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Permanent magnet motors (PMMs) have emerged as key components in numerous industrial applications due to their high efficiency, compact size, and robust performance characteristics. However, to attain optimal performance in PMM drives, accurately predicting and mitigating core losses is paramount. This paper aims to provide a comprehensive review of advancements and methodologies for enhancing the performance of PMM drives by integrating equivalent circuit models (ECMs) that account for core losses. Firstly, the significance of core losses in motor drives is underscored, alongside a survey of research endeavors dedicated to core loss reduction. Notably, emphasis is placed on mathematical models offering both swift computation and reasonable accuracy. Subsequently, the paper delves into the development of ECMs, focusing on approaches adept at capturing core loss effects across diverse operating conditions. Moreover, this paper explores the utilization of these improved ECMs in the design and control of PMMs to achieve enhanced performance. By integrating core loss considerations into design and control strategies, PMM drives can optimize efficiency, torque production, and overall system performance. In summary, this paper may consolidate the current state-of-the-art techniques for enhancing PMM performance through the integration of core-loss-aware ECMs. It highlights key research directions and opportunities for further advancements in this critical area, aiming to foster the development of more efficient and reliable PMM-based systems for a wide range of industrial applications. [ABSTRACT FROM AUTHOR]

The highway cycle is an important consideration in the EV's new European driving cycles (NEDCs) range, as the steady-state efficiency improvement in such conditions can be greatly beneficial. In the model predictive control (MPC) of the permanent magnet synchronous motors (PMSMs), the predicted next-step feedback reference generated by the equivalent circuit model (ECM) will contribute directly to the voltage vector selection, therefore influencing the performance of the motor control. In the current MPC scheme, when the conventional ECM is applied, it only considers copper loss, and the core loss is usually disregarded. In some circumstances, such as the highway cycle of EVs, the motors are at high speed, the torque is low, and the core loss can be significant in the losses, thus affecting the accuracy of control and the efficiency of the system; hence, the introduction of core loss ECM into the MPC would be beneficial. This paper aims to investigate the steady-state efficiency improvement of a novel ECM of PMSM considering core loss ECM, and the comparison will be based on model predictive direct torque control (MPDTC) using the core loss ECM, which will be compared to MPDTC with the conventional ECM of the PMSM. The results demonstrate the proposed ECM's efficiency improvement in various conditions, the limitations of the model and the simulation are discussed, and future work is proposed. [ABSTRACT FROM AUTHOR]

The operation of the electricity network has grown more complex due to the increased adoption of renewable energy resources, such as wind and solar power. Using energy storage technology can improve the stability and quality of the power grid. One such technology is flywheel energy storage systems (FESSs). Compared with other energy storage systems, FESSs offer numerous advantages, including a long lifespan, exceptional efficiency, high power density, and minimal environmental impact. This article comprehensively reviews the key components of FESSs, including flywheel rotors, motor types, bearing support technologies, and power electronic converter technologies. It also presents the diverse applications of FESSs in different scenarios. The progress of state-of-the-art research is discussed, emphasizing the use of artificial intelligence methods such as machine learning, digital twins, and data-driven techniques for system simulation, fault prediction, and life-assessment research. The article also addresses the challenges related to current research and the application of FESSs. It concludes by summarizing future directions and trends in FESS research, offering valuable information for further advancement and improvement in this field. [ABSTRACT FROM AUTHOR]

With the increasing demand for smaller, lighter, and more affordable electromagnetic devices, there is a growing trend toward developing high-power-density transformers and electrical machines. While increasing the operating frequency is a straightforward approach to achieving high power density, it can lead to significant power loss within a limited volume, resulting in excessive temperature rise and device degradation. Therefore, it is crucial to design high-power-density electromagnetic devices that exhibit low power loss and efficient thermal dissipation to address these challenges. Advanced techniques, such as the utilization of novel and advanced electromagnetic materials, hold great promise for overcoming these issues. Specifically, nanocrystalline and amorphous magnetic materials have emerged as highly effective solutions for reducing power loss and increasing efficiency in electromagnetic devices. This paper aims to provide an overview of the application of nanocrystalline and amorphous magnetic materials in transformers and electrical machines, along with key technologies and the major challenges involved. [ABSTRACT FROM AUTHOR]

The demand for a reliable, cheap and environmentally friendly source of energy makes the integration of renewable energy into power networks a global challenge. Furthermore, reliability, as one of the core elements of efficient and cost-effective energy management options, is still among the dominant factors/techniques that receive more attention for realistic penetrations of renewable energy into the electricity grid. This paper proposes an efficient way of energy management for a grid-connected microgrid. The grid-connected microgrid used in the analysis consists of solar photovoltaic (P.V.) and battery. In this microgrid configuration, oftentimes, the output power might not be equal to the system demand; in this regard, it is expected that the mismatch between these output powers is not zero. However, to reduce the mismatch between demand and supply to be close to zero, this paper proposes strategies of increasing the rated power of solar, battery and grid separately and combining them with a view of finding the cheapest option among these strategies. The results have shown that the cost increment for different options is USD 280.792, 84.48 and 48.204 for storage, P.V. and grid, respectively. These have shown that the storage option is the most expansive option for improving P.V. grid-connected microgrids. This is followed immediately by the P.V. option, which is weather dependent. On the other hand, the grid option is the cheapest option for system reliability improvement. This paper is expected to be useful to both new researchers and experts who are working in energy management with an emphasis on the reliability aspect. [ABSTRACT FROM AUTHOR]

