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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]

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]

In this article, we present a dual-stator structure-parallel fault-tolerant machine (DSSPFTM). In this machine, the radial-flux dual-stator structure with a higher density is adopted to the fault-tolerant system. For better performance in fault condition, the combination of permanent-magnet component (PMC) and reluctance component (RC) in the rotor and large-opening slot is proposed. Because of the same poles and torque-variation principle, the PMC and RC are combined. The PMC is devised to supply most of the torque in normal conditions, while the RC provides enough self-inductance for limiting current under short-circuit (SC) occasion. Most of the flux leakage is separated from the active flux and the overload ability is improved. The design process of DSSPFTM is described in steps and details. Based on the fundamental of maximum torque under normal conditions, PMC and RC are integrated together. The end flux leakage originating from the adjacency of RC to PMC and the effect of RC length on torque are analyzed. The back-EMF, torque, inductance, loss, efficiency, and SC analysis are demonstrated. The stress and deformation distribution of the rotor and the comparison with the traditional structure are conducted. A prototype DSSPFTM is designed and manufactured. The experiments accord with simulations, indicating that the DSSPFTM with fault tolerance can improve the torque density effectively. [ABSTRACT FROM AUTHOR]