This study presents an overview of the multipath conductor concept and some recent developments of multipath conductors especially in the field of electromagnetic interference (EMI). Multipath conductors are made up of several layers of materials with different electromagnetic properties. The conductors are configured to conduct currents in parallel. These current may contain low-frequency desired currents and undesirable higher frequencies. These multipath conductors are used as a lowpass dissipative filter to reduce EMI in compact power electronics circuits by replacing the conventional filter. This new type of filtering structure has several advantages over the convention filters. The purpose of this study is to review the work done so far in terms of the analytical and software analysis of multipath conductor based EMI filters. This will create interest among the new researchers in this developing field by understanding the basic technique and applications to aid in their research further.

This study presents a detailed analysis about the impact of hybrid superconducting fault current limiter (HSFCL) on distance relay performance through the analytical and simulation techniques. For assessments, two possible installation locations for HSFCL (before or after potential transformer (PT)) are considered here which has not been evaluated in the literature so far. Moreover, the impact of action time of fast mechanical switch implemented in the HSFCL structure on impedance trajectory and trip time is investigated. The obtained results show the adverse impact of HSFCL on distance relay performance in all cases. Specially, for forward faults, the worst case happens when HSFCL is installed at the downstream of PT. Using quadrilateral characteristic instead of mho can improve the performance of distance relay; however, this way does not fulfil the enough security and sensitivity under different conditions. Therefore, two approaches are proposed to overcome these challenging situations: (i) modifying trip region of distance relay with respect to the HSFCL impedance and (ii) the new impedance calculation procedure. The significant aspect of the proposed solutions compared with the existing techniques is that the accuracy of distance relay is improved without using additional hardware to provide information from HSFCL.

Over a transformer's operational lifetime, the moisture content of its insulation pressboard increases because of the ageing of its internal insulation. Thus, this moisture content becomes an important index for judging the ageing of this insulation. In this study, to analyse the moisture content of a transformer's insulation pressboard using the dielectric response insulation technique, the XY-equivalent model analysis method for classical transformers is combined with a dielectric-constant algorithm for mixed media. In addition, a new method for calculating the moisture content of a pressboard is obtained via cyclic iterative comparison calculations based on the dielectric response translation formula, the temperature, and the material activation energy. The XY-equivalent models of transformers with various proportions are derived under laboratory conditions. The moisture contents of the transformers’ insulating pressboards are obtained under the corresponding dielectric loss factor curves by using the proposed moisture content calculation method, which provides a result that is within 4.83% of that provided by the IDAX-300 moisture content analysis algorithm, thus demonstrating its validity.

A time-domain virtual electromagnetic interference (EMI) receiver model algorithm for corona-originated EMI of dc transmission line is proposed. The presented model is based on short-time fast Fourier transform (FFT) and digital quasi-peak, peak and average detector algorithms together with the measured corona current. The virtual EMI receiver model algorithm is verified by comparing with measurement results of conducted interference of the three regular waveforms. The influences of computational accuracy on the conducted interference are discussed. Through utilising the laboratory-scale corona cage to generate corona current, the 0.5 MHz excitation current is calculated by using short-time FFT and excitation function theory. The measured and computational average value, root mean square value, quasi-peak value and peak value of EMI receiver response to corona current sequence are obtained. It is found that computations of radio interference have a good agreement with the measured results.

In this study, the AC breakdown (BD) voltages and partial discharge (PD) activities of mineral-oil (MO)-based nanofluids were investigated under controlled conditions. The aim of this research is to improve the dielectric properties of MO by amalgamation with various types of nanoparticles, i.e. semiconducting and dielectric nanoparticles. Two types of nanoparticles, i.e. titanium dioxide and barium titanate with mean diameters of <100 nm were used in the nanofluid samples prepared for the experiments. The AC BD voltages of the nanofluids were investigated according to IEC 60156. In addition, PD characteristics of the MO-based nanofluids were examined including PD inception voltage (PDIV) characteristics and PD activity with a needle-plane electrode configuration. The test circuit was set up in accordance with IEC 60270 and the experiment was performed in conformity with IEC 61294 at room temperature. The test results showed that the AC BD voltages of the modified liquids were clearly influenced by the type of nanoparticles added, with the AC BD voltages of the MO with nanoparticles being slightly higher than those of the unmodified MO used for comparison. Furthermore, the nanoparticles also demonstrated a propensity to increase the PDIV of the nanofluids compared with the PDIV of the MO.

Blood leakage and resultant loss during haemodialysis therapy are life-threatening complications. As the venous needles (at arterial/venous sites) disconnect from blood lines, little reaction time is left to stop the blood loss. The authors integrate the wireless flexible sensor with a virtual internal impedance model to design a warning tool to early detect blood leakage and further lower the mortality rate it causes. This flexible sensor is fabricated via a screen-printing technique by printing electronic circuits on a soft substrate in an array configuration. The virtual internal impedance model employed is advantageous for both detecting if any short-circuit branch resistance develops and estimating the virtual internal impedances of the sensor. Once the metering nodal voltage changes, the estimated quantity resistances and near infinite resistances are employed to separate a short circuit from an open circuit. The algorithm developed can be implemented in an embedded system via a wireless fidelity wireless network through cloud computing. The experimental results show feasibility and potential of specifications for commercial design.

