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The evolution of digital electronic systems to ever‐faster pulse rise times has placed increased demands on printed wiring board (PWB) materials. Signal loss associated with dielectric materials has driven development and commercialization of cost‐effective low loss laminate materials. In order to provide a better understanding of conductor material and surface finish choices, efforts have been made to quantify the impacts of these factors on loss. An alternative test approach has been identified which provides a measure of conductor performance, decoupled from both system geometry and the influence of laminate material.

The purpose of this paper is to devise an analytical approach to calculate conductor winding losses, considering multiple contributing aspects simultaneously. These include the geometric configuration of coil windings, frequency of the electric current and the dependency on the coil temperature, derived studying a coupled fluid–solid model considering the cooling system characteristics. The obtained results allow identifying power loss trends according to such system variables as coolant inlet temperature or overall flow rate of the motor.

An easy-to-use coupled analytical approach is applied, which is suitable for rapid estimations of the impact of parameter variation on the resulting conductor winding power losses that facilitates decision-making in the design process of electric aircraft engines.

In the considered cooling parameters, the overall conductor winding power losses vary approximately between 6 kW and 7.2 kW. More than 95 per cent of this loss is because of direct current losses. These losses cause the variation in maximal coil temperature ranging between 115°C and 170°C.

The SP260D motor is set and was currently tested in Extra 330. It recently broke two world records.

One of the current trends in aircraft engineering is electric aircraft. Advantages of electric aircraft include improved manoeuvrability because of greater torque from electric motors, increased safety because of decreased chance of mechanical failure, less risk of explosion or fire in the event of a collision and less noise. There will be environmental and cost benefits associated with the elimination of dependency on fossil fuels and resultant emissions.

The use of a novel fluid–solid interaction model for predicting conductor winding power loss of the SP260D electric aircraft motor has not been done earlier. A novel alternative derivation of the widely applied Dowell’s formula (Dowell, 1966) is presented for the estimation of proximity losses in square winding conductors.

The purpose of this paper is twofold. First, it aims to study the proximity‐effect power loss in the foil, strip (rectangular), square, and solid‐round wire inductor windings. Second, it aims to optimize the thickness of the foil, strip, square wire windings, and the diameter of the solid‐round‐wire, the minimum of winding AC resistance and the minimum of winding AC power loss for sinusoidal inductor current.

The methodology of the analysis is as follows. First, the winding resistance of the single‐layer foil winding with a single turn per layer and uniform magnetic flux density B is derived. Second, the single‐layer foil winding with uniform magnetic flux density B is converted for the case, where the magnetic flux density B is a function of x. Third, the single‐layer winding is replaced by the winding with multiple layers isolated from each other. Fourth, transformation of the multi‐layer foil winding into different conductor shapes is performed. For the solid‐round‐wire windings, the results of the derivation are compared to Dowell's equation and verified by measurements.

Closed‐form analytical equations for the optimum normalized winding size (thickness or diameter) at the global or local minimum of winding AC resistance are derived. It has been shown that the AC‐to‐DC winding resistance ratio is equal to 4/3 (F_Rv=4/3) at the optimum normalized thickness of foil and strip wire winding h_opt/δ_w. The AC‐to‐DC winding resistance ratio is equal to 2 (F_Rv=2) at the local minimum of the square wire and solid‐round‐wire winding AC resistances. Moreover, it has been shown that for the solid‐round wire winding, the proximity‐effect AC‐to‐DC winding resistance ratio is equal to Dowell's AC‐to‐DC winding resistance ratio at low and medium frequencies. The accuracy of equation for the winding AC resistance of the solid‐round wire winding inductors has been experimentally verified. The predicted results were in good agreement with the measured results.

It is assumed that the applied current density in the winding conductor is approximately constant and the magnetic flux density B is parallel to the winding conductor (b>>h). This implies that a low‐ and medium‐frequency 1‐D solution is considered and allows the winding size optimization. This is because the optimum normalized winding conductor size occurs in the low‐ and medium‐frequency range. The skin‐effect winding power loss is much lower than the proximity‐effect winding power loss and therefore, it is neglected.

This paper presents derivations of closed‐form analytical equations for the optimum size (thickness or diameter) that yields the global minimum or the local minimum of proximity‐effect loss. A significant advantage of these derivations is their simplicity. Moreover, the paper derives equations for the AC‐to‐DC winding resistance ratio for the different shape wire windings, i.e. foil, strip, square and solid‐round, respectively.

The purpose of this paper is to compare the performance of conventional, novel E‐ and C‐core switched‐flux permanent magnet (SFPM) machines having different combinations of stator and rotor pole numbers, with particular reference to the conductor and magnet eddy current loss and iron loss.

The electromagnetic performance of the analysed machines is compared using the finite element (FE) analysis.

Both iron and conductor eddy current losses increase with the rotor pole number, while the 11‐ and 13‐rotor pole machine always exhibit lower magnet eddy current loss than those of the 10‐ and 14‐rotor pole machines, respectively. The E‐ and C‐core machines use half the number and volume of magnets and also exhibit higher efficiency than those of the conventional SFPM machine.

Investigation of the influence of stator and rotor pole combinations on the performances of conventional, novel E‐ and C‐core SFPM machines, include losses and efficiency.

To examine the impact of oxide and oxide alternative processes on signal loss in commercial RF applications.

Stripline conductors were formed using traditional oxide, oxide dissolution/reduction, and oxide alternative processes. Conductor geometry was measured and surface topography was characterized. Effective dielectric constants and characteristic impedance for each system was determined. Finally, line loss for each treatment and rework condition was charted to nearly 20 GHz. Electrical measurements were performed by taking S‐parameter measurements through 20 GHz using an agilent vector network analyzer (VNA).