Electric motors play a crucial role in modern industrial and domestic applications. With the trend of more and more electric drives, such as electric vehicles (EVs), the requirements for electric motors become higher and higher, e.g., high power density with good thermal dissipation and high reliability in harsh environments. Many efforts have been made to develop high performance electric motors, such as the application of advanced novel electromagnetic materials, modern control algorithms, advanced mathematical modeling, numerical computation, and artificial intelligence based optimization design techniques. Among many advanced magnetic materials, soft magnetic composite (SMC) appears very promising for developing novel electric motors, thanks to its many unique properties, such as magnetic and thermal isotropies, very low eddy current loss, and the prospect of low-cost mass production. This paper aims to present a comprehensive review about the application of SMC for developing various electric motors for electric drives, with emphasis on those with three-dimensional (3D) magnetic flux paths. The major techniques developed for designing the 3D flux SMC motors are also summarized, such as vectorial magnetic property characterization and system-level multi-discipline robust design optimization. Major challenges and possible future work in this area are also discussed. [ABSTRACT FROM AUTHOR]

High-temperature superconductor (HTS) bulks have demonstrated extremely intriguing potential for industrial and commercial applications due to their capability to trap significantly larger magnetic fields than conventional permanent magnets. The magnetic field in electrical rotating machines is a combination of alternating and rotational fields. In contrast, all previous research on the characterization of electromagnetic properties of HTS have solely engrossed on the alternating AC magnetic fields and the associated AC loss. This research paper gives a thorough examination of the AC loss measurement under various conditions. The obtained results are compared to the finite element-based H-formulation. The AC loss is measured at various amplitudes of circular flux density patterns and compared with the AC loss under one-dimensional alternating flux density. The loss variation has also been studied at other frequencies. The findings in this research paper provide more insights into material characterization, which will be useful in the design of future large-scale HTS applications. [ABSTRACT FROM AUTHOR]

The magnetic properties of magnetic cores are essential for the design of electrical machines, and consequently appropriate mathematical modeling is needed. Usually, the design and analysis of electrical machines consider only the one-dimensional (1D) magnetic properties of core materials, i.e., the relationship of magnetic flux density (B) versus magnetic field strength (H), and their associated power loss under 1D magnetization, in which the B and H are constrained in the same orientation. Some studies have also been performed with the two-dimensional (2D) magnetizations in which the B and H are vectorial, rotating on a plane, and they may not be in the same direction. It has been discovered that the 2D rotational property is very different from its 1D alternating counterpart. However, the magnetic fields in an electrical machine, in particular claw pole and transverse flux machines, are naturally three-dimensional (3D), and the B and H vectors are rotational and may not lie on the same plane. It can be expected that the 3D vectorial property might be different from its 2D or 1D counterpart, and hence it should be investigated for the interests of both academic research and engineering application. This paper targets at a general summary about the magnetic material characterization with 3D vectorial magnetization, and their application prospect in electrical machine design and analysis. [ABSTRACT FROM AUTHOR]

Over time, high-temperature superconductor (HTS)-coated conductors (CCs) have proven to be promising candidates for future high-efficiency and high-power density electrical machines. However, their commercialization is handicapped due to the AC dissipative loss that occurs upon exposure to external magnetic fields. In rotating electromagnetic devices, the external magnetic field is a combination of alternating and rotating magnetic fields. Most of the research is devoted to the effect of exposure of the superconductors to alternating magnetic fields only. This article presents an investigation to observe the behavior of HTSCCs under rotating magnetic fields, particularly the AC loss, using a finite-element-based homogeneous H-formulation technique. Our investigation shows that the AC loss could be considerably high when HTSCCs are exposed to rotating magnetic fields and, ultimately, could affect the cooling efficiency of future high-efficiency and high-power density electrical machines. [ABSTRACT FROM AUTHOR]

High-temperature superconducting materials have shown great potential for the design of large-scale industry applications. However, they are complicated under AC conditions, resulting in penalties such as power loss or AC loss. This loss has to be considered in order to design reliable and efficient superconducting devices. Furthermore, when superconductors are used in rotating machines, they may be exposed to rotating magnetic fields, which is critical for the design of such machines. Existing AC loss measuring techniques are limited to measuring under one-dimensional AC magnetic fields or transport currents. Therefore, it is essential to develop and investigate robust experimental techniques to investigate the loss mechanism in HTS machines. In this paper, a new and novel experimental technique has been presented to measure AC loss in rotating magnetic field conditions. The loss under rotating magnetic fields is measured and compared by numerical modeling methods, and the results show a strong correlation with the numerical modeling and show the effectiveness of the experimental setup. [ABSTRACT FROM AUTHOR]

Amorphous metal (AM), specifically amorphous ferromagnetic metal, is considered as a satisfactory magnetic material for exploring electromagnetic devices with high-efficiency and high-power density, such as electrical machines and transformers, benefits from its various advantages, such as reasonably low power loss and very high permeability in medium to high frequency. However, the characteristics of these materials have not been investigated comprehensively, which limits its application prospects to good-performance electrical machines that have the magnetic flux density with generally rotational and non-sinusoidal features. The appropriate characterization of AMs under different magnetizations is among the fundamentals for utilizing these materials in electrical machines. This paper aims to extensively overview AM property measurement techniques in the presence of various magnetization patterns, particularly rotational magnetizations, and AM property modeling methods for advanced electrical machine design and analysis. Possible future research tasks are also discussed for further improving AM applications. [ABSTRACT FROM AUTHOR]

