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Photocatalysts that combine with dielectric and magnetic properties are vital because of a wide variety of applications for these combinations, and nanostructured magnetic semiconductive materials have attracted significant interest due to their potential applications. A series of Cd 0.4 Co 0.6 Dy X Ce X Fe 2-2X O 4 spinel nano ferrites (nFs) were synthesized by using a highly efficient low-temperature method of citrate sol-gel auto-combustion for Methylene Blue (MB) dye degradation photocatalysts under visible light irradiation that combines with dielectric and magnetic properties are vital because of a wide variety of applications for these combinations, and nanostructured magnetic semiconductive materials have attracted significant interest due to their potential applications. The recycled MB is one of the hazardous textile dyes that is used extensively but causes risks for both humans and the environment. The prepared Dy3+ and Ce3+ doped Cd–Co nFs were polycrystalline with cubic structure, and crystalline size was increased from 15.78 to 21.02 nm with higher crystallinity, and the surface morphology changes from a spherical shape to a hexagonal shape with higher doping concentrations. The direct optical band gap values are increased. FTIR spectra reveal the stretching vibrations along the [M↔O] bond tetrahedral (A) and octahedral (B) sites. HRTEM results revealed that the prepared Cd–Co nFs have higher crystalline nature and high porosity. VSM indicates the sample's soft magnetic action and hysteresis loops showed the highest saturation magnetization (Ms) is 12.243 emu/g, and retentivity increases around 6.038 emu/g, decreasing the dielectric tangent loss, dielectric constant and dielectric loss. The AC conductivity raised with applied frequency. The PL gives a blue emission, and photocatalytic has the highest degradation activity 40.93 % of MB would be successful after 120 min irradiation of X = 0.07 Dy3+ and Ce3+ doped Cd–Co nFs. [Display omitted] [ABSTRACT FROM AUTHOR]

When magnetic saturation occurs during the operation of a permanent magnet (PM) slotless brushless DC motor, the material permeability will no longer be a constant value, and the neglected magnetic saturation model used for motor optimization will no longer be applicable. And considering that the increase in motor torque will lead to a high temperature rise of the winding, therefore, an electromagnetic heat coupling model applicable to the occurrence of magnetic saturation in the motor is established, and the model is utilized in combination with the particle swarm algorithm to enhance the maximum output torque of the motor. Firstly, a 100 W, 16,400 r/min high-speed PM slotless DC brushless motor is taken as the object of study, and its electromagnetic–thermal coupling model is established to derive the analytical equations for the electromagnetic torque with respect to the split ratio, the thickness of the stator yoke, the PM thickness, and the copper loss. Secondly, based on the modeling, the motor was optimized using a particle swarm algorithm to maximize the output torque and minimize the copper loss. Finally, a prototype was fabricated and verified with the prototype through no-load and load experiments. The difference between the theoretical maximum output torque and the experimental maximum output torque is less than 8%. The results show that this method can effectively predict the maximum output torque of the motor in the case of magnetic saturation, and the model is suitable for increasing the maximum output torque of slotless brushless DC motors under space constraints. [ABSTRACT FROM AUTHOR]

In permanent magnet synchronous motor (PMSM) sensorless drive systems, the motor inductance is a crucial parameter for rotor position estimation. Variations in the motor current induce changes in the inductance, leading to core magnetic saturation and degradation in the accuracy of rotor position estimation. In systems with constant load torque, the saturated inductance remains constant. This inductance error causes a consistent error in rotor position estimation and some performance degradation, but it does not result in speed estimation errors. However, in systems with periodic load torque, the error in the saturated inductance varies, consequently causing fluctuations in both the estimated position and speed errors. Periodic speed errors complicate speed control and degrade the torque compensation performance. In this paper, we propose a wavelet denoising-group method of data handling (GMDH) based method for accurate inductance estimation in PMSM sensorless control systems with periodic load torque compensation. We present a method to analyze and filter the collected three-phase current signals of the PMSM using wavelet transformation and utilize the filtered results as inputs to GMDH for training. Additionally, a method for magnetic saturation compensation using the inductance parameter estimator is proposed to minimize periodic speed fluctuations and improve control accuracy. To replicate the load conditions and parameter variations equivalent to the actual system, experiments were conducted to measure the speed ripples, inductance variations, and torque component of the current. Finally, software simulation was performed to confirm the inductance estimation results and verify the proposed method by simulating load conditions equivalent to the experimental results. [ABSTRACT FROM AUTHOR]

This work involves an efficient approach for the modeling and discrimination of the stator asymmetries and magnetic saturation in the self-excited induction generators. For this purpose, an improved model considering magnetic saturation has been developed for the self-excited induction generators operating under asymmetrical load conditions. Magnetic saturation must be considered for the modeling and analysis of the self-excited induction generators. This is because linear modeling with fixed parameters never makes it possible to analyze the performances of such machines. Due to fact that the magnetic saturation and stator asymmetries both cases generate similar harmonic components through the stator voltages and currents, we have to elaborate an improved model to evaluate the electromagnetic performances and to clearly discriminate the stator asymmetries and magnetic saturation. The contribution of this work is that a state model has been developed considering the increase of the common point voltage during asymmetrical conditions and the derivation of the machine inductances due to magnetic saturation. Various electromagnetic characteristics have been extracted such as stator voltages, currents and common point voltage. It will be deduced that the common point voltage can be considered as an interesting signal for the discrimination of the stator asymmetries and magnetic saturation. The concordance between simulation and experimental results shows the consistency of this approach for the modeling and discrimination of the stator asymmetries and magnetic saturation in the self-excited induction generators. [ABSTRACT FROM AUTHOR]

