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This paper investigates the eddy current loss mechanism of a dual permanent-magnet-excited machines (DPMM). Based on the flux modulation effect, abundant harmonics are induced in the air gap of DPMM. The harmonics of air-gap flux density due to rotor PMs, stator PMs, and armature reaction are investigated qualitatively and separately. Then, the orders, frequency, and rotation speed of the harmonics are deduced theoretically. The harmonics that contribute to the eddy current losses are deduced accordingly. Finally, the loss distribution of the proposed DPMM is estimated through simulation and the thermal field of the proposed motor is analyzed. A prototype is fabricated to validate the analysis. Temperature rise of both stator and rotor PMs under rated load condition is measured through experiment.

This article proposes a novel compact dual-permanent magnet (PM) dual-stator generator for hybrid ac/dc generation system. Two sets of windings are installed in the inner and outer stator separately. It has two electric ports, in which one is used to generate ac voltage and the other electric port that also generates ac voltage is rectified to obtain the dc voltage. The key of the generator is that two stators share one rotor with consequent PM structure, and the output power of the machine is much higher than that of the machine with only one stator. Besides, with two separated stator core and armature windings, the reliability of the proposed generator is improved. The advantage of the proposed dual-stator dual-PM generator is illustrated theoretically, and its slot/pole selection guideline is given. Comprehensive sensitivity analysis of the proposed generator is performed and multilevel design optimization method is adopted. The efficiency, torque ripple, and total harmonic distortion of the inner and outer armature windings of the generator after optimization are calculated to verify the effectiveness of the proposed machine design.

This paper proposes a novel direct-drive dual-PM motor for electric automatic guided vehicles (AGV). The proposed motor has split teeth on stator and dual PMs in stator and rotor sides, which contributes to reduced torque ripple, and enhanced torque. The airgap field of the proposed motor is analyzed theoretically, and the slot/pole selection guide line is concluded. The simulation results of the airgap flux density are shown and Fourier Transformation (FFT) analysis results agree well with the theoretically analyses results. Besides, the effects of design parameters of the proposed motor to the performances of the proposed motor are investigated. And it is found that reduced slot open could produce improved efficiency and decreased torque ripple. The efficiency of the proposed motor is relatively high within the operation range. A corresponding prototype is fabricated and the experiment validates the design.

In this article, the optimal configuration of the stator for the dual-permanent-magnet vernier machine (DPMVM) is investigated. A novel numerical model used to perform the optimization and compare the performances between different permanent magnet (PM) arrangements on the stator part is first presented in this article. According to the proposed numerical model, the effects of the location of PMs at different positions of the stator are studied in terms of output torque, torque ripple, efficiency, and power factor (PF). It is found that the PMs at stator slots contribute more to the output torque than PMs on stator teeth. Moreover, it is found that the stator PMs will add extra cogging torque to the machine compared with the rotor-PM machine. The PF of the dual-PM machine with the combination of the selected stator slots and rotor poles can be higher than 0.9, which is relatively higher compared with both the rotor-PM machine and stator-PM machine.

Electric motors have a wide range of applications in a diverse range of industries. This paper presents a novel magnetic resonant coupling motor (MRCM), constructed without any iron or permanent-magnet core, i.e., a novel coreless and magnetless electric motor. Different from the conventional operation principle of existing electric motors, the application of the wireless power transfer system using magnetic resonant coupling technology is the key feature of the proposed MRCM. By adjusting the excitation frequency in accordance with the trajectory of resonant frequency splitting, a large electromagnetic force in different direction can be developed. Besides, the proposed MRCM has an inherent merit of unity power factor. This paper presents a new design concept, which could well be a promising start for a new generation of future electric motor.

Biased flux machines (BFMs) have biased magnetic flux in the core and allows flexibility to adjust the field with a dc current. The conventional topology exploration methods for BFMs are based on the flux observation. It is time consuming and ineffective since the initial structure searching process is guideless. Meanwhile, BFMs usually work with arbitrary magnetic field harmonics instead of the fundamental one. The torque components of these machines and their essential operation principle have not been fully revealed. To solve these issues, in this paper, a topology exploration method for BFM based on magnetic field modulation mechanism is proposed, and the torque generating principle is analyzed. With this method, some new BFM structures have been developed and their torque components have been developed. It is shown that various space harmonics have contributed to constant torque rather than the fundamental one. To verify the feasibility of this design method, one double stator BFM is selected as a case study. Simulation and experimental results have verified that this design method is feasible and effective since the prototype has good sinusoidal back electromotive force waveforms and well performance. Besides, it is practical to realize flux weakening and strengthening the control with biased current.

