ventricular mechanical energy) and LV end-systolic elastance (Emax) by 47 +/- 14 and 38 +/- 15%, respectively. Unchanged maximum rate of left ventricular pressure rise and time-varying elastance during the isovolumic contraction period at the same EDV indicated that these contractions started with the same contractile state although the quicker ejection caused the greater deactivation. If the PVA deficit due to systolic pressure deficit is attributable to an internal energy-dissipating resistive element, VO2 in the velocity run will not as much decrease in proportion to PVA as in the isovolumic or slowly ejecting control run. However, the decreases in PVA due to increased -dV/dt decreased VO2 to the same extent as in the control run. This result negated the possibility that the pressure and PVA deficits would be caused by a mechanical energy-losing process. The same results were obtained whether or not Emax was decreased by quick ejection. We conclude that the pressure and PVA deficits and the proportionally decreased VO2 during quick ejection are mainly attributable to suppression of a ventricular mechanical energy generation process, but not of mechanical energy-losing process, by ejecting deactivation.

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Lee, Taeyeong, Hokyeong Kim, Nayoung Lee, Taehoon Chin, Hanyoung Bu et Younghoon Cho. « Performance evaluation of GaN FET-based matrix converters with dv/dt filters for variable frequency drive applications ». Journal of Power Electronics 20, n^o 3 (13 mars 2020) : 844–53. http://dx.doi.org/10.1007/s43236-020-00070-2.

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Schroedermeier, Andy, et Daniel C. Ludois. « Integration of Inductors, Capacitors, and Damping Into Bus Bars for Silicon Carbide Inverter dv/dt Filters ». IEEE Transactions on Industry Applications 55, n^o 5 (septembre 2019) : 5045–54. http://dx.doi.org/10.1109/tia.2019.2920596.

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Sun, Yu Xin, Chang Sheng Xu et Huang Qiu Zhu. « A Three-Level DTC System Based on Virtual Space Vector Modulation for Bearingless Permanent Magnet Synchronous Motor ». Applied Mechanics and Materials 703 (décembre 2014) : 356–59. http://dx.doi.org/10.4028/www.scientific.net/amm.703.356.

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In This paper, a direct torque control (DTC) method for bearingless permanent magnet synchronous motor (BPMSM) based on three-level neutral-point clamped (NPC) inverter is described. Through the analysis of virtual space vector modulation, an independent control strategy is adopted into the suspension winding control and a flux linkage error vector SVM-DTC method supplied by three-level NPC inverter is introduced into the torque windings control. By using the proposed control strategy, the neutral-point voltage variation can be greatly limited and the voltage shifting can be eliminated. The results of simulation verify the feasibility of the control algorithm, the dv/dt of output voltage and the torque ripple are restrained effectively, satisfactory robustness and the good performance of the radial levitation can be achieved in a wide speed range by using the proposed method.

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Malhan, Rajesh Kumar, S. J. Rashid, Mitsuhiro Kataoka, Yuuichi Takeuchi, Naohiro Sugiyama, F. Udrea, G. A. J. Amaratunga et T. Reimann. « Switching Performance of Epitaxially Grown Normally-Off 4H-SiC JFET ». Materials Science Forum 600-603 (septembre 2008) : 1067–70. http://dx.doi.org/10.4028/www.scientific.net/msf.600-603.1067.

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Static and dynamic behavior of the epitaxially grown dual gate trench 4H-SiC junction field effect transistor (JFET) is investigated. Typical on-state resistance Ron was 6 – 10mΩcm2 at VGS = 2.5V and the breakdown voltage between the range of 1.5 – 1.8kV was realized at VGS = −5V for normally-off like JFETs. It was found that the turn-on energy delivers the biggest part of the switching losses. The dependence of switching losses from gate resistor is nearly linear, suggesting that changing the gate resistor, a way similar to Si-IGBT technology, can easily control di/dt and dv/dt. Turn-on losses at 200°C are lower compared to those at 25°C, which indicates the influence of the high internal p-type gate layer resistance. Inductive switching numerical analysis suggested the strong influence of channel doping conditions on the turn-on switching performance. The fast switching normally-off JFET devices require heavily doped narrow JFET channel design.

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Jayakumar, Vinoth, et Bharatiraja C. « Model Predictive Control of PMSM Motor Drive for Electric Vehicle Applications with Space Vector Modulation ». ECS Transactions 107, n^o 1 (24 avril 2022) : 14465–72. http://dx.doi.org/10.1149/10701.14465ecst.