This paper presents the results of a comprehensive investigation into the comparative analysis and design optimization of ferrite-based surface permanent magnet vernier machines (SPMVMs). While SPMVMs boast a simple mechanical structure and enhanced torque density attributed to the flux modulation effect, they suffer from a persistent challenge of low power factor. Several factors hinder the adoption of low-cost ferrite magnets in SPMVMs. First, ferrite magnets are prone to irreversible demagnetization, constraining the allowable range of magnet thickness. Second, the reduced residual magnetic flux density of ferrite magnets exacerbates the decrease in power factor and machine efficiency. Thus, achieving optimal performance in ferrite-based SPMVMs necessitates the careful selection of various design parameters. To address these issues, this study employs a surrogate-based metaheuristic optimization algorithm with adaptive sampling to identify the optimal solution. Additionally, the integration of a Halbach array is explored to further enhance the performance of the three-slot/two-pole SPMVM topology. Subsequently, two ferrite-based SPMVM baseline models—one with a conventional SPM structure and another with a Halbach magnet array—are thoroughly designed, optimized, and subjected to detailed performance analysis using the 2D finite element method. [ABSTRACT FROM AUTHOR]

Purpose: This paper considers the air gap tracking problem of the levitation control system for medium and low-speed maglev vehicles subject to magnetic nonlinearities and track irregularities. Method: The static and dynamic magnetic field characteristics are investigated, and an improved electromagnetic force model to consider both the magnetic saturation and eddy current effect is developed. By merging neural networks (NNs), a robust adaptive control scheme is proposed, which can deal with the modeling uncertainties and magnetic nonlinearities without requiring precise model information, leading to enhanced levitation performance from the aspects of suspension safety and ride comfort. Based on the Lyapunov method, the continuity of the control signal and uniformly ultimately boundedness(UUB) of all closed-loop signals can be guaranteed. Results and conclusion: With the dynamic model of the whole suspension bogie and random irregularities, numerical simulations under various operation conditions, including constant speed, horizontal curve and vertical curve, validating the developed control scheme improves the suspension safety while maintaining the ride comfortability for passengers. [ABSTRACT FROM AUTHOR]

The synchronous reluctance machine is well-known for its highly nonlinear magnetic saturation and cross-saturation characteristics. For high performance and high-efficiency control, the flux-linkage maps and maximum torque per ampere table are of paramount importance. This study proposes a novel automated online searching method for obtaining accurate flux-linkage and maximum torque per ampere Identification. A limited 6 × 2 dq-axis flux-linkage look-up table is acquired by applying symmetric triangle pulses during the self-commissioning stage. Then, three three-dimensional modified linear cubic spline interpolation methods are applied to extend the flux-linkage map. The proposed golden section searching method can be easily implemented to realize higher maximum torque per ampere accuracy after 11 iterations with a standard drive, which is a proven faster solution with reduced memory sources occupied. The proposed algorithm is verified and tested on a 15-kW SynRM drive. Furthermore, the iterative and execution times are evaluated. [ABSTRACT FROM AUTHOR]

The analysis of the reluctance coil launcher (RCL) basically relies on the finite element method (FEM), but the method is time-consuming and does not meet the real-time requirements for control, which seriously hampers the expansion of engineering application areas. To address this problem, this study proposes a numerical calculation method dedicated to RCL based on the mathematical equations of electromagnetic coupling, in which the magnetic saturation problem is corrected by the inductance lookup table method, and the inductance in the coupling circuit is updated in real time according to the instantaneous current and the instantaneous position of the projectile. The accuracy of the calculation method is verified and the reasons for the errors are analyzed by establishing finite element simulation model, MATLAB/Simulink model and experimental platform for a single-stage and a three-stage RCL and comparing the obtained data. When the discharge voltage of the capacitor is 300 V, the accuracy of the projectile muzzle velocity in the single-stage and three-stage is 98.42% and 98.20% respectively, which indicates that the calculation method is correct under specific conditions. The time consumed by the method is only about 1/1000 of that of FEM, which even includes the compilation time of the software MATLAB/Simulink, illustrating the advantages of the algorithm and its application prospects.

Reluctance coil launchers usually use a pulse current formed by capacitive discharge to excite the excitation coil when launching. The pulse current peaks are high, and the projectile usually undergoes deep magnetic saturation, resulting in low launching efficiency. To address this problem, this article proposes using distributed feeder circuit to drive reluctance coil launchers, replacing the traditional single set of large-capacity capacitor discharge scheme with multiple small-capacity capacitors discharged in a time-sequential manner, so as to reduce the peak current and suppress magnetic saturation problems. The study includes two main aspects, one is to study the effect of the driving method on the launch performance and analyze the reasons; the other is to propose the calculation of the time-varying data in the launch process by the time-segmented calculation method. The efficiency of the model described in the paper is only 1.301% when using a single high-capacity capacitor for launching, while the launching efficiency is increased to 3.535% when driven by the distributed feeder circuit, indicating that the method can effectively improve the launching performance.

Power transmission lines are equipped with various electronic devices, including power line inspection robots, safety sensors, and monitoring systems. However, providing power to devices installed on these lines often requires extensive construction and poses many challenges. Therefore, to solve such problems, active research is being conducted on Magnetic Energy Harvesters (MEHs) that harness the magnetic field generated by the current in the power lines to harvest electricity. A crucial design objective of the MEH is to maximize harvested power even if the saturated region is partially included, unlike a current transformer (CT), which must maintain an unsaturated state throughout the operating region. In this paper, design considerations of an MEH are discussed in comparison to the CT. Specifically, this paper formulates the relationship of the airgap between core cutting surfaces, the timing of power harvesting, and the amount of harvested power. It was observed that the MEH core should be designed to have a B-H curve close to the step function by minimizing the airgap and selecting magnetic material with high saturation magnetic flux density to achieve high harvesting power. An optimal MEH model for harvesting the maximum power for each given input current condition is presented. Furthermore, experiments were conducted to verify that 28 W of power was harvested under the input current condition of 150 Arms.

