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In this paper, a novel 3/27/24 (pole pairs of inner rotor permanent magnet [PM]s/modulator/outer rotor PMs) high torque density yokeless magnetic gear with asymmetric Halbach PM array is presented and optimized for electric vehicle powertrain. The key is to improve the torque performance by replacing the magnetic steel with the light nonmagnetic material as the rotor core and employing the embedded magnetic steel bar as well as trapezoidal PM structure to form a low magnetic resistance in the magnetic circuit. The proposed machine has significant performance improvements in two aspects. Firstly, it has high torque density and low iron loss with the yokeless structure. Secondly, it has a high anti‐saturation capability and low torque ripple with the asymmetric Halbach PM array and the embedded magnetic steel bar. The proposed structure is optimized by the co‐simulation of the finite‐element method and C++ optimization software. For a clear evaluation, the proposed structure is compared with generalized solutions in terms of performance and cost. Comparison results indicate that the proposed solution has the highest output torque, torque density, and torque per PM weight among solutions, reaching 214.1 N·m, 58.2 N·m/kg, and 95.6 N·m/kg, which greatly enhances the performance of the magnetic gear. [ABSTRACT FROM AUTHOR]

Here, a novel DC‐excited doubly salient machine with a claw‐shaped modular stator and three‐dimensional (3D) complementary magnetic circuit is proposed for wind power generation application. The key is to artificially construct a 3D complementary structure to suppress torque ripple and employ auxiliary slot‐opening PMs to relieve DC‐saturation in the stator core and improve overload capability. The novel 3D complementary structure provides an alternative magnetic path for the main flux, so the flux leakages in the air gap at open‐circuit position are effectively cancelled, and the flux in the yoke remains relatively constant. Hence, the output torque ripple is suppressed. Furthermore, the saturation issue in the stator is solved with auxiliary permanent magnets which have opposite magnetization direction to that of DC field excitation. Therefore, the torque capacity of the machine is improved. Here, the machine structure and operation principle are introduced, and a 2D equivalent model is also developed to replace the 3D model to improve the calculation efficiency. Multi‐objective optimization algorithm is developed to improve the performance of this new machine. The validity of machine design is finally verified with 2D and 3D finite element analysis. [ABSTRACT FROM AUTHOR]

This paper presents a novel doubly‐fed doubly‐salient machine (DF‐DSM) with DC‐saturation‐relieving effect for wind power generation application, which possesses the advantages of enhanced torque density, reduced torque ripple and improved power density. The key is that PMs are introduced into the stator slot openings to mitigate the saturation effect in stator core caused by DC field excitation, and relatively large excitation current can be fed into stator field windings, which contributes to improved power density of machine. In addition, with the armature winding artificially connected, the reluctance of all magnetic paths is kept the same, and the variation of self‐inductance is compensated, and the torque ripple is greatly suppressed. In this paper, the machine structure and DC‐saturation‐relieving working principle are introduced. The slot‐pole combinations are analysed, and dimension parameters are optimized. By using time‐stepping finite‐element analysis, the electromagnetic performance of optimal machine is evaluated which verifies the validity of the proposed design. [ABSTRACT FROM AUTHOR]

With the wide applications of dual‐rotor flux‐modulation machines for the growing wind power generations, research activities for the control of dual‐rotor flux‐modulation machines are intensified in recent years. Most of the existing control schemes are based on indirect measurements of the d‐axis inductance, the q‐axis inductance and the stator resistance to achieve high torque density and low torque ripple for the dual‐rotor flux‐modulation machines. However, conventional measurements of the d‐axis inductance, the q‐axis inductance and the stator resistance may suffer from (i) low accuracy and (ii) additional sensor costs. To this end, an adaptive differential evolution algorithm is proposed to identify the machine parameters by considering the magnetic saturation and cross‐coupling issue at low rotational speed of dual‐rotor flux‐modulation machines. Finite element analysis is adopted in simulation to preliminarily monitor the actual machine parameter values based on the length and cross section area of the conductor and inductance matrix computation. Both simulation and experimental results reveal that the adopted adaptive differential evolution algorithm can identify the three parameters more steadily and accurately than the conventional genetic algorithm. [ABSTRACT FROM AUTHOR]

This study proposes a novel power supply system that utilises wind power to produce AC and DC power. A special designed generator based on bidirectional flux modulation effect is the key part of the proposed power supply system. The novel power system has a compact structure since the proposed generator has two electric port. There are three essential points that make the proposed system outstanding. One is the contra‐rotating rotors, which will cluster wind power even under low wind speed. Second one is the dual armature winding structure, which will provide AC and DC power simultaneously. There are two electric port in the proposed generator. One port can produce AC power to the non‐sensitive resistive load. The other can provide AC power with different frequency to the rectifier to obtain DC power. The induced voltage due to flux modulation effect can be used to offer AC power, and the induced voltage due to the outer rotor can be used to offer DC power. The voltage frequency of two sets windings is different. The last one is the air gap flux rotation speed amplification due to flux modulation effect. Time stepping finite element method is used to analyse the dynamic performance of the proposed machine. [ABSTRACT FROM AUTHOR]