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We have developed a transverse flux linear switched reluctance motor (TFLSRM) in which 12 primary-side poles, each composed of four sectors, boost efficiency over the whole operating range. Each sector can operate independently, enhancing the robustness of the system by providing fault tolerance. We present a standard design method for the machine based on a power output equation related to the machine dimensions, air gap, force, efficiency, operating velocity, and required voltage. We illustrate the procedure by designing a sector for a three-phase, 250 W prototype TFLSRM. The method uses finite-element analysis to calculate the flux density, thrust force, and normal force versus position and current prior to construction of the prototype. Calculated and experimental results match within 5%, validating the design procedure. Index Terms--Finite-element method, linear switched reluctance motor, machine design, transverse flux motor.

In the European Union, the average load factor of electric motors in both industrial and tertiary sectors is estimated to be less than 60%. However, in some industrial sectors, the average load factor for some motor power ranges can be as low as 25%. Most oversized three-phase induction motors operate with low efficiency and power factor, which is, by far, the most important cause for poor power factor in industrial installations. In the low-load operating periods, motor performance can be improved both in terms of efficiency and power factor if the magnetizing flux is properly regulated. In this paper, a multiflux level, three-phase, squirrel-cage induction motor is proposed, in which the efficiency and power factor can be both maximized as a function of load. This novel motor can be a surplus value in industry due to its flexibility, particularly, for variable load applications in which significant energy savings can be obtained, and can also be used as new or rewound general purpose spare motor (with several levels of voltage, magnetizing flux and/or power). The proposed motor has a stator winding with two sets of turns, sharing the same positions in the stator slots (which can be connected either in series or in parallel). Among all the possible stator winding connections, six modes were selected and analyzed (two of which are new). The basic principles for proper connection mode change are discussed. An electronic device and a contactor concept for automatic connection mode change are proposed. As far as the authors know, this concept is described and analyzed for the first time. Index Terms--Energy efficiency, energy savings, multiflux stator winding, induction motors, power factor, stator winding connection modes.

The performance of the oversized three-phase induction motors can be improved, both in terms of efficiency and power factor, with the proper change of the stator winding connection, which can be delta or star, as a function of their load. A practical method is proposed to quickly and easily evaluate which stator winding connection is more appropriate for the actual motor load profile, in order to increase the motor efficiency and power factor. This new method is suitable for in-field evaluation, because it requires only the use of inexpensive equipment and has enough accuracy to allow a proper decision to be made. The automatic change of the stator winding connection, as a function of the motor line current, is also analyzed. When properly applied, these methods can lead to the improvement of the efficiency and power factor of permanently oversized motors, motors with a load variation between low load and near full load during their duty cycle, and/or motors driving high-inertia, low duty cycle loads. The proposed methods are particularly suitable to industrial plants where typically many electric motor systems are oversized and/or can have a wide load variation. In these conditions, the active and reactive electrical energy bill can be significantly reduced. Index Terms--Energy efficiency, motor oversizing, power factor, savings, stator winding connection change, three-phase induction motor.

In the European Union (EU), variable-speed drives (VSDs) were identified as the motor systems technology having the most significant electricity savings potential. In the EU, the identified economic electricity savings potential with the application of VSDs, by the year 2015, in industrial and tertiary sectors, are 39 and 8 TWh/year, respectively. However, only a small percentage of this potential is being used. In this paper the characterization of the current market of the VSDs is presented, including the average prices, the installation costs, and the total sales in each EU country, per power range. Selected VSD applications are presented. The key barriers to a wider application of VSDs are identified. In particular, the power quality and reliability problems associated with the use of VSDs are presented and possible technical solutions are discussed. Index Terms--Electric motor efficiency, electricity conservation, energy-efficient motor systems, market transformation, motor drives, motor systems, variable-speed drives (VSDs).