The inherent complexity leads to intricate equations, making it challenging for design engineers and researchers to model and analyze MCRs effectively. Despite the increasing attention given to MCRs in power systems, the need for simplified theoretical foundations and design models persists. This paper addresses the challenges posed by the complex excitation conditions of magnetic controlled reactors (MCRs), which are subject to both alternating current and direct current excitations by presenting the theoretical basis, ontological structure, working principle, and design model of MCRs in a systematic manner for enhanced comprehension. Graphical and equivalent electric circuit approaches are employed to derive mathematical expressions, while ANSYS simulation is utilized to create a 3D structure model of the MCR. The simulation results, compared with theoretical analyses, demonstrate that the MCR exhibits alternate magnetization and demagnetization between its two core limbs in a cycle. This suggests that the magnetic valves on both sides alternate between saturation and unsaturation in each cycle. Furthermore, the research reveals that the MCR’s entire capacity can be smoothly adjusted by varying the saturation degree of the magnetic valve core. Overall, this research contributes to a deeper understanding of MCRs under actual operating conditions and serves as a crucial foundation for further investigations into their performance design.

In this research, we investigate the effect of carbon nanotubes (CNTs) as a substrate on the morphology, size, magnetic behavior and band gap energy (Eg ) of nickel ferrite nanoparticles. Synthesis of NiFe2O4 nanoparticles carried out using a direct co-precipitation method in aqueous solution containing carbon nanotubes. The samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-visible Spectrophotometer and vibrating sample magnetometer (VSM). The results showed that using the CNT as a supporter reduced the size and band gap energy of NiFe2O4 nanoparticles, changed the morphology of the powder from an aggregate state to a filament state and it increased the magnetic saturation properties of nanoparticles. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to present a new Hybrid Analytical Model (HAM) based on Winding Function Theory (WFT) for electromagnetic analysis of the performance of one typical Unbalanced Two-Phase Induction Motor (UTPIM). Difierent indexes of electromagnetic modeling, such as winding distribution, slotting efiect, and magnetic saturation, can be accurately considered by using the proposed HAM. To obtain this new hybrid technique, WFT is reformulated to consider magnetic saturation in addition to the inuence of slotting and winding distribution. The Conformal Mappings (CMs) are used to calculate the slotted air-gap length accurately. The Magnetic Equivalent Circuit (MEC) model is used to consider the Magneto-Motive Force (MMF) drop in stator and rotor cores due to the excitation of one phase-winding. The results obtained from CMs and MEC are then utilized in reformulated WFT to calculate the inductances of the respective phase-winding. Transient analysis is then done to calculate the indexes of performance, such as air-gap magnetic field, phase currents, electromagnetic torque, and rotor speed, by using the lookup table of inductances while considering difierent capacitors in the auxiliary phase. In each step, the accuracy of analytical results is confirmed by comparing with corresponding results obtained from the Finite Element Method (FEM). [ABSTRACT FROM AUTHOR]

In this study, a generalized torque estimation method is proposed for synchronous motors, including surface permanent magnet synchronous motors (SPMSMs), synchronous reluctance motors (SynRMs), and interior permanent magnet synchronous motors (IPMSMs) for building the analytical motor model. The average motor torque is estimated using the Lorentz force by the generated flux density in the air gap to determine the relationships among torque, flux density, and injected current. In the proposed method, the generated flux density is derived step by step by considering the effects of magnetic flux saturation, the stator slot, the rotor barrier, and permanent magnets (PMs) to ensure that the generated average torque complies with the operating condition of the motor. To verify the proposed method, the output torque of finite element analysis (FEA), Maxwell 2D, is compared to the proposed method in a SPMSM. Moreover, a phasor diagram is plotted to determine the mechanism through which torque is generated in SynRMs and IPMSMs. A SynRM and an IPMSM with ferrites PMs are analyzed using the proposed method, FEA, and the experimental results of this study indicate the effectiveness. [ABSTRACT FROM AUTHOR]

Electromagnetic force is a very important parameter for push-pull solenoids, but it is difficult to calculate analytically due to the nonlinear variation of the magnetic field. Aiming at this problem, To address this problem, the use of magnetic vector potential theory in a columnar coordinate system was investigated to solve the electromagnetic force of a cylindrical push-pull electromagnet. The whole solenoid magnetic field was divided into several sub-domains and the boundary conditions were defined to obtain the sub-domain magnetic vector equations which can be solved numerically, and then the electromagnetic characteristic data such as magnetic vector potential, inductance and electromagnetic force were calculated by MATLAB programming. Comparing the two cases of B-H curves of iron core permeability in finite element with constant value of 10 000 and electric soft iron respectively, the calculation accuracy and error variation trend of this numerical algorithm were illustrated, and the reason for the formation of the error were analyzed. With the increase of current the core will be magnetically saturated, when the magnetic saturation problem is not serious, the calculation result of numerical algorithm has high accuracy. With the increase of current, the error increases rapidly after the core is magnetically saturated. In the experiment, different sizes of excitation currents were applied to the cylindrical push-pull electromagnet, and the output thrust results obtained were consistent with theoretical analysis. [ABSTRACT FROM AUTHOR]

