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The adoption of assisted reluctance machines in various applications is becoming popular. The use of permanent magnets in synchronous reluctance machines solves some drawbacks and improves the performance; in general, sintered magnets with regular shapes have been adopted. On the other hand, this approach does not permit to fill completely the flux barriers. The proposed solution consists of the use of bonded magnets. Two types of ferrite magnets, sintered and bonded, have been considered in the study. Different parameters have been investigated, both in the production process and in the performance evaluation. The simulation results have been compared to the reference synchronous reluctance machines. A prototype machine has been prepared, and different experimental tests have been performed. Satisfactory matching between measurement and simulation results has been observed. [ABSTRACT FROM AUTHOR]

One of the main obstacles to the robust optimization for permanent magnet machines is the high computational burden, which is mainly caused by the robustness evaluation process considering the manufacturing uncertainties. In this paper, a sequential sampling Kriging model is adopted to estimate the design robustness, and the problem of high-dimensional variables for the surrogate model due to uncertainties is avoided through adopting the worst-case based approach. To further reduce the number of finite element analyses (FEA) required for constructing a metamodel, a multi-points sequential sampling process with a two-step optimization oriented surrogate model updating algorithm is proposed. Compared with the FEA directly based robust optimization in previous work, similar Pareto Fronts are achieved by adopting the meta-model proposed algorithm but the overall run time reduced by 75%. In the end, an optimization problem for a 1.2 kW motor is considered by applying the proposed algorithm, and two prototypes with deliberately designed tolerances, imitating the worst-case scenarios in the real world, are manufactured. The worst-case torque ripple is reduced from 7.6% to 4.8% after optimizing, and this verifies the efficacy of the proposed algorithm. [ABSTRACT FROM AUTHOR]

A new vector-phasor combined with an analytic method for solving complex flux distributions is proposed. The flux leakage and losses in the end region of a 1266 MW scale generator are analyzed by both finite element simulation and an analytical method. The deviation of the calculated result between the analytical model and the finite element method is very small. The analytical model can acquire current data for fast prediction of the flux density. The analytical and numerical results of the flux distribution are found to be in a satisfactory agreement. In addition, the ability to reduce the eddy current losses in the end regions is also researched using various of structural solutions. [ABSTRACT FROM AUTHOR]

In the last decade, the trend toward higher efficiency and higher torque density electrical machines (EMs) without permanent magnets (PMs) for the industrial sector has rapidly increased. This work discusses the latest research and industrial advancements in synchronous reluctance machines (SynRMs), being the emergent motor topology gaining wide acceptance by many industries. This article presents an extensive literature review covering the background and evolvement of SynRM, including the most recent developments. Nowadays, SynRM has found its niche in the EM market, and the reasons for that are highlighted in this work together with its advantages and disadvantages. The key journal publications in SynRM topics are discussed presenting the biggest challenges and the latest advancements with particular regards to the design methodology. This article aims to provide a thorough overview to the research community and industry about SynRM. There is a clear potential for SynRM to take over a significant portion of the EM market in the near future to meet efficiency standards in industrial applications without the use of rare-Earth PM technology. [ABSTRACT FROM AUTHOR]

The cage losses in induction machines due to spatial or time harmonics in the air-gap field are a crucial parameter for a precise estimation of the machine efficiency. Using finite element, the common approach to consider the overall cage losses, by performing complete time-domain analyses. Alternatively, a rough estimation is achieved introducing equivalent parameters in the circuital model. In this article, a methodology for cage losses computation due to air-gap spatial field harmonics is described. The proposed finite element procedure is faster than the time-domain analysis since it is based on magneto-static and linear time-harmonic simulations to carefully consider the iron saturation and compute the induced currents in a specific working point. In the article, a detailed procedure description and comparison with respect to the time-domain approach is reported. [ABSTRACT FROM AUTHOR]

This paper is focused on the design, optimisation and control of a permanent magnet assisted synchronous reluctance machine (PMaSynRel) for low cost high efficiency household appliances, in particular a motor for washing machine. The design and optimisation of the motor aims at maximising the torque produced and power factor, while minimise torque oscillations and the losses, thus improving the efficiency. A campaign of tests has been carried out on the prototype of the optimised machine, comparing finite element results and experimental measurements as a validation of the proposed design. In addition, torque ripple measurements are confirming that the solution proposed is meeting the optimisation design targets. The outcomes of this project are demonstrating that PMaSynRel drives are a suitable candidate for white goods sector, and that the proposed design is able to boost the performance and efficiency class with respect to the state-of-the-art solutions. [ABSTRACT FROM AUTHOR]

