CARLOS ANTONIO FRANCA SARTORI

CARLOS ANTONIO FRANCA SARTORI

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Compatibilidade e resiliência eletromagnética em sistemas elétricos e eletrônicos
2022 - ROQUE, ACASSIO M.; SARTORI, CARLOS A.
Nonlinear metamaterial lenses for inductive power transmission systems using Duffing-resonator based unit cells
2021 - ALMEIDA, JORGE V. de; GU, XIAOQIANG; MOSSO, MARBEY M.; SARTORI, CARLOS A.F.; WU, KE
Metamaterials (MTMs) based on a periodic array of resonant coils have been shown to behave as μ-negative (MNG), enabling the focusing of magnetic flux. The phenomenon has been deployed by designers to boost the efficiency of many inductively coupled systems, such as magnetic resonance imaging, underwater and underground communications, and charging base stations (CBS) for consumer electronics and implanted devices. However, due to their dependency on high-Q unit cells, linear MNG-like MTMs have limited bandwidth, restricting their use in many applications, notably in near-field simultaneous wireless information and power transmission (NF-SWIPT) systems. To improve the tight constraints of the amplitude-bandwidth trade-off of artificial magnetic lenses, this paper presents a theoretical analysis of nonlinear MTMs based on a lattice of Duffing resonators (DRs). Additionally, it introduces a criterium for the quantification and evaluation of the amplitude-bandwidth enhancement. The analytical results are based on a circuit model and further verified by numerical simulations using commercial software. The preliminary findings in this paper open up possibilities for nonlinear MTM lenses and can be applied to enhance the linear amplitude-bandwidth limit.
Analysis of the resonance phenomenon in unmatched power cables with the resonance surface response
2021 - BADE, TAMIRIS G.; ROUDET, JAMES; GUICHON, JEAN-MICHEL; KUO-PENG, PATRICK; SARTORI, CARLOS A.F.
Power converters are an essential part of modern power systems, giving flexibility to the power transportation and allowing the insertion of a wide range of different energy sources. One drawback of the converters is that the supraharmonic conducted emissions introduced by them can compromise the stability of these systems through electromagnetic interference (EMI). Electromagnetic compatibility (EMC) filters are used to prevent such problems. Nevertheless, these filters are designed to respect standards based on measurements in conditions considerably different from real applications. Particularly, if a converter is connected to electrically long cables its conducted emissions may be amplified by the resonance phenomenon. The method described in this paper allows the definition of a range for the filters input impedances where the conducted emissions in a long cable will not be amplified beyond established levels. In some cases the method allows the visualization of three-dimensional surfaces indicating the magnitude, frequency and position of the resonance phenomenon. In the general case these surfaces are defined on higher dimensions and can be analyzed with deterministic optimization algorithms. The originality of this paper resides in the generalized analysis of the resonance phenomenon, that it is based on frequency-dependent cable parameters and applies to unbalanced systems.
A parametric study of inductive SWIPT systems assisted by metamaterial using virtual magnetic TL-based channel modeling
2021 - ALMEIDA, JORGE V. de; SILVA, EDUARDO C. da; MOSSO, MARBEY M.; SARTORI, CARLOS A.F.
This paper presents a general methodology based on the description of the inductive channel as virtual magnetic transmission-lines (VMGTLs). In comparison with other existing methods, VMGTL approach presents a better physical insight of the channel behavior since the model correctly preserves the energy flow between the transmitting and receiving coils. Besides that, it facilitates the integration into the analysis of highly nonlinear and dispersive structures such as metamaterial (MTM) lenses. Particularly, the virtual-TL analogy clarifies that the enhancement of the transmission gain between any two coils assisted by MTM is not due to an enhanced coupling between the drivers, as usually claimed, but to the emergence of propagating near-field modes supported by the MTM. This approach, by means of a parametric study, also indicates, for the first time, that MTMs could be employed not only for the increasing of power but also of data transfer due to the emergence of a sub-resonant region of minimum distortion. Nonetheless, since both effects are mutually exclusive, no passive MTM structure could simultaneously improve power and data transmission.
Virtual magnetic TL-based channel modeling of SWIPT systems assisted by MTMs
2020 - ALMEIDA, JORGE V. de; SILVA, EDUARDO C. da; MOSSO, MARBEY M.; SARTORI, CARLOS A.F.
This paper describes a general methodology for the description of inductive power and data transfer based on virtual magnetic transmission-lines (VMGTLs). This approach presents a better physical insight on the channel behavior since the model correctly preserves the energy flow between the transmitting and receiving coils. Particularly, the virtual-TL analogy clarifies the mechanism of transmission gain improvement between any two coils assisted by MTM lenses. Based on the results of this work, these lenses do not enhance the magnetic coupling between the drivers, as usually claimed, but create conditions to propagating near-field modes to increase their power transfer. This approach also reveals that MTMs could be employed not only for the increasing of power transfer but also for enlarging the inductive channel bandwidth.
