Conductor Width Research Articles

Electrodynamic analysis of a sinusoidal antenna for small wave sizes

Background. The work is aimed at developing and researching rigorous methods for calculating thin-wire structures with a complex generatrix shape, having small wave sizes, as well as studying the physical processes occurring in them. A special case of such structures is a sinusoidal antenna operating in a standing current wave mode. Aim. In progress the solution of internal and external problems of electrodynamics is carried out for a sinusoidal antenna of small wave sizes located above an infinitely extended ideal reflector. The currents on the elements of the structure are calculated, its input resistance and radiation characteristics are determined. Methods. The research is based on a strict electrodynamic approach, within the framework of which, for the specified structure in the thin-wire approximation, an integral representation of the electromagnetic field is formed, which, when considered on the surface of conductors together with boundary conditions, is reduced to a system of Fredholm integral equations of the second kind, written relative to unknown current distributions on conductors (internal task). Results. A mathematical model of the radiating structure is proposed, determined: the input resistance of the structure and the basic characteristics of its radiation. It is shown that the operating range of a sinusoidal antenna in the standing wave mode is determined by the quality factor of the input impedance resonances; An increase in the width of the sinusoidal conductor leads to a decrease in the resonant frequencies of the input resistance with a simultaneous increase in the quality factor of the resonances. Conclusion. From a practical point of view, the use of the considered structure allows significantly reduce the dimensions in comparison with a thin electric vibrator, however in this case, the operating range will be correspondingly narrowed, which is determined, due to the weak dependence of the radiation characteristics on frequency, by the quality factor of the resonances. The current distribution on the generatrix of the structure can be considered as a «projection» standing surface wave localized in the plane of a sinusoidal conductor, and resulting from the superposition of forward and backward surface (slow) waves propagating at a speed significantly lower than the speed of light. To further clarify the physics of the processes occurring in the structure, one should use spectral analysis of current functions and study the distributions of the electromagnetic field in the near zone of the structure.

Effects of lateral critical current nonuniformity on stresses in dry-wound high-field REBCO coils

Abstract The distribution of critical current density (jc) in REBCO coated conductors affects the magnetization behaviors and subsequently screening-current-induced stresses, particularly for solenoid magnets in high fields. This paper studies numerically the correlation between lateral jc profile across conductor width and stress distribution in pancake coils. The modeling framework considers bending, winding, thermal contraction, and magnetic forces including coupled electromagnetic-mechanical behaviors, i.e., the deviation of the perpendicular field away from axial direction due to tilting deformation. The lateral nonuniformity is introduced using trapezoidal functions, emulating typical jc profiles originated in pristine tapes and those caused by slitting. First, parametric studies are carried out on the small test coils previously reported in the 'Little Big Coils' (LBC) paper. It is shown that while slitting edge defects have a moderate impact on peak strains, imperfections in the pristine tape with a larger shoulder width can accelerate the penetration process, shifting peak force to the structurally resilient middle section. Similar behaviors are found in the LBC3 case study, suggesting that lateral jc nonuniformity may have contributed to the observed degradation states in pancakes with different slit-edge orientations. Furthermore, the manipulation of lateral jc profile is proposed as a strategy to manage stresses in high field solenoids. This is demonstrated in the design study of a hypothetical REBCO insert. By adjusting the lateral jc distribution and the overall scaling factor, magnet designs with a reasonable current margin and moderate peak strain can be found. The multi-width concept is then applied to allow for a higher operating current and a larger margin for the end pancakes. Albeit being a generic case, this study highlights the sensitivity of peak stresses in high-field magnets to jc distribution. This feature may be taken into account to fine-tune magnet designs and adjust coil assemblies for better overall performance. It also emphasizes the need for careful characterization and effective control of lateral jc distributions in REBCO coated conductors.

A GCPW slow‐wave transmission line with improved wavelength reduction technique by adopting capacitor array

AbstractThis letter presents a grounded coplanar waveguide (GCPW) slow‐wave transmission line (SWTL) with an improved wavelength reduction technique by adopting capacitor array. By cross‐interleaving additional capacitors between a signal line and side ground planes, the total capacitance in the capacitor array increases approximately two times compared to the conventional structure, allowing designers to choose a smaller signal conductor's width for higher inductance, thus, improving wavelength reduction performance while preserving the same characteristic impedance. At the 150 GHz frequency of interest, the proposed GCPW SWTL shows approximately 20% and 62.16% reduction in wavelength compared to the reported GCPW SWTL and regular CPW, respectively, with the same characteristic impedance. To prove the effectiveness of the proposed SWTL concept, the proposed GCPW SWTL test patterns are fabricated in a 65 nm CMOS process.

