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A low switching frequency of power converter is mandatory in high-power motor drives to suppress the switching loss and thermal stress. In this case, the asynchronous modulation may incorporate abundant harmonics. The well-known approach to solve the problem is to adopt the synchronous modulation. Among existing techniques, synchronous space vector modulation (SSVM) owns the simpler implementation. However, it is a big challenge to establish a closed-loop scheme based on SSVM. Therefore, this manuscript proposes the flux trajectory tracking based implementation of SSVM for induction motors. A state observer is first built up in a hybrid reference frame to acquire the stator flux with a long sampling period. Then, the stator flux is enforced to move on a predefined trajectory with an adjustable rotation speed. As a result, synchronizations and symmetries of voltage pulses, smooth transitions between different pulse patterns and fast dynamic response can be achieved without complex compensations and extraction of fundamental signals. Both simulations and experiments verify the effectiveness of proposed method. Particularly, the current harmonics are effectively suppressed compared with traditional method with asynchronous modulation. [ABSTRACT FROM AUTHOR]

The dual-stator winding induction generator (DWIG) is an alternative main generator in a variable frequency ac power system. So far, the existing studies have not covered the issue of DWIGs excitation controllability, which is a matter of importance for airworthiness. In this article, we develop an impedance-based modeling and analysis technique to investigate DWIGs excitation controllability. Two related topics are presented: the spontaneous self-excitation analysis in uncontrolled system and the implicit internal self-excitation pattern analysis in actively controlled system. In the topic about spontaneous self-excitation, a virtual impulse source technique is developed to derive the impedance-based method properly in the analysis for uncontrolled DWIG. In the second topic, the analysis performed in the presence of a closed-loop controller figures out the same underlying mechanism in both the plant's open-loop stability and the spontaneous self-excitation. The experimental results verify the proposed analysis and techniques that benefit the comprehensive understanding and practical application of DWIG-based power system. [ABSTRACT FROM AUTHOR]

This paper studies the challenging person re-identification (Re-ID) task under the cloth-changing scenario, where the same identity (ID) suffers from uncertain cloth changes. To learn cloth- and ID-invariant features, it is crucial to collect abundant training data with varying clothes, which is difficult in practice. To alleviate the reliance on rich data collection, we reinforce the feature learning process by designing powerful complementary data augmentation strategies, including positive and negative data augmentation. Specifically, the positive augmentation fulfills the ID space by randomly patching the person images with different clothes, simulating rich appearance to enhance the robustness against clothes variations. For negative augmentation, its basic idea is to randomly generate out-of-distribution synthetic samples by combining various appearance and posture factors from real samples. The designed strategies seamlessly reinforce the feature learning without additional information introduction. Extensive experiments conducted on both cloth-changing and -unchanging tasks demonstrate the superiority of our proposed method, consistently improving the accuracy over various baselines. [ABSTRACT FROM AUTHOR]

A novel 24/17-pole 3-phase stator wound field flux switching (SWFFS) machine with the combination of overlapping armature winding (OAW) and asymmetric stator poles (ASP) is proposed for higher torque density in this article. First, the air-gap modulation principle of the 24/17-pole OAW-SWFFS machine is analyzed to better understand its torque production mechanism. Second, since the torque capacity will be greatly restricted by the serious magnetic saturation which is introduced by the OAW configuration, two effective measures are proposed from two perspectives in this article to solve this problem. The first measure is to reduce the magnetic saturation directly by optimizing the area ratio of armature slot and excitation slot, and thus, the torque density can be improved effectively. The second measure is to further enhance the open circuit flux linkages, back electromotive force (EMF), and thus, the torque density by adopting the proposed ASP structure. Furthermore, the accurate ASP distances which are corresponding to the largest back EMF can be obtained effectively based on the air-gap field modulation theory. Finally, the proposed design is validated experimentally by a prototype machine. The simulated and experimental results show that about 25.7% higher torque density can be obtained when compared with 24/14-pole SWFFS machine. [ABSTRACT FROM AUTHOR]

Visible-infrared person re-identification (VI-ReID) is an emerging and challenging cross-modality image matching problem because of the explosive surveillance data in night-time surveillance applications. To handle the large modality gap, various generative adversarial network models have been developed to eliminate the cross-modality variations based on a cross-modal image generation framework. However, the lack of point-wise cross-modality ground-truths makes it extremely challenging to learn such a cross-modal image generator. To address these problems, we learn the correspondence between single-channel infrared images and three-channel visible images by generating intermediate grayscale images as auxiliary information to colorize the single-modality infrared images. We propose a grayscale enhancement colorization network (GECNet) to bridge the modality gap by retaining the structure of the colored image which contains rich information. To simulate the infrared-to-visible transformation, the point-wise transformed grayscale images greatly enhance the colorization process. Our experiments conducted on two visible-infrared cross-modality person re-identification datasets demonstrate the superiority of the proposed method over the state-of-the-arts. [ABSTRACT FROM AUTHOR]

Active disturbance rejection control using extended state observer (ESO) is less dependent on the knowledge of the system. It has proved to be an excellent scheme for speed control of electrical drives. However, for time-varying disturbance, the observation precision of conventional ESO is undesired, which limits the speed tracking accuracy. Accordingly, this article proposes an enhanced speed controller for electrical drives based on adaptive switching high-order ESO (ASHESO). First, the critical parameters affecting the steady-state performance of ASHESO are determined according to frequency analytical results. Then, optimized observer gain is obtained by modifying a part of pole locations, which weakens the influence of noise on estimated state. Finally, an adaptive switching gain mechanism is proposed according to the closed-loop tracking error and the swiftness of dynamic response is maintained. The proposed speed controller has achieved high estimation accuracy for disturbance and strong immunity to measurement noise. The feasibility and effectiveness of the strategy is verified on a laboratory permanent magnet synchronous motor (PMSM) drive system. [ABSTRACT FROM AUTHOR]

The general rules of rotor pole and armature winding configurations combinations for 24-slot stator wound field flux switching machines (SWFFSMs) are investigated thoroughly in this article. Meanwhile, based on the virtual coil method, a novel general auxiliary evaluation variable, which is proportional to the fundamental amplitude of open-circuit flux-linkage of armature coil is proposed in this article. Hence, these SWFFSMs with larger open-circuit flux-linkage and back-EMF can be obtained effectively. In addition, the effect of rotor poles on the complementarity of armature windings is analyzed so that more sinusoidal and symmetrical back-EMF can be acquired. Furthermore, for these SWFFSMs with larger open-circuit back-EMF, the torque capability is restricted to a considerable extent due to the deep magnetic saturation caused by overlapping armature winding. Hence, a new method by optimizing the ratio of armature slot area and excitation slot area is proposed in this article to ensure that the higher torque density of selected SWFFSMs can be maintained. To verify the validity of analysis and methodology proposed in this article, seven representative SWFFSMs are chosen for verification at no load by the finite-element analysis (FEA) while a 24s/17p SWFFSM with the highest torque density is chosen for further verification at on-load conditions by the FEA and experiments. [ABSTRACT FROM AUTHOR]