| 1. |
- Kristanl, Matej, et al.
(författare)
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The Seventh Visual Object Tracking VOT2019 Challenge Results
- 2019
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Ingår i: 2019 IEEE/CVF INTERNATIONAL CONFERENCE ON COMPUTER VISION WORKSHOPS (ICCVW). - : IEEE COMPUTER SOC. - 9781728150239 ; , s. 2206-2241
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Konferensbidrag (refereegranskat)abstract
- The Visual Object Tracking challenge VOT2019 is the seventh annual tracker benchmarking activity organized by the VOT initiative. Results of 81 trackers are presented; many are state-of-the-art trackers published at major computer vision conferences or in journals in the recent years. The evaluation included the standard VOT and other popular methodologies for short-term tracking analysis as well as the standard VOT methodology for long-term tracking analysis. The VOT2019 challenge was composed of five challenges focusing on different tracking domains: (i) VOT-ST2019 challenge focused on short-term tracking in RGB, (ii) VOT-RT2019 challenge focused on "real-time" short-term tracking in RGB, (iii) VOT-LT2019 focused on long-term tracking namely coping with target disappearance and reappearance. Two new challenges have been introduced: (iv) VOT-RGBT2019 challenge focused on short-term tracking in RGB and thermal imagery and (v) VOT-RGBD2019 challenge focused on long-term tracking in RGB and depth imagery. The VOT-ST2019, VOT-RT2019 and VOT-LT2019 datasets were refreshed while new datasets were introduced for VOT-RGBT2019 and VOT-RGBD2019. The VOT toolkit has been updated to support both standard short-term, long-term tracking and tracking with multi-channel imagery. Performance of the tested trackers typically by far exceeds standard baselines. The source code for most of the trackers is publicly available from the VOT page. The dataset, the evaluation kit and the results are publicly available at the challenge website(1).
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| 2. |
- Kristan, Matej, et al.
(författare)
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The first visual object tracking segmentation VOTS2023 challenge results
- 2023
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Ingår i: 2023 IEEE/CVF International conference on computer vision workshops (ICCVW). - : Institute of Electrical and Electronics Engineers Inc.. - 9798350307443 - 9798350307450 ; , s. 1788-1810
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Konferensbidrag (refereegranskat)abstract
- The Visual Object Tracking Segmentation VOTS2023 challenge is the eleventh annual tracker benchmarking activity of the VOT initiative. This challenge is the first to merge short-term and long-term as well as single-target and multiple-target tracking with segmentation masks as the only target location specification. A new dataset was created; the ground truth has been withheld to prevent overfitting. New performance measures and evaluation protocols have been created along with a new toolkit and an evaluation server. Results of the presented 47 trackers indicate that modern tracking frameworks are well-suited to deal with convergence of short-term and long-term tracking and that multiple and single target tracking can be considered a single problem. A leaderboard, with participating trackers details, the source code, the datasets, and the evaluation kit are publicly available at the challenge website1
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| 3. |
- Zhong, Ziqian, 1995, et al.
(författare)
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Disentangling the effects of vapor pressure deficit on northern terrestrial vegetation productivity
- 2023
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Ingår i: Science Advances. - 2375-2548. ; 9:32
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Tidskriftsartikel (refereegranskat)abstract
- The impact of atmospheric vapor pressure deficit (VPD) on plant photosynthesis has long been acknowledged, but large interactions with air temperature (T) and soil moisture (SM) still hinder a complete understanding of the influence of VPD on vegetation production across various climate zones. Here, we found a diverging response of productivity to VPD in the Northern Hemisphere by excluding interactive effects of VPD with T and SM. The interactions between VPD and T/SM not only offset the potential positive impact of warming on vegetation productivity but also amplifies the negative effect of soil drying. Notably, for high-latitude ecosystems, there occurs a pronounced shift in vegetation productivity's response to VPD during the growing season when VPD surpasses a threshold of 3.5 to 4.0 hectopascals. These results yield previously unknown insights into the role of VPD in terrestrial ecosystems and enhance our comprehension of the terrestrial carbon cycle's response to global warming.
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| 4. |
- Zhu, Jingwei, et al.