The present work proposes a nonlinear model of a buck–boost DC-DC power converter considering the nonlinear magnetic characteristics of the power inductor and electrical losses of the system. The Euler–Lagrange formalism is used for formulating the proposed model. Previous research works have reported mathematical models to describe power inductor dynamics. However, a gap in the literature remains regarding modeling this kind of element when it operates within power converters. Also, a linear-based controller scheme is proposed to regulate a non-ideal buck–boost DC-DC power converter. A methodology for tuning the proposed controller is presented, which considers the nonlinear model structure of the power converter, the linearization procedure based on an identification process, and a frequency domain analysis based on the approximated linear model. Finally, the tuned control scheme is tested on the nonlinear model of the power converter under several operational conditions showing excellent performance by effectively regulating the output voltage. The results are compared with those derived from alternative control strategies, and a better performance is generally obtained. [ABSTRACT FROM AUTHOR]

In this article, a clear and concise analytical method for predicting the performance of a Liquid-cooling eddy current brake (LC-ECB) is proposed. The LC-ECB has a coolant channel in the rotor to allow direct cooling of the inner surface of the stator. The static air-gap magnetic field distribution is obtained by the dynamic magnetic equivalent circuit (MEC) method, and the magnetic flux leakage and global magnetic saturation effects are fully considered. The magnetic field intensity distribution function of the eddy current reaction magnetic field is derived for the first time based on Ampere circuital theorem. Considering the local magnetic saturation and skin effect, a novel double-iteration algorithm based on the conservation principle of magnetic pressure drop is applied to obtain the transient air-gap flux density distribution, and then the brake torque expression is obtained. The finite element method (FEM) and experimental results show that the proposed method is feasible and effective. The new model is easy to program and can be easily used in the initial design and optimization of LC-ECB. [ABSTRACT FROM AUTHOR]

The study of magnetic saturation modeling is as old as the machines themselves. The existence and importance of magnetic saturation in induction machines have been experimentally verified and well recognized. The conventional model of induction machines is based on linear magnetic properties of the machine. As in any electromagnetic system, the presence of magnetic saturation introduces nonlinearity in the behavior of induction machines also. The cardinal challenge in the modeling of induction machines is that the machine has to be accurately modeled so that realistic performance characteristics can be predicted. Unfortunately, conventional models are not suitable for predicting the dynamic performance of induction machines subjected to physical phenomena such as magnetic saturation. Various modeling techniques have been developed in dealing with the problem of magnetic saturation. This paper provides a review of the effect of magnetic saturation on induction machines as well as the major techniques used to incorporate its effects in the induction machine model. [ABSTRACT FROM AUTHOR]

Fe65Co35 based soft magnetic alloys (SMAs) have been gaining attention for their superior magnetic features and playing significant roles in composite permanent magnets, magnetic storage and automotive electrification technologies. In the present work, the Fe65Co35 alloy were produced by arc melting with subsequent annealing. The effects of arc melting and annealing upon the structural and magnetic properties of the soft magnetic phase of the alloy Fe65Co35 have been investigated. The variation in magnetic and microstructural characteristics with melting and annealing have been observed using the X-ray diffractometer (XRD), scanning electron microscope (SEM), and the vibrating sample magnetometer (VSM). The XRD patterns verified the existence of the Fe65Co35 alloy. After melting and annealing, the alloy surface morphologies were examined using SEM. In this approach, the Fe65Co35 alloy was annealed at 600 °C for 4 h in an argon environment which resulted in the highest saturation magnetization of 237 emu/g and the lowest coercivity of 31 Oe. The rise in saturation magnetization was attributed to the removal of impurities, during the melting and annealing process.

When magnetic saturation occurs during the operation of a permanent magnet (PM) slotless brushless DC motor, the material permeability will no longer be a constant value, and the neglected magnetic saturation model used for motor optimization will no longer be applicable. And considering that the increase in motor torque will lead to a high temperature rise of the winding, therefore, an electromagnetic heat coupling model applicable to the occurrence of magnetic saturation in the motor is established, and the model is utilized in combination with the particle swarm algorithm to enhance the maximum output torque of the motor. Firstly, a 100 W, 16,400 r/min high-speed PM slotless DC brushless motor is taken as the object of study, and its electromagnetic–thermal coupling model is established to derive the analytical equations for the electromagnetic torque with respect to the split ratio, the thickness of the stator yoke, the PM thickness, and the copper loss. Secondly, based on the modeling, the motor was optimized using a particle swarm algorithm to maximize the output torque and minimize the copper loss. Finally, a prototype was fabricated and verified with the prototype through no-load and load experiments. The difference between the theoretical maximum output torque and the experimental maximum output torque is less than 8%. The results show that this method can effectively predict the maximum output torque of the motor in the case of magnetic saturation, and the model is suitable for increasing the maximum output torque of slotless brushless DC motors under space constraints.

In permanent magnet synchronous motor (PMSM) sensorless drive systems, the motor inductance is a crucial parameter for rotor position estimation. Variations in the motor current induce changes in the inductance, leading to core magnetic saturation and degradation in the accuracy of rotor position estimation. In systems with constant load torque, the saturated inductance remains constant. This inductance error causes a consistent error in rotor position estimation and some performance degradation, but it does not result in speed estimation errors. However, in systems with periodic load torque, the error in the saturated inductance varies, consequently causing fluctuations in both the estimated position and speed errors. Periodic speed errors complicate speed control and degrade the torque compensation performance. In this paper, we propose a wavelet denoising-group method of data handling (GMDH) based method for accurate inductance estimation in PMSM sensorless control systems with periodic load torque compensation. We present a method to analyze and filter the collected three-phase current signals of the PMSM using wavelet transformation and utilize the filtered results as inputs to GMDH for training. Additionally, a method for magnetic saturation compensation using the inductance parameter estimator is proposed to minimize periodic speed fluctuations and improve control accuracy. To replicate the load conditions and parameter variations equivalent to the actual system, experiments were conducted to measure the speed ripples, inductance variations, and torque component of the current. Finally, software simulation was performed to confirm the inductance estimation results and verify the proposed method by simulating load conditions equivalent to the experimental results.