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The Multi-Level Inverters (MLI) are most predominantly used in industrial applications as they reduce dv/dt ratio, switching stress of the power semiconductor switches, etc. The industries are slowly shifting from three phase inverters to five phase inverters as they produce lower current per phase, less switching losses, low Common Mode Voltage (CMV), etc. The Space Vector Modulation (SVM) is one of the controlling techniques for driving the inverters which reduces the Total Harmonic Distortion (THD) and improves the dc link balancing. The switching vectors available for five phase Three Level (3L) Neutral Point Clamped (NPC) Inverter is 243 vectors, out of which 51 vectors are selected that produce zero CMV. The controlling of the inverter is done by Model Predictive Control (MPC) Technique in which the error is reduced. The performance of the inverter is evaluated through MATLAB Simulink.

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Wu, Zebing, Huaping Jiang, Zhenhong Zheng, Xiaowei Qi, Hua Mao, Li Liu et Li Ran. « Dynamic dv/dt Control Strategy of SiC MOSFET for Switching Loss Reduction in the Operational Power Range ». IEEE Transactions on Power Electronics 37, n^o 6 (juin 2022) : 6237–41. http://dx.doi.org/10.1109/tpel.2021.3137825.

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Stein, C. M. de O., H. L. Hey, J. R. Pinheiro, H. Pinheiro et H. A. Gründling. « A new ZCZVT commutation cell for PWM DC-AC converters ». Sba : Controle & ; Automação Sociedade Brasileira de Automatica 15, n^o 2 (juin 2004) : 162–71. http://dx.doi.org/10.1590/s0103-17592004000200005.

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This paper proposes a new auxiliary commutation cell for PWM inverters that allows the main switches to be turned on and off at zero voltage and zero current. The main switches zero current turn-on reduces the undesired effects of parasitic inductances related to the circuit layout. The main diodes reverse recovery losses are minimized since di/dt and dv/dt are controlled. The ZCZVT commutation cell is located out of the main power path of the converters and is activated only during switching transitions. Additionally, the auxiliary switches are turned on and off at ZCS and use the same ground signals of the upper main switches. The commutation losses are practically reduced to zero. Soft switching operation is guaranteed for full load range without changes in command strategy. The operation of the ZCZVT PWM full-bridge DC-AC Converter is analyzed and an auxiliary commutation cell design procedure based on the analysis is proposed. Experimental results are presented to demonstrate the feasibility of the proposed commutation cell.

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Chaturvedi, Pradyumn, Shailendra Jain et Pramod Agarwal. « Carrier-Based Common Mode Voltage Control Techniques in Three-Level Diode-Clamped Inverter ». Advances in Power Electronics 2012 (19 septembre 2012) : 1–12. http://dx.doi.org/10.1155/2012/327157.

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Switching converters are used in electric drive applications to produce variable voltage, variable frequency supply which generates harmful large dv/dt and high-frequency common mode voltages (CMV). Multilevel inverters generate lower CMV as compared to conventional two-level inverters. This paper presents simple carrier-based technique to control the common mode voltages in multilevel inverters using different structures of sine-triangle comparison method such as phase disposition (PD), phase opposition disposition (POD) by adding common mode voltage offset signal to actual reference voltage signal. This paper also presented the method to optimize the magnitude of this offset signal to reduce CMV and total harmonic distortion in inverter output voltage. The presented techniques give comparable performance as obtained in complex space vector-based control strategy, in terms of number of commutations, magnitude, and rate of change of CMV and harmonic profile of inverter output voltage. Simulation and experimental results presented confirm the effectiveness of the proposed techniques to control the common mode voltages.

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Ji, Shiqi, Li Zhang, Xingxuan Huang, James Palmer, Fred Wang et Leon M. Tolbert. « A Novel Voltage Balancing Control With dv/dt Reduction for 10-kV SiC MOSFET-Based Medium Voltage Modular Multilevel Converter ». IEEE Transactions on Power Electronics 35, n^o 11 (novembre 2020) : 12533–43. http://dx.doi.org/10.1109/tpel.2020.2987962.

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Williams, Matthew J., Nicholas K. Lee, Joseph A. Mylott, Nicole Mazzola, Adeel Ahmed et Vinay V. Abhyankar. « A Low-Cost, Rapidly Integrated Debubbler (RID) Module for Microfluidic Cell Culture Applications ». Micromachines 10, n^o 6 (30 mai 2019) : 360. http://dx.doi.org/10.3390/mi10060360.

