Iet Electric Power Applications最新文献

A position sensorless control method for interior permanent magnet synchronous motors (IPMSMs) has been developed to reduce cost and improve reliability. The performance of position estimation largely depends on the motor parameters. Inductance varies due to magnetic saturation during operation. Therefore, model-based position estimation deteriorates if the inductance variation is not taken into account. Traditional position estimation methods use an ideal IPMSM model that assumes the d-axis and q-axis are completely magnetically decoupled, that is, only the d-axis and q-axis self-inductances are considered. However, in reality, a cross-coupling effect exists in actual IPMSMs, resulting in mutual inductance between the d-axis and q-axis. This mutual inductance also degrades position estimation performance, particularly under heavy load conditions. Thus, it is important to identify the inductance while considering both magnetic saturation during operation and cross-coupling, in order to achieve accurate position estimation. In this paper, we propose a novel flux observer that accounts for the cross-coupling inductance and present an adaptive approach. Using the adaptive scheme, time-varying parameter identification can be effectively addressed. The effectiveness of the proposed method is verified through experimental results.

The intermittent and variable nature of external wind speeds often causes traditional wind power systems to misalign with electricity demand resulting in significant wind energy waste and reduced utilisation efficiency. Additionally, the growing global population and economic development have increased demands for residential heating and industrial thermal energy. In order to improve the controllability of wind energy conversion and simultaneously meet the heat demand, this study proposes a novel dual-stator generator capable of electrical-thermal flexible output, which offers significant advantages in terms of adaptable electrothermal energy output and enhanced operational efficiency. Initially, the topology and magnetic circuit model of the generator are systematically established, with its parameters meticulously designed to accommodate the simultaneous generation of both electrical and thermal energy outputs. Subsequently, in order to meet the standards of the power grid, a comprehensive multi-objective optimisation methodology is implemented to enhance the operational performance of the generator, achieving remarkable improvements: a 63.31% reduction in harmonic content, a 20.50% increase in heating capacity, a 44.35% reduction in torque pulsation, a 0.13% improvement in conversion efficiency, and a 13.60% enhancement in power density. Through the significant reduction of harmonic content and torque pulsation, the proposed design significantly enhances grid compatibility while minimising mechanical vibrations, thereby ensuring stable power generation even under highly fluctuating wind speed conditions. Finally, through extensive testing under various operational conditions, the generator demonstrates a remarkable 2:1 adjustable ratio of electrical-to-thermal output across variable wind speeds, achieving a peak efficiency of 97.41%.

Permanent magnet motors (PMMs) are a good choice for many applications due to their merits. These motors include synchronous motors (SMs) and flux modulation motors (FMMs). Their principles of operation depend on the air-gap permeance harmonics. Permeance harmonics are one of the main factors influencing the performance characteristics of PMMs, including torque, back-electromotive force (EMF), power factor, flux-linkage, phase inductance, and flux-weakening capability. This paper investigates the effect of air-gap permeance harmonics on PMM performance. For this purpose, the winding function theory (WFT) and the Fourier series are used and various PMM structures having different effective permeance harmonics are presented. Since it is not possible to analyse all these structures, four structures of conventional PMMs are selected as representatives of all the structures. In this paper, the improved analytical modelling of WFT is used, in which the turn function is modified to include the saturation and slot effects. Also, it is possible to calculate the leakage inductance between two stator teeth. Ansys Maxwell software is applied to verify the analytical modelling. Finally, two designs of FMM with different air-gap permeances are analysed and compared. The superior structure of this FMM is fabricated and tested to confirm the simulation results.

Dual three-phase induction motor drives are gaining attention in applications where reliability is a critical concern, such as automotive. Although the dual-stator winding reduces the impact of stator phase failures, these motors remain susceptible to broken rotor bar (BRB) faults. This paper presents a comprehensive methodology for their detection. The proposed approach encompasses all the key components of the detection algorithm, from motor modelling—used to generate a virtual dataset for training—to the selection of the most suitable variables for machine learning classification. Technical challenges, practical implementation insights, and experimental validation on real motors are discussed to provide a thorough understanding of the methodology and best design practices.

The equivalent circuit method is an accurate and versatile tool to estimate the losses and efficiency of induction motors during energy audits. However, determining the circuit parameters of in-service motors usually involves disrupting their operation. A less intrusive option is to estimate the parameters from performance data provided in catalogues and datasheets. Nine parameter estimation methods are assessed in this work according to accuracy and robustness criteria. Three relatively simple methods stand out with good performance on both criteria. Yet, the combination of high accuracy and total absence of failures is not observed in any of the tested methods. Additionally, a conceptual error repeated in four references regarding the use of the Thévenin equivalent is identified and corrected. Finally, a case study of loss estimation in two tested motors shows that good accuracy is achievable as long as the data reported by the manufacturer matches the real motor characteristics. A mismatch between reported and real characteristics may be detected by comparing the measured input power with its calculated value for the same slip.