One of the keys to the success of the fourth industrial revolution (Industry 4.0) is to empower machinery with cyber–physical systems connectivity. The digital twin (DT) offers a promising solution to tackle the challenges for realizing digital and smart manufacturing which has been successfully projected in many scenes. Electrical machines and drive systems, as the core power providers in many appliances and industrial equipment, are supposed to be reinforced on the verge of Industry 4.0 in the fields of design optimization, fault prognostic and coordinated control. Therefore, this paper aims to investigate the DT modelling method and the applications in electrical drive systems. Firstly, taking the high-speed permanent-magnet machine drive system as an example, multi-disciplinary design fundamentals and technologies, aiming at building initial mechanism and simulation models, are reviewed. The state-of-the-art of DT technologies is figured out to serve for high-precision and multi-scale dynamic modelling, by which a framework for DT models of electrical drive systems is presented. More importantly, fault diagnosis and optimization strategies of electrical drive systems in the decision and application layer are also discussed for the DT models, followed by the conclusions presenting open questions and possible directions. [ABSTRACT FROM AUTHOR]

The circumferential and axial widths of permanent magnet (PM) pole and E-shape stator pole of linear rotary motor with interlaced PM poles are very influential to the back electromotive force (EMF) and the flux leakage analysis is complex, which causes difficulty in optimization of the motor structure. One of the key issues in optimization design is to calculate the flux leakage accurately. In this article, the main flux and side flux variation laws of stator pole are derived by analytical method. The flux leakage can be divided into the flux leakage between the PM and the mover, flux leakage on the stator tooth tip, and the flux leakage between the adjacent PM poles and stator pole. The 3-D flux leakage calculation model is built, which is suitable for the calculation of magnetic flux based on different motor operating principles. Then the rotational and rectilinear back EMFs are calculated by analytical method, which are consistent with the results analyzed by 3-D finite element method. [ABSTRACT FROM AUTHOR]

Electric vehicles are regarded as a significant way to mitigate the global energy crisis and the environmental pollution problem. Motor control is a very important part for electric vehicles. As for hardware, a motor controller usually has components such as a power module, microprocessor unit, IGBT driver, sensors, and resolver-to-digital convertor. As for software, a field-oriented control (FOC) with space vector pulse width modulation (SVPWM) is a popular method, while model predictive control (MPC) has recently shown great potential in motor drives. In this paper, both FOC and MPC are discussed and the performances are compared based on experiments. As the implementation is on a digital processor, the discretization and normalization are addressed, and the flux observer and speed estimation are discussed. Some practical issues for implementation are also talked about, such as field weakening control, overmodulation, etc. This paper focuses on how to implement the improved motor control for electric vehicles as industrial applications. The steady-state torque performances of this motor controller are verified by motor test-bench experiments. MPC shows as good performance as FOC in these experiments. [ABSTRACT FROM AUTHOR]

High-temperature superconductor (HTS) bulks have shown very promising potential for industrial applications due to the ability to trap much higher magnetic fields compared to traditional permanent magnets. In rotating electrical machines, the magnetic field is a combination of alternating and rotating fields. On the contrary, all studies on electromagnetic characterization of HTS presented in the literature so far have only focused on alternating AC magnetic fields and alternating AC loss due to the unavailability of robust experimental techniques and analytical models. This paper presents a numerical investigation on the characterization of HTS bulks subjected to rotating magnetic fields showing AC loss, current density distribution in three-dimensional axes, and trapped field analysis. A three-dimensional numerical model has been developed using H-formulation based on finite element analysis. An HTS cubic sample is magnetized and demagnetized with two-dimensional magnetic flux density vectors rotating in circular orientation around the XOY, XOZ, and YOZ planes. [ABSTRACT FROM AUTHOR]

Fe-based amorphous magnetic materials are recently attracting strong interests for constructing high-power density and high-efficiency rotating electrical machines due to their attractive properties, such as low core loss and high magnetic saturation. Accurate measurement and modeling of the rotational core losses of the core magnetic materials, and the corresponding patterns of rotating magnetic flux density ($B$) and magnetic field strength ($H$) are important for the analysis and design of electrical machines. This article presents the measurement of rotational core loss of a Fe-based amorphous magnetic material (amorphous 1k101), and its corresponding modelings under two-dimensional (2-D) circularly and elliptically rotating magnetic fields. In addition, an improved and simplified analogical model of rotational hysteresis loss is proposed for such magnetic materials. The circular and elliptical $B$ loci and the corresponding $H$ loci have been investigated to acquire the perception of anisotropy and permeability of the amorphous materials. The proposed theory and models are experimentally verified. [ABSTRACT FROM AUTHOR]

This paper reviews the state-of-the-art of mitigation technologies of low frequency current ripple (LFCR) injected into fuel cell (FC). Although there are their own merits and demerits, the optimized LFCR control techniques and topology structures are characterized in many aspects like performance, durability, reliability and lifetime of FC. Three mains topologies and mitigation methods of LFCR have been investigated based on the literature review, which are the passive compensation methods, active compensation methods, and passive and active hybrid compensation methods. Some rules based tables are set to evaluate the LFCR against the topologies, control strategies, current ripple, application and advantages/limitations. Moreover, the mitigation control strategies are compared side by side with their specific applications in FC system. To select and implement them, this review can provide a reference and basis for the researchers in related fields. Finally, a case study in an uninterruptible power supply application is conducted. • Generation mechanism and performance effect of low frequency current ripple (LFCR). • A review on three main types of LFCR mitigation technologies in fuel cell (FC). • A case study with passive and active hybrid LFCR compensation method. • A reference and basis for the researchers in the related fields of LFCR and FC. [ABSTRACT FROM AUTHOR]