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Microfluidic platforms use controlled fluid flows to provide physiologically relevant biochemical and biophysical cues to cultured cells in a well-defined and reproducible manner. Undisturbed flows are critical in these systems, and air bubbles entering microfluidic channels can lead to device delamination or cell damage. To prevent bubble entry into microfluidic channels, we report a low-cost, Rapidly Integrated Debubbler (RID) module that is simple to fabricate, inexpensive, and easily combined with existing experimental systems. We demonstrate successful removal of air bubbles spanning three orders of magnitude with a maximum removal rate (dV/dt)max = 1.5 mL min−1, at flow rates required to apply physiological wall shear stress (1–200 dyne cm−2) to mammalian cells cultured in microfluidic channels.

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Lee, Gi-Young, Min-Shin Cho et Rae-Young Kim. « Lumped Parameter Modeling Based Power Loop Analysis Technique of Power Circuit Board with Wide Conduction Area for WBG Semiconductors ». Electronics 10, n^o 14 (18 juillet 2021) : 1722. http://dx.doi.org/10.3390/electronics10141722.

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With the development of wide-bandgap (WBG) power semiconductor technology, such as silicon carbide (SiC) and gallium nitride (GaN), the technology of power converters with high efficiency and high-power density is rapidly developing. However, due to the high rate-of-rise of voltage (dv/dt) and of current (di/dt), compared to conventional Si-based power semiconductor devices, the reliability of the device is greatly affected by the parasitic inductance component in the switching loop. In this paper, we propose a power loop analysis method based on lumped parameter modeling of a power circuit board with a wide conduction area for WBG power semiconductors. The proposed analysis technique is modeled based on lumped parameters, so that power loops with various current paths can be analyzed; thus, the analysis is intuitive, easy to apply and realizes dynamic power loop analysis. Through the proposed analysis technique, it is possible to derive the effective parasitic inductance component for the main points in the power circuit board. The effectiveness of the lumped parameter model is verified through PSpice and Ansys Q3D simulation results.

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Ashraf, Naveed, Tahir Izhar et Ghulam Abbas. « A Single-Phase Buck-Boost Matrix Converter with Low Switching Stresses ». Mathematical Problems in Engineering 2019 (20 février 2019) : 1–19. http://dx.doi.org/10.1155/2019/6893546.

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The suggested single-phase ac-to-ac matrix converter operated with inverting and noninverting characteristics may solve the grid voltage swell and sag problem in power distribution system, respectively. It is also employed as a direct frequency changer for domestic induction heating. The output voltage is regulated through duty cycle control of high frequency direct PWM (DPWM) and indirect PWM (IDPWM) switching devices. The DPWM control switches control the switching states of IDPWM switching devices. The inverting and noninverting characteristics are achieved with low voltage stresses and hence low dv/dt across the high and low frequency-controlled switches. This reduces their voltage rating and losses. The high voltage overshoot problem in frequency step-up operation is also analyzed. The sliding mode (SM) controller is employed to solve this problem. Pulse selective approach determines the power quality of load voltage. The validity of the mathematically computed values is carried out by modelling the proposed topology in MATLAB/Simulink environment and through hardware results.

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Clark, E. B., N. Hu, D. R. Turner, J. E. Litter et J. Hansen. « Effect of chronic verapamil treatment on ventricular function and growth in chick embryos ». American Journal of Physiology-Heart and Circulatory Physiology 261, n^o 1 (1 juillet 1991) : H166—H171. http://dx.doi.org/10.1152/ajpheart.1991.261.1.h166.

