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In this paper, design and optimization of a ladder-type single-sided linear induction motor (Ladder SLIM) for machine tool applications is investigated. High-speed linear induction machines suffer from the end-effect phenomenon, which can reduce the thrust and result in declined output characteristics. Although it is common to consider this phenomenon in high-speed applications, it is essential to take it into account in the design and analysis of low-speed low-air-gap linear machines. In addition, Ladder SLIMs have significant flux density ripples, and using skewed bars for secondary of the machine is a common solution for it. Therefore, providing required equations, an algorithm for designing a Ladder SLIM considering the end-effect phenomenon based on Duncan model is proposed, and effect of several design parameters on the output characteristics are analyzed. In order to find the optimum design parameters, a multiobjective optimization problem considering efficiency, power factor, and braking force due to the end effect is defined. This problem is optimized with two algorithms, interior point and genetic algorithms, and results are compared. Finally, the validity of the obtained solution is verified using a 2-D and 3-D time-stepping finite-element method. [ABSTRACT FROM AUTHOR]

In this paper, a study of the performance and experimental results for a low-speed linear induction motor (LIM) with toroidal winding is presented. The main idea behind the proposed winding is to provide better performance and efficiency in space-constrained applications where a LIM with much higher primary length in comparison with the primary width is required. The LIM with toroidal winding in this case enjoys the advantage of short end-connection length, which can provide more superior performance than a distributed winding linear induction motor (DWLIM). Also, as the motor is designed to operate at low speed, the output power, and thus efficiency, would be low, and then the performance of such machines cannot be evaluated in terms of output power or efficiency. However, an improvement in performance, and thus efficiency, may be achieved when the low-speed motor is fed from a low-frequency supply. This paper mainly focuses on the design optimization, prototyping, and performance evaluation of a low-speed LIM with toroidal winding, and also provides a detailed comparison between the LIM with toroidal winding and a DWLIM. [ABSTRACT FROM AUTHOR]

This paper presents a multidisciplinary design algorithm of the ultra-high-speed electrical machine (UHSEM). Presented algorithm enables UHSEM design with a rotational speed of 0.5–1.2 Mrpm, taking into account the mutual influence of thermal, mechanical, and electromagnetic processes. Based on the algorithm, the 138 W UHSEM with a 1.2 Mrpm rotational speed was calculated. Material selection for the active parts of the machine is described. Analysis of the suitable bearings for UHSEM application is presented. Mechanical, electromagnetic, and cooling design aspects are shown with example of the calculated machine. To evaluate the effectiveness of the developed computer models and the calculation method, the experimental model of the 100 W UHSEM was tested in the motor mode at the rotational speed of 500 000 rpm. The test results demonstrated that the multidisciplinary design algorithm has high accuracy and is suitable for UHSEMs. The discrepancy between developed models and experimental results does not exceed 7%. [ABSTRACT FROM AUTHOR]

A new singly fed mechanical-offset (SF-MO) magnetless machine that can produce the desired torque performances for electric vehicle applications is proposed in this paper. By purposely mismatching the angle between two torque producing segments, the proposed SF-MO machine can well integrate individual torque components to reduce the resultant torque ripple values. Based on the electrical-offset concept, the proposed machine needs only one set of inverter. Therefore, the proposed machine can employ conventional control algorithm to reduce the hardware count of power electronics and to ease control complexity. Various machine performances are analyzed by using finite element method while experimental prototype is also built for verification. [ABSTRACT FROM AUTHOR]

Reliability of battery diagnosis depends on accurate estimation of the state of charge (SOC) and battery characterizing parameters including maximum capacity, internal impedance, polarization coefficients, and their probabilistic characterizations. This paper develops a framework that employs real-time operating data to estimate jointly the SOC and parameters, performs statistical analysis to derive quantitative diagnostic procedures with error analysis. Convergence of the algorithms, asymptotic distributions, and diagnosis reliability analysis are performed rigorously by using stochastic differential equations, central limit theorems, and large deviations principles. Simulated case studies and experimental data are used to illustrate the diagnosis algorithms and their capabilities. Experimental studies are conducted to verify the results. [ABSTRACT FROM PUBLISHER]