(författare)
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Performance Improvement of Surface Permanent Magnet Vernier Motor by Adjusting Current Control Angle Considering Magnetic Saturation
- 2022
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Ingår i: 2022 IEEE Transportation Electrification Conference and Expo, ITEC 2022. ; , s. 61-66
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Konferensbidrag (refereegranskat)abstract
- Surface permanent magnet vernier motors (SP-MVMs) possess the characteristics of high torque density and simple structure, making them a compelling technology for gearless applications, such as in-wheel motors and robots. This paper investigates the impact of current control angle on the magnetic saturation at the rated operating point for SPMVMs. The magnetic saturation analysis is conducted on motors with various magnet thickness to identify the effect of magnetic saturation level on the performance metrics. Focus is placed on selecting the optimal current angle to achieve both high torque density and power factor at the rated point. It shows that SPMVMs with small magnet thickness exhibit higher torque density and power factor simultaneously than those with thick magnet, if appropriate current control angle is set at the rated operating point. Moreover, the selection of the current angle has no significant impact on the flux weakening capability. This finding can be used to define the optimal current control angle of SPMVMs at the rated operating point for improved performance and reduced power burden on the inverter. The simulation results show that a high torque density of 23 Nm/L and a high power factor of 0.92 is achieved. Part of the experiment has been conducted for SPMVMs.
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| 5. |
- Zhong, Ziqian, 1995, et al.
(författare)
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Reversed asymmetric warming of sub-diurnal temperature over land during recent decades
- 2023
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Ingår i: Nature Communications. - 2041-1723. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- In the latter half of the twentieth century, a significant climate phenomenon “diurnal asymmetric warming” emerged, wherein global land surface temperatures increased more rapidly during the night than during the day. However, recent episodes of global brightening and regional droughts and heatwaves have brought notable alterations to this asymmetric warming trend. Here, we re-evaluate sub-diurnal temperature patterns, revealing a substantial increase in the warming rates of daily maximum temperatures (Tmax), while daily minimum temperatures have remained relatively stable. This shift has resulted in a reversal of the diurnal warming trend, expanding the diurnal temperature range over recent decades. The intensified Tmax warming is attributed to a widespread reduction in cloud cover, which has led to increased solar irradiance at the surface. Our findings underscore the urgent need for enhanced scrutiny of recent temperature trends and their implications for the wider earth system.
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| 6. |
- Zhu, Jingwei, et al.
(författare)
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Comprehensive Armature Reaction Modeling and Flux Weakening Optimization of a Surface Permanent Magnet Vernier Motor
- 2023
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Ingår i: IEEE Transactions on Industrial Electronics. - 0278-0046 .- 1557-9948. ; 70:9, s. 8709-8722
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Tidskriftsartikel (refereegranskat)abstract
- Surface permanent magnet vernier motors (SPMVMs) possess the potential for direct-drive applications due to the feature of high torque density. This paper presents a deep investigation into the armature reaction modeling and a semi-analytical optimization framework considering the constant power speed range (CPSR) in the flux weakening region for the SPMVM. The new armature reaction model can identify the armature air gap flux density of each harmonic component and armature flux linkage accurately, by conducting harmonics analysis, slot leakage flux computation and slotting effect evaluation, permitting to calculate the inductance. Then, the results from the armature reaction model and those obtained from finite element analysis (FEA) at the rated operating point together are applied to a comprehensive semi-analytical motor optimization framework developed for SPMVMs. The optimization framework is able to reflect the motor performance metrics over the entire speed range, with torque density, power factor and CPSR as objectives. Finally, a prototype designed according to the trade-offs of the optimization objectives is fabricated to confirm the validity of the armature reaction model and optimization framework.
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| 7. |
- Abbas, Amr A., et al.