Introduction. The active and reactive (inductive) winding resistances of three-phase asynchronous motors (IM) are investigated. These important parameters are determined during design and are the basis for calculating a number of energy parameters and characteristics. Problem. In the classical design of IM, the winding resistances are determined with insufficient accuracy due to a number of assumptions and conventions. Especially it concerns the operation of IM with increased slip and it affects the accuracy of realization of its design data, starting parameters and characteristics. Goal. The paper aims to further develop the IM design system by numerical-field computational analysis of active and reactive resistances of the IM windings in the whole range of changes in its slip and calculation of the mechanical characteristic of IM to confirm the adequacy of the calculations of these resistances. Methodology. Resistances of the IM windings are determined by numerous calculations of the magnetic fields of dispersion with the FEMM program within stator and rotor teeth steps, and with current displacement in a squirrel-cage rotor core. Everything is done in the slip range when operating from start-up to idle with changing currents in the slots and the corresponding magnetic saturation of the core teeth. A Lua script has been created for the calculations, controlling the FEMM program and providing automation of all calculations. Results. The numerical-field method shows that the classical design method gives very large errors in determining the magnetic conductivities of IM slot dispersion, as well as current displacement in the bars of the squirrel-cage rotor winding. This is especially evident with increased slips in the start-up mode. Originality. Numerical estimates of the differences between the classical and numerical-field methods are given and the origin of errors is analyzed: the strong saturation of the teeth of the stator and rotor cores. This leads to a significant decrease in the magnetic conductivities of slot dispersion and the practical absence of current displacement in the rotor bars, on which the main emphasis was previously made. The obtained results made it possible to calculate the mechanical characteristic of the IM according to a transparent formula without the use of correction coefficients and reference graphical functions. Practical value. The provided technique of numerical-field analysis and the obtained results of the calculation of active and reactive winding resistances and mechanical characteristic are recommended as a basis for the improvement of the IM design system.

In order to solve the accurate calculation problem of spoke-type permanent magnet machines with multi-layer winding structure in the magnetic field, based on the two-dimensional subdomain analytical modeling idea, a magnetic density analytical calculation method considering the saturation effect at the rotor magnetic bridge and stator multi-layer winding structure is proposed. In this method, the magnetic vector potential calculation of multi-layer armature winding can be calculated by subdomain division in the stator slot. Then, the saturation effect at the spoke-type rotor core magnetic bridge is equivalent by using an equivalent air gap. To ensure the accuracy of calculation, the error check and cyclic iteration are applied in this method. The key contribution of this method is effectively solving the interior permanent magnet machines′ magnetic field calculation problem in the traditional subdomain modeling method due to the inability to consider the finite magnetic permeability of the core. Taking 8-pole 9-slot and 10-pole 12-slot permanent magnet machines as examples, finite element models with different winding structures are built to validate the validity of the proposed method. The results show that the analytical method achieves a reduction in the computation time while maintaining the calculation accuracy.

In this article, an efficient multi-objective optimization strategy for the Halbach array permanent magnet synchronous machine (PMSM) is developed by taking into consideration the nonlinear B-H behavior of soft magnetic materials. Based on the harmonic modeling (HM) technology, the electromagnetic performances (EPs) of the Halbach array PMSM can be computed. To specifically model the local magnetic saturation, the stator teeth are separated into several annular layers, and each tooth is further divided into several regions along the tangential direction. Then, the parameters of the Halbach array PMSM are optimized utilizing combined nonlinear semi-analytical model (SAM) and non-dominated sorting genetic algorithm II (NSGA-II). To validate the effectiveness and accuracy of the developed optimization scheme, a Halbach array prototype is then manufactured in accordance with the optimization results. The multi-objective rapid optimization strategy developed in this article, which includes but is not limited to Halbach array permanent magnet (PM) machines, serves as a reference for the design and optimization of various PM machines. [ABSTRACT FROM AUTHOR]

The paper considers the model predictive current control (MPCC) of an induction motor (IM) drive and evaluates five IM models of different complexities—from conventional to magnetic saturation, iron losses, and stray-load losses—for the MPCC design. The validity of each considered IM model and the corresponding MPCC algorithm is evaluated by comparison of the following performance metrics: the total harmonic distortion of the stator current, the average switching frequency, the rotor flux magnitude error, the rotor flux angle error, and the product of the first two metrics. The metrics' values are determined in wide ranges of the rotor speed (0.1–1 p.u.) and load torque (0–1 p.u.) through simulations performed in the MATLAB Simulink environment. The obtained results allow us to identify the IM model that offers the best tradeoff between the practicability and accuracy. Furthermore, a control effort penalization (CEP) is suggested to reduce the average switching frequency and, hence, the power converter losses. This involves constraining the simultaneous switching to a maximum of two branches of the three-phase power converter, as well as inclusion of the weighted switching penalization term in the cost function. Finally, the performance—both steady-state and dynamic—of the proposed MPCC system with CEP is compared with that of the analogous field-oriented controlled (FOC) IM drive. The inverter switching frequency is reduced more than twice by including the frequency-dependent iron-loss resistance in the MPCC. It is additionally reduced by implementing the proposed CEP strategy without sacrificing many other performance metrics, thus achieving a performance comparable to the FOC IM drive. [ABSTRACT FROM AUTHOR]