This paper introduces a battery charging scheme from a solar photovoltaic (SPV) by using a single sensor-based maximum power point tracking (MPPT) strategy. Here, for quick and efficient tracking, a novel hybrid “Cauchy and Gaussian sine cosine optimization” (CGSCO) algorithm is proposed for MPPT, which is based on only a single current sensor. The main objective of the CGSCO algorithm is, maximum extraction of the power from SPV panel and efficiently charging the battery through maximizing the charging current of the battery. Due to the single sensor, the cost of the charging scheme is very low, as well as the algorithm complexity and computational burden are very less, so it can be easily implemented on the low-cost microcontroller. In this paper, a single current sensor-based battery charging scheme by CGSCO algorithm is tested on MATLAB simulator and verified on a developed hardware of the SPV system. The panel condition, with and without shaded as well as dynamic environmental condition (variable temperature and insolation), is considered during simulation as well as on hardware implementation. Moreover, the tracking ability is compared with the most recent state of the art techniques (Grey wolf optimization and Lagrange interpolation particle swarm optimization (LIPSO)) as well as compared with “CGSCO with the conventional dual (voltage and current) sensor-based MPPT scheme.” The efficient battery charging with quick MPPT by CGSCO algorithm w.r.t. all state of the art techniques as well as dual sensor-based MPPT scheme, in steady-state as well as in dynamic conditions meets the motive of the work. [ABSTRACT FROM PUBLISHER]

For power conversion systems interfaced to four-wire supplies, four-leg converters have become a standard solution. A four-leg converter allows good compensation of zero-sequence harmonics and full utilisation of the dc-link voltage. These are very important features when unbalanced and/or nonlinear loads are connected to the system. This paper proposes a three-dimensional space vector modulation (SVM) algorithm and provides a comprehensive analysis of the algorithm implemented on a three-level, four-leg neutral-point-clamped converter. The algorithm allows a simple definition of the different switching patterns and enables balancing of the dc-link capacitor voltages using the redundancies of the converter states. A resonant controller is selected as the control strategy to validate the proposed SVM algorithm in a 6 kW experimental rig. [ABSTRACT FROM AUTHOR]

This paper proposes a new hybrid maximum power point tracking (MPPT) algorithm combining grey wolf optimization (GWO) and perturb & observe (P&O) technique for efficient extraction of maximum power from a photovoltaic system subjected to rapid variation of solar irradiance and partial shading conditions. GWO handles the initial stages of MPPT followed by application of the P&O algorithm at the final stage in view of achieving faster convergence to the global peak (GP). This MPPT thus overcomes the computational overhead as encountered in the case of a GWO-based MPPT algorithm reported earlier by Mohanty et al. The idea behind using the hybrid technique is to scale down the search space of GWO which helps to speed up for achieving convergence toward the GP. The proposed MPPT algorithm is first implemented using MATLAB/Simulink and subsequently an experimental setup is prepared for its practical implementation. From the obtained results, it is confirmed that the proposed MPPT provides superior tracking performance in any weather conditions compared to both GWO and PSO+PO-based MPPT algorithms. [ABSTRACT FROM AUTHOR]

Grid code specifications for voltage ride-through (VRT) of power generating units are based on time-domain envelopes of permissible terminal voltage magnitudes. Since an infinite number of voltage trajectories can be inscribed within a given enclosure, verifying that a given apparatus will withstand any such disturbance can be a daunting task. This paper tackles the VRT verification problem for doubly fed induction generator (DFIG)-based wind turbines. To this end, reachability analysis is employed to calculate sets that enclose all possible trajectories of the dynamic states of a DFIG-based system when perturbed by unknown-but-bounded grid voltage disturbances. [ABSTRACT FROM PUBLISHER]

A photovoltaic (PV) generation system (PGS) is becoming increasingly important as renewable energy sources due to its advantages such as absence of fuel cost, low maintenance requirement, and environmental friendliness. For large PGS, the probability for partially shaded condition (PSC) to occur is also high. Under PSC, the P–V curve of PGS exhibits multiple peaks, which reduces the effectiveness of conventional maximum power point tracking (MPPT) methods. In this paper, a particle swarm optimization (PSO)-based MPPT algorithm for PGS operating under PSC is proposed. The standard version of PSO is modified to meet the practical consideration of PGS operating under PSC. The problem formulation, design procedure, and parameter setting method which takes the hardware limitation into account are described and explained in detail. The proposed method boasts the advantages such as easy to implement, system-independent, and high tracking efficiency. To validate the correctness of the proposed method, simulation, and experimental results of a 500-W PGS will also be provided to demonstrate the effectiveness of the proposed technique. [ABSTRACT FROM AUTHOR]

