This study proposes a fault-tolerant control method for permanent magnet synchronous motors (PMSMs) based on the active flux linkage concept, which addresses permanent magnet (PM) demagnetisation faults in PMSMs. First, a mathematical model for a PMSM is established based on active flux linkage, and then the effect of PM demagnetisation on the PMSM is analysed. Second, the stator current in the static coordinate is set as the state variable, an observer is designed based on a sliding-mode variable structure, and an equation for active flux linkage is established for dynamic estimation based on the equivalent control principle of sliding-mode variable structure. Finally, the active flux linkage for the next moment is predicted according to the operating conditions of the motor and the observed values of the current active flux linkage. The deadbeat control strategy is applied to eliminate errors in the active flux linkage and realise the objective of fault-tolerant control. A timely and effective control for demagnetisation faults is achieved using the proposed method, which validity and feasibility are verified by the simulation and experiment results.

Owing to aggressive shrinking in nanometre scale as well as faster devices, particle strike manifesting itself into transient fault spanning multiple cycle and multiple units will be the centre-focus of application specific datapath generated through high-level synthesis (HLS)/architectural synthesis. Addressing each problem above separately leads to large area/delay overhead; thus tackling both problems concurrently, leads to huge incurred overhead. To tackle this complex problem, this paper proposes a novel low cost particle swarm optimisation driven dual modular redundant (DMR) based HLS methodology for generation of a transient fault secured design secured against its temporal and spatial effects. The authors' approach provides a low cost optimised fault secured solution through a particle swarm optimisation exploration framework based on user area-delay constraints. Results indicated that proposed approach obtains an area overhead reduction of 34.08% and latency overhead reduction of 5.8% compared with a recent approach.

This study presents the work carried out by the authors to apply Intel MKL PARDISO (a parallel sparse matrix solver) to the load flow solution algorithms of MATPOWER and OpenDSS. The goal is to explore the potential execution time reduction obtained when working with large power systems and multi-core installations. Test systems of different sizes were solved in order to observe the time reduction as function of the system size and the number of cores used in the parallel execution. Results show that except for the full Newton–Raphson algorithm, one should not expect a reduction in execution times when using a parallel routine. The use of a parallel sparse matrix solver is only justified when the sparse matrix must be recalculated at every step of the solution process or the systems under study are much larger than those analysed here. This study also presents how a parallel computing solution can be implemented in different applications by using available high-performance parallel libraries.

A dynamic mathematical model, using number of rotor bars as parameter, is reached for cage induction motors through the use of coupled-circuits and the concept of winding functions. The exact MMFs waveforms are accounted for by the model which is derived in natural frames of reference. By knowing the initial motor parameters for a priori adopted number of stator slots and rotor bars model allows change of rotor bars number what results in new model parameters. During this process, the rated machine power, number of stator slots and stator winding scheme remain the same. Although presented model has a potentially broad application area it is primarily suitable for the analysis of the different stator/rotor slot combination on motor behaviour during the transients or in steady-state regime. The model is significant in its potential to provide analysis of dozen of different number of rotor bars in a few tens of minutes. Numerical example on cage rotor induction motor exemplifies this application, including three variants of number of rotor bars.

Since multicast reduces bandwidth consumption in multimedia grid computing, the middleware for monitoring the performance and topology of multicast communications is important to the design and management of multimedia grid applications. However, the current middleware technologies for multicast performance monitoring are still far from attaining the level of maturity and there lacks consistent approaches to obtain the evaluation data for multicast. In this study, to serve a clear guide for the design and implementation of the multicast middleware, two algorithms are developed for organising all constituents in multicast communications and analysing the multicast performance in two topologies – ‘multicast distribution tree’ and ‘clusters distribution’, and a definitive set of corresponding metrics that are comprehensive yet viable for evaluating multicast communications are also presented. Instead of using the inference data from unicast measurements, in the proposed middleware, the measuring data of multicast traffic are obtained directly from multicast protocols in real time. Moreover, this study makes a middleware implementation which is integrated into a real access grid multicast communication infrastructure. The results of the implementation demonstrate the substantial improvements in the accuracy and real time in evaluating the performance and topology of multicast network.

In this study, a three-phase diode bridge rectifier and a single-phase voltage source inverter topology has been proposed for feeding single-phase utility grid employing a three-phase induction generator fed from wind energy. A self-excited induction generator configuration has been chosen for wide speed operation of wind turbine system, which gives the scope for extracting maximum power available in the wind. In addition to maximum power point tracking (MPPT), the generator can be loaded to its rated capacity for feeding single-phase utility grid using a three-phase induction machine, whereas it is not possible with existing configurations because of the absence of power converters. For the proposed system, MPPT algorithm has been devised by continuously monitoring the grid current and a proportional resonant controller has been employed for grid synchronisation of voltage source inverter with single-phase grid. A MATLAB/Simulink model of the proposed system has been developed to ascertain its successful working by predetermining the overall performance characteristics. The present proposal has also been tested with sag, swell and distortion in the grid voltage. The control strategy has been implemented using field programmable gate array (FPGA) controller with modularised programming approach. The efficacy of the system has been demonstrated with the results obtained from an experimental set-up in the laboratory.