This article proposes a robust control strategy for five-level T-type (5L-T) hybrid power converters to achieve superior dynamic performance for effectively regulating the dc-bus voltage under external disturbances and generating high-quality grid current at the same time. A new filter-less dc-bus ripple voltage estimation method and a simple technique to remove this ripple component from the measured dc-bus voltage of a single-phase converter are developed. A sliding-mode control (SMC) incorporated with an extended-state observer (ESO) is employed for the outer voltage control loop, and to dynamically calculate the input (i.e., the active power reference) for the inner current-tracking controller. The proposed SMC-ESO approach presents a high disturbance rejection capability and robustness against the dc-bus load variation, and thus, significantly improves the dynamic and steady-state performance during system uncertainties. Moreover, a finite control set-model predictive control algorithm is derived as the inner current controller to track their references while balancing the dc-bus capacitor voltages. The effectiveness of the proposed controller is demonstrated and verified through measurement results. [ABSTRACT FROM AUTHOR]

To deeply understand the influences of power converter's low frequency current ripple (LFCR) and harmonics on a proton exchange membrane fuel cell (PEMFC) in its power conditioning system (PCS), a comprehensive measurement and analysis of the influences of LFCR and harmonics on PEMFC's performance and durability is investigated in this paper. Based on an equivalent circuit model of PEMFC stack and a mechanism model for evaluating the LFCR effects on the PEMFC, this paper studies primarily and systematically the comprehensive influences of LFCR and harmonics on PEMFC performances and durability, such as (1) degrading the PEMFC performance, (2) shortening the lifetime of PEMFC, (3) reducing the stack output power, (4) lowing its availability efficiency, (5) producing more heat and raising the PEMFC temperature, (6) consuming more fuel, and (7) decreasing the fuel utilization. Finally, a Horizon 300 W PEMFC stack is implemented and tested. • Investigating comprehensive influences of power converter LFCR and harmonics on FC. • Indicating the mechanism and model for evaluating the LFCR effects on a PEMFC. • Reducing performance, lifespan, power, efficiency, and hydrogen utilization of FC. • Increasing the thermal and temperature, and fuel consumption of FC. [ABSTRACT FROM AUTHOR]

Flux reversal linear rotary permanent magnet actuator (FR-LRPMA) is a two-degree-of-freedom actuator with two ferromagnetic (Fe) poles and two permanent magnet (PM) poles mounted on the surface of each stator pole. The flux linkage waveform of the actuator is more sinusoidal than that of the traditional topology, which are analyzed by the ideal linear model of one stator section of the proposed actuator. In order to reduce the amplitudes of the cogging torque and detent force, a key space gap parameter of the FR-LRPMA between the Fe pole and PM pole is studied in the circumferential and axial directions. The expressions of cogging torque and detent force are derived by the magnetomotive force analytical method, which are used to obtain the optimal space gap parameter value. The electromagnetic characteristics of the actuator are analyzed by the finite-element method. The amplitudes of cogging torque and detent force are reduced and the back electromotive force waveform is more sinusoidal than that of the original topology, which are verified by the experiment. [ABSTRACT FROM AUTHOR]

Soft magnetic composite (SMC) materials and SMC electromagnetic devices have attracted strong research interest in the past decades. However, SMC devices have large core loss that needs to be put into consideration even at the design stage. Effective and accurate prediction of the core loss becomes crucial for the design and optimization of high-performance motors with these materials. Equivalent circuit model is a widely used method for machine analysis, due to the advantages in the fast calculation with a clear physical mechanism. This paper presents an equivalent circuit model to predict the core loss of a claw-pole permanent magnet motor with SMC stator core. All the parameters including the equivalent core-loss resistance in the equivalent circuit model are identified based on the finite-element method to achieve high accuracy, and the effectiveness of the parameters identification methods is experimentally verified. The proposed equivalent circuit model can predict the core loss and motor’s performance efficiently both under no-load and loading conditions. [ABSTRACT FROM AUTHOR]

Considering the special characteristics existing in the pulse-width modulated (PWM) switching converter, a general method for the time-stepping finite element analysis based electromagnetic field coupling with its feeding circuit used in the analysis of PWM switching converter considering hysteresis effects is introduced in this paper. Comparing with the electromagnetic field-circuit indirect coupling method (ICM), the proposed method has overcome the drawback that the ICM cannot take the hysteresis effects into account. Compared with the electromagnetic field-circuit direct coupling method (DCM), the proposed method has the similar accuracy but higher efficiency. Furthermore, like the ICM, the proposed method also divides the system with higher state dimensions produced by the DCM into two subsystems with lower state dimensions; this may reduce the algorithm convergence problem which often happens in high dimensional systems. [ABSTRACT FROM AUTHOR]

Winding inductance is an important parameter in determining the performance of electrical machines, particularly those with large inductance variation. This paper investigates the influence of winding inductance variation on the performance of a three-phase three-stack claw pole permanent magnet motor with soft magnetic composite (SMC) stator by using an improved phase variable model. The winding inductances of the machine are computed by using a modified incremental energy method, based on three-dimensional nonlinear time-stepping magnetic field finite element analyses. The inductance computation and performance simulation are verified by the experimental results of an SMC claw pole motor prototype. [ABSTRACT FROM AUTHOR]

Magnetorheological fluid (MRF) materials are used in many devices as smart materials. However, the application of this material is limited to damper or vibration absorber because of the lack of understanding of its magnetic hysteresis properties. This paper systematically presents our recent investigation and simulation on the magnetic hysteresis properties of MRF materials. The measurement of its magnetic hysteresis property was accomplished by using a two-dimensional single sheet tester with an MRF sample container. An extended large-scale atomic/molecular massive parallel simulator, which is combined with the Stoner–Wohlfarth hysteresis model, was employed for simulating the magnetic hysteresis properties of MRF material. The measurement and simulation results are compared, analyzed, and discussed. The results will be useful for modeling of magnetic hysteresis properties of MRF materials. [ABSTRACT FROM AUTHOR]