Effect Comparison of Different Conductor Widths in Magnetic Dam for Protection of NI REBCO Pancake Coils

Effect Comparison of Different Conductor Widths in Magnetic Dam for Protection of NI REBCO Pancake Coils

Experimental characterisation and statistical modelling of woven carbon fibre weld conductors for electrical resistance welding of thermoplastic composites

Resistance welding of high-performance thermoplastic composites is a promising joining technique for the structural assembly of aerospace components. Knowledge of the weld conductor resistance as a function of its dimensions, as well as external boundary conditions such as contact preparation and pressure, can be used to scale welding parameters. This paper presents a comprehensive review on the weld conductor contact preparation, length, width and contact pressure dependent resistance with respect to the Toray 5HS T300JB carbon woven prepreg 281 gsm fibre architecture. The study is based on a 4-wire resistance measurement of the carbon fibre fabric weld conductors and was conducted to provide a solid basis for defining the weld conductor’s resistance, considering the dependence on length, width and contact pressure. The experimentally determined resistance values were approximated using linear and non-linear regression functions and combined into a general formulation with respect to the investigated carbon fibre fabric architecture. The least squares fit of experimental versus model data confirmed a very high model confidence. Thus, the model allows a simplified transfer of electrical properties for process pre-design and scaling considering weld conductors with the same fibre architecture.

Time Domain Simulated Characterization of the Coplanar Waveguide in an On-Chip System for Millimeter Waveform Metrology

We investigate the time domain characterization of a coplanar waveguide (CPW) based on an on-chip electro-optic sampling (EOS) system for millimeter waveform metrology. The CPW is fabricated on a thin layer of low-temperature gallium arsenide (LT-GaAs), and the substrate material is GaAs. A femtosecond laser generates and detects ultrashort pulses on the CPW. The forward propagating pulses are simulated using a simplified current source for the femtosecond laser at different positions on the CPW for the first time. Then, the influences of the CPW geometry parameters on the measured pulses are discussed. The varying slot width has larger influences on the amplitude of millimeter wave pulses than the center conductor width and the pumping gap. Finally, in the frequency range of 10 GHz to 500 GHz, the transfer functions calculated by the time domain pulses are in good agreement with the transfer functions calculated by the frequency domain ports. The above results are important for improving the measurement precision of the millimeter waveform on the CPW for millimeter waveform metrology.

The Resistor Network Approach to Modeling Screen-Printed Silver Ink Under Uniaxial Stretch

Abstract Flexible electronic devices are used in a wide variety of applications that utilize their unique ability to stretch, bend, and twist. Experimental methods were developed for evaluating the piezoresistive behavior of printed conductive inks under uniaxial strain. DuPont 5025 screen-printed silver ink on Kapton and Melinex substrates was stretched until substrate failure. Kapton samples were found to rupture at around 60% strain and have a relative resistance, R/R0, of about 30–40 at substrate rupture. On Melinex substrates, the ink was found to electrically fail before the substrate ruptured but could be stretched to strains exceeding 130% or higher before failing. The relative resistance values for these high strains in the Melinex samples were erratic and could exceed 1000 and in one case more than 30,000. The ink strain to failure exhibited a dependence on conductor width with narrower conductors failing before wider ones. Finally, a 2.5D RVE model that accounts for ink filler volume fraction, particle size distribution, contact resistance, and electron tunneling was developed that accurately predicts the piezoresistive behavior of 5025 ink up to 60% axial strain. An initial parametric study found that increasing the volume fraction of the RVE results in improved electrical performance.

Measurement and analysis of winding stresses in dry-wound pancake coils considering nonlinear compressive behaviors

Considering coil stress management, conductor thermal stability, and susceptibility to delamination, the dry-winding approach has been gradually applied and tested in high-temperature-superconducting coils wound with REBa2Cu3O (REBCO) coated conductors (CCs). In dry-wound coils, the winding tension can be a useful tool for managing the mechanical stresses and maintaining the structural stability. It is also related to the contact resistivity characteristics of no-insulation and metal-as-insulation coils. In this paper, we present a study on the winding stresses in dry-wound pancake coils considering nonlinear compressive behaviors in the radial direction. Coils wound with stainless-steel (SS) tapes and REBCO CCs were prepared, respectively, with various sizes (90–140 turns) and winding tensions (26–61 MPa). The radial pressure was obtained by applying the pressure measurement films, which cover a pressure range up to 50 MPa. A relatively moderate radial pressure buildup was observed in coils wound with SS tapes, indicating that the effective radial modulus of the coil as an entity is considerably lower compared to the tensile modulus in the azimuthal direction. This is consistent with the nonlinear stress–strain relationship of stacked thin sheets under transverse compression, which can be further explained by the contact behaviors between two rough surfaces. The average radial pressure in CC coils shared similar characteristics as that in SS coils, whereas the radial stress along the conductor edges were significantly higher compared to the middle. Cross-sectional microscopy of the CCs suggests that this can be primarily attributed to the thickness variations across the conductor width. These results suggest that the microscopic rough-surface contact and thickness variation of the wound tape play a critical role in the coil stiffness as well as the winding stress distributions.