The methods employed were sufficient to statistically characterize the increased loss associated with thick oxides and high‐microetch oxide alternatives. Lower etch oxide alternatives yielded benefits for signal integrity. Of importance, rework procedures gave unacceptable increases in line loss. Overall, however, the loss due to innerlayer bonding processes was not of sufficient magnitude to elevate oxides as a primary contributor to conductor loss. For the relative simple, high production system employing epoxy substrate, oxide loss was found to be far less than substrate effects, imaging quality, and foil treatment.

Electrical engineers and printed circuit board (PCB) designers strive to focus their efforts on improving the PCB processes leading to maximum conductor loss in the electronic system. This work shows that oxide treatments are not a primary factor in affecting loss. Significant improvements in signal integrity may be achieved, however, with the use of low‐etch oxide alternatives and with restrictions on oxide rework. In addition, this paper allowed for new interpretations of VNA data for better modeling of PCB system data using non‐classical analysis.

This paper aims to introduce a technique for optimizing conductor dimensions for construction of helical planar inductor windings with reduced ac‐ and dc‐resistance. The loss reduction is evaluated on simulation and experimental level.

Helical planar windings are currently manufactured by forming each conductive and insulating layer individually. The conductive layers are only interconnected later to form the winding. This process allows greater freedom in selecting the optimum conductor dimensions on a per‐layer basis. Methods are proposed for sinusoidal and non‐sinusoidal current excitation waveforms and shaped windings are introduced for further loss reduction where conductors are in close proximity to air gaps in magnetic cores.

Traditional optimization of the conductor thickness used for foil wound inductors renders one single value used for each of the respective layers in the winding. This is a result of the manufacturing process involved in making traditional “barrel” windings. This optimization technique has simply been applied in planar inductors for the lack of alternatives up to now. It will be shown that large loss reduction may be achieved by manipulating the conductor dimensions of each layer individually.

A new approach to optimization problems verified experimentally offers more efficient inductors.

The purpose of this paper is to establish an accurate model to quantify the effect of conductor roughness on insertion loss (IL) and provide improved measurements and suggestions for manufacturing good conductive copper lines of printed circuit board.

To practically investigates the modified model of conductor roughness, three different kinds of alternate oxidation treatments were used to provide transmission lines with different roughness. The IL results were measured by a vector net analyzer for comparisons with the modified model results.

An accurate model, with only a 1.8% deviation on average from the measured values, is established. Compared with other models, the modified model is more reliable in industrial manufacturing.

This paper introduces the influence of tiny roughness structures on IL. Besides, this paper discusses the effect of current distribution on IL.

The purpose of the paper is to provide a comparison of first‐ and second‐order two dimensional finite element models for evaluating the electromagnetic properties and calculating AC loss in high‐temperature superconductor (HTS) coated conductors.

The models are based on the two‐dimensional (2D) H formulation, which is based on directly solving the magnetic field components in 2D. Two models – one with a minimum symmetric triangular mesh and one with a single‐layer square mesh – are compared based on different types of mesh elements: first‐order (Lagrange – linear) and second‐order (Lagrange – quadratic) mesh elements, and edge elements.

The number and type of mesh elements are critically important to obtain the minimum level of discretization to achieve accurate results. Artificially increasing the superconductor layer and choosing a minimum symmetric mesh with triangular edge elements can provide a sufficiently accurate estimation of the hysteretic superconductor loss for a transport current.

This paper describes how the selection of mesh type and number of elements affects the computation speed and convergence properties of the finite element model using two different types of meshing. It offers an insight into the different factors modelers must consider when modeling HTS coated conductors and the methods that may be applied when extending the model to complex device geometries, such as wound coils.

The purpose of this paper is to investigate the possibility of utilizing printed circuit board (pcb) technology to manufacture coaxial transformers and to increase the predictability, accuracy and repeatability of the transformers leakage inductance.

The geometry of a coaxial transformer is approximated using pcb techniques. Several different geometries are presented with the outer coaxial conductor being approximated by discrete conductors varying from four to 36 in number. Finite element methods as well as experimental results are used to support the proposed ideas. A planar transformer is also analyzed in the same way to emphasize the design advantages offered by the proposed quasi‐coaxial transformer.

The proposed multi‐conductor structures can be applied as co‐axial transformers. The experimental values obtained for the leakage inductance of the coaxial structures correspond well to the predicted values. This is not the case for conventional planar structure where adjustments need to be made in the finite element analysis simulations to accommodate the shortcomings of the analytical calculations.

In applications where the prediction of the leakage inductance of a transformer is important, this method may be applied and has the advantage of conventional pcb manufacture techniques.

The authors aim to search for a practical and accurate way to get good loss estimates for coil filaments in electrical machines, for example transformers. At the moment including loss estimations into standard finite element computations is prohibitively expensive for large coils.

A low-dimensional function space for finite element method (FEM) is introduced on the filament-air interface and then extended into the filament to significantly reduce the number of unknowns per filament. Careful choice of these extensions enables good loss estimate accuracy. The result is a system matrix assembly block that can be used verbatim for all filaments, further reducing the cost. Both net current and voltage per length of the filament are readily available in the problem formulation.

The loss estimates from the developed model agree well with traditional FEM and the computation times are faster.

To produce accurate loss estimates in large coils, the low-dimensional function space is constricted on the filament boundaries. The proposed method enables electrical engineers to compute the ohmic losses of individual conductors.