Maximum power point tracking (MPPT) is an important function in all photovoltaic (PV) power systems. The classical “hill climbing” and “incremental conductance” MPPT algorithms are widely applied in many papers and applications. Both algorithms perturb the operating conditions of the PV array and detect the changes in generated power. Since the detected change in generated power also could be a result of changes in irradiance, both algorithms are prone to failure in case of large changes in irradiance. This paper starts to discuss the size of the perturbation of the operating conditions for both algorithms, based on the single-diode model. The result is used to select the updating frequency for the two algorithms, in order not to run away under certain dynamic conditions. Both algorithms are implemented in an inverter and tested over 16 days of simultaneous operation. Basic statistical procedures, the paired t-test, have been applied to the data with the conclusion that the two algorithms perform equally good. [ABSTRACT FROM AUTHOR]

Coreless dual disks hysteresis motors (CDDHM) have been recently introduced. The CDDHM presents some improvements in power factor and efficiency compared to general hysteresis machines. However, there is not much design or manufacturing experience available and an initial design methodology has not yet been proposed for the new machine. According to this and existing inherent complexity in the model of hysteresis motors, it is difficult to achieve an optimal design solution by applying a conventional optimization method. In this paper, an initial design approach is proposed. Then, a genetic algorithm-based method is developed to find the high-efficiency solution for an optimal CDDHM. The optimized motor has been manufactured and fitted in a test facility with a torque meter. Some experiments are carried out to prove the optimal design. Furthermore, start-up characteristics of the motor are predicted from the model and validated by a routine test. [ABSTRACT FROM AUTHOR]

This paper presents a high-gain observer of the rotor position for the control of surface permanent magnet synchronous machines under loaded conditions, e.g., saturation. Determining the rotor flux position of permanent magnet AC machines under no load is simpler, since its flux and rotor position coincide. However under load and in the presence of saturation in particular, the flux is comprised of two components: one due to the rotor magnets and the other due to the stator current. This causes the magnetic axis to shift from the rotor position, which in turn causes an error in a control algorithm that uses conventional rotor position estimation. This paper characterizes this error through a nonlinear model of the machine and finite element analysis. Design and analysis of a general position observer algorithm for PMAC machines accounting for saturation is presented, along with its implementation for a control methods using back EMF measurement and high-frequency Injection. Experimental results validating the nonlinear model of the machine, existence of the saturation-induced error, and performance of the proposed observer are also given. [ABSTRACT FROM PUBLISHER]

This paper presents a search-based approach to efficiency optimization of a vector controlled self-excited induction generator (SEIG). The main parts of the control system, besides the SEIG, are a prime mover, a three-phase power converter, and a dc load. The optimization algorithm is executed online and it relies on fuzzy logic (FL) to minimize the internal losses of the SEIG. This is done by adjusting the rotor flux reference. As opposed to existing strategies, additional effort is made to ensure stable operation of the SEIG while the optimization is put on hold and also to avoid the optimization-induced detuning. The iron losses of the SEIG are accounted for in the proposed vector control algorithm as dependent on both the operating flux and frequency. The simulation model of the control system is developed in the MATLAB/Simulink for the purpose of FL controller design, followed by experimental validation. The control algorithm is experimentally implemented using dSpace DS1104 board. [ABSTRACT FROM PUBLISHER]

This paper focuses the analysis around a grid-connected converter that operates under unbalanced voltage and current conditions. Two different scenarios have been selected to validate the proposed algorithms. In the first scenario, the converter operates as a reactive power compensator, exchanging reactive power with the grid, and minimizing the dc bus voltage oscillations. The second scenario is more challenging, since it operates as a load balancer. In this application, the unbalanced current consumption of the load is compensated by the converter, exchanging positive and negative sequence currents with the grid. Another objective in this second scenario is to compensate the reactive power of the unbalanced load. It is important to highlight that in both scenarios, any maximum limit of the converter can be exceeded due to the specific unbalanced voltage and current conditions. Three variables are considered critical for the converter: 1) output ac current limit; 2) output ac voltage limit; and 3) dc bus voltage oscillation limit. Thus, this paper proposes a control method, which limits online the reactive power reference in the first scenario and the exchanged current references in the second scenario in order not to exceed any of the mentioned critical variables. The corresponding experimental results are shown in Part II of this paper so as to validate the limitation algorithm obtained by means of the mathematical analysis carried out in Part I. [ABSTRACT FROM AUTHOR]