Design Consideration and Conductor Selection of a Low AC Loss HTS REBCO Magnet Carrying High Currents at 20 K and 40 K

AC loss in high temperature superconductor coils have been frequently studied, however, mostly for AC power ap-plications at 77 K, rather than specifically for high current but low frequency AC superconducting magnet at 20-40 K. Due to their easy operation and Helium shortage, more HTS magnet systems employ conduction-cooling with cryocoolers. The HTS magnets are known for high stability and likely tolerate high AC loss, but it is unclear what is the maximum AC frequency assuming that cry-ocooler has limited capability (a few hundred Watts) for the 20-40 K temperature range. This paper will specifically study AC loss in a simple HTS dipole but with three conductor/cable options using simulations, (1) 12 mm wide tape, (2) two parallel 6 mm wide tapes, and (3) 6/2 (six 2 mm strands) Roebel cables. It has been found that the magnet at 5 Hz generates 200 – 400 W AC loss at 20 K or 40 K, potentially be cooled by two single stage cryocoolers. The 6/2 Roe-bel cable based magnet may allow higher frequency (6-8 Hz) due to its transposition and narrower conductor width.

Analytical Model for Evaluating the Reliability of Vias and Plated Through-Hole Pads on PCBs

Currently, there is a need to increase the density of interconnections on printed circuit boards (PCBs). Does this mean that the only option for quality PCB manufacturing is to proportionally increase precision of equipment, or is there another way? One of the main constraints on increasing the density of PCB interconnections is posed by the transition holes. As the number of conductive layers increases, the number of vias increases and they cover a significant space on the PCB. On the other hand, reducing the size of the vias is limited by the capability of spatial alignment of the PCB stack during manufacturing. There are standards that set limits for the design of contact pads on a PCB (IPC-A-600G, IPC-6012B). However, depending on the precision of production, the contact pads may be of poor quality. This raises the issue of determining the reliability of a contact pad with defined parameters at the design stage, taking into account manufacturing capabilities. This research proposes an analytical method for evaluation of reliability of a via or plated through-hole based on calculation of its probability of production in accordance with the current standards. On the basis of the method, a model was developed both for the case of a contact pad without any conductors connected to it (nonfunctional contact pad) and for the real case with a connected conductor. The model estimates the probability of making an acceptable via for a given reliability class depending on parameters such as the conductor width (minimum permissible and usable), drilled hole diameter, and pad diameter, as well as the accuracy of the drilling operation. The analysis of the modeling results showed that for the real case, a reduction in the reliability class would insignificantly affect the probability of making an acceptable via due to the tight limitation on the connection place of the conductor and the contact pad. In conclusion, we propose an algorithm for determining the optimal parameters of teardrops to minimize the negative impact of the conductor on the reliability of the vias.

Impact of Dimensions, Apertures and Terminals on Stray Inductance of the Laminated Busbar

This paper presents a systematic investigation of the impact of physical parameters such as dimensions, apertures and terminals, on the busbar inductance. A planar laminated busbar with copper conductors and a polyamide insulator is studied using a 3D FEM (Finite Element Modelling) based simulation software. The impact of dimensions such as conductor length, width and thickness, depth of insulator, the effects of aperture number, size, position and connection terminals on the busbar inductance are examined. The magnetic flux density, current density involved and its dependence on the self and mutual inductance of the laminated busbar is analyzed. Laminated busbars provided lower inductance with decreased conductor length, thickness, aperture diameter and depth of insulator. Also, the increased width of the busbar is of the essence for the design of a low inductance busbar. Low inductance laminated busbars are highly beneficial in power converters, powertrain inverters in electric vehicles, photovoltaic converters.