The structure of the reluctance electromagnetic launcher (REML) is equivalent to an inductor with a movable iron core. The dynamic current in the launching process is easy to be measured by instruments, but the data such as the position, velocity of the projectile and the equivalent inductance are not only difficult to solve by analytical methods, but also difficult to measure by instruments, which seriously hinders the development of the control technology. To solve this problem, referring to the method of introducing the inductance matrix into the motor algorithm model to realize semi‐analytic calculation, a special algorithm model is proposed to calculate the launch process data of REML based on the current data. According to the working characteristics of the reluctance coil transmitter, it is pointed out that its inductance matrix should be specifically expressed as a three‐dimensional data table rather than a traditional two‐dimensional table. The current can be obtained by closed‐loop calculation according to the proposed algorithm block diagram when the circuit parameters are known, or measured by instruments when the circuit parameters are unknown, and then the launch process data is obtained indirectly through calculation. In this study, an experimental platform was built, and the algorithm model was established using MATLAB/Simulink. The comparison of the dynamic launch process data of the finite element method (FEM) showed that the method was feasible. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This paper proposes a stator core design to achieve variable-flux characteristics enhanced by magnetic saturation in fractional-slot concentrated winding (FSCW) permanent-magnet (PM) motors without additional excitation systems, complicated structures, or active controls. Magnetic saturation induced at suitable locations can enhance variable-flux characteristics because the PM flux linkage is variable with the magnetic saturation in cores. In distributed winding configurations, magnetic saturation is induced symmetrically for each rotor pole by the fundamental that is dominant in the spatial distribution of the air-gap flux density. The magnetic saturation at each rotor pole can enhance variable-flux characteristics. In FSCW configurations, magnetic saturation is not induced symmetrically for each rotor pole because of several dominant space harmonics. The magnetic saturation at several rotor poles cannot enhance variable-flux characteristics. In the proposed design, the stator core has thin tooth tips for inducing magnetic saturation. The magnetic saturation in the stator core achieves the variable-flux characteristics that are effective for expanding the operating region or decreasing electromotive force and increasing torque. The efficacy of the proposed design is determined by estimating motor performance through a finite element method analysis and demonstrating the actual motor performance of a prototype. [ABSTRACT FROM AUTHOR]

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This paper presents the results of a comprehensive investigation into the comparative analysis and design optimization of ferrite-based surface permanent magnet vernier machines (SPMVMs). While SPMVMs boast a simple mechanical structure and enhanced torque density attributed to the flux modulation effect, they suffer from a persistent challenge of low power factor. Several factors hinder the adoption of low-cost ferrite magnets in SPMVMs. First, ferrite magnets are prone to irreversible demagnetization, constraining the allowable range of magnet thickness. Second, the reduced residual magnetic flux density of ferrite magnets exacerbates the decrease in power factor and machine efficiency. Thus, achieving optimal performance in ferrite-based SPMVMs necessitates the careful selection of various design parameters. To address these issues, this study employs a surrogate-based metaheuristic optimization algorithm with adaptive sampling to identify the optimal solution. Additionally, the integration of a Halbach array is explored to further enhance the performance of the three-slot/two-pole SPMVM topology. Subsequently, two ferrite-based SPMVM baseline models—one with a conventional SPM structure and another with a Halbach magnet array—are thoroughly designed, optimized, and subjected to detailed performance analysis using the 2D finite element method.

Increasing the power density in switched mode power supplies is one of the main goals in power electronics. This aim can be achieved by using smaller inductors operating at partial magnetic saturation. In this work, a partially saturating ferrite core inductor is exploited in a switching DC-DC boost converter, regulated through nonlinear model predictive control. A nonlinear behavioral inductor model, identified through experimental measurements, accounts for both magnetic saturation and losses. The simulation results show that the converter output voltage is correctly regulated and the imposed current constraints are fulfilled, even when partial magnetic saturation occurs. Comparisons with traditional control techniques are also presented. [ABSTRACT FROM AUTHOR]

Introduction. The active and reactive (inductive) winding resistances of three-phase inductions motors (IMs) are investigated. These important parameters are determined during design and are the basis for calculating a number of energy parameters and characteristics. Problem. In the classical design of IM, the winding resistances are determined with insufficient accuracy due to a number of assumptions and conventions. Especially it concerns the operation of IM with increased slip and it affects the accuracy of realization of its design data, starting parameters and characteristics. Goal. The paper aims to further develop the IM design system by numerical-field computational analysis of active and reactive resistances of the IM windings in the whole range of changes in its slip and calculation of the mechanical characteristic of IM to confirm the adequacy of the calculations of these resistances. Methodology. Resistances of the IM windings are determined by numerous calculations of the magnetic fields of dispersion with the FEMM program within stator and rotor teeth steps, and with current displacement in a squirrel-cage rotor core. Everything is done in the slip range when operating from start-up to idle with changing currents in the slots and the corresponding magnetic saturation of the core teeth. A Lua script has been created for the calculations, controlling the FEMM program and providing automation of all calculations. Results. The numerical-field method shows that the classical design method gives very large errors in determining the magnetic conductivities of IM slot dispersion, as well as current displacement in the bars of the squirrel-cage rotor winding. This is especially evident with increased slips in the start-up mode. Originality. Numerical estimates of the differences between the classical and numerical-field methods are given and the origin of errors is analyzed: the strong saturation of the teeth of the stator and rotor cores. This leads to a significant decrease in the magnetic conductivities of slot dispersion and the practical absence of current displacement in the rotor bars, on which the main emphasis was previously made. The obtained results made it possible to calculate the mechanical characteristic of the IM according to a transparent formula without the use of correction coefficients and reference graphical functions. Practical value. The provided technique of numerical-field analysis and the obtained results of the calculation of active and reactive winding resistances and mechanical characteristic are recommended as a basis for the improvement of the IM design system. [ABSTRACT FROM AUTHOR]