In this study, a rectenna operating at the GSM-900 frequency band has been fabricated and tested. This rectenna composed of a 2 × 1 T-shaped monopole array antenna and an energy processing circuit. In order to reduce the gap between adjacent antenna elements in the array structure, the proposed array antenna uses a ground stub. Compared with other array antennas, the proposed array antenna with the ground stub reduces the size up to 50% without affecting the gain and bandwidth. An antenna prototype is fabricated and experimentally tested. The measured antenna's gain and bandwidth are 3.2 and 152 MHz, respectively, hence showing its suitability for radio-frequency (RF) energy harvesting application. For this to be feasible, the developed array antenna is matched with the rectifier at GSM-900 using a single stub matching network. The measured result demonstrates that the proposed rectifier circuit offers the conversion efficiency of 21.2 and 63.6% for an input power of −20 and 0 dBm, respectively. Finally, the rectifier performance is attested experimentally with the developed array antenna. The rectenna's measured RF-to-dc conversion efficiency was found to be 60% at the far-field distance from the transmitting antenna.

In this study, the influence of stator/rotor-pole combinations on electromagnetic performance in partitioned stator doubly salient permanent magnet (PS-DSPM) machines is investigated, in terms of open-circuit flux-linkage, back-electromotive force (EMF), cogging torque and on-load torque characteristics. Analytical deduction shows that by modifying the all poles wound winding to alternate poles wound winding in the 12/11- and 12/13 stator/rotor-pole PS-DSPM machines, the fundamental distribution factor and hence the fundamental winding factor can be enhanced, resulting higher torque density. Consequently, among the 12-stator-pole all and alternate poles wound PS-DSPM machines, the 10- and 11-rotor-pole machines exhibit the highest torque density, respectively. However, the 12/10- and 12/14-pole alternate poles wound PS-DSPM machines suffer from higher phase back-EMF even harmonics, resulting larger torque ripple. The 12/10- and 12/11-pole all and alternate poles wound prototypes are built and tested to verify the finite-element analysis.

In this study the authors present a novel image denoising method based on applying adaptive thresholding on partial differential (PDEs) methods. In the proposed method the authors utilise the adaptive thresholding to blend the total variation filter with anisotropic diffusion filter. The adaptive thresholding has a high capacity to adapt and change according to the amount of noise. More specifically, applying a hard thresholding on the higher noise areas, whereas, applying soft thresholding on the lower noise areas. Therefore, the authors can successfully remove the noise effectively and maintain the edges of the image simultaneously. Based on the adaptation and stability of the adaptive thresholding we can achieve; optimal noise reduction and sharp edges as well. Experimental results demonstrate that the new algorithm consistently outperforms other reference methods in terms of noise removal and edges preservation, in addition to 4.7 dB gain higher than those in the other reference algorithms.

A novel wideband patch antenna with a differential-fed structure is proposed in this study. For this antenna, an H-shaped patch is first adopted to build a compact design. Then, by introducing a via-wall-plate pair as the differential feeding scheme, favourable radiation patterns and enhanced operating bandwidth can be achieved in a low profile. Furthermore, a Marchand balun is incorporated into the overall design to facilitate the test and direct integration with existing single-end radio-frequency circuits. The proposed antenna, which is designed and fabricated, using low-temperature co-fired ceramic technology, could be used to develop a highly integrated system-in-package. The measured results demonstrate that the proposed antenna with a low profile of 0.06λ ₀ obtains an impedance bandwidth of 11.2%, a peak gain of 7.1 dBi, and a low cross-polarisation of better than −20 dB.

Multi-port measurements are a big challenge in circuits' verification, especially when the frequency increases. This study presents a new technique for measuring S-parameters of multi-port ultra-wideband (UWB) microwave and mm-wave circuits. The concepts are based on direct or indirect applying modulated UWB impulse radio in desired bandwidth to the one port of the modified multi-port circuit and gathering the reflected signal in the same port and the output signal in the second port in time domain, and the other ports are left opened with a special designed added electrical length. Then by applying intelligent windowing in time domain to the gathering data, and using fast Fourier transform, the desired S-parameters are extracted. Validation of this technique is verified by design and fabrication of a three-port UWB Wilkinson power divider in 22–30 GHz. The simulation and measurement results of the reflection and transmission S-parameters by using this new technique are very close to those are extracted with the conventional vector network analysers S-parameters measurements and show the ability and the accuracy of this technique.

Direction-of-arrival (DOA) estimation of radio signals is of utmost importance in many commercial and military applications. In this study, the authors propose an efficient field-programmable gate array (FPGA) architecture for implementing a recently published DOA estimation algorithm. This algorithm estimates DOAs by making use of QR decomposition of the received data matrix of four- and eight-element uniform linear antenna arrays. The hardware implementation has been thoroughly analysed and experimentally validated by building a real-time prototype of the DOA estimation algorithm. The experimental results show good agreement between DOA estimates obtained by the prototype and true values.

The amount of light flicker in an AC–DC light-emitting diode (LED) driver is dependent on the size of filter capacitors. In this study, a study is conducted on reducing the size of filter capacitor in an AC–DC buck–boost/flyback LED driver using flicker index and per cent flicker light measures. Using this approach, a procedure for minimising the filter capacitance is presented. It is then concluded that relatively small filter capacitors such as film or ceramic capacitors can be chosen while meeting light flicker requirements. Hence, an LED drive with a longer lifetime can be achieved when compared with a driver using electrolytic capacitors. Experimental studies are presented for a 20 W AC–DC buck–boost/flyback LED driver prototype which utilises ceramic capacitors for driving Cree CR22-32L and XLamp XP-G LED strings.