Análise comparativa de métodos ativos de redução de sobretensão em motores por superposição de pulsos
2020 - SANTOS, DANIEL de P. dos; SARTORI, CARLOS A.F.
Sobretensão em motores elétricos acionados por conversores estáticos de frequência representam grande risco à integridade do equipamento e se intensificam à medida que tais conversores aperfeiçoam sua velocidade de chaveamento. Os métodos ativos de redução de sobretensão por superposição de pulsos se utilizam dos próprios conversores de frequência para suprimir ou minimizar os pulsos refletidos através do cabo de acionamento do motor, que geram a sobretensão. Esse artigo explora alguns desses métodos em termos de eficácia, flexibilidade e robustez e faz uma análise comparativa destes. Também são realizadas comparações entre sistemas de acionamento dotados de IGBTs de silício e de MOSFETs de carbeto de silício.
Mu-negative metamaterials seen as band-limited non-foster impedances in inductive power transmission systems
2019 - ALMEIDA, JORGE V. de; SIQUEIRA, GLAUCIO L.; MOSSO, MARBEY M.; SARTORI, CARLOS A.F.
In the last decade, various works have demonstrated that a class of artificial material called metamaterials (MTM) can synthesize mu-negative (MNG) media capable of evanescent-wave focusing which largely enhances the magnetic coupling between coils, which is the basic mechanism of Inductive Power Transmission (IPT) systems. In the present work, MTM-enhanced coupling in IPT systems is examined through analytical and numerical results, which are validated by experimental data. Adopting a transmission-line (TL) based approach to describe the general MTM-enhanced IPT system, it is evidenced that MNG MTMs can be interpreted as a negative impedance from a circuital point of view.
Frequency-domainmodeling of unshielded multiconductor power cables for periodic excitation with new experimental protocol for wide band parameter identification
2019 - BADE, TAMIRIS G.; ROUDET, JAMES; GUICHON, JEAN-MICHEL; SARTORI, CARLOS A.F.; KUO-PENG, PATRICK; SCHANEN, JEAN-LUC; DERBEY, ALEXIS
A complete modeling technique for unshielded power cables is proposed. The focus is on applications where the resonance phenomena take place in electrically long cables and is originated from periodic excitation, such as power converters. The resonance problems caused by switching converters tend to become more common with the advent of wide band gap semiconductors. This paper includes a new experimental protocol specific for unshielded power cable parameter identification in a wide frequency band, from DC up to medium frequencies (tens of MHz), with an impedance analyzer. It also introduces a frequency-domain simulation tool with conversion to the time domain, via the Fourier series. This frequency-domainmodeling is straightforward, and its accuracy depends only on the accuracy of the cable parameter identification.
Modeling of a metamaterial in the FEA of a contactless transcutaneous energy transfer device
2018 - CARVALHO, G.D.; SILVA, V.C.; HAFFNER, F.; SARTORI, C.A.F.; LEBENSZTAJN, L.; KRAHENBUHL, L.
Metamaterials are difficult to deal with in computational electromagnetic modelling, e.g. finite element analysis. The reason is the prohibitive discretization refinement needed to account for their actual electromagnetic field distribution profile, within the frequency range used in contactless energy transfer devices. We propose an approach to simplify the modeling of a metamaterial in finite element simulations and present an analysis of its impact in the evaluation of the magnetic field distribution in the vicinity of the metamaterial.
Impact of mismatch cables impedances on active motor terminal overvoltage mitigation using parallel voltage source inverters
2017 - SANTOS, DANIEL de P. dos; SARTORI, CARLOS A.F.
Non-treated transient motor terminal overvoltage due high-speed switching sources and long cable length can be twice the original source voltage amplitude. In some cases, this overvoltage can cause premature motor insulation failure. A topology widely applied in industry is subject of this overvoltage: motors driven by voltage source inverter, connected by long feeding cable. There are several passive methods effective in mitigating overvoltage, but most of them are based in lossy and bulky passive component filters. A different approach is proposed by two low loss active methods for overvoltage mitigation with simple topologies. It consists in using voltage source inverters with specific switching strategy in order to attenuate the main cause of overvoltage: the superposition of traveling reflected pulses at the motor terminals. As promising methods for overvoltage mitigation, some specific studies regarding its particularities must be carried on in order to clear understand all its benefits and possible drawbacks. The present paper discusses the vulnerability of these overvoltage mitigation methods to some internal parameter variation. The impact of cables impedance variation due heating –and impedance mismatch– is highlighted, since it is intrinsic to the system and can degrades overvoltage mitigation.