(författare)
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Fast and Accurate Non-linear Model for Synchronous Machines Including Core Losses
- 2024
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Ingår i: IEEE Transactions on Energy Conversion. - 1558-0059 .- 0885-8969. ; In Press
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a fast and accurate state-space model for synchronous machines taking into consideration the machine geometry, material non-linearities and core losses. The model is first constructed by storing the solutions of multiple static finite element (FE) simulations into lookup-tables (LUTs) to express the stator flux linkages as functions of the state variables, i.e., the winding currents and the rotor position. Different approaches are discussed to include the core loss into the model. A novel approach is presented for constructing a pre-computed LUT for the core loss as a function of the state variables and their time derivatives so that the loss can be directly interpolated when time-stepping the state-space model. The Simulink implementation of the proposed core-loss model shows a good match with time-stepping FE results with a 120-fold speedup in computation. In addition, comparison against calorimetric loss measurements for a 150-kVA machine operating under both sinusoidal and pulse-width modulated voltage supplies is presented to validate the model accuracy.
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| 8. |
- Chen, Hao, 1988, et al.
(författare)
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A Permanent Magnet Brushless Doubly-Fed Electric Machine for Variable-Speed Constant-Frequency Wind Turbines
- 2023
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Ingår i: IEEE Transactions on Industrial Electronics. - 0278-0046 .- 1557-9948. ; 70:7, s. 6663-6674
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Tidskriftsartikel (refereegranskat)abstract
- A permanent magnet brushless doubly-fed electric machine is presented in this paper. This machine is developed for variable-speed constant-frequency wind energy generation applications. Differing from conventional doubly-fed electric machines based on induction machines, a permanent magnet rotor provides the magnetic field excitations for both the control winding and the power winding in the presented machine. The operating principle of the presented machine for the variable-speed constant-frequency operation is revealed in detail. Compared to a counterpart machine, the presented machine exhibits significantly improved back- electromotive force, torque/power density, torque per magnet volume, efficiency, etc. Finally, a proof-of-concept prototype of the presented machine is fabricated, and the corresponding experimental results are provided to verify the fact that the presented machine is capable of achieving the variable-speed constant-frequency function.
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| 9. |
- Chen, Hao, 1988, et al.
(författare)
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Comparative Study and Design Optimization of a Dual-Mechanical-Port Electric Machine for Hybrid Electric Vehicle Applications
- 2022
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Ingår i: IEEE Transactions on Vehicular Technology. - 0018-9545 .- 1939-9359. ; 71:8, s. 8341-8353
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Tidskriftsartikel (refereegranskat)abstract
- A new dual-mechanical-port (DMP) electric machine for hybrid electric vehicle applications, particularly in the power-split continuously variable transmission systems, is proposed in this paper. In order to comprehensively and quantitatively evaluate the pros and cons of the proposed machine, a comparative study of four DMP electric machines with different topologies is conducted. These four investigated DMP electric machines include a conventional DMP machine, a DMP machine with spoke-type permanent magnets, a DMP machine with reluctance rotor, and a DMP machine with open slots which is the proposed machine in this paper. Even though these four machines have similar topologies, they have different operating principles, which are demonstrated in detail. The comparison results indicate that the DMP machine with open slots outperforms the others in terms of torque/power density, efficiency, magnet utilization, etc. Accordingly, the DMP machine with open slots is selected for further investigation and optimization. A large-scale multi-objective optimization is carried out for this machine, where the differential evolution algorithm serves as a global search engine to target optimal performance. Finally, an optimal design is prototyped, and the experimental results are performed to verify the effectiveness of the analysis and simulation results in this paper.
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| 10. |
- Chen, Hao, 1988, et al.
(författare)
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Design and Analysis of a Variable-Speed Constant-Amplitude Wind Generator for Stand-Alone DC Power Applications
- 2023
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Ingår i: IEEE Transactions on Industrial Electronics. - 0278-0046 .- 1557-9948. ; 70:8, s. 7731-7742
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Tidskriftsartikel (refereegranskat)abstract
- This article presents the design and analysis of a permanent magnet (PM) wind generator, which consists of two sets of windings, and two rotors. The proposed PM wind generator is designed for variable-speed constant-amplitude voltage operation in dc power applications, in order to maximize the utilization of wind energy and make the electricity more accessible to stand-alone situations, e.g., remote areas and offshore islands. The operating principle of the variable-speed constant-amplitude voltage operation of the proposed PM wind generator is demonstrated in detail. A comparative study is carried out among the proposed generator, a conventional surface-mounted PM synchronous generator, and an existing counterpart generator used for the same application. The results show that compared to the conventional PM synchronous generator and the existing counterpart, the proposed PM wind generator exhibits the advantages of high induced voltage, high torque/power density, high efficiency, etc. Finally, the proposed PM wind generator is prototyped and manufactured. The validity of the variable-speed constant-amplitude operation of the proposed generator under both steady-state and dynamic conditions, is verified by experimental results.