The advanced sensorless technology of the permanent magnet synchronous machine (PMSM) can replace the position sensor on the machine side, however, the encoder is still the necessary feedback on the load side for a full-closed-loop servo system. This article proposes a sensorless drive scheme assisted by the computer vision to further replace the load side encoders, so to form a quasi-sensorless servo system. Although the vision technology can easily provide the load position for the closed-loop motion control, the feedback continuity cannot be satisfied especially for the multi-object scenarios, where the vision capture device and the computation ability cannot provide an ideal image processing. The issue of spatial-temporal discontinuity is discussed and the solution on basis of fusing the electrical and kinetic models is proposed. With this idea, the only feedback of the full-closed-loop servo drive is the computer vision, the motor side and load side encoders are both cancelled, and the reliable control performance with respect to the heavy load and high precision positioning is maintained. The scheme is validated on a heavy-load full-closed-loop servo bench driven by a sensorless PMSM with only feedback captured from a regular camera.

By incorporating the advantages of magnetic gearing effect and claw pole structure, a new type of claw-pole electric-excitation field-modulation (CPEEFM) machine has been developed, which has potential direct-drive application prospects due to its flexible field regulation ability and high rotor reliability. However, the axial asymmetry and the flux distribution complexity make it difficult to analytically calculate the iron loss. The purpose of this paper is to propose an improved iron loss calculation model for this CPEEFM machine, in which the iron loss coefficients are corrected accordingly by introducing the three-dimensional (3-D) flux density distortion rate to fully consider the influence of axial flux distribution in addition to the radial and tangential flux distributions. Taking a 24-slot/14-pole CPEEFM machine as an example, its iron loss characteristics under different operation conditions are calculated by the proposed model and compared with the traditional Bertotti model and the 3-D finite element analysis (FEA) implemented by JMAG software based on Fast Fourier Transform (FFT) model, which shows an acceptable consistency and improved accuracy. Furthermore, a prototype is finally fabricated and the experimental testing is carried out to verify the validity of the proposed iron loss analysis model.

The solid-state transformer (SST) is an emerging technology that offers promising benefits for electricity distribution and transmission systems, as well as its connection with sources of renewable energy (RE), battery storage, and electric vehicles. The high-frequency magnetic link (HFML)-based SST has enormous promise for solving problems associated with connecting the grid with RE and nonlinear loads and providing extra control functionality. Conventional modular SST topology with multiple active bridge (MAB) converters considers individual multi-winding HFML (MWHFML) in each phase. These systems have the drawbacks of power mismatch between the windings of MWHFML, system complexity for extended modular design, and system cost. This paper proposes a novel SST topology using a three-phase high-frequency magnetic link (TPHFML). Instead of using individual HFML in each phase of a three-phase system, only one TPHFML is used to simplify the entire SST topology. The proposed system reduces the power mismatch issues in the HFML, simplifies the system configuration, reduces 50% of components, and improves the overall efficiency. The proposed TPHFML-based SST system can offer approximately 11.45% higher efficiency than that of the existing MWHFML-based SST system. Experimental tests were carried out successfully to validate the scaled-down prototype of the proposed TPHFML-based SST topology.

This paper addresses the problem of traditional search coils being unable to detect the rotor position of permanent magnet synchronous motors (PMSMs) in low-speed regions. A rotor position detection method based on the mutual inductance effect of search coils is proposed. By designing the structure of the search coils, the mutual inductance effect of the armature winding on the search coils and the influence of the coil's back electromotive force on rotor position detection is eliminated. An ultrahigh-frequency sinusoidal voltage signal with a frequency of 100 kHz is injected into the search coils. The rotor position is calculated by extracting the effective value of the mutual inductance voltage, achieving rotor position detection across the full speed range of the motor. An experimental prototype containing search coils was fabricated, and the experimental results verified the correctness of the theoretical analysis and the effectiveness of the proposed method.

High-temperature superconducting (HTS) materials show potential advantages for direct drive wind turbine generators by enabling higher power density and lower volume. However, incorporating HTS windings necessitates a cryogenic system, which can increase costs, add weight and reduce overall generator efficiency. Consequently, investigating AC losses in HTS windings is crucial given the losses largely influence the cryogenic requirements. C-GEN is a permanent magnet synchronous generator conceived by the University of Edinburgh, which is characterised by modular structures for easy installation and maintenance. In this work, we have numerically investigated the AC losses in a MW-class direct drive air-cored HTS wind turbine generator, which has evolved from the C-GEN topology. Finite-element method (FEM) modelling was applied using COMSOL Multiphysics to build generator models equipped with HTS windings. Four designs were analysed in this study. Design-1 follows a conventional C-GEN structure and serves as a reference, utilising permanent magnets (PMs) for the rotor and air-cored copper windings for the stator. Designs-2 and 3 incorporate partial HTS structures. Design-2 replaces the stator copper coils with HTS windings, whereas Design-3 substitutes the rotor permanent magnets with closed magnetic loop (CML) HTS coil arrays. Design-4 features a fully HTS design, with both HTS rotor and stator windings. Dynamic analysis of the AC losses in HTS windings was conducted. The simulation results show that both partially and fully HTS designs provide higher power density compared with conventional design.