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A conventional electric vehicle charger (EVC) charges only one EV concurrently. This leads to underutilization whenever the charging power is less than the EVC-rated capacity. Consequently, the cost-effectiveness of conventional EVCs is limited. Reconfigurable EVCs (REVCs) are a new technology that overcomes underutilization by allowing multiple EVs to be charged concurrently. This brings a cost-effective charging solution, especially in large car parks requiring numerous chargers. Therefore, this paper proposes an optimal planning strategy for car parks deploying REVCs. The proposed planning strategy involves three stages. An optimization model is developed for each stage of the proposed planning strategy. The first stage determines the optimal power rating of power modules inside each REVC, and the second stage determines the optimal number and configuration of REVCs, followed by determining the optimal operation plan for EV car parks in the third stage. To demonstrate the effectiveness of the proposed optimal planning strategy, a comprehensive case study is undertaken using realistic car parking scenarios with 400 parking spaces, electricity tariffs, and grid infrastructure costs. Compared to deploying other conventional EVCs, the results convincingly indicate that the proposed optimal planning strategy significantly reduces the total cost of investment and operation while satisfying charging demands. [ABSTRACT FROM AUTHOR]

Touch voltages are more likely to appear on long‐distance pipelines that lie in shared corridors with transmission lines. The touch voltage level varies with soil resistivity and can become hazardous while maintenance is being undertaken, necessitating risk assessment. Therefore, a novel approach is proposed that achieves better accuracy in the risk assessment of hazardous touch voltages appearing on pipelines than current approaches. The proposed approach incorporates soil resistivity measurements taken over a 1‐year period, allowing for the derivation of soil models, touch voltage hazard profiles versus time and, thus, a probability reduction factor that can be integrated into a probabilistic risk calculation. Using a probability reduction factor is a key aspect to improving the accuracy of risk assessment, allowing pipeline asset operators to clearly identify whether or not, risk mitigation action is required. Further, the proposed approach allows appropriate risk mitigation actions to be identified. The efficacy and significance of the proposed approach are demonstrated through a case study on an area of land near a shared gas pipeline and transmission line corridor. The case study results show how appropriate safety levels can be achieved by adjusting the number of work day per year and temporary protection settings. [ABSTRACT FROM AUTHOR]

A new method for the generation of high-quality sinusoidal signals is presented. Multibit binary signals are represented using uniformly weighted single bit streams that can then be processed by digital logic. Building blocks that are useful for the construction of the sinusoidal generator are also presented. The bit-stream representation has the advantage of having the characteristics of a classical pulsewidth-modulation signal and hence can be used to drive high-power switching devices with minimal conditioning. The technique is simple and can easily be implemented using digital logic on a field-programmable gate array (FPGA). The operation of a single-phase inverter using the proposed technique is demonstrated using an Altera Stratix FPGA and a custom-built power stage. The complete digital design uses less than 200 logic elements. The performance of this technique is quantified using simulations and practical measurements. Practical implementations lead to total harmonic distortion measures ranging between 0.75 % and 4.92 %. Index Terms--Bit streams, inverter, pulsewidth-modulation (PWM) generation, variable-frequency drives.

Field-aligned starting (FAS) is a new technique for starting three-phase cage induction motors on either three-or single-phase supply lines with minimal inrush currents. FAS generates a high impulselike torque to start the motor that is independent of the mains supply, before connecting the already spinning motor to the mains supply. In contrast to conventional starting techniques, FAS imposes higher than normal/rated voltage and current conditions on the machine at starting, and as such, the transient performance of FAS operated motors is complex in nature and largely governed by a number of key circuit variables, the values of which are critical for an efficient and economical design of FAS. A detailed insight into the influence of these key parameters on transient performance during startup is essential to avoid time consuming and inefficient trial and error design methods currently utilized in FAS designs. This paper addresses this need through the investigation of both the functionality and the extent of impact of the key variables on the starting performance of FAS. A transient model is utilized, and both experimental and simulated results suggest that, for a given set of circuit components, the proper selection of variable values is critical to achieve the best possible performance at startup. Index Terms--Energy conversion, induction motors, parameter estimation, transient analysis.