This paper presents a hybrid power and energy source supplied by a proton exchange membrane fuel cell (PEMFC) as the main power source in an uninterruptible power supply (UPS) system. To prevent the PEMFC from fuel starvation and degradation and realize their seamless linking in the hybrid UPS system, the power and energy are balanced by the battery and/or supercapacitor (SC) as two alternative auxiliary power sources. Based on the modeling and sizing of hybrid power and energy components, the power and energy management strategies and efficiency measurements of four operating modes in UPS system are proposed. To evaluate the proposed strategies, an experimental setup is implemented by a data acquisition system, a PEMFC generating system, and a UPS system including AC/DC rectifier, DC/AC inverter, DC/DC converter, AC/DC recharger and its intelligent control unit. Experimental results with the characteristics of a 300 W self-humidified air-breathing of PEMFC, 3-cell 12 V/5 Ah of batteries, and two 16-cell 120 F/2.7 V of SCs in parallel corroborate the excellent management strategies in the four operating modes of UPS system, which provides the basis for the optimal design of the UPS system with hybrid PEMFC/battery/SC power sources. [ABSTRACT FROM AUTHOR]

An uninterruptible power supply (UPS) system with different input current ripple reduction methods is proposed, and a comparison research has been conducted about these methods. The proposed UPS system consists of a 63-cell 300 W proton exchange membrane (PEM) fuel cell stack, two 16-cell supercapacitors (SCs) in series, a high-efficiency push–pull DC/DC converter and a half-bridge DC/AC inverter. Besides that the traditional push–pull DC/DC converter has inherent advantages of low input-current stress and high voltage conversion ratio, the SCs, LC filter, and an active clamp circuit are employed to reduce the input current ripples in the UPS system. First, the input current ripple generation and performance without an external component are analyzed and modeled in the PEM fuel cell. Then the input current ripple reduction methods mentioned above are proposed and operated in the designed UPS system. Finally, the experimental results show that the input current ripple can be further reduced by using different current ripple reduction approaches, and the active compensation method has better performance than the passive compensation method. The input current ripple is less than 5% of the rated input current. [ABSTRACT FROM AUTHOR]

To improve its performance, extend its lifetime, and overcome the problem of the slow dynamic during the start-up and the operation process of a proton exchange membrane fuel cell (PEMFC), this paper presents current short circuit and smart energy management approaches for a main PEMFC with auxiliary PEMFC, battery and supercapacitor as hybrid power source in parallel with an intelligent uninterrupted power supply (UPS) system. The hybrid UPS system consists of two low-cost 63-cell 300 W PEMFC stacks, 3-cell lead-acid battery, and 20-cell series-connected supercapacitors. Based on the designed intelligent hybrid UPS system, experimental tests and theoretical studies are conducted. Firstly, the modeling of PEMFC is obtained and evaluated. Then the performance improvement mechanism of the current short circuit is proposed and analyzed based on the Faradaic process and non-Faradaic process of electrochemical theory. Finally, the performances of the main PEMFC with the auxiliary PEMFC/battery/supercapacitor hybrid power source and intelligent energy management are experimentally measured and analyzed. The proposed current short circuit method can significantly extend the lifetime, improve the performance of PEMFC and decrease the size of the main FC for stationary, backup power sources and vehicular applications. [ABSTRACT FROM AUTHOR]

This paper presents the core loss computation in a permanent magnet transverse flux motor (TFM) with soft magnetic composite stator core and mild steel rotor yoke, in which the magnetic fluxes rotate. The computation is based on modified core loss models and finite element magnetic field analysis [finite element analysis (FEA)]. The coefficients for the core loss models are obtained by curve-fitting measurements on samples, and the magnetic flux density patterns in the motor are obtained by time-stepping FEA while operating conditions are considered. The computations of the motor core losses agree with the measured values on the TFM prototype. [ABSTRACT FROM AUTHOR]

Abstract: The turbine nacelle with traditional wind power generation system is heavy, especially in offshore applications due to the large mass of the power frequency step-up-transformer operated at 50 or 60Hz, and copper conductor generator. For example, the weight and volume of a 0.69/33kV 2.6MVA transformer are typically in the range of 6–8t and 5–9m3, respectively. The weight for a 10MW direct drive permanent magnet generator is about 300t. These penalties significantly increase the tower construction, and turbine installation and maintenance costs. The tower cost represents 26% of the total component cost of the turbine and on average about 20% of the capital costs are associated with installation. Typical maintenance cost of an offshore wind turbine is about 2.3cents/kWh, which is 20% higher than that of an onshore based turbine. As alternative approaches to achieve a compact and lightweight offshore wind turbine nacelle, different concepts have been proposed in recent years, such as step-up-transformer-less system, medium-frequency (in the range of a few kHz to MHz) power transformer-based system, multilevel and modular matrix converter-based system and superconducting generator-based system. This paper aims to review the technical challenges, current research and developmental trends, and possible future directions of the research to reduce the weight and volume of the nacelle. In addition, a comprehensive review of traditional wind power generation technologies is conducted in this article as well. [Copyright &y& Elsevier]

• Characterization of a Fe-based amorphous magnetic material by modified J-A model. • Proposal of an additional error criterion along with general error criterion for the identification of the J-A model parameters. • Proposal of a modified J-A model especially at low magnetic induction levels. • Incorporation of dynamic loss models into the proposed modified J-A model. The physical behaviour of a magnetic material can be characterized by Jiles-Atherton (J-A) model where some model parameters are generally identified by optimization techniques. For identification of model parameters using optimization techniques, an error criterion based on the error between the measured and calculated magnetic flux density (B) or magnetic field strength (H) is commonly considered where the relative error in the calculation of iron loss is ignored. Consequently, the calculated iron loss from B - H loop sometimes highly differs from its experimental value. In this paper, the error criteria for J-A model's parameter identification are designed as the combination of the relative iron loss error criterion and the general existing error criterion. Furthermore, a modified J-A model is proposed to improve the agreement between experimental and calculated results especially at the low magnetic induction levels by introducing a scaling factor in the anhysteretic magnetization. The proposed modified J-A model and the effectiveness of the error criteria for its parameter identification are tested by comparing calculated results with the experimental results as well as recently works in the literature. [ABSTRACT FROM AUTHOR]