Chrysanthemum (Chrysanthemum × morifolium) is an important horticultural crop with great ornamental and economic value. Most chrysanthemum cultivars are self-incompatible, which limits the creation of pure chrysanthemum lines which are the material basis for breeding and theoretical research. Here, artificial self-pollination and natural cross-pollination were used to analyze the self-compatibility (SC) and cross-compatibility (CC) of 85 chrysanthemums cultivated by our research group. By conducting a phenotypic study, observing of pollen germination in vitro and in vivo and gene expression analyses, we explored the reasons for the self-compatibility of chrysanthemum and identified self-compatible mutants. It was found that there were wide variations in self-compatibility among different chrysanthemum cultivars and the SC index ranged from 0 to 5.64, which could classify the chrysanthemum cultivars into three types: self-compatibility (SC index ≥ 1), self-incompatibility (SI, 1 > SC index > 0) and high self-incompatibility (SC index = 0). Seven chrysanthemum cultivars with self-pollinated progenies (‘Hongguan’, K183−8, A22, B12, D87, D76 and S8) were selected, and the pollen germination rates in vitro and in vivo were not significantly related to SC. The pollen tube of ‘Hongguan’ could pass through its own stigma and grow toward the embryo sac along the style, and there was no obvious inbreeding depression in self-pollinated progenies of ‘Hongguan’. In addition, we found that one S-locus receptor kinase (SRK), two S-locus cysteine-rich protein (SCR), two exocyst complex component EXo70A1 (Exo70A1) and one thioredoxin h-like 1 (THL1) were important for regulating self-compatibility of C. × morifolium. Our results not only laid a material foundation for creating pure lines through continuous self-pollination and analyzing the regulation mechanism underlying SC variation but also provided the possibility for theoretical research on the important ornamental traits of chrysanthemums in the future.

In this paper, numerical method coupled with a novel model is proposed and applied to permanent magnet synchronous motor with reluctance-torque-assisted, aiming to obtain a motor with high efficiency, low torque ripple and maintain a good saliency ratio. Time-stepping finite-element-method coupled with multi-objective genetic algorithm is used to perform the further optimization. Through the proposed design method, the efficiency of the motor under rated condition will be improved and higher than 92% which can satisfy IE4 standard and the torque ripple is no greater than 5%, which is relatively low compared with the initial design.

A logistic model with impulsive Holling type-II harvesting is proposed and investigated in this paper. Here, the species is harvested at fixed moments. By using the techniques derived from the theory of impulsive differential equations, sufficient conditions for both permanence and extinction of the system are established, respectively. Sufficient conditions which ensure the existence, uniqueness, and global attractivity of a positive periodic solution of the system are obtained. Our study shows that impulsive controls play an important role in maintaining the sustainable development of the ecological system. Compared with the linear impulsive capture or continuous nonlinear-type capture, our study shows that the nonlinear impulsive capture could lead to more complicated dynamic behaviors. Numeric simulations are carried out to show the feasibility of the main results. The results obtained here maybe useful to the practical biological economics management.

A general pattern, which can include different types of permanent magnet (PM) arrangement in PM synchronous motors (PMSMs) is presented. By varying the geometric parameters of the general pattern, the template can automatically produce different types of PM arrangement in the rotor. By choosing the best arrangement of PMs using optimization method, one can obtain a better performance and lower manufacturing cost. Six of the most widely used conventional types of rotor structures can be obtained through the parameter variation of the general pattern. These types include five embedded PM types and a traditional surface-mounted PM type. The proposed approach combines optimization method embedded with finite element method (FEM) for solving the multi-objective optimization for the PM structures. To save computing load, this paper employs a strategy of sub-group optimization, which is on account of the impact levels of the design parameters on the objective functions, and a parallel computation, which is a valid method to shorten the computing time. As an application example, a PMSM is optimally designed. Its simulation results and prototype experiments are provided to showcase the effectiveness of the proposed method.