Search

In order to reduce the torque ripple and the unbalanced electromagnetic force on the rotor of the dual‐parallel rotor permanent magnet motor, a dynamic Kriging surrogate model is proposed to optimize its structural parameters. In the process of constructing the dynamic Kriging surrogate model, the concept of key sampling space is introduced, which solves the problems of low optimization efficiency and poor model accuracy of the traditional static surrogate model based on ‘one‐time’ sampling. The topological structure of the dual‐parallel rotor permanent magnet motor is introduced, and a prototype is used to verify the accuracy of the numerical model. The optimization parameters are determined, and the initial sampling space of each optimization parameter is determined according to the influence law of a single parameter on the optimization objectives. The initial sample database of the Kriging surrogate model is established, and a dynamic criterion for adding sample points is proposed. Combined with the NSGA‐II algorithm, the surrogate model is constructed and solved. The optimal solution is substituted into the numerical model, which verifies the feasibility and correctness of the proposed optimization design method. The accuracy of the dynamic Kriging surrogate model is discussed and compared with the traditional static surrogate model. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This paper presents a strategy for direct‐driving a turbine with an external rotor high‐speed permanent magnet motor. It is used to improve the large footprint, low efficiency, high maintenance costs, and high vibration risk of turbines. Combining the characteristics of the working conditions of pipeline gas transmission, this paper takes a 200 kW, 10 000 rpm external rotor high‐speed permanent magnet motor as an example. This paper analyzes the eddy current losses in the rotor due to the armature magnetomotive force generated by the stator fundamental and harmonic currents. To reduce eddy current losses in permanent magnets, a circumferentially segmented pole structure is proposed for theoretical comparison and FEA with common surface‐mounted pole structures under different loads and work angles. The results confirm that the circumferentially segmented pole can effectively reduce the eddy current loss of the permanent magnet rotor. The effect of variations in the pole arc coefficient on eddy current losses in permanent magnets is also analyzed. Finally, the temperature field simulation of the motor is carried out under consideration of wind mill losses. By setting up three comparison groups with different conditions, this paper analyses the influence of the temperature and flow rate of the gas on the temperature rise and heat dissipation of the motor in a high‐temperature gas environment. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

In order to improve the reliability of the traditional doubly salient electro‐magnetic generators (DSEG) and realize the isolation of interphase magnetic circuit, a U‐shaped rotor stator excitation generator (UR‐SEG) for vehicle applications is proposed in this paper. The machine has the interphase physical isolation and short flux path structure because of the U‐shaped rotors. According to the theoretical analysis of the fault‐tolerant characteristics of this UR‐SEG, the characteristic of the phase electromotive force (EMF) of the UR‐SEG completely overlaps with the EMF of front and rear phase in the entire power generation stage is revealed. Then the flux linkage, EMF, output voltage of both normal and faulty states are comparative investigated using the two‐dimensional finite element method (FEM). The output characteristics of the normal state and four faulty states of the machine with different exciting currents are researched, and the influence rules of fault on output characteristics are obtained. Finally, the outstanding fault‐tolerant characteristics of the UR‐SEG were verified by the experimental results. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Hybrid excited machine (HEM) is a novel type of machine which has attracted much attention as it is able to adjust the flux linkage flexibly and ensure the wide speed range operation. In this paper, a novel brushless HEM with permanent magnet (PM) located in rotor is further researched. By supplying specific armature currents, the sub‐harmonic component magnetomotive force (MMF) in stator MMF would be generated and utilized to realize the brushless hybrid excited operation. Firstly, the generation principle of the sub‐harmonic component is derived analytically. Secondly, during the brushless hybrid excited operation, the influence of the stator current amplitude ratio m$$ m $$ is quantitatively studied. Thirdly, based on 2D finite element analysis (FEA), the electromagnetic performance of the brushless HEM is analyzed under different operation statuses over a wide speed range. At last, the experiment is performed based on a 6 kW brushless HEM prototype machine, and the correctness of the theoretical analysis and FEA results are validated by the test. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This paper deduces an exact model of analytical calculation for the multilayer rotor eddy current losses of high‐speed permanent magnet machines based on the subdomain method. The analytical calculation model solution domain is divided into six parts of subdomains, including permanent magnet, shielding layer, metal retaining sleeve, air gap, slot openings, and windings. The Laplace equation of the air subdomain and the diffusion equation of the eddy current subdomain and the windings subdomain are established with the vector magnetic potential as the independent variable. The eddy current losses of the permanent magnet, shielding layer, and retaining sleeve of the multilayer rotor are calculated considering the slots effect and eddy current reaction. This analytical model is used to study the interfering factors of the multilayer rotor eddy current losses including the shielding layer thickness, carrier ratio, and modulation ratio. Finally, the correctness and regularity of the analytical calculation model are proved by finite element analysis and machine experiment analysis. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