In [1], Table I should be replaced by the following table. TABLE I Main Structure Parameters of ES-LRMPMG Parameters Value Parameters Value Parameters Value Rso (mm) 59 ws (mm) 10.5 wpmθ (mm) 11 Rsi (mm) 19.3 wsa (mm) 18 wspa (mm) 46.5 Rr (mm) 15.7 Rpm (mm) 18.7 wga (mm) 6 Rsh (mm) 10 hsy (mm) 10 wpma (mm) 11.4 [ABSTRACT FROM AUTHOR]

Soft magnetic composite (SMC) materials are especially suitable for developing electrical machines with complex structure and three-dimensional (3-D) magnetic flux path. In these SMC machines, the magnetic field is in general 3-D and rotational, so the mechanism and calculation of core loss may be quite different from that in traditional electrical machines with laminated steels in which the magnetic field is restrained. This paper investigates the calculation of core loss in a permanent magnet claw pole motor with SMC stator core. First, core loss models are developed based on the experimental data on SMC samples by using a 3-D magnetic property tester. Then, 3-D magnetic time-stepping field finite element analysis (FEA) is conducted to find the flux density locus in each element when the rotor rotates. The core loss is computed based on the magnetic field FEA results by using the developed core loss models. The calculations agree well with the experimental measurements on the SMC motor prototype. [ABSTRACT FROM PUBLISHER]

In the vector control system of a tubular oscillating permanent magnet synchronous linear motor, it is difficult to obtain accurate feedback information from the conventional mechanical sensors under bad and complex working conditions. This paper presents a new predictive current control designed to estimate the speed of the tubular oscillation permanent magnet synchronous linear motor. It implements two control techniques: The first technique is using the sliding-mode observer's speed observer for speed estimation. The second is to design a deadbeat predictive current control to replace the PI regulator in the conventional current loop; it solves the difficulties of global optimization and PI parameter setting. The simulation and experimental results show that this method gives a good dynamic performance. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents the development of an intelligent uninterruptible power supply (UPS) system with a hybrid power source that comprises a proton-exchange membrane fuel cell (PEMFC) and a battery. Attention is focused on the architecture of the UPS hybrid system and the data acquisition and control of the PEMFC. Specifically, the hybrid UPS system consists of a low-cost 60-cell 300W PEMFC stack, a 3-cell lead–acid battery, an active power factor correction ac–dc rectifier, a half-bridge dc–ac inverter, a dc–dc converter, an ac–dc charger and their control units based on a digital signal processor TMS320F240, other integrated circuit chips, and a simple network management protocol adapter. Experimental tests and theoretical studies are conducted. First, the major parameters of the PEMFC are experimentally obtained and evaluated. Then an intelligent control strategy for the PEMFC stack is proposed and implemented. Finally, the performance of the hybrid UPS system is measured and analyzed. [Copyright &y& Elsevier]

Abstract: Soft magnetic composite (SMC) materials are especially suitable for construction of electrical machines with complex structures and three-dimensional (3D) magnetic fluxes. In the design and optimization of such 3D flux machines, the 3D vector magnetic properties of magnetic materials should be properly determined, modeled, and applied for accurate calculation of the magnetic field distribution, parameters, and performance. This paper presents the measurement of 3D vector magnetic properties and determination of 3D reluctivity tensor of SMC. The reluctivity tensor is a key factor for accurate numerical analysis of magnetic field in a 3D flux SMC motor. [Copyright &y& Elsevier]

A novel programmed hybrid spreading spectrum modulation method to mitigate electromagnetic interference (EMI) emission and bearing current in the context of miniaturised and lightweight synchronous machine drives is proposed. The proposed method adopts the combination of conventional pulsewidth modulation (PWM) and low common mode voltage PWM. The offline look‐up table for switching frequency is acquired by analysing the root mean square voltage values at different modulation indices and angles. By adjusting the switching frequency according to this table, the spectrum can be spread into the sidebands of the switching frequency, and the harmonic spike can be suppressed. To address the challenge of increased current ripple and harmonic distortion in high torque density motors under overload conditions, a motor model that considers the cross‐saturation and slotting effect is presented. This motor model is used to derive the switching frequency correction factors, aiming to mitigate the influence of saturation and slotting effect on harmonic amplification. The proposed method is well‐suited for controlling synchronous motors using three‐phase two‐level voltage source inverters. The simulation and experimental results validate the effectiveness of the proposed method, showcasing its advantages in terms of computational complexity reduction and significant attenuation of peak EMI currents. [ABSTRACT FROM AUTHOR]

• Characterization of hysteretic effects of Fe-based amorphous magnetic materials. • Calculation of total core loss of Fe-based amorphous magnetic materials. • Development of a generalized inverse Preisach model. • Proposed a technique to find out the feedback coefficient of the Preisach model. • Investigation of the effects of minor loops by inverse Preisach models. Fe-based amorphous magnetic materials are attracting more and more attentions in the application of low and medium frequency transformers due to their favorable properties of low core loss and high saturation magnetic flux density. Accurate modelling of their static and dynamic characteristics is required for analysis and design optimization of low and medium frequency transformers. In particular, for numerical analysis using the vectorial magnetic potential, an inverse magnetic hysteresis model is needed to predict the magnetic field strength from the magnetic flux density. When the excitation varies with time, the magnetic hysteresis model must be able to predict the dynamic hysteresis characteristics. This paper presents a generalized inverse Preisach dynamic hysteresis model for dynamic characterization of Fe-based magnetic materials. This model incorporates the reversible magnetization and magnetization dependent hysteresis, as well as all core loss components, including the hysteresis, eddy current, and excess losses. The proposed model can predict accurately the magnetic field strength from the magnetic flux density and hence accurate core losses. The predicted results are verified by experimental measurements. [ABSTRACT FROM AUTHOR]