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| 11. |
- Cosmas, John, et al.
(författare)
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Towards joint communication and sensing (Chapter 4)
- 2023
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Ingår i: Towards Sustainable and Trustworthy 6G: Challenges, Enablers, and Architectural Design. - 9781638282396 ; , s. 121-158
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Localization of user equipment (UE) in mobile communication networks has been supported from the early stages of 3rd generation partnership project (3GPP). With 5th Generation (5G) and its target use cases, localization is increasingly gaining importance. Integrated sensing and localization in 6th Generation (6G) networks promise the introduction of more efficient networks and compelling applications to be developed.
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| 12. |
- Despeisse, Mélanie, 1985, et al.
(författare)
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Battery Production Systems: State of the Art and Future Developments
- 2023
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Ingår i: IFIP Advances in Information and Communication Technology. - 1868-4238 .- 1868-422X. ; 692, s. 521-535
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Konferensbidrag (refereegranskat)abstract
- This paper discusses the state of the art in battery production research, focusing on high-importance topics to address industrial needs and sustainability goals in this rapidly growing field. We first present current research around three themes: human-centred production, smart production management, and sustainable manufacturing value chains. For each theme, key subtopics are explored to potentially transform battery value chains and shift to more sustainable production models. Such systemic transformations are supported by technological advances to enable superior manufacturing performance through: skills and competence development, improved production ergonomics and human factors, automation and human-robot collaboration, smart production planning and control, smart maintenance, data-driven solutions for production quality and its impact on battery performance (operational efficiency and durability), circular battery systems supported by service-based business models, more integrated and digitalized value chains, and increased industrial resilience. Each subtopic is discussed to suggest directions for further research to realise the full potential of digitalization for sustainable battery production.
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| 13. |
- Keyu, Guo, et al.
(författare)
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A Phase-Domain Model of Dual Three-Phase Segmented Powered Linear PMSM for Hardware-assisted Real-Time Simulation
- 2022
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Ingår i: IEEE Transactions on Industry Applications. - 0093-9994 .- 1939-9367. ; 58:4, s. 4511-4521
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a Hardware-assisted real-time simulation phase-domain (PD) model of a dual three-phase segmented powered linear permanent magnet synchronous machine (SP-LPMSM) used in electromagnetic launch is established. The model is able to consider the end-effect, saturation effect, coupling effect and open-phase fault conditions, which are specially occurs in the segmented structure in SP-LPMSM. The unbalanced inductances and saturation effect caused by the segmented structure are investigated and a simplified look-up table for inductances is introduced. Additionally, to accurately evaluate the coupling effect, the permanent magnet (PM) flux linkage is decoupled into the product of unit PM flux linkage and coupling coefficient. In order to avoid the numerical impulse caused by the derivative in the progress of calculating back-EMF, sigmoid function is adopted to express the coupling coefficient. Meanwhile, to make the PD-model compatible with the open-circuit fault conditions, incidence matrices and current constraint matrices are introduced to unify the PD-models with different winding connection types and open circuit faults into one general form. The PD-Model realized in Field-Programmable Gate Arrays (FPGA) based hardware is validated in comparison with finite element analysis results.
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| 14. |
- Lindström, Michelle, et al.
