Search

The axial flux permanent magnet (AFPM) machines with the parallel magnetic circuit (PMC) rotor can effectively improve its torque density. The PMC rotor consists of two sub‐rotors, radial Halbach array permanent magnet (PM) and tangential PM. The magnetic fields generated by two sub‐rotors are not in the same 2‐D analytical planes. In this paper, an equivalent analytical model of PMC‐AFPM machines is proposed to solve this problem. The radial Halbach array PM rotor is equated to the axial Halbach array PM rotor based on the equivalent transformation principle. The exact subdomain models of equivalent axial Halbach array PM rotor and tangential PM rotor are built respectively and then superimposed to obtain the magnetic field distribution. The electromagnetic characteristics of the PMC‐AFPM machine under no‐load and load conditions are calculated by the proposed analytical model and compared with calculations of the finite element model (FEM). The results verify the accuracy of the equivalent analytical model. The comparative analysis of the AFPM machines with PMC rotor and tangential PM rotor verifies the advantage of PMC rotor configuration to improve the torque density. © 2024 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This paper investigates the influence of the loss distribution and magnetic saturation on the efficiency performance, which includes the location of maximum efficiency point, the size of high‐efficiency region and the value of maximum efficiency, for an interior permanent magnet synchronous motor (IPMSM). The loss expressions considering magnetic saturation are first proposed and then the efficiency‐losses function model of the IPMSM is constructed. The efficiency performance of the motor is analyzed quantitatively. The general principle is summarized including adjusting the location of maximum efficiency point, expanding the size of high‐efficiency zone and improving the maximum value of efficiency from the perspective of loss distribution and magnetic saturation. Two IPMSMs with different magnetic circuit characteristics are designed to verify the correctness of the analytical method by finite‐element analysis (FEA). Finally, prototypes are manufactured for the experiment and measurement results are given for validations. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Because the magnetic circuits of homopolar inductor machines (HIMs) are three‐dimensional (3‐D), a 3‐D finite element model (FEM) is usually built to accurately compute the cogging torque in HIMs, but the drawback is very time‐consuming in modeling and computing. Therefore, a two‐dimensional (2‐D) FEM of HIMs is needed to simplify the computation of the 3‐D FEM. However, the existing odd harmonic 2‐D FEM cannot accurately predict the cogging torque in HIMs. To address this problem, this paper proposes a full‐order harmonic 2‐D FEM. First, the analytical expressions of HIM cogging torque are derived by the combination of energy method and air‐gap field modulation principle. Based on the obtained analytical expressions, the equivalent principles between the 3‐D and 2‐D FEMs are analyzed. According to the above equivalent principles and taking a 48‐slot/4‐tooth (48S4T) permanent magnet (PM) HIM as an example, a full‐order harmonic 2‐D FEM of the example machine excited by a field winding is proposed. The structure of the full‐order harmonic 2‐D FEM is described in detail. The turn number of field winding and field current amplitude of the proposed 2‐D FEM are investigated. The differences between the odd harmonic 2‐D and full‐order harmonic 2‐D FEMs are also analyzed. Finally, the cogging torque in the 48S4T PM HIM with distinct rotor tooth‐arc to tooth‐pitch ratios is computed by 3‐D, odd harmonic 2‐D and full‐order harmonic 2‐D FEMs of the machine, respectively. The results illustrate that compared with the odd harmonic 2‐D FEM, the full‐order harmonic 2‐D FEM can shorten the calculation time and has the similar computation accuracy as the 3‐D FEM. Moreover, the experimental validation is performed on a prototype of the 48S4T PM HIM. The error between the maximum cogging torque obtained by the full‐order harmonic 2‐D FEM and experiments is only 2.12%. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

The dual‐stator permanent magnet (PM) machine has the advantages of high torque density, high efficiency, and compact size, which makes it suitable for low‐speed high‐torque applications. A dual‐stator low‐speed high‐torque permanent magnet drive machine (DLHPMDM) is discussed and studied in this paper, which is applied to the ball mill application. First, in order to meet the requirements of high efficiency and high reliability, a DLHPMDM with the inner and outer windings connected in parallel is obtained through the designs carried out in terms of the magnetic circuit structure, structural size, and the pole‐slot number combination. However, for the DLHPMDM with the inner and outer windings connected in parallel, the power allocation between the inner and outer machines is a critical problem that needs to be accurately analyzed, and the circulating current between the two sets of windings is also a particular issue that merit attention. Therefore, a new modeling method is proposed for the DLHPMDM to solve such cases more accurately. The proposed new method combines the advantages of the rapidity of the finite element analysis (FEA) with current excitations and the accuracy of the FEA with voltage excitations. Finally, a prototype of the DLHPMDM is manufactured and tested. The feasibility of the design theory and the validity of the proposed modeling method is verified by both the tested and simulated results. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

In this paper, a novel doubly salient PM motor based on parallel path magnetic technology (PPMT) is presented. PPMT is an advanced magnetic control technology, which can be applied to linear and rotary actuators. First, the fundamental principle of the PPMT prototype is elaborated, and then a comprehensive research and analysis of PPMT motor is carried out, with particular emphasis on machine topology, operation principle and electromagnetic performance. The equivalent no‐load PM magnetic circuit model is established and equations for calculating the main PM flux are derived. Besides, a dual‐stator 6‐pole PPMT motor prototype has been developed to valid the analysis. According to the similarity of topology and operation principle, comparison between the FSPM machine and PPMT machine is conducted, which leads to the conclusion that the PPMT motor has lower cogging torque, lower torque ripple and better sine back EMF waveform, the PPMT motor is more suitable for servo applications compared to FSPM motor. Finally, to improve the power density of PPMT motor, FE parametric modeling method for designing the three coupled stator parameters, which are the PM width, the stator yoke width and the second airgap length is given out. © 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]

Asymmetric vibration‐based haptic devices are being developed to apply to various applications such as navigation systems. A mobile‐type three‐dimensional haptic device requires a compact structure. Then, we focused on a three‐degree‐of‐freedom oscillatory actuator (3‐DOFOA). However, conventional 3‐DOFOAs are large in size and weight because they need a large and complicated support mechanism on the outside of the magnetic circuit. Furthermore, they do not satisfy both the requirement of similar force characteristics in each axis and no interference. To address these issues, we propose a novel 3‐DOFOA integrated with a support mechanism that has equal static characteristics in each axis without interference. The proposed structure and operating principle are described in detail in this paper, as well as the force, frequency characteristics, and acceleration responses. As these results, it can be concluded that the proposed actuator is suitable for use as a haptic device. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]