Permanent magnet synchronous motor (PMSM) possesses the advantages of low power loss, high power density and high torque density and, hence, has achieved broad applications in both industrial drives and home appliances. With the increasing demands for high power density, the PMSM often operates at high speed and high frequency, leading to high power loss and temperature rise. Consequently, proper consideration of power loss, including the core loss, has attracted much attention for the modelling, designing, controlling and optimizing of PMSMs. However, the widely used equivalent circuit model, capable of providing good analysis results with fast calculation, often ignores the core loss, which may lead to unsatisfactory motor performance. This paper aims to investigate the development of equivalent circuit models, with predictable core loss for PMSMs, and proposes novel equivalent circuit models, which improve the core loss prediction accuracy in the load conditions. Some thoughts about the further improvement of the models are proposed and discussed. [ABSTRACT FROM AUTHOR]

Recent advances in magnetic materials have led to the development of compact and light weight, medium and high frequency transformers, which would be a possible solution to reducing the size and weight of wind turbine power generating systems. This paper presents the overall design and analysis of a Metglas amorphous alloy 2605SA1 based medium frequency transformer to generate the isolated balanced multiple DC supplies for medium voltage converter systems. A comprehensive electromagnetic analysis is conducted on the proposed design based on experimental results. The test stand, data analysis, and test results are discussed. [ABSTRACT FROM AUTHOR]

Magneto-rheological elastomer (MRE) is a new kind of smart material. Its rheological properties can be altered and controlled in a real time manner when it is applied an external magnetic field. For calculating magnetic properties of MRE material, usually Maxwell-Garnet equation is used to acquire an approximately effective permeability. This equation treats the magnetic property of particles as linear. However, when the applied magnetic field is alternating or rotating, the nonlinearity of magnetic property and magnetic hysteresis cannot be neglected. Hence, the measurement and modelling of the magnetic properties under alternating and rotating magnetic fields are essential to explore new applications of the material. This paper presents the investigation on the magnetic hysteresis properties of MRE material under one-dimensional (1-D) alternating and two-dimensional (2-D) rotating magnetic field excitations. A kind of MRE material, consisting of 70% carbonyl iron particles, 10% silicone oil, and 20% silicone rubber, was used to investigate the magnetic properties. The diameter of carbonyl iron particles is 3-5 μm. The measurement results, such as the relations between magnetic field intensity (H) and magnetic flux density (B) under different magnetic field excitations on the MRE sample, have been obtained and analyzed. These data would be useful for design and analysis of MRE smart structures like MR dampers. [ABSTRACT FROM AUTHOR]

Soft magnetic composite (SMC) materials are especially suitable for construction of low-cost high-performance motors with three-dimensional (3-D) magnetic fields. The 3-D finite-element analysis (FEA) conducted in the design of a claw pole transverse flux motor (CPTFM) with an SMC core reveals very complicated B (flux density) loci in the core when the motor rotates. In order to understand and account for the effects of the patterns of B loci on motor parameters and performance such as core losses, a 3-D magnetic property testing system was built for magnetic measurement on a cubic SMC sample. 3-D rotational core loss models in SMC materials and rotating motors are developed. [ABSTRACT FROM AUTHOR]

This paper presents a finite element analysis (FEA) based method for analyzing and controlling the bias magnetic state of the transformer of a pulse-width-modulation (PWM) switching full bridge dc-dc converter. A field-circuit indirect coupling method for predicting the transient bias magnetic state is introduced first. To increase flexibility of the proposed method, a novel transformer model which can address not only its basic input-output characteristic, but also the nonlinear magnetizing inductance, is proposed. Both the asymmetric characteristic and the variable laws of the current flowing through the two secondary windings during the period of PWM switching-off state are highlighted. Finally, the peak magnetizing current controlled method based on the on-line magnetizing current computation is introduced. Analysis results show that this method can address the magnetic saturation at winding ends, and hence many previous difficulties, such as the start-up process and asymmetry of power electronics, can be easily controlled. [ABSTRACT FROM AUTHOR]

This paper presents a new single-source three-phase seven-level inverter with an inherent three-time voltage boosting capability for medium-voltage applications. The proposed topology is comprised of series connection of two switched-capacitor (SC) networks with an added half-bridge module per phase. Each of such integrated SC networks requires a single capacitor associated with three active power switches. The three-time voltage boosting feature of the proposed topology can reduce the dc-link voltage requirements by 50% in comparison to the traditional neutral point clamped (NPC), flying capacitors, active NPC (ANPC), hybrid clamped ANPC, and cascaded H-bridge topologies, and 75% to advanced ANPC topologies. It can also reduce the number of required switches and capacitors as well as their voltage stresses compared to those state-of-the-art topologies reported in the literature. By integrating “n” number of added SC networks in the proposed seven-level basic topology, the number of output voltage levels can be extended to 2n+3 per phase. A finite control set model predictive control algorithm is also derived to control the converter in both the active and reactive power exchanges modes without distorting the generated grid current quality. The capacitor voltage balancing is inherent in the proposed topology, and thus, there is no need for any additional voltage balancing circuit, which further reduces the control complexity. The performance of the proposed topology and its control algorithm are validated by several measurement results. [ABSTRACT FROM AUTHOR]