An 8-pole 48-slot dual three-phase synchronous reluctance motor has been tested under half control mode, that is, when only a single three-phase system is supplied while the other is not operating. Changing the terminal connections of the motor prototype available, two different winding configurations have been tested. This allows their performances to be experimentally compared. At first, the cross coupling effect between the axis in $dq$ reference is analyzed, by measuring the flux linkages for different current combinations. The torque characteristics are compared in terms of torque map, maximum torque capability and torque ripple. Then the finite element analysis has been used to explain the experimental results and to investigate the radial forces on the rotor. Finally, the impact of a lack of symmetry between the two three-phase system is investigated. [ABSTRACT FROM AUTHOR]

This article discusses a method to consider the effects of the manufacturing uncertainties on the additional cogging torque harmonics. With this method, the sensitivity analysis can be incorporated into the design stage instead of just checking it afterwards. With the authors’ previous work of the worst-uncertain-combination-analysis (WUCA) method, several design parameters and their effects on the additional cogging torque harmonics under uncertainties are discussed. It is demonstrated that a design with inherent robustness can be obtained through the proper selection of pole-arc coefficient and slot-opening width. In addition, a sensitivity index is proposed to estimate the effects of parameter uncertainties on torque harmonics. Some suggestions on improving the design robustness are consequently provided from the aspects of tolerances control and parameter design. The deductions are verified through finite element analysis (FEA) on different pole/slot configurations. [ABSTRACT FROM AUTHOR]

This article covers the design methodologies and optimization techniques studied in the performance improvement of line-start permanent magnet synchronous motors (LSPMSMs). LSPMSM performance improvement using design techniques are chiefly limited to either the transient or the steady-state performance improvement, and a focus on only the transient performance improvement may degrade the steady-state performance of the LSPMSM and vice versa. Optimization studies of LSPMSMs can be categorized in terms of optimization aim in three classifications: transient performance improvement, steady-state performance improvement, and simultaneous improvement of both transient and steady-state performances. This study indicates the impact of various variables on the LSPMSM performance improvement. The optimization review shows that starting cage optimization without considering the steady-state characteristics as constraints results in synchronous performance degradation. The steady-state performance optimization with transient characteristics as constraints results in a minor synchronous performance improvement though there is the lowest transient performance sacrifice. Multi-objective optimization, including a transient and a steady-state characteristic as individual objectives, resulted in a more optimum LSPMSM with overall performance improvement. Finally, suggestions for optimization implementation of LSPMSMs are presented for future research work. [ABSTRACT FROM AUTHOR]

The starting and synchronization process of high-voltage permanent magnetic synchronous motors (HVPMSM) is a complex electromechanical transient problem. This paper proposes a multi-objective five-dimensional optimization method for starting characteristics of HVPMSM based on quadratic response surface models (QRSM) combined with Cuckoo search algorithm. Eighty-nine sets of transient finite element models were developed. To obtain starting current, starting time, starting torque and torque ripple, the transient process of HVPMSM is calculated with different cage bar width, cage bar depth, cage bar conductivity, and slot wedge conductivity. Steady-state and locked rotor experiments are conducted to verify the accuracy of the FEA. Then, the Cuckoo search method is employed to optimize design parameters achieved by the finite element models to obtain the minimum starting current, the maximum starting torque, the shortest starting time, and the minimum torque ripple, while maintaining high output performance and low cost. The results demonstrate that QRSM combined with Cuckoo search algorithm accurately describe the non-linear relationship between the structural characteristics, material properties and output performance of the HVPMSM. The best solutions are consistent with the results of the finite element analysis. In addition, the theoretical method is verified by experiments. [ABSTRACT FROM AUTHOR]

This paper presents a novel design concept for Synchronous Reluctance (SynRel) machines aimed at reducing the torque ripple. Two general sizing approaches based on the homothetic scaling principle are defined and compared. An in depth analysis on the torque ripple, for a wide range of scaled geometries, evaluated by finite element, has been carried out at different operating conditions. A further analysis is performed on 4 scaled geometries that have been optimized starting from 4 random rotor geometries. It is shown that the main rotor geometrical variables converge to similar values for all scaled machines. The accuracy of the proposed model is then validated by comparing the FE simulated torque ripple waveforms with the experimental data carried out, for a range of operating conditions, on a machine prototype. The outcome of this work is a fast and accurate scaling technique for the preliminary design of SynRel machines with reduced torque ripple. [ABSTRACT FROM AUTHOR]

This article compares the characteristics of a dual three-phase synchronous motor under different operating conditions such as healthy, half-control, and postfault conditions. The inductances are analyzed to confirm the interaction between two three-phase systems, and induced voltages of each phase are measured to verify the interaction behaviors. The postfault characteristics are analyzed under open-circuit faults (single-open-switch and single-open-phase faults) and short-circuit faults (single-short-switch and one-three-phase-short faults). The predicted results are validated by experimental tests. Moreover, the half-control mode is investigated as a strategy to operate with high efficiency and tolerant mode. [ABSTRACT FROM AUTHOR]