Electromagnetic Characteristics of an Outer-rotor Magnetic-Concentrating PMVM for Power Supply System on Offshore Islands and Reefs

doi:10.12382/bgxb.2025.0691

Abstract

Abstract:

On the vast ocean，some islands and reefs are scattered and far apart from each other.The traditional energy power generation mode is facing prominent problems such as difficulties in power supply guarantee，and high operation and maintenance costs，etc.In order to fully develop renewable energy in the ocean and build a sustainable offshore energy supply system，the offshore wind power generation technology is gradually becoming a strategic choice to solve the problem of power supply in remote islands and reefs.As a new type of electromagnetic energy conversion device based on advanced magnetic field modulation theory，the permanent magnet vernier motor (PMVM) has demonstrated unique advantages in the fields of ship propulsion and offshore wind power generation due to its excellent low-speed and high torque characteristics，and is particularly suitable for use as the core power generation unit of offshore island microgrids.A multi-node magnetic circuit analytical model system is structured for tangential excitation PMVM.An accurate analytical solution for the air gap magnetic field in this structure is obtained through rigorous mathematical modeling.Based on the theory of magnetic field modulation and the principle of electromechanical energy conversion，the quantitative relationship among the core electromagnetic parameters such as air gap magnetic field，no-load back electromotive force，electromagnetic torque and armature inductance with the size of motor are systematically established.Taking into account the bilateral slotting effect，the error of the core electrical parameters is controlled within 2%.Specifically，the direct current attenuation method is used to achieve the high-precision experimental calibration of motor inductance parameters.The error between the predicted values of the analytical model and the measured data is controlled within 3%，fully verifying the effectiveness of the theoretical model.This study provides a complete theoretical analysis framework and engineering practice guidance for the rapid design and optimization of tangential excitation structure PMVM.The accuracy and engineering applicability of the analytical model are confirmed through the comparative verification of finite element simulation and prototype experiments.

Key words: PMVM, magnetic circuit method, analytic method, magnetic field distribution, inductance calculation

WU Bo, QIAO Mingzhong, XIA Yihui, ZHAO Shiyao, WANG Kangning, QIU Hongming, YAO Yujie, YANG Keke. Electromagnetic Characteristics of an Outer