Condition monitoring can diagnose the inception of fault mechanisms in induction motors, thus avoiding failure and expensive repairs. Therefore, there is a strong need to develop an efficient condition monitoring approach. The main aim is to achieve a relatively low cost and non-invasive system which is still powerful in terms of monitoring for online detection of developing faults. The paper addresses rotor eccentricity faults and studies conventional monitoring techniques for induction motors. The eccentricity-generated additional air-gap flux waves should be reduced in order to reduce the unbalanced magnetic pull (UMP) when there is an eccentric rotor. The radial forces in an induction motor are calculated, and the characteristics of UMP are described. [ABSTRACT FROM AUTHOR]

If the batteries are charged by clean renewable energy sources, electric vehicles (EVs) can have zero gas emission, contributing greatly toward the preservation of the green environment. In a smart micro-grid, EVs together with other distributed energy storage units can be used to supply electricity to the loads during the peak hours so as to minimize the effects of the load shedding and improve the quality of electricity. To achieve these goals, an isolated hybrid multi-port converter is required to control the power flows and balance the energy among renewable energy sources, EVs, and the grid. In this paper, a new isolated multi-port converter is proposed, which can control the power flow in multiple directions. The converter is modeled in the matlab/Simulink software environment and this validates the technology with a laboratory prototype test platform. The modeling, implementation, and results are discussed comprehensively. [ABSTRACT FROM AUTHOR]

A number of research works have been carried out based on the optimization of linear generators for harvesting oceanic wave energy, but no significant method of shape optimization for determination of the optimal shape of linear generator has been found. Moreover, inclusion of some parameters, such as shape of linear generator's translator and stator, has been considered out of the scope of the conventional-, adaptive-, or knowledge-based genetic algorithms. This paper proposes a novel method through which any type of linear generator's shape can be optimized graphically. A mathematical model of the proposed method including human intervened genetic algorithm is presented. The proposed method has been applied to a direct-drive system-based linear generator where the maximization of electrical power output and minimization of steel core volume have been considered as the optimization objectives. The optimization parameters have been further optimized graphically within functional volumetric and electromagnetic constraints to achieve improved design solutions. The proposed method has included comprehensive geometric dimensions, magnetic, and electrical parameters. Finally, the shape of steel cores of the translator and special m-shaped stator of the linear generator is determined and simulated using the copper wire. This optimized shape of the linear generator is capable of satisfying the multiobjectives of maximal electrical power generation and reduction of its size. The ANSYS/Ansoft software has been used to create the platform for analyses of the whole system. [ABSTRACT FROM PUBLISHER]

In interior permanent magnet synchronous motor (IPMSM) position‐sensorless drives, the high‐frequency (HF) square‐wave voltage injection method is often used to estimate the rotor position and speed in low‐speed range by tracking the salient polarity of the motor. In order to reduce the torque ripple caused by HF signal injection, a strategy to update the magnitude of the injected signal online by back propagation neural network is proposed in this paper. With the proposed method, the neural network can update the magnitude of the injected signal online according to the d‐axis current and the position error information. It can not only ensure the accuracy of position extraction but also effectively reduce the current harmonics caused by the injected signal, and then the torque ripple can be reduced. In addition, the proposed method is easy to implement, resulting in low computation burden. Finally, the experiments are implemented on a 1‐kW IPMSM drive. The experimental results show that compared with the conventional fixed magnitude injection, the peak‐to‐peak value of the torque ripple is reduced by nearly half along with the decrease of the injected magnitude. [ABSTRACT FROM AUTHOR]

This paper puts forward a concept for measuring rotor eccentricity in a wound rotor induction machine. The analysis is fully developed in the theory section, then an experimental rig is described and measurements are taken. These are compared with the calculated values. Pole-specific search windings are necessary in a wound rotor machine, because standard sideband current measurement techniques are only valid for cage induction machines. The search coils can also be used to suppress unbalanced magnetic pull. [ABSTRACT FROM PUBLISHER]

Finite-control-set model predictive current control (FCS-MPCC) always has large steady-state fluctuation and computational burden. In this paper, a novel FCS-MPCC without a modulator to drive permanent magnet synchronous hub motors (PMSHMs), which combines virtual vectors expansion scheme and duty cycle control was proposed. The lack of a modulator reduces the complexity of the control system. The virtual vectors are synthesized by using active vectors, which improve the accuracy of voltage selection, and further improve PMSHM's steady-state performance and reduce current harmonics. The duty cycle control uses a zero vector to obtain better steady-state performance. However, the duty cycle of the virtual vectors is limited by the synthesis method, and further analysis is needed. A new calculation process is proposed to reduce the amount of calculation. The deadbeat principle is used to get reference voltage which determines sectors. Then, the best voltage vector in the selected sector is determined by the predetermined cost function. The traditional MPCC and the duty cycle MPCC (DCMPCC) are used as a comparison item to compare with the proposed method to illustrate its effectiveness. Results confirm that improved MPCC has good steady-state performance while maintaining a fast dynamic response. [ABSTRACT FROM AUTHOR]

This paper proposes a complex vector discrete current controller based on the flux-linkage data to solve the current loop oscillation problem of high power-density synchronous machines. An offline flux-linkage table measurement method considering cross saturation is introduced, and the data are used to deduce the symmetrical complex vector model. The influence of latch and delay of inverters on the line voltage of machines at high speed is analyzed and compensated during the controller design process. The proposed controller, which only needs to tune one parameter, can deal with the inductance mismatch issues caused by iron core saturation. The controller can be adopted in the current loop of saturated salient or nonsalient synchronous machines. Simulations and experiments have verified the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]