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Adjustment of myocardial mass to work load is a fundamental characteristic of the heart. We studied the effect of verapamil, a calcium channel blocker, on growth and function of chick embryonic ventricle. We treated stage 18 chick embryos with verapamil delivered to the extraembryonic vascular bed by a miniosmotic pump and compared them with saline-treated control and untreated embryos. At stages 24, 27, and 29, we measured ventricular pressure and dP/dt by a servo-null system, dorsal aortic stroke volume and dV/dt by pulsed-Doppler, and ventricular and embryo wet weights. Mean myocyte profile area was measured by digital planimetry technique, and cell growth response by DNA and protein assay. Verapamil treatment decreased ventricular pressure in experimental (P less than 0.05) compared with saline control and normal embryos; at stage 27, 1.59 +/- 0.21 vs. 2.17 +/- 0.05 and 2.35 +/- 0.08 (SE) mmHg, respectively. Mean dorsal aortic blood flow decreased in experimental (P less than 0.05) vs. control and normal embryos; at stage 27, 0.98 +/- 0.07 vs. 1.54 +/- 0.10 and 1.56 +/- 0.07 mm3/s, respectively. Stroke volume remained the same in all experimental, normal, and control embryos except at stage 29. Ventricular weight decreased in experimental (P less than 0.05) vs. control and normal embryos; at stage 27, 1.09 +/- 0.07 vs. 1.51 +/- 0.08 and 1.54 +/- 0.11 mg, respectively. Embryo weights, myocyte size, and cytoplasmic fractional volume were similar in all groups. Morphology of ventricles was normal. DNA was lower in experimental (P less than 0.05) compared with control and normal embryos.(ABSTRACT TRUNCATED AT 250 WORDS)

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Yue, Yun Tao, et Zhi Yong Xu. « Research on Neutral-Point Balancing for Three-Level Space Voltage Vector Converter ». Advanced Materials Research 748 (août 2013) : 473–76. http://dx.doi.org/10.4028/www.scientific.net/amr.748.473.

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A novel hybrid clamped dual-PWM three-level converter topology is proposed for induction motor drives in this paper. The switching states of hybrid clamp three-level converters increase to sixty-four from twenty-seven switching states of diode clamp three-level converters. In order to realize optimization of its redundant voltage space vectors by detecting voltage of clamp capacitor and difference of capacitor voltage in DC side, Generating an optimized switching pattern, The hybrid clamped three-level converter increases the voltage levels number, reducing the harmonics associated to the commutation frequency and limiting the dv/dt by all the switches . It can quickly balance the DC voltage, Realized system of 4-Quardant Running. the control circuit and main circuit was designed with DSP and CPLD, experimentation results proved it is very effective and practicability.

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Ashraf, Naveed, Tahir Izhar, Ghulam Abbas, Valentina E. Balas, Marius M. Balas, Tsung-Chih Lin, Muhammad Usman Asad, Umar Farooq et Jason Gu. « A Single-Phase Buck and Boost AC-to-AC Converter with Bipolar Voltage Gain : Analysis, Design, and Implementation ». Energies 12, n^o 7 (10 avril 2019) : 1376. http://dx.doi.org/10.3390/en12071376.

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In this research, a new single-phase direct AC-to-AC converter, operating in buck and boost mode, with a bipolar voltage gain, is proposed. The operation is accomplished through high frequency direct and indirect PWM control of a single switch with low voltage stresses. This reduces, not only the control effort, but also the switching losses. The low voltage stresses across the high frequency switches, reduce the dv/dt problem significantly without any loss and bulky voltage snubber arrangement. The operation, in its all-operating modes, has a low inductor ripple current and switching current. The proposed converter may be employed as an AC voltage restorer in a power distribution system to cope with the voltage sag and swell issues. The detailed analysis of the proposed converter is carried out in order to compare its performance with the existing converters. The simulation results obtained using the MATLAB/Simulink environment are verified through experimental results.

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Sivakumar, N., et A. Sumathi. « Fuzzy Logic Controller for Cascaded H-Bridge Multilevel Inverter ». IAES International Journal of Artificial Intelligence (IJ-AI) 4, n^o 3 (1 septembre 2015) : 105. http://dx.doi.org/10.11591/ijai.v4.i3.pp105-112.

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This paper proposes fuzzy logic controller based seven-level hybrid inverter for photovoltaic systems with sinusoidal pulse width-modulation (SPWM) techniques. Multi-Level Inverter technology have been developed in the area of high-power medium-voltage energy scheme, because of their advantages such as devices of high dv/dt rating, higher switching frequency, unlimited power processing, shape of output waveform and desired level of output voltage, current and frequency adjustment.This topology can be used there by enabling the scheme to reduce the Total Harmonic Distortion (THD) for high voltage applications. The Maximum Power Point Tracking algorithm is also used for extracting maximum power from the PV array connected to each DC link voltage level. The Maximum Power Point Tracking algorithm is solved by Perturb and Observer method.It has high performance with low Total Harmonic Distortion and reduced by this control strategy. The proposed system has verified and THD is obtained by using MATLAB/simulink.The result is compared with the hardware prototype working model.