Since 1998, 817 motor efficiency test data sets, in the 1-500-hp (0.75-375 kW) range have been collected from several sources in different countries around the world, for 50 and 60 Hz. The test data include the motor efficiency using the IEC 34-2 and IEEE 112-B test standards, and the quantification of the stray load losses (SLLs), using the IEEE 112-B method. In 125 cases, the test data include the efficiency computed with both methods. The aim of this paper was the quantification of the discrepancy between the two mentioned standards, and to establish an approximate method to allow the comparison between motors tested with the two standards. Based on the significant number of collected motor data sets, it was concluded that, when compared to the IEEE 112-B standard, the IEC 34-2 standard is less accurate, and gives typically higher efficiency values, mainly because of the SLLs estimation procedure. The IEEE 112-B SLLs computed values are typically higher than the IEC SLLs predefined values, on average of 1.0 and 0.8 percentage points for 50-Hz and 60-Hz motors, respectively. Also, the average SLLs values vary slightly with the motor power. Using efficiency measurements made with both standards on the same motors, it was possible to confirm that the SLLs are the main reason for the observed discrepancy in the efficiency values. The results of the analysis carried out in this paper offer the possibility of comparing the efficiency of motors tested under the IEC 34-2 standard with motors tested with IEEE 112-B, leading to a choice of the most cost-effective option. This paper also provides a key contribution to the ongoing revision of the EEC 34-2 standard. Index Terms--Efficiency testing standards, induction motors, market transformation, motor testing, stray load losses.

This study proposes an induction motor drive system based on the LC filter integrated quasi‐Z source indirect matrix converter (QZS‐IMC). The proposed drive system shows the following features: (i) variable voltage control of inductor motor is achieved by the rectifier stage and variable frequency control is achieved by the inverter stage; (ii) automatic low voltage ride through ability enhances capability of the proposed drive against grid voltage sag; (iii) wide voltage gain range ensures the drive system with high performance in wide speed range; (iv) there is no additional input filter. The voltage control implementation in the rectifier stage is proposed to benefit low voltage stress and low converter loss. The control method combines motor vector control, minimum shoot‐through duty cycle and maximum modulation indexes. As a result, the input power supply voltage and dc‐link voltage are maximally utilised and the power loss is reduced. Simulation and experimental results verify the proposed QZS‐IMC motor drive system. [ABSTRACT FROM AUTHOR]

Summary: The existing model of LC filter integrated quasi‐Z source indirect matrix converter (QZS‐IMC) was derived using the DC circuit modeling method, which is mainly effective in DC circuit. As an ac circuit, the existing voltage boost ratio model of LC filter integrated QZS‐IMC exhibits a big error from the real boost ratio. Moreover, current amplitude and phase angle of QZS network were not considered in the existing model. This paper proposes a new comprehensive model of LC filter integrated QZS‐IMC taking into account the circuit's ac characteristics. The new model shows that voltage boost ratio is strongly related to QZS network inductance, capacitance, and frequency of input power supply. It can be concluded from the new model that the boost ratio is higher than 1/(1 − 2D), which is the boost ratio of existing model. Moreover, the new model shows that power factor affects voltage gain of QZS‐IMC system. The new model is compared with the existing model, circuit simulation, and experimental test. The results verify the new model and analysis. [ABSTRACT FROM AUTHOR]

The existing single‐phase, quasi‐Z‐source inverter (qZSI), photovoltaic (PV) power system with integrated battery energy storage (BES), abbreviated as BES‐qZSI‐PV power system, has several well‐known advantages, but cannot operate at night because there is no PV power input. In this study, a solution to overcome this issue is proposed. First, the power circuit of the conventional BES‐qZSI‐PV topology is modified to allow its operation at both day and night. Then, the system model for the night‐operation mode is built and a qZS network parameters' design method to limit the double‐line frequency harmonic at the dc side is developed. A control strategy to ensure the high‐performance operation of the system at all times, is proposed. Based on an experimental platform of single‐phase BES‐qZSI‐PV power system, three groups of experimental tests with different qZS network parameters and battery voltages are carried out to verify the model and parameters design method by means of comparing the experimental, circuit‐based simulated, and model‐based calculated results. The proposed BES‐qZSI‐PV system performance is experimentally evaluated in steady‐state operation and day‐to‐night transit operation, as well as by the power efficiency curves in day‐ and night‐modes. [ABSTRACT FROM AUTHOR]

Byline: Anibal T. de Almeida, Fernando J.T.E. Ferreira Electric motors are repaired 2-3 times over their lifetime. Poor repair practices, particularly widespread in developing countries, can lead to a significant increase in motor losses. It is estimated that worldwide poor repair leads to annual electricity losses of approximately 40 TWh, representing 20 Mtons of CO2 emissions. The main objective of this paper is to provide a technical basis for designing demand side management actions, which address the motor repair market. This paper brings into focus motor repair process trends, energy-efficient motors, typical repair process, actions to promote energy-efficient motor repair, energy-efficient motor rebate schemes to replace old, badly damaged motors and the factors influencing payback. This paper will be useful to energy policy makers, and Demand Side Management (DSM) staff in energy agencies and electric utilities.