(författare)
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Lsm7 phase-separated condensates trigger stress granule formation
- 2022
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Stress granules are non-membranous organelles connected to stress responses and age-related disease. Here, the authors identify a conserved yeast protein, Lsm7, that facilitates stress granule formation through dynamic liquid-liquid phase separation condensates upon 2-deoxy-D-glucose-induced stress. Stress granules (SGs) are non-membranous organelles facilitating stress responses and linking the pathology of age-related diseases. In a genome-wide imaging-based phenomic screen, we identify Pab1 co-localizing proteins under 2-deoxy-D-glucose (2-DG) induced stress in Saccharomyces cerevisiae. We find that deletion of one of the Pab1 co-localizing proteins, Lsm7, leads to a significant decrease in SG formation. Under 2-DG stress, Lsm7 rapidly forms foci that assist in SG formation. The Lsm7 foci form via liquid-liquid phase separation, and the intrinsically disordered region and the hydrophobic clusters within the Lsm7 sequence are the internal driving forces in promoting Lsm7 phase separation. The dynamic Lsm7 phase-separated condensates appear to work as seeding scaffolds, promoting Pab1 demixing and subsequent SG initiation, seemingly mediated by RNA interactions. The SG initiation mechanism, via Lsm7 phase separation, identified in this work provides valuable clues for understanding the mechanisms underlying SG formation and SG-associated human diseases.
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| 15. |
- Shen, Fawen, et al.
(författare)
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A Dual-Permanent-Magnet Machine with Asymmetric Stator Teeth-Tips
- 2024
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Ingår i: IEEE Transactions on Transportation Electrification. - 2332-7782. ; 10:1, s. 252-262
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Tidskriftsartikel (refereegranskat)abstract
- Dual-permanent-magnet machines (DPMMs) have attracted increasing attentions due to their merit of high torque density. Nevertheless, DPMMs suffer from low PM utilization ratio owing to large PM consumption. To improve the situation, this paper presents a DPMM with asymmetric stator teeth-tips, termed as AST-DPMM. The key of the proposed design is to arrange wide and narrow stator teeth-tips alternatively. By building an analytical model of the AST-DPMM, the impact of asymmetric stator teeth-tips is investigated. It is found the asymmetric stator teeth-tips can enhance the working harmonics by generating new magnetomotive force harmonics and permeance harmonics. Hence, it can achieve high torque density and improve PM utilization ratio simultaneously. The performance comparisons together with other machines are conducted to evaluate the investigated AST-DPMM. Finally, a prototype of the AST-DPMM is fabricated, and the experimental testing is conducted to verify the proposed ideas.
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| 16. |
- Tang, Junfei, 1990, et al.
(författare)
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Comprehensive Dynamic Current Control of Electrically Excited Synchronous Machines With Magnetic Mutual Couplings
- 2024
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Ingår i: IEEE Transactions on Industrial Electronics. - 0278-0046 .- 1557-9948. ; In press
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Tidskriftsartikel (refereegranskat)abstract
- Electrically excited synchronous machines have become an attractive solution to electric vehicles. The excitation of the machine is controllable by adjusting the field current. However, due to the magnetic mutual couplings between stator and rotor windings, a voltage will be induced in the stator winding in case of a current rise in the field winding and vice-versa. In this article, a dynamic current control algorithm is proposed in which magnetic mutual couplings are comprehensively taken into consideration. To achieve this, first, the expected current derivatives are determined according to the error. Then, the voltages across all self- and mutual inductances are calculated correspondingly. In the end, the resistive voltages, inductive voltages, and the cross-coupling terms are summed up to construct the total controller output. To make sure that the control still works when the voltage output limit is reached, an antiwindup algorithm with adaptive bandwidth is proposed to cooperate with the dynamic current control algorithm. The results from simulations and experiments show that smoother responses can be achieved with the proposed control method.
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| 17. |
- Tang, Junfei, 1990, et al.
(författare)
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Dynamic Current Reference Determination of Electrically Excited Synchronous Machines Based on Torque Gradients of Copper Losses
- 2024
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Ingår i: IEEE Transactions on Power Electronics. - 0885-8993 .- 1941-0107. ; 39:6, s. 7423-7433
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Tidskriftsartikel (refereegranskat)abstract
- Electrically excited synchronous machines (EESMs) have become an attractive solution to electric vehicles. The excitation of the machine can be regulated by adjusting field current. This introduces one additional degree of control freedom. The control of armature current in stator and field current in rotor is expected to not only reduce the total losses, but also dynamically redistribute the load on both windings so that neither of them overheats. To realize this function, an algorithm is proposed in this study to dynamically determine the current references in EESM torque control. A cost function is introduced by placing weights on stator and rotor copper losses separately. The weights can be adjusted dynamically. The cost function is minimized by moving the current reference vector. The moving of the vector is orthogonally decomposed into a torque-related component and a cost-related component. When current or voltage limits are reached, a cancellation technique is activated to constrain the reference vector. It is shown in experimental results that expected performance is achieved in all operating conditions.