This paper presents a semianalytical technique that predicts the propagation characteristics of high-voltage (HV) transient pulses along a single-wire electric fence line with an earth return. The technique models the fence line in the frequency domain to facilitate an analytical solution for the propagation of HV pulses along the line. The frequency-domain solution is then transformed into time domain through a numerical Laplace inversion algorithm to determine the propagation characteristics of the line at a given location and time. For various line conditions, the propagation characteristics of HV pulses are investigated, and results indicate that the parameters of fence lines are frequency dependent, and an accurate insight into the propagation characteristics of HV pulses along single-wire fence lines can only be achieved through a frequency-dependent fence model. As confirmed by simulations of power systems computer-aided design, the proposed technique based on a frequency-dependent fence model is accurate, and can be considered an invaluable tool for designing complicated electric fence networks. Index Terms--Electric fence, pulse transmission.

Field aligned starting (FAS) is a new technique for starting three-phase cage induction motors on single-phase supply lines with minimal inrush currents. It uses a simple energy storage system to generate a very high impulsive torque by which the motor is started before being connected to the mains supply. The spinning motor can then be connected to the mains to operate in a standard Steinmetz connection without incurring high inrush currents, if the moment of mains connection is properly timed. This paper presents a transient model and an accompanying parameter estimation method through which the transient behavior of three-phase induction motors operated with FAS can be analyzed. The proposed model is based on instantaneous symmetrical components and is used to investigate a 3 kW motor started under various operating conditions. The proposed parameter estimation method and the developed transient model are both validated by experimental results. Index Terms--Energy conversion, induction motors, parameter estimation, transient analysis.

This paper presents a new model that facilitates a comprehensive analysis of split-capacitor push-pull parallel resonant converter (PPRC) topology in three different modes. The three modes, named as Normal, Buck, and Boost, are realized by operating the converter with a variable switching frequency, which is generated by modulating the damped resonant frequency with a variable phase-shift. The proposed modes allow the converter to operate with a variable voltage gain over a wide load range with zero-voltage switching (ZVS). In this paper, the operation and behavior of the converter in Boost mode is analyzed in detail through derivation of explicit analytical expressions for voltage gain, ZVS frequency and other circuit variables. Experimental results of a 150 W prototype PPRC converter, controlled by the proposed technique, are presented and compared with simulations and theoretical results to prove the validity of both the proposed model and control technique. The results indicate that the gain of the prototype converter can be increased up to about 145% of the nominal voltage and the parasitic elements have only minor impact on the performance. Index Terms--Power converters, power electronics, resonant converters.

This paper presents a technique for the suppression of voltage transients through the use of dynamically reconfigurable supercapacitor (SC) banks. The technique requires a minimum of two SC banks to transfer power from a mains supply to load in complete isolation. The banks are operated independently as energy-storing elements in one of the three states of charging, discharging, or idling, and transition of banks from one state to another with isolation is realized dynamically by inductively coupled power-transfer technology with no physical contacts. The proposed technique has no direct connection between the mains supply and load at any given moment, and power transfer takes place in complete isolation with built-in protection for both common- and differential-mode transients. Sizing of the banks with respect to various types of SCs and system parameters is analyzed. Comparisons between simulations and experimental results of two prototype systems, subjected to combination transient surges specified by IEC61000-4-5 standard, are presented with a discussion to show the validity of the proposed concept and its suitability for uninterruptible power systems and emergency power supplies. Index Terms--Electromagnetic induction, power supplies, supercapacitors (SCs), surge protection, uninterruptible power systems (UPSs).

This paper presents an analytical solution for the magnetic field inside an unconventional ironless brushless (ILBL) dc motor design. We discuss the unique characteristics of the design, which adopts an 'inside-out' construction with an internal ironless stator. With the intention of obtaining an analytical solution for the magnetic field, we propose a model based on a magnetic pole concept for representing the magnetic circuit. The magnetic field inside the motor, which has no iron for guiding magnetic flux paths, is obtained by solving Laplace's equation for magnetic scalar potential. We present both analytical and numerical solutions for the magnetic field and compare them with measured results of a 20-pole prototype IL design to show the validity of the model. The IL design is simple, easy to manufacture and, as indicated by the results, has an optimum number of magnets, for which its performance becomes maximum. Index Terms--Brushless machines, Laplace equation, magnetic analysis, permanent magnets.