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Gilbert, R. J., S. K. Sarna et D. R. Harder. « Effect of morphine on electrophysiological properties of circular and longitudinal muscles ». American Journal of Physiology-Gastrointestinal and Liver Physiology 252, n^o 3 (1 mars 1987) : G333—G338. http://dx.doi.org/10.1152/ajpgi.1987.252.3.g333.

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We have measured the effects of morphine on the intracellular electrophysiological properties of smooth muscle cells from the circular and longitudinal muscle layers of the canine jejunum. Morphine hyperpolarized the circular muscle membrane by approximately 12 mV and increased the electrical control activity (ECA) amplitude and dV/dt. Morphine had no significant effect on the electrical properties of the longitudinal muscle cells. The morphine-induced hyperpolarization of the circular muscle membrane was blocked by tetrodotoxin (TTX) and naloxone, but not by atropine and hexamethonium, propranolol, or phentolamine. Morphine significantly increased the slope of the resting membrane potential vs. the log of the potassium concentration in bathing medium from 38 to 50 mV/decade. The sodium permeability to potassium permeability ratio, calculated from the Goldman constant field equation, was reduced by morphine from 0.13 to 0.07 at mM of K+. The above results suggest that when measured by intracellular techniques, morphine hyperpolarizes the circular muscle membrane by release of a nonadrenergic, noncholinergic neurotransmitter. The mechanism of this hyperpolarization is consistent with an increase in potassium conductance.

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Musumeci, Salvatore, Fabio Mandrile, Vincenzo Barba et Marco Palma. « Low-Voltage GaN FETs in Motor Control Application ; Issues and Advantages : A Review ». Energies 14, n^o 19 (6 octobre 2021) : 6378. http://dx.doi.org/10.3390/en14196378.

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The efficiency and power density improvement of power switching converters play a crucial role in energy conversion. In the field of motor control, this requires an increase in the converter switching frequency together with a reduction in the switching legs’ dead time. This target turns out to be complex when using pure silicon switch technologies. Gallium Nitride (GaN) devices have appeared in the switching device arena in recent years and feature much more favorable static and dynamic characteristics compared to pure silicon devices. In the field of motion control, there is a growing use of GaN devices, especially in low voltage applications. This paper provides guidelines for designers on the optimal use of GaN FETs in motor control applications, identifying the advantages and discussing the main issues. In this work, primarily an experimental evaluation of GaN FETs in a low voltage electrical drive is carried out. The experimental investigation is obtained through two different experimental boards to highlight the switching legs’ behavior in several operative conditions and different implementations. In this evaluative approach, the main GaN FETs’ technological aspects and issues are recalled and consequently linked to motion control requirements. The device’s fast switching transients combined with reduced direct resistance contribute to decreased power losses. Thus, in GaN FETs, a high switching frequency with a strong decrease in dead time is achievable. The reduced dead time impact on power loss management and improvement of output waveforms quality is analyzed and discussed in this paper. Furthermore, input filter capacitor design matters correlated with increasing switching frequency are pointed out. Finally, the voltage transients slope effect (dv/dt) is considered and correlated with low voltage motor drives requirements.

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Collin, Ryan, Alex Yokochi et Annette von Jouanne. « Novel Characterization of Si- and SiC-Based PWM Inverter Bearing Currents Using Probability Density Functions ». Energies 15, n^o 9 (21 avril 2022) : 3043. http://dx.doi.org/10.3390/en15093043.

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The high frequency PWM voltage pulses from a two-level six-switch inverter produce a common-mode voltage in an electric machine’s windings, a fraction of which appears on the machine shaft due to electrostatic (capacitive) coupling. When the shaft voltage exceeds the dielectric strength of the bearing lubricating grease, electric discharge machining (EDM) electrostatic discharges occur within the bearing, which can lead to premature failure. According to pulsed dielectric theory, the breakdown voltage across a dielectric increases with an increase in voltage slew rate (dv/dt). Therefore, the faster voltage rise times of wide bandgap devices are expected to produce higher magnitude shaft voltages and EDM bearing currents. This paper presents circuit modeling of EDM currents and compares the shaft voltage and bearing current amplitudes of silicon- and silicon carbide-based PWM inverters through experimental measurements and a statistical analysis using probability density functions. The statistical analysis provides insights regarding the correlation between bearing failure and the number of damage causing discharges over time which is a key step in developing bearing lifetime prediction models.