Mandrel Bend Test of Screen-Printed Silver Conductors

Abstract Flexible electronics are electronic devices and components that can be stretched, bent, twisted, and folded without losing their functionality. Flexible electronics is conformable, lightweight, easily tailorable, and low-cost, and thus, flexible electronics is increasingly being explored in health care, internet of things, automotive, aerospace, communication, safety, security, and food-related applications. Also, flexible electronics can now support increased functionality as well as various fabrication techniques. With an increased adaptation of flexible electronics, research is being conducted to better understand the failure mechanism of flexible electronics and thus improve their reliability and service life. In this paper, a cyclic mandrel bend test has been designed and carried out on printed conductors with PET and PI substrates. With the designed test apparatus, both tensile and compressive bend tests have been performed. Using a four-wire method, the resistance change of the printed conductors with different widths has been measured in situ under tensile and compressive loading conditions using mandrels with different radii. The results have been compared among different conductor widths, bending modes, and substrate materials. Besides, in situ SEM images have been taken to understand the failure mechanisms of the printed conductors. Based on the study, it is seen that there exists a direct correlation between the mandrel diameter, the damage in the printed conductor, and thus, the resistance change with cyclic mandrel testing. Also, it is seen that the damage under compressive bending mode is significantly lower than the damage under tensile bending mode.

Magnetization Loss Measurements of Spiral Copper-Plated Multifilament Coated Conductors With Various Filament and Conductor Widths

We can achieve both small magnetization loss and the robustness against local defect or local normal transition by winding copper-plated multifilament coated conductor spirally. The particular focus of this study is the impact of narrowing conductor (tape) width as well as filament width on magnetization losses. We measured the magnetization losses of various spiral copper-plated multifilament coated conductors, separated them into hysteresis losses and coupling losses, and examined the impact of narrowing filament width and conductor width. We demonstrated that the magnetization loss of the spiral 2 mm-wide coated conductor with 0.2 mm-wide filaments and 10 μm-thick copper was one-twentieth of that of a flat standard 4 mm-wide coated conductor in transverse ac magnetic fields of 65.44 Hz.

Measurements of Coupling Time Constants and Geometry Factors of Coupling Losses in Spiral Copper-Plated Multifilament Coated Conductors

Spiral geometry is effective to reduce coupling time constants of copper-plated multifilament coated conductors. We wound copper-plated multifilament coated conductors with various specifications spirally on round cores, and measured their magnetization losses in a wide range of frequency to determine their coupling time constants as well as the geometry factors of coupling losses. The core diameter was decreased down to 2.5 mm in order to show the feasibility of such conductors with reasonably high overall current density. The influence of various conductor parameters such as copper thickness, conductor width, and number of striations (filament width) as well as core diameter on coupling time constants and geometry factors were studied. By using the obtained coupling time constants and geometry factors, we calculated coupling losses of various conductors, whereas we calculated their hysteresis losses by using Brandt and Indenbom's formulae. These calculated hysteresis losses and coupling losses were compared with measured magnetization losses for various conductors.

EVALUATION OF SYSTEMATIC ERRORS OF STRIP ASYMMETRIC HUMIDITY SENSOR

The methodical estimation of the methodical component of the error arising at measurement of humidity of heterogeneous dispersed dielectrics by the band asymmetric sensor is carried out. In the process of evaluation it was shown that the most significant component of methodological error occurs due to changes in temperature and frequency of the information wave. Temperature-dependent values included in the mathematical model of the band asymmetric humidity sensor are: relative dielectric constant of the substrate dielectric and the object of control, length and width of the central conductor, substrate dielectric thickness. The dielectric constant of the dielectric of the object of control depends on the frequency of the information wave, and this parameter is directly included in the coefficients of the sensor conversion equation. The results of the research showed that in the process of measuring the conversion of humidity in the band asymmetric sensor there is a methodological component of the error associated with changes in temperature and instability of the frequency of the information wave. To ensure a frequency error at a level not exceeding 0.5%, the error of instability of the frequency of the information wave when converting humidity into the output amplitude of the information wave should not exceed ± 3 kHz, provided by existing RF generators. It is advisable to remove the temperature component of the error using the method of correction. The mathematical model of band asymmetric measurement of moisture conversion of heterogeneous dispersed dielectrics in the high-frequency region was also improved.

Impact of Copper Thickness, Conductor Width, and Number of Striations on Coupling Loss Characteristics of Copper-Plated Multifilament-Coated Conductors

This article investigates the coupling loss characteristics of multifilament-coated conductors that have been plated with copper to connect electrically all the filaments to enhance their stability. Short pieces of copper-plated multifilament-coated conductors were prepared, each of which simulated a half-pitch of the conductor wound spirally on a round core with respect to the loop of the coupling current, and their magnetization losses were measured. The measured magnetization loss was separated into the hysteresis and coupling losses. This article focused on the latter one, which is peculiar to copper-plated multifilament-coated conductors, and the reduction of which is important for their applications. The coupling time constants as well as the geometry factors of the coupling losses and the magnitudes of coupling losses were studied using copper-plated multifilament-coated conductors with various copper thicknesses, numbers of striations, and conductor widths. Numerical electromagnetic field analyses were conducted, and the numerical and measured results were compared.