Some major problems in the motor drive are the overshoot or undershoot of transient response characteristics and a parameter mismatch due to magnetic saturation. This study proposed a 3D inductance map combined with a maximum-torque-per-ampere (MTPA) map based on a finite-element (FE) motor model considering a cross-coupling magnetic saturation impact to overcome this problem. The proposed FE motor model has a high accuracy of no-load back electromotive force (e.m.f.) around 98.3% compared to the measurement results. Then, nine scenarios of vector control combinations of inductance maps and current supply variations of β 0°, 45°, and MTPA were investigated. As a result, the transient response improvement for β 0°, 45°, and MTPA without the map and with Ld and Lq maps is 63%, 10%, and 15%, respectively. Moreover, for the steady-state response, the average torque improvement between MTPA and Idref 0 A control is 9.21%, 8.97%, and 8.98% for the no-map, ave-map, and 3D-inductance-map conditions, respectively. The MTPA trajectory characteristic was also updated to illustrate the actual MTPA condition compared to the conventional MTPA control. In detail, the proposed method has reduced the parameter mismatch for the current control loop in the transient state and improved the MTPA control trajectory for the steady-state response. Finally, the improvement of vector control characteristics of the proposed method was verified by an FE simulation and experimental measurement results. [ABSTRACT FROM AUTHOR]

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The synchronous reluctance motor (SynRM) has significant nonlinear characteristics due to the problems of magnetic saturation and cross-coupling and the poor adaptability of the general controller to parameter changes seriously affects the control performance of the motor. In order to solve the above problems, this paper proposed a control system for the SynRM with a brain emotion controller based on empirical information to solve the motor control problem of magnetic saturation. Firstly, the nonlinear mathematical model of the SynRM considering magnetic saturation is established by introducing the magnetic saturation parameter. Secondly, the sensory input function and emotional cue function based on systematic error are given and the vector control system of the SynRM considering magnetic saturation is designed. The influence of the parameters and the learning rate of the brain emotional learning based intelligent controller (EI-BELBIC) on the adjustment range of the controller parameters is studied. Then the SynRM is controlled under different working conditions and the control effect is observed. The results show that the designed vector control system of the SynRM based on EI-BELBIC has strong reliability, accurate control, rapid response, and strong anti-interference ability under magnetic saturation. [ABSTRACT FROM AUTHOR]

Abstract A new hybrid analytical model (HAM) based on conformal mapping (CM) method and magnetic equivalent circuit (MEC) model is presented in this paper for electromagnetic modelling of cage rotor induction motors (CRIMs) used in electric submersible pumps (ESPs). For every operating point, the iron parts are modelled with a non‐linear MEC model to calculate the equivalent virtual currents, which represent the influence of magneto motive force (MMF) drops and MMF sources in stator and rotor cores. The effects of the equivalent virtual currents on the air‐gap magnetic field are then considered using the CM method and Hague's solution. This approach for calculating the air‐gap field is also used to prepare a 3‐D lookup table (3‐D LUT) for each element of inductance matrix and derivative of inductance matrix in terms of rotor position. These LUTs are then used for transient modelling and analysis of CRIM under no‐load and loading conditions. The accuracy of proposed HAM is validated by comparing the results obtained through HAM with corresponding results obtained from finite element method and experiment set‐up.

Accurate modeling of motor magnetic fields facilitates all aspects of motor analysis, design, and optimization. Existing methods are difficult to balance the speed and accuracy of modeling, among which the widely popular finite element method is relatively time-consuming and the accuracy of magnetic circuit modeling is difficult to guarantee. In this regard, this paper presents a magnetic equivalent circuit model based on the multiple flux source network for interior permanent magnet (IPM) machines. The model considers the magnetic saturation effect through a non-linear iterative process. The accuracy improvement of the proposed model has been verified by comparison with the traditional single-flux-source model. Furthermore, the proposed model greatly saves the calculation time while bringing fairly good accuracy compared to the finite-element method, which is beneficial for the design optimization of the IPM machines.

This paper introduces a comprehensive examination of vector-controlled- (VC-) based techniques intended for induction motor (IM) drives. In addition, the evaluation and critique of modern control techniques that improve the performance of IM drives are discussed by considering a systematic literature survey. Detailed research on variable-speed drive control, for instance, VC and scalar control (SCC), was conducted. The SCC-based systems' speed and V/f control purposes are clarified in closed and open loops of IM drives. The operations, benefits, and drawbacks of the direct and indirect field-oriented control systems are illustrated. Furthermore, the direct torque control (DTC) method for IMs is reviewed. Numerous VC methods established along with microprocessor/digital control, model reference adaptive control (MRAC), sliding mode control (SMC), and intelligent control (in terms of fuzzy logic (FL) and artificial neural networks (ANNs)) are described and examined. Uncertainties in the IM parameter are a considerable problem in VC drives. Therefore, this problem is addressed, and some studies that attempted to provide solutions are listed. Magnetic saturation and core loss impact are mentioned, as they are important issues in IM drives. Toward demonstrating the strengths and limitations of various VC configurations, a few experiments were simulated via MATLAB® and Simulink® that show the influence of machine parameter variation. Efforts are made to supply powerful guidelines for practicing engineers and researchers in AC drives. [ABSTRACT FROM AUTHOR]