This study proposed the nodal dynamic equation to solve the electromagnetic transient of linear switching circuit. The nodal dynamic equation is derived from the principle of energy conservation. By using trapezoidal method and time step to discrete the dynamic equation, its time discrete format is equivalent to the EMTP equation. Comparing with the EMTP method, the proposed method can change its numerical integration method and time step flexibly in the simulation. It is more suitable to solve the switching circuit.

Permanent magnet (PM) axial flux machines are well adopted in microelectromechanical systems application, which needs a short axial length. PM micromotors have special characteristics such as transition zone which made their analysis different from macro ones. Due to the three-dimensional (3D) nature of PM micromotors, analysis and design of these micromotors require a fast and adopted 3D analytical model. This study presents a new 3D analytical model for a PM micromotor. In the presented analytical model, the micromotor is divided into several radial slices to take into account a part of 3D effects. In each slice, magneto-quasi-static Maxwell's equations are solved and back-electromotive force voltage is calculated as the most important parameter of micromotors. The accuracy of the model is verified by experimental and a 3D finite-element method model. The universality of the presented analytical model is challenged by using micromotors with different PM shapes including circular and trapezoidal. The presented analytical model is much faster than the 3D finite element model, but has the same accuracy, which makes it suitable for sensitive analysis and optimisation procedures.

Electrocardiograph (ECG) denoising is a preliminary step in QRS complex detection and ECG beat classification process. An ECG denoising methodology is proposed that uses ensemble empirical mode decomposition (EEMD) for decomposing input ECG to its intrinsic mode functions (IMFs). Then noisy-IMFs are identified by the proposed method that uses squared distance similarity measure. On selected noisy-IMFs, hard thresholding, by the evolutionary optimisation algorithms (EOAs)-based thresholds, is applied. For selecting the best performing EOA, algorithms namely artificial bee colony, particle swarm optimisation (PSO), and cuckoo search (CS) optimisation are implemented. The proposed methodology is tested with the Massachusetts Institute of Technology and Beth Israel Hospital (MIT-BIH) arrhythmia database and is evaluated in terms of signal-to-noise ratio (SNR) and mean-square error (MSE). In comparison with state-of-the-art methods, the proposed method is found to be the best attaining maximum SNR and MSE for PSO and CS algorithm optimised thresholding.

The near-field validation of computational electromagnetic models of personal wireless communication devices is becoming indispensable, especially, when assessing specific absorption rate (SAR) compliance to regulatory limits by computer simulation. A possible practice for such validation is to compare measured and simulated electromagnetic field distributions in a standard flat phantom designed for SAR compliance measurements. The authors recently presented an input impedance measurement-based validation method. They extend their scheme with a deconvolution procedure. This enables near field validation based on the reconstructed field obtained by the deconvolved measurement of the impedance change compared to the calculated . However, the reconstruction problem is inherently ill conditioned and requires numerical treatment. They demonstrate that the regularisation of the convolution matrix makes the reconstruction of the field feasible with promising error. Through examples of a 1 GHz printed inverted F and a 1.8 GHz printed monopole antenna, they show that the mean-square error as low as 1% between the original and the reconstructed is achievable with the proposed method.

Here, a new winding is proposed for 5-X variable reluctance resolver. In the proposed winding method, all the stator teeth are devoted to the signal windings and a peripheral slot is added to the stator core including two excitation coils. The performance of the resolver is discussed using the proposed winding and all previous winding methods. It is shown the position error of the resolver is less than that of the previously proposed methods and it can offer much simpler manufacturing process and consequently lower cost. All the analyses are performed using three-dimensional time stepping finite element method and finally, a prototype of the resolver is built and tested. The comparison between simulation and test results verifies the success of the proposed winding method.

In this work, the modelling and regulation of two mechanical systems are studied. The model is employed to describe the system dynamic behaviour. The regulator is employed to force the system states to track constantly wanted signals. The stability of the advised regulator is analysed via the Lyapunov technique. The recommended strategy is applied to a magnetic generator and in a hexarotor.