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Esenboğa, Burak, et Tuğçe Demirdelen. « Soft-Switching Smart Transformer Design and Application for Photovoltaic Integrated Smart City Power Distribution ». Sustainability 15, n^o 1 (20 décembre 2022) : 32. http://dx.doi.org/10.3390/su15010032.

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Smart city power distributions have become promising technologies to meet the demand for energy in developed countries. However, increase in smart grids causes several power quality problems on the smart grid, in particular, current and voltage harmonic distortions, sudden voltage sag and swells, fault current, and isolation deterioration. Smart transformers are potential solutions to improve the power quality on the electric grid. They present energy efficiency, ensure grid reliability and power flow control, voltage regulation, bidirectional power flow, fault current limiting, harmonic blocking, and galvanic isolation. Therefore, this paper offers an optimal selection of a three-stage (AC-DC-DC-AC) smart transformer model and power control strategy for solar PV power plant integrated smart grids. The topology of the rectifier, isolated bidirectional converter, and inverter has soft-switching features. This enables low conduction loss, low electromagnetic interference (EMI), high efficiency, achievable zero-voltage switching for converters, and zero-current switching for electrical auxiliary systems. Operation strategies of the proposed ST, PWM control, voltage, and current control between converters, including a medium-voltage (MV) high-frequency transformer to realize a 10 kVA, 450 Vdc to 220 Vdc, or 220 Vac ST, are presented. Significantly, the ST prototype achieves 96.7% conversion efficiency thanks to its control strategy, even under unstable power generation conditions from the solar PV plant. Experimental results obtained on the 344 Vac 10.4 A load current validates the dv/dt rate 6.8 kV/us. The dynamic and experimental results of the proposed bidirectional smart transformer demonstrate the success in preventing power quality problems for photovoltaic integrated smart city power distribution.

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Gadde, Srinivas, Bhanu Ganesh Lukka et Shankar Mahesh Kumar Gali. « A Hybrid Cascaded Multilevel Converter for Battery Vitality Administration Connected In Electric Transport for Battery Energy Management ». E3S Web of Conferences 87 (2019) : 01015. http://dx.doi.org/10.1051/e3sconf/20198701015.

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In the (EV) electrical vehicles energy storage system plays a crucial role. Normally, in electrical vehicles large number of cells connected in series to increase the output voltage for driving motor. Battery cells will have different electrochemical characteristics which cause the difference in terminal voltage (or) (SOC) state of charge imbalances between the each cell. In this paper cascaded multilevel converter which involves in both management of energy and motor drives proposed for electric vehicles and each battery cell can be controlled to the circuit or bypassed by a half-bridge converter. All these half-bridges are cascaded to the output staircase shape dc voltage. And H-bridge converter will be used to change the direction of dc bus voltage to convert it ac voltage. The advantage of the converter will have multilevel voltages with small dv/dt and lesser harmonics. So, it is helpful to make better performance of motor drives. Through separate control according to state of charge of each cell the energy utilization of batteries can be improved drastically. By using the fuzzy logic controller for current measurement the THD can be reduced drastically. In order to verify the performance of proposed converter simulation done in matlab.

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Wei, Shusheng, et Wusong Wen. « High-Frequency Oscillation of the Active-Bridge-Transformer-Based DC/DC Converter ». Energies 15, n^o 9 (2 mai 2022) : 3311. http://dx.doi.org/10.3390/en15093311.

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The dual-active-bridge converter (DAB) has attracted tremendous attention in recent years. However, its EMI issues, especially the high-frequency oscillation (HFO) induced by the dv/dt and parasitic elements of the transformer, are significant challenges. The multi-active-bridge converter (MAB) based on the multi-winding transformer also faces similar problems, which are even more complicated. This article investigates the HFO of active-bridge-transformer-based DC/DC converters including DAB and MAB. Firstly, the general HFO model is studied using the analysis of the AC equivalent circuit considering the asymmetrical parameters. Ignoring the AC resistance in the circuit, the high-order model of the voltage oscillation could be reduced to a second-order system. Based on the simplified model, the oscillation voltage generated by an active bridge is analyzed in the time domain. Then, a universal active voltage-oscillation-suppression method-selected harmonic-elimination phase-shift (SHE PS) modulation method is proposed. The impacts of the system parameters on the method are also revealed. The experimental results show the excellent performance of the proposed active suppression method, with voltage spike amplitude (VSA) reductions of 92.1% and 77.8% for the DAB and MAB prototypes, respectively.