In this article, the magnetic energy harvester (MEH) based on the current transformer is an innovative method to provide a potential solution for the power supply of sensor networks. Due to the current fluctuation and nonlinearity of the core, the harvester may produce insufficient power at low primary currents, while the core saturates at high primary currents. Aiming at resolving this problem, a novel method is proposed to improve the performance of MEH. In this method, a capacitor and two switches are used to store energy and modulate the core saturation. The performed analyses demonstrate that the proposed method enhances the harvested power under different primary current and load conditions. This is especially more pronounced at low primary currents and loads. It is found that for a low primary current of 2 Arms at 50 Hz, the harvested power increases by 206%. Moreover, applying this method can also reduce the load voltage by controlling the alternating on–off of the switches, thereby protecting the harvester in case of high primary currents. The theoretical calculation, circuit simulation, and experimental results demonstrate the effectiveness of this method. [ABSTRACT FROM AUTHOR]

This paper introduces the modeling and fault diagnosis of rotor eccentricities of permanent magnetic synchronous machine (PMSM). The modeling of machine in healthy and fault condition have been proposed based on magnetic equivalent circuit (MEC). Nevertheless, the research methods of diagnosis and modeling are common, this paper tends to provide a fast computation and more detailed model with reasonable degree of accuracy. Firstly, the MEC modeling of PMSM in the electric and magnetic fields are introduced and next, the different fault conditions are carried out. Also to consider the eccentricity fault of an interior mounted PMSM, a methodology based on MEC is proposed. The accuracy of this model will be verified by comparing with identical results obtained by finite element method (FEM). [ABSTRACT FROM AUTHOR]

This article presents the process of building a hybrid analytical model (HAM) for surface-mounted permanent-magnet machines. The HAM couples a reluctance network (RN) model in the stator region with a magnetic scalar potential analytical model in the air gap and magnets regions. This hybrid model can deal with the slotting effect with straight teeth, and takes magnetic saturation into account in the stator iron material using the RN model. It is calculated under open-circuit and loaded conditions. The magnetic flux density, flux linkage, back electromotive force (EMF), and torque of the machines are also calculated. This hybrid model is compared with the subdomain method. It is also compared with the finite element method (FEM) both in terms of the size of the matrix that needs to be calculated and in terms of the torque error. We analyzed this method for two surface-mounted permanent-magnet machines, one with a symmetry factor of four and another with a symmetry factor of three. In both cases, HAM reduced the size of the matrix that needed to be solved compared to FEM. In the machine with a symmetry factor of three, when the matrix size of both FEM and HAM was around 1700 × 1700, the torque error of FEM was 2.62% compared to the high-mesh-density FEM simulation, while the torque error of HAM was only 0.17% compared to the same simulation. HAM also had significant advantages over the subdomain method, as it reduced the torque error from 16.8% to 0.08% in the case of high magnetic saturation. The HAM can, hence, play a significant role in the design and optimization of surface-mounted permanent-magnet machines, especially in cases where magnetic saturation is present. [ABSTRACT FROM AUTHOR]

This paper presents the design and an analysis of a surface PM vernier generator (SPMVG) for MW-scale direct-drive (DD) wind turbine application. An SPMVG has the advantage of higher torque density; however, especially at higher power ratings with increased electrical loadings, the power factor worsens and there are some serious concerns including magnetic saturation of cores and PM demagnetization. These issues are directly related to machine design parameters such as PM dimensions, applied electrical loading, slot geometry and the choice of slot–pole combination. It is determined that depending on the PM thickness and a few other design variables, each slot–pole combination has an optimal value of specific electrical loading. The use of the optimal value of specific electrical loading ensures that the machine is not saturated, the performance is optimum and the power factor is not unnecessarily degraded. Moreover, under certain design constraints, design criteria are developed that ensure the proper choice of various entailed design variables. By using the developed design criteria, the trends of various electromagnetic performances with variation in the slot–pole combination are discussed. The obtained trends clearly show that each slot–pole combination offers a certain torque density and power factor; thus, it serves as a guide for the selection of the slot–pole combination considering the required torque density and/or certain power factor limit. Finally, by using the developed design approach, an SPMVG for rated power of 15 MW is designed; the design objectives are to maximize torque per volume with a power factor limit of 0.4. Moreover, the various aspects of the performances of the designed SPMVG are comprehensively compared against a conventional PM DD 15 MW generator. [ABSTRACT FROM AUTHOR]

This article proposes a three-phase four-wire inverter drive system for an adjustable field interior permanent magnet synchronous motor utilizing magnetic saturation. The magnetic saturation is regarded as a phenomenon of a decrease in permeability depending on an extra magnetic field. In the proposed motor, the number of flux linkage can be controlled by modulating the permeability of magnetic leakage paths in the rotor. However, the proposed adjustable field method requires an additional magnetomotive force (m.m.f.) to control the permeability. Therefore, a zero-sequence current iz fed by the three-phase four-wire inverter is utilized as the additional m.m.f. source. Thereby, the field control can be achieved with a simple three-phase inverter without sacrificing the number of switching devices compared with conventional motor drives. In the article, the control algorithm of the three-phase four-wire inverter is discussed, and its usefulness is verified by comparing the proposed drive system with other methods or systems. [ABSTRACT FROM AUTHOR]