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| 18. |
- Tang, Junfei, 1990, et al.
(författare)
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Observations of Field Current and Field Winding Temperature in Electrically Excited Synchronous Machines with Brushless Excitation
- 2022
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Ingår i: 2022 International Conference on Electrical Machines, ICEM 2022. ; , s. 841-847
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Konferensbidrag (refereegranskat)abstract
- Electrically excited synchronous machines have become an alternative in electrification of transportations and renewable power generations. To reduce the extra effort in the maintenance of sliprings and brushes for field excitation, brushless excitation has been developed. However, when brushless excitation is adopted, the field winding becomes physically inaccessible when the machine is rotating. To solve this problem, an algorithm is proposed in this study to observe the field current and field winding temperature of an EESM with brushless excitation. The stator currents are measured and then used to correct the machine state predictor. The correction of the state prediction is interpreted to adjust the field winding resistance and temperature value. The algorithm is evaluated in simulations. The estimations of field current and field winding temperature track the measurements successfully.
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| 19. |
- Xie, Shuangchun, et al.
(författare)
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Investigation on Stator Shifting Technique for Permanent Magnet Vernier Machines with Two-Slot Pitch Winding
- 2023
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Ingår i: IEEE Transactions on Industrial Electronics. - 0278-0046 .- 1557-9948. ; 70:7, s. 6585-6596
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Tidskriftsartikel (refereegranskat)abstract
- This paper investigates the stator shifting technique (SST) for permanent magnet vernier (PMV) machines equipped with two-slot pitch winding (TSPW). By employing SST, TSPWs can be generated from the combination of two sets of fractional-slot concentrated windings (FSCWs), with various shift angles. The effects of various shift angles on armature magnetomotive force (MMF) harmonic contents are explored. It shows that proper shift angles can be selected to preserve the working component while eliminating loss-producing harmonics. Besides, the implementation of various shift angles leads to uneven stator teeth structure, which affects field modulation. Therefore, the output torque capability, phase inductance, power factor, core losses, and fault-tolerance are affected by different shift angles. This paper aims to exploit the full potential of TSPW-PMV machines by SST, considering the synthetic effects on harmonic reduction and field modulation. Through the exemplification of 24- slot, 19-rotor pole pair, and 5-armature pole pair PMV machines, it indicates SST is a more general and flexible design method that can provide new design opportunities and improve various performance metrics by introducing shift angle as an additional design variable. Finally, a prototype of the double-layer TSPW-PMV machine with optimal shift angle is fabricated for concept validations.
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| 20. |
- Yan, Yuming, et al.
(författare)
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Hybrid-Magnet Variable Flux Memory Machine With Improved Field Regulation Capability for Electric Vehicle Applications
- 2023
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Ingår i: IEEE Transactions on Transportation Electrification. - 2332-7782. ; 9:1, s. 586-597
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Tidskriftsartikel (refereegranskat)abstract
- This article aims to investigate a novel hybrid-magnet variable flux memory machine (VFMM) with improved field regulation capability for electric vehicle applications. Two sets of permanent magnets (PMs), i.e., high-energy-density neodymium-iron-boron PM and low coercive force (LCF) PM, are arranged in a delta array to improve field regulation capability and torque density. The machine topology, key features, and operating principle of the presented machine are demonstrated. Based on the simplified magnetic circuit model, the underlying design tradeoffs of the presented machine are revealed qualitatively. The nonlinear magnetic circuit model of the presented machine taking saturation and hybrid-magnet leakage flux into consideration is built for machine analysis. Electromagnetic performance comparisons are carried out by finite element analysis between the presented VFMM and the existing VFMM. The results show that the presented machine can achieve significantly improved flux regulation capability while maintaining the high output torque due to the improved arrangement of hybrid magnetic branches and enhanced flux concentration effect. Finally, the investigated VFMM is prototyped. The operating principle and predicted results are verified by experimental results.
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