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Wu, Zhixuan, Guorong Zhu, Qian Wang, Shengjie Yang, Jing V. Wang et Jianqiang Kang. « Study on Adaptive Cycle Life Extension Method of Li-Ion Battery Based on Differential Thermal Voltammetry Parameter Decoupling ». Energies 14, n^o 19 (30 septembre 2021) : 6239. http://dx.doi.org/10.3390/en14196239.

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Battery aging leads to reduction in a battery’s cycle life, which restricts the development of energy storage technology. At present, the state of health (SOH) assessment technology, which is used to indicate the battery cycle life, has been widely studied. This paper tries to find a way to adjust the battery management system adaptively in order to prolong the battery cycle life with the change of SOH. In this paper, an improved Galvanostatic Intermittent Titration Technique (GITT) method is proposed to decouple the terminal voltage into overpotential (induced by total internal resistance) and stoichiometric drift (caused by battery aging, indicated by OCV). Based on improved GITT, the open circuit voltage-temperature change (OCV-dT/dV) characteristics of SOH are described more accurately. With such an accurate description of SOH change, the adaptive method to change the discharge and charge cut-off voltage is obtained, whose application can prolong battery cycle life. Experiments verify that, in the middle of a battery’s life-cycle, the adaptive method to change the discharge and charge cut-off voltage can effectively improve the cycle life of the battery. This method can be applied during the period of preventive maintenance in battery storage systems.

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Kumar, Ravi Ranjan, et Jayanti Choudhary. « A novel multilevel inverter with reduced components and minimized voltage unbalance ». International Journal of Power Electronics and Drive Systems (IJPEDS) 13, n^o 4 (1 décembre 2022) : 2365. http://dx.doi.org/10.11591/ijpeds.v13.i4.pp2365-2377.

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Multilevel inverters are an emerging area of research in the field of power electronic circuits and applications. It has many advantages like near-sinusoidal output voltage, lower total harmonic distortion (THD), reduced dv/dt stress, lower peak inverse voltage (PIV) and so on. But there are some associated problems as well such as cost, size complexity, and capacitor unbalance voltage. Here a novel nine level inverter topology has been proposed which addresses the issue of high no of switching and capacitor voltage unbalance. The proposed system has numerous advantages. The cost, size and complexity are reduced and the voltage unbalance problem is solved. The voltage stress across the switches is also reduced. The power loss distribution among the switches is optimum. So, the efficiency of the system is improved. Hence the overall system performance is improved. The system performs well for varying load like resistive, inductive as well as motor load. The stator voltage speed control of a single-phase induction motor has also successfully been achieved. The pulse width modulation PWM technique has been used for producing the switching pulses. The complete simulation analysis of these systems has been realized using MATLAB software. A comparative analysis of this system with the recently proposed systems has been done which shows significant advantages in all the above mention areas.

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Venkatasubramanian, D., et S. P. Natarajan. « Analysis of Harmonics and Ripple Current in Multi-Module Converters with Increasing Number of Modules for High Power Applications ». International Journal of Power Electronics and Drive Systems (IJPEDS) 7, n^o 4 (1 décembre 2016) : 1402. http://dx.doi.org/10.11591/ijpeds.v7.i4.pp1402-1409.

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Controlled rectifiers are considered as the most important hardware part in the field of HVDC systems in transmission lines and can be used for a number of power electronics based system operation, control and utility applications. In this paper, a brief design of a 12-pulse, 24-pulse, 36-pulse and a 48-pulse converter connected to the grid is presented along with the harmonic and ripple current analysis with its comparison statistics and thus providing a justification for the suitable ones. The performance of the 12, 24, 36 and 48-pulse converters are compared for their effectiveness in both quantitatively as well as qualitatively. Further, comparison of the 48-pulse converter on its THD and current ripple which is connected towards the grid with simple pulse width modulation technique is also proposed. It combines all features of the low switching concepts and DC current re-injection techniques. Some basic topological explanation of the controlled rectifiers and simulation results using MATLAB are also presented in this paper in order to justify the harmonic analysis. The simulation results along with the quantitative results shows the effectiveness of the proposed scheme for the cancelation or the elimination of the harmonics result in maximum harmonic mitigation, for high power utility applications, the 48-pulse converter is most fitting to improve the conversion efficiency, low di/dt and dv/dtand active and reactive power controllability.