Parametric Analysis for Performance Optimization of Line-Start Synchronous Motor with Interior Asymmetric Permanent Magnet Array Rotor Topology

Line-start synchronous motors have attracted researchers’ interest as suitable replacements of asynchronous motors due to their high efficiency, which has been provoked by strict regulations regarding applicable efficiency classes of motors in the EU market. The research becomes even more challenging as it takes into consideration the diverse rotor topologies with different magnet locations for this type of motor. The rotor configuration with an interior asymmetric permanent magnet (PM) array rotor was chosen for analysis and optimization in this paper as this specific configuration is particularly challenging in terms of placing the magnets with adequate dimensions into the existing rotor of the asynchronous motor with a squirrel cage winding, in order simultaneously to obtain good operational characteristics such as high efficiency and power factor, good overloading capability and low material consumption. Therefore, an optometric analysis is performed in order to find the best configuration of the air gap length, magnet thickness, magnet width and number of conductors per slot, along with modifications of the rotor slot. The motor outer dimensions remained unchanged compared with the starting model of the line-start motor derived from the asynchronous motor, which is a product of the company Končar. The optimized model obtained higher efficiency, power factor and overloading capability than the starting model, along with good starting and synchronization capabilities.

Modeling, Investigation, and Mitigation of AC Losses in IPM Machines with Hairpin Windings for EV Applications

Interior permanent magnet (IPM) machines with hairpin windings have attracted significant attention in EV applications owing to their low DC resistance and excellent thermal capabilities. In this paper, we present a comprehensive investigation of AC winding losses in IPM machines for traction applications, including analytical modeling, the influence of design parameters, and finite element (FE) verification. The proposed analytical model can predict the trends in AC winding losses for any number of bar conductors and slot/pole combinations. The results of the parametric study, obtained via the analytical model, are presented to examine the effects of key design parameters, such as conductor width and height, phase arrangement, and slot-per-pole-per-phase (SPP). To incorporate more practical issues into the analysis of IPM machines with hairpin windings, extensive FE simulations were conducted. The results indicated that the AC winding losses decrease with an increasing number of conductor layers and phases inside the slot.

Refinement of the method for selecting the width of the conductor of printed circuit boards on a metal base, working in the absence of convection

The article proposes a refined method for calculating the width of the conductors of printed circuit boards on a metal base for the onboard devices of spacecraft, depending on the current flowing. The constructed refined mathematical model of the process of conductive heat exchange between the conductors and the metal base is described. The results of calculations of various, most common, locations of layers of printed circuit boards are presented. An analysis was carried out and a refined methodology was developed based on the results obtained. It allows you to easily (without complicate calculations) calculate the necessary values of the width of conductors. This technique is based on graphical methods, but allows you to perform technical calculations with sufficient accuracy. Accuracy is achieved by using special formulas that simplify the determination of the value of a physical quantity on a logarithmic scale. The disadvantages of the proposed method are indicated.

Analytical expressions for electrodynamic parameters of the shielded microstrip line

On the basis of an electrodynamic model of a screened microstrip line, built on the basis of the projection method using the Chebyshev basis, which explicitly takes into account the edge features of the field, a mathematical model of a microstrip line with a strip conductor was developed. The line width does not exceed the height of the substrate. In this case, the current density on the strip conductor is approximated by only one basis function. Analytical expressions are presented in the form of a sum of slowly and rapidly converging series to determine the main electrodynamic parameters of the line – wave resistance and deceleration coefficient. Due to logarithmic features, slowly converging series are summed up and transformed into rapidly converging power series. In addition, limit expressions in the form of improper integrals are given for the main electrodynamic parameters of an open microstrip line in the quasi-static approximation. Due to the logarithmic features, these integrals are also converted to rapidly converging power series. As a result, simple approximate formulas were obtained. They allow calculating the deceleration coefficient and wave impedance of the line with an error not exceeding 1%, when the width of the strip conductor is less than twice the thickness of the substrate. The results of calculating the electrodynamic parameters obtained on the basis of the developed mathematical model and on the basis of the projection method with an accuracy of up to 5 significant digits are presented. These results make it possible to establish the limits of applicability of the quasi-static approximation and to determine the error in calculating the deceleration coefficient and wave resistance using the obtained analytical expressions. The error does not exceed 0.1%, if the width of the strip conductor is less than twice the thickness of the substrate in a wide range of changes in the substrate dielectric constant and frequency.