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In this article, a new dual-modulator magnetic-geared machine (DM-MGM) is proposed for tidal-power generation with the virtue of high-torque output at low speed. First, the requirement of the DM-MGM for tidal-power generation is derived. Then, the flux-modulation principle and flux-enhancing effect of the extra modulator of the proposed DM-MGM are elaborated. After that, a finite-element analysis and multi-objective genetic algorithm (FEA-GA) combined method is used to solve a multi-objective optimization problem for the DM-MGM design. The electromagnetic performances of the optimized DM-MGM with different pole-pair combinations are quantitatively compared by FEA. The results show the effectiveness of the proposed machine, which is suitable to be applied in the tidal-power-generation scenario. [ABSTRACT FROM AUTHOR]

The power split system is the key power transmission component in hybrid electric vehicles (HEVs). This article presents a new interior consequent-pole permanent-magnet (PM) magnetic-geared double rotor machine (ICPMDM) with a double rotor structure, which is suitable as the power split system for HEVs. Since the common existing magnetic-geared double-rotor machine (MGDBM) adopts the surface-mounted PMs on its rotor, it suffers from the problem that the PMs might fly away during high-speed situations. The key of the proposed machine is to insert the PMs with the same polarity into the rotor core, and the flux barrier is added to increase the main flux. So its mechanical structure is more robust, while the electromagnetic performance does not deterioriate. Then, the working principle is analyzed, and the structure is optimized. Additionally, the performances of the conventional machine and proposed type are quantitatively compared. The result shows that proposed machine has more advantages for the power split system in HEVs than the conventional machine. [ABSTRACT FROM AUTHOR]

Electric continuously variable transmission (e-CVT) device is a key component in hybrid electric vehicles (HEVs), which serves to perform the energy transmission among the initial combustion engine, battery, and output shaft. This paper presents a novel consequent-pole PM magnetic-geared double-rotor machine (CPDRM) that utilizes the magnetic gearing effect to transmit the power with a high efficiency. The artistry of CPDRM is to insert a dc winding within the center of the stator on the circumferential direction. Therefore, the machine can extend the constant-power region by changing the current direction and amplitude of dc windings. Meanwhile, the flux density within the air gap is changed accordingly. Then, the working principle of CPDRM and the flux change process are illustrated by employing the magnetic circuit method. Finally, a finite-element method model is constructed to verify the performances of the CPDRM under different operating modes. The result shows that the proposed machine has an excellent flux-weakening ability, and it can serve as a suitable candidate as an e-CVT component for HEVs. [ABSTRACT FROM AUTHOR]

This paper proposes dual-stator permanent magnet Vernier (DS-PMV) machines for direct-drive applications. Also, the quantitative comparison of DS-PMV machines is carried out in terms of no-load performance and output torque characteristic. First, the operation principle is elaborated. Then, the theoretical expressions of air-gap magnetic fields are derived through the magnetic circuit approach. Moreover, the basic machine performances with different pole–slot configurations are quantitatively compared. The corresponding demonstration results are given, which verify that the designs without auxiliary teeth tend to have lower amplitudes of back electromotive force (EMF) harmonics, higher rated average torque, and lower torque ripple. [ABSTRACT FROM AUTHOR]

This paper proposes the design and multi-mode operation of a new double-stator toroidal-winding permanent-magnet vernier (DSTW-PMV) machine, which is for the wind-photovoltaic (W-PV) hybrid generation system. In the W-PV system, the wind and PV power are complementary with each other for power variation reduction. Through the multi-mode operation, the output voltage of the machine can be stabilized with high continuity under different rotational speeds to solve the inherently indeterminate wind speed problem and further improve the power smoothness of the whole W-PV system. First, the machine optimization is carried out to obtain the optimal pole-pair combination and geometrical topology for the proposed machine. Second, based on the optimal topology, the multi-mode operation principle of the output voltage adjustment is illustrated. By utilizing the diversities of the toroidal winding configurations and terminal connection strategies, the proposed machine accommodates 54 operating modes with different output voltages under rated speed. Accordingly, under the rated output voltage, the machine speed can be extended to three rated speed with high continuity. Furthermore, some modes generate the rated output voltage with identical speed, which contributes to the high redundancy and high operating efficiency. Hence, with the multi-mode operation and the auxiliary of the PV power, the whole power generation system accommodates the higher flexibility, stability, reliability, and efficiency. [ABSTRACT FROM AUTHOR]

This paper presents the design and optimization procedure of a novel mechanical-offset complementary-stator flux-reversal (MOCS-FRPM) machine. First, based on the original topologies, the pole-pair and flux modulation pole optimizations contribute to the high power density, efficiency, and larger torque capacity for the machine design. Second, based on the 2-D optimization results, the 3-D mechanical-offset structures are adopted for the torque ripple suppression. In fact, compared with the 3-D non-offset machine, the rotor mechanical-offset topology possesses the better torque performance, which can decrease the torque ripple by 34.6%, and with a slight 6.4% reduction of the torque average. Thus, through the proposed optimization procedure, the new complementary-stator machine accommodates the merits of the large torque capacity, low torque ripple, high efficiency, and high reliability. Also, the artful incorporation of the 2-D and 3-D optimizations leads to the reduced computation time and higher optimization efficiency. [ABSTRACT FROM AUTHOR]

In permanent-magnet synchronous motor (PMSM), the winding current consists of different orders of harmonics due to the manufacture error, deadtime, and disturbances. This article proposes a winding current harmonic suppression method for PMSM by reducing the dominant fifth- and seventh-order current ripples. First, with reference frame transformation, the fifth- and seventh-order current ripples convert to sixth-order ripples in the synchronous reference frame (SRF). Then, with further transformation, these sixth-order ripples turn to dc signals. Next, the type-II Chebyshev filter is designed to extract these dc signals. Also, the proportional–integral (PI) controller is adopted to generate the current harmonic control voltage, which is setting the dc current harmonic signals reference to be zero. Finally, the current harmonic control voltage is compensated to the voltage reference in the SRF. Both the simulation and experimental results are presented to verify the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

The permanent-magnet Vernier (PMV) machine has been welcomed for direct-drive applications recently. Also, the fault tolerance is critical for special machine design in hostile conditions. This article proposes an efficient PMV machine with the modular winding configuration, which takes the fault-tolerant capability into account, especially the open-circuit fault. With the modular winding design, the better isolation between phases and modules can be obtained instead of dividing the stator core into segments. Meanwhile, the high efficiency needs to be guaranteed under both normal and partial-module operations. Therefore, the machine design, basic characteristics, and the fault-tolerant operation are performed and verified. Finally, the efficiency performances under normal and modular operations are analyzed and compared, which demonstrates the validity of the proposed idea and relevant considerations. [ABSTRACT FROM AUTHOR]