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Mirza, Arshiah Yusuf, Ali Bazzi, Hiep Hoang Nguyen et Yang Cao. « Motor Stator Insulation Stress Due to Multilevel Inverter Voltage Output Levels and Power Quality ». Energies 15, n^o 11 (2 juin 2022) : 4091. http://dx.doi.org/10.3390/en15114091.

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Multilevel Inverters (MLIs) are widely sought after in medium-voltage applications like electric ships, electric aircraft, and renewable energy integration due to excellent advantages like lower device stress, better power quality, and modularity. However, non-sinusoidal excitations from MLIs pose a serious problem to motor-insulation and lead to their premature breakdown. This paper investigates stress in medium-voltage motor insulation when the stator winding is excited by 3-, 5-, and 7-level multilevel inverter output waveforms. The effect of firing angle on insulation stress is also studied for each of the multilevel inverters. Results show that in addition to the number of output voltage levels, PWM wave shape is a critical factor which affects the insulation stress. Both these factors work together to impact the insulation health. A strong correlation is shown between the increase in the voltage root mean square (RMS) value and increase in dielectric stress when ignoring the dv/dt impact for a fixed DC input voltage and operating frequency of the inverter. Similarly, the dielectric stress in the stator insulation increased with an increase in firing angle for each of the MLIs. This paper shows a potential that both the RMSs can be optimized to reduce the insulation stress and improve the power quality of MLIs in medium voltage drives.

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Hochet, Antoine, et Rémi Tailleux. « Comments on “Diathermal Heat Transport in a Global Ocean Model” ». Journal of Physical Oceanography 49, n^o 8 (août 2019) : 2189–93. http://dx.doi.org/10.1175/jpo-d-19-0055.1.

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AbstractHolmes et al. (2019) have proposed a new theoretical framework for studying ocean heat uptake in potential temperature coordinates. One important step in their derivations requires understanding the temporal changes of the volume of water V with temperature greater than some value, which they write as the sum of two terms. The first one is due to the surface freshwater fluxes and is well defined, but the second one—attributed to the volume fluxes through the lower boundary of the domain—is given no explicit expression. What the authors mean exactly is unclear, however, because in the incompressible Boussinesq approximation, the use of a divergenceless velocity field implies that the sum of the volume fluxes through any kind of control volume must integrate to zero at all times. In this comment, we provide two alternative explicit mathematical expressions linking the volume change of Holmes et al. (2019) to the diabatic sources and sinks of heat that clarify their result. By contrasting Holmes et al.’s (2019) approach with that for a fully compressible ocean, it is concluded that the volume considered by Holmes et al. (2019) is best interpreted as a proxy for the Boussinesq mass M0 = ρ0V, where ρ0 is the reference Boussinesq density. If V were truly meant to represent volume rather than a proxy for the Boussinesq mass, the Boussinesq expression for dV/dt would have to be regarded as inaccurate because of its neglect of the volume changes resulting from mean density changes.

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D’Amato, Davide, Jelena Loncarski, Vito Giuseppe Monopoli, Francesco Cupertino, Luigi Pio Di Noia et Andrea Del Pizzo. « Impact of PWM Voltage Waveforms in High-Speed Drives : A Survey on High-Frequency Motor Models and Partial Discharge Phenomenon ». Energies 15, n^o 4 (15 février 2022) : 1406. http://dx.doi.org/10.3390/en15041406.

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The insulation system’s dielectric of the electric motor is very often subjected to severe electrical stress generated by the high dv/dt seen at the machine’s terminals. The electrical stress and high reflected wave transient overvoltage are even more evident in case of high-speed machines fed by high-frequency (HF) converters featuring very fast wide-bandgap devices. They are promoting the occurrence of partial discharges and consequently accelerate ageing. As this is serious issue and the main cause of the drive failure, it is important to analyse and characterise the surges at the motor terminals. Several HF models of motors have been proposed in the literature for this purpose. This article presents a survey on HF motor models, which is crucial in understanding and studying the most critical parameter identification and overvoltage mitigation techniques. Moreover, it offers a comparison of the models’ main features as well as a comparison with the experimental voltage waveform at motor terminals. A general overview of the partial discharge (PD) phenomenon is also provided, as it is favoured by HF operation and together with HF motor modelling provides key insights to the insulation ageing issue. In particular, an analysis of the effects of PWM waveform affecting insulation is given, as well as useful methods for developing strategies for the inspection and maintenance of winding insulation.

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