Induction motors fail due to many reasons, and many are rewound two or more times during their lifetimes. It is generally assumed that a rewound motor is not as efficient as the original motor. Precise estimation of efficiency of a refurbished motor or any existing motor is crucial in industries for energy savings, auditing, and management. Full-load and partial-load efficiency can be measured by using the dynamometer. This paper presents a novel technique for estimating refurbished induction motors’ full-load and partial-load efficiencies from only no-load tests. The technique can be applied in any electric motor workshop and eliminates the need for the dynamometer procedure. It also eliminates the need for the locked-rotor test. Experimental and field results of testing eight induction motors are presented, and the degree of accuracy is shown by comparing the estimated efficiencies against the measured values. To provide the necessary credits to the proposed technique, an error analysis is conducted to investigate the level of uncertainty through testing three induction motors, and the results of uncertainty of the direct measurements and no-load measurements using the proposed technique are presented. [ABSTRACT FROM AUTHOR]

This paper presents a novel fourth-order generalized integrator using a frequency locked loop (FOGI-FLL) based control algorithm for a single-stage three-phase grid-interfaced solar energy conversion system (SECS) with the distribution static compensation (DSTATCOM) capabilities. The proposed FOGI-FLL control algorithm suffices multifarious power quality objectives in the distribution network such as harmonics mitigation, reactive power compensation, load balancing, etc. The FOGI-FLL has good frequency tracking performance along with high dc offset rejection and high-order harmonic filtering capabilities. Simulated results demonstrate the satisfactory response of the system under load unbalancing, variable insolation, and system frequency variation. The effectiveness and advantages of the proposed algorithm are shown by comparing it with conventional algorithms. To validate the control algorithm, an experimental prototype is developed and test results depict the performance and behavior of the system under various conditions such as load unbalancing, variable insolation, photovoltaic (PV) to DSTATCOM mode, DSTATCOM to PV mode, and voltage sag and swell. The total harmonics distortions in grid currents and grid voltages are found well within limits according to IEEE-519 and −929 standards. [ABSTRACT FROM AUTHOR]

This paper studies a dual-level response surface methodology (DRSM) coupled with Booth's algorithm using a simulated annealing (BA-SA) method as a multiobjective technique for parametric modeling and machine design optimization for the first time. The aim of the research is for power maximization and cost of manufacture minimization resulting in a highly optimized wind generator to improve small power generation performance. The DRSM is employed to determine the best set of design parameters for power maximization in a surface-mounted permanent magnet synchronous generator with an exterior-rotor topology. Additionally, the BA-SA method is investigated to minimize material cost while keeping the volume constant. DRSM by different design functions including mixed resolution robust design, full factorial design, central composite design, and box-behnken design are applied to optimize the power performance resulting in very small errors. An analysis of the variance via multilevel RSM plots is used to check the adequacy of fit in the design region and determines the parameter settings to manufacture a high-quality wind generator. The analytical and numerical calculations have been experimentally verified and have successfully validated the theoretical and multiobjective optimization design methods presented. [ABSTRACT FROM AUTHOR]

A common practice in induction machine parameter identification techniques is to use external measurements of voltage, current, speed, and/or torque. Using this approach, it has been shown that it is possible to obtain an infinite number of mathematical solutions representing the machine parameters. This paper examines the identifiability of two commonly used induction machine models, namely the T-model (the conventional per phase equivalent circuit) and the inverse Γ-model. A novel approach based on the alternating conditional expectation (ACE) algorithm is employed here for the first time to study the identifiability of the two induction machine models. The results obtained from the proposed ACE algorithm show that the parameters of the commonly employed T-model are unidentifiable, unlike the parameters of the inverse Γ-model which are uniquely identifiable from external measurements. The identifiability analysis results are experimentally verified using the measured operating characteristics of a 1.1-kW three-phase induction machine in conjunction with the Levenberg–Marquardt algorithm, which is developed and applied here for this purpose. [ABSTRACT FROM PUBLISHER]