An attitude algorithm is used by a given magnetic and inertial measurement unit (MIMU) for weight fusion of the outputs of gyroscope and the outputs of the subunit constructed by accelerometer and magnetometer for attitude calculation of a rigid body. It has been proved that the weight assigned to the outputs of gyroscope determines the overall performances of attitude algorithm. A new weight adaptive regulation method based on Kalman filter and hidden Markov model is proposed, and then a new attitude algorithm is constructed by the integration of that method with recursive quaternion estimation algorithm. The authors’ attitude algorithm is compared with some other related attitude algorithms in their experiments. With the outputs of the sensors in MTi as the inputs of the new attitude algorithm, the maximum attitude estimation errors in response to three-dimensional random movements and the changes of their amplitudes are 2.85° and 6.82°, respectively, and the Allan variance of attitude drift in response to motionless conditions is 2.1×10⁻⁴°. Other attitude algorithms cannot simultaneously achieve similar dynamic and similar static performances comparing to their attitude algorithm. The results validate the overall performance improvement of their attitude algorithm.

Initial alignment and positioning assisted by star sensors have been a popular research direction for the inertial navigation system. In this study, an analytic method is proposed to achieve the integration implementation of coarse alignment, calibration and positioning for swaying base. Gyroscope bias, accelerometer bias and attitude estimations are given in analytical forms on the basis of the attitude matrix provided by the star sensor. Positioning can be realised by transforming the accelerometer calibration part when the position information is not available. Compared with the previous approaches, the proposed method establishes the intuitive relationship between the navigation parameters and sensor errors, and is easy to implement. Furthermore, the proposed method can be extended to moving base when the velocity measurement is available. Both the simulation and experimental results show that the proposal analytic method can provide both good initial attitude and sensor parameters for fine alignment process.

Here, a multiple-input–multiple-output (MIMO) Phantom Omni robot made by SensAble Technologies Inc. is identified by using a least-square support vector regression (LS-SVR). To this end, a two-stage hybrid optimisation strategy combining coupled simulated annealing as a priori optimisation strategy and a derivative-free Simplex method as a complementary stage is proposed to solve the LS-SVR model selection problem. This extra step is a fine-tuning procedure to enhance the optimal tuning parameters and hence lead LS-SVR to a better performance. Generalised v-fold cross-validation is considered as the criterion of LS-SVR model selection problem. The Phantom robot model is implemented via OPAL-RT to assess the performance of the proposed algorithm compared with firefly algorithm and adaptive particle swarm optimisation in solving LS-SVR model selection in practical application of the Phantom robot modelling. Finally, the proposed approach is validated and implemented in the hardware-in-the-loop based on OPAL-RT to integrate the fidelity of physical simulation as well as the flexibility of numerical simulations.

This study presents the results of optical spectrometry based measurements performed in three commercial dielectric liquids: synthetic ester, natural ester, and mineral oil. The optical spectra collected concern the breakdown initiated by standard lightning impulse voltage of positive polarity in a point-plane electrode system. The obtained results showed the differences between the spectra. The relationships between emission from atomic hydrogen (656.3 nm) and continuum concerning the wavelengths between 380 and 600 nm attributed to dissociation and fragmentation of molecules and recombination of molecular fragments were assessed as different for the distinctive liquids tested. The emission from atomic hydrogen was dominant in the case of mineral oil, however, for natural ester and first of all for synthetic ester, the light from the mentioned continuum had the highest intensity. Thus, this may be supposed that the differences in the spectra resulting from the different proportions of the physical processes responsible for the breakdown in a given liquid. It seems that in ester liquids the way for direct excitation and ionisation of liquid molecules is easier, so easier rotational and vibrational types of excitation of the high number density main molecules may take place giving a reflection in the optical spectra registered.

Capacitive high-voltage bushing is one of the typical oil-immersed paper insulation equipment, which is an indispensable external connection component for power transformers. In order to evaluate the effectiveness of frequency domain spectroscopy (FDS) for diagnosing moisture content of oil-immersed paper insulation bushing, this article studied the frequency-domain dielectric characteristics of oil-immersed paper insulation samples and field bushing. At the same time, the basic principle of interfacial polarisation is used to analyse the samples and field bushing with non-uniform moisture content. The results show that the moisture content affects the whole frequency band of the FDS curve. When the distribution of moisture content is non-uniform, the paper with high moisture content has a great influence on the whole FDS curve of oil-immersed paper insulation. In addition, the FDS curves will show a significant loss peak. The frequency of the peak point gradually moves towards the high frequency as the non-uniformity of the moisture content distribution increases. The experimental results show that the variation law of oil-immersed paper insulation can be used to quantitatively evaluate the moisture content and moisture type of oil–paper insulation power equipment.

A dual-gate aluminium gallium arsenide (GaAs)/GaAs pseudomorphic high electron mobility transistor is analysed based on the distributed modelling approach, wherein the transistor is considered as an active multi-conductor transmission line. Discretisation of the governing matrix Telegrapher's equation is carried out using the implicit Crank–Nicolson-finite-difference time-domain (CN-FDTD) method. The results obtained from the proposed method are compared with the results of the conventional leap-frog (LF) FDTD scheme. It is observed that the unconditionally stable CN method is in good agreement with the LF method even by increasing the time step size by the factor of 5000, leading to a dramatic decrease in the central processing unit time.