In induction motor no‐load test, the no‐load losses usually include the stator copper loss, iron loss, the friction, and the windage losse, and the stray loss, and the rotor aluminum loss often is ignored. In this paper, a new method that separates the rotor aluminum loss from the no‐load losses is mentioned. Although, in IEEE Standard 112 and IEC34‐2, the rotor aluminum loss is neglected in no‐load test. However, in proposed method, the rotor aluminum loss is considered as an important part of the no‐load loss. Therefore, this paper intends to develop a new testing method to obtain the rotor aluminum loss under no‐load condition. In this case, six induction motors of the same kind (3 kW, four‐poles) are chosen to carry out no‐load and ideal no‐load tests. Through the comparative analysis of experimental data, the no‐load rotor aluminum loss accounts for about 13.4% of the no‐load loss, and the test approach can also explain that this part loss is not generated by higher harmonics. Based on these results, this paper demonstrates that the rotor contact resistance has great influence for the no‐load rotor aluminum loss, and a rotor resistance analysis model with rotor contact resistance is proposed. Final, the proposed method offers the possibility of taking measures on rotor resistance to improve motor efficiency. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

In this article, a 16/6 bearingless switched reluctance motor (BSRM) with segment hybrid rotor teeth has been presented. To realize the decoupling control of torque and suspension force, the rotor teeth were divided into three torque teeth and three suspension teeth, and both of them are embedded in support part. First, both torque and suspension force are generated by short‐circuit excitation, the flux linkage coupling between torque windings and suspension windings was eliminated, and the separate control of torque and suspension force was achieved. Then, by increasing the pole arc of suspension teeth, the inductance of suspension windings is kept constant, which eliminates the influence on the output torque when adjusting suspension force. Finally, the coupling degree is further reduced by using nonmagnetic material as the supporting part. In addition, to achieve a greater output torque, the torque teeth are processed into U‐shape and optimized the pole arc of stator teeth and rotor teeth. The characteristics of inductance, flux linkage, and output torque are analyzed by the finite‐element method, and the results show that the proposed structure basically achieves the decoupling control of torque and suspension force. © 2020 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

The distribution characteristics of fault electromagnetic field and temperature field and the unbalanced stresses on the rotor could be obtained through establishing a three‐dimensional model of the rotor and two‐dimensional models of the stator and rotor, and respectively solving the electromagnetic field and the temperature field of excitation winding inter‐turn short circuit fault by using the finite element analysis method. Two kinds of unbalanced stresses can be respectively equivalent to the unbalanced masses on the rotor surface. The equivalent centrifugal forces as excitation are added into the rotor dynamic equation, and solving the dynamic equation of the rotor by means of Newmark can finally obtain the rotor vibration response. The results show that the fault will cause the changes of amplitude and phase of rotor fundamental frequency vibration. So the amplitude and phase difference of the rotor fundamental frequency vibration can be used as the fault criterion in order to make an accurate diagnosis of excitation winding inter‐turn short circuit fault. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

For the design of an Interior Permanent Magnet (IPM) motor with small torque ripple and large driving torque, the optimal design method called the ON/OFF method is attractive, because a new magnetic circuit, which we could not imagined beforehand, may be obtained. In this paper, a non-parametric optimization technique to find a new magnetic circuit which minimizes a torque ripple and maximizes a driving torque of IPM motor is examined. The effectiveness of the ON/OFF method for the optimal design of a motor is examined by applying it to the design of the verification model of the IPM motor established by the technical committee of IEE of Japan. Factors affecting torque ripple and driving torque of the obtained optimal motor core are also discussed. [ABSTRACT FROM PUBLISHER]

Focuses on the excitation control under early valve actuation of turbine in Japan. Usage of early valve control technique to improve the transient stability; Suppression of the rotor swing quickly by controlling the excitation using a power system stabilizer; Discussion of the realization of optimal control based on the feedback control and its comparison with the conventional scheme.

The article presents in-flight global positioning system (GPS)-signal-reception anomalies observed using the Japan Aerospace Exploration Agency's (JAXA) research helicopter. Anomalies include GPS masking and multipath that degrade positioning accuracy. Multipath signals are caused by the rotor and engine structures around the GPS antenna. The standard code-minus carrier (CMC) technique was applied to isolate the error residuals on the code-phase measurements. For data collection, a Trimble 4000 SSI GPS receiver was used. When the helicopter banks to the right, the probability of the rotor head masking the GPS signal increases.