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Permanent-Magnet Synchronous Linear Motors (PMSLM) are more and more frequently used as all-electric direct-drive actuators in those applications where a force needs to be developed along a fixed direction. In this paper, an accurate 3D thermal model of a PMSLM is derived through a lumped-parameter network approach which exploits all the symmetries in the actuator structure to maximize the spatial density of nodes. Numerically-efficient techniques are then proposed to solve the thermal network analytically. Some experimental validations are finally presented based on the thermal testing of a laboratory prototype.

[EN] The fault diagnosis of rotating electrical machines has received an intense amount of research interest during the last 30 years. Reducing maintenance costs and preventing unscheduled downtimes, which result in losses of production and financial incomes, are the priorities of electrical drives manufacturers and operators. In fact, both correct diagnosis and early detection of incipient faults lead to fast unscheduled maintenance and short downtime for the process under consideration. They also prevent the harmful and sometimes devastating consequences of faults and failures. This topic has become far more attractive and critical as the population of electric machines has greatly increased in recent years. The total number of operating electrical machines in the world was around 16.1 billion in 2011, with a growth rate of about 50% in the last five years [1].

As a result of socio-economic growth and paying attention to environmental aspects requirement in order to improve the reliability and achieve higher service, better power quality and increasing energy efficiency are taken more into consideration. Thus, home micro-grids (H-MG) with non-dispatchable Source and interruptible loads can be used as the primary tool to achieve the stated objectives. In order to implement the energy management system (EMS) an algorithm is presented in this paper. EMS which is based on harmony search method for multi-purpose extrapolation of a sample H-MG with renewable energy sources (RES) as well as compound resources of backup power such as micro-turbine and battery for levelling the mismatch of power or for additional power saving in case of necessary. In this paper, the harmony search (HS) for an algorithm to minimize the costs associated with sources, RLD and reduce the price of the electricity (i.e. market clearing price) with respect to the proposed price of production and supply, the price of non-interruptible loads, the optimal production of each of the existing resources in the micro grid is determined. For reliability enhancement the uncertainty is considered in using wind turbines (WT), photovoltaic (PV), load demand and market clearing price in the algorithm. The recommended algorithm system is tested on a H-MG sample. These results show the capability of the HS approach in supplying the load requested.

This paper presents a Multi-stage stochastic bi-level model for the expansion planning of Wind resources in power systems at a multi-stage horizon. In this paper, the power system consists of a combination of fossil fuel technologies and Wind resources for investment. Demand is characterized by a certain number of demand blocks. The uncertainty of demand for each this block (for each time period of the curve) is determined by the scenario. Afterwards, the suggested model is converted to a mathematical programming with some equilibrium constraints. Following that, after linearization, a mixed integer linear program is obtained. This framework is examined on the IEEE RTS 24-bus network. The obtained simulation results confirm that this model can be appropriately used as a means to analyze the behavior of investments in wind and thermal units.

This paper reports on the results of a research aimed at investigating the opinions of conservation officers toward the installation of photovoltaic roof tiling systems in buildings of historic importance in England. The study aims at providing useful and new information on the possibilities and limitation of photovoltaic systems in buildings of historic importance to the operators working in the area. The research is based on the analysis of 117 surveys completed by officers working in planning departments in councils across England; including metropolitan districts, London boroughs, unitary authorities, counties and district councils. Results suggest that PV roof tiling systems currently only have a limited application as energy efficiency systems in buildings of historic importance. Consequently, they are only partially known by conservation officers. It also became evident that more succinct legislation on the installation of these systems to listed buildings would provide clearer objectives to the officers in charge of approving or rejecting applications. Lastly, it emerged that the whole system would benefit from stakeholders (such as Historic England and the UK Government) working together to provide more consistent approach when producing guidance documents.

Slotless permanent magnet machines are attractive in some modern drive and power generation fields, where the cogging torque and additional losses need to be minimized or removed. The stator slotless design can be combined with different surface permanent magnet (SPM) rotor topologies. In this paper, explicit analytical expressions are derived to analytically compute the slotless machine torque and no-load back Electro-Motive Force in the case of segmented SPM rotor with parallel, radial, or Halbach-array magnetization patterns. The expressions are found by solving the magnetic field due to the slotless stator winding and to the permanent magnet blocks; the latter modeled through equivalent surface current densities. The accuracy of the method is successfully assessed by comparison with the finite-element analys is (FEA). The proposed formulas are an effective alternative to the FEA to quickly compare different design solutions as well as to optimize them. Application examples are provided in which the presented method is adopted to define the machine cross section that maximizes the torque density.

The computation of end-coil leakage inductances of electric machines is a challenging task due to the complicated leakage flux 3-D distribution in the winding overhang region. In this paper, the problem of computing the field-circuit leakage inductance of round-rotor synchronous machines is addressed. The proposed method is fully analytical and descends from the symbolical solution of Neumann integrals applied to the computation of self-inductance and mutual inductance combined with the method of mirror images to account for core effects. With respect to existing analytical approaches, the methodology requires neither numerical integral solutions nor discretizing the end-coil geometry into small straight elements. The accuracy of the proposed technique for computing the mutual inductance between two single-end turns is assessed against measurements on a dedicated experimental setup. The extension of the method to the computation of the entire field-circuit end-coil leakage inductance is assessed by comparing with the 3-D finite-element analysis.

Round conductive bars embedded in semi-closed slots are frequently used in the construction of electric machinery, for instance in the squirrel cage of induction motors. Frequently, such as in the study of induction motor steady-state performance at rated slip, it is useful to estimate the slot leakage inductance of these conductors under the hypothesis of no eddy currents and no magnetic saturation. This is usually done through simple approximated analytical formulas available in the literature. In this paper, an improved explicit ready-to-use leakage inductance expression for circular bars embedded in semi-closed slots is derived by solving Poisson's equation in the slot domain. The precision of the proposed formulation is assessed against Finite Element Analysis (FEA) for various slot geometries and is shown to always give very accurate results, with errors below 2%. Conversely, approximated simplified formulas available from the literature are demonstrated to possibly give large errors, which exceed 20% for some explored slot geometries.

Squirrel-cage induction motors are the most widely used type of electric machinery in industrial applications thanks to their rugged, cheap and robust construction. For the fast prediction of induction motor steady-state performance without the need for time-consuming finite-element analyses, the equivalent circuit parameters of the machine need to be calculated, including rotor slot leakage inductances. This paper, in particular, proposes a new improved analytical formula to determine the rotor slot leakage inductance in squirrel-cage induction motors with rectangular-shaped bars. The formula is obtained by solving Poisson's equation in the slot domain. Results are assessed by comparison against Finite Element Analysis (FEA). The precision of the presented methodology is also compared to that of approximated analytical models available from the literature. The comparison shows that the accurate formula proposed is in excellent agreement with FEA with errors below 2%, while the simplified model generally leads to errors above 10% which increase as the height-to-width bar ratio decreases.

This paper analyzes a different approach for actuation of shipboard loads such as rudders, stabilizing fins, or other linear drives, which are usually powered by oil-fed actuators. Hydrostatic transmissions are classically used when the highest torques/forces with low speeds are demanded. However, the oil used as force-transmission fluid is troublesome due to environmental issues. Oil production, use, and final disposal is costly and presents environmental risks. Also the maintenance onboard ship is intensive and hazardous for the operators. A full electric solutions is ulteriorly studied in this paper, based on a prototyped linear machine using permanent magnets and inverter feeding. Copper, friction, and iron losses are the main limiting factors in developing the required thrust at low speed, which is, ultimately, the main obstacle to a gear-less or direct-drive full-electric application. This paper shows incremental work on the prototype, through a dedicated circuit model accounting for all the machine losses and providing an affordable model of machine overall efficiency. The model will be used in further works to asses the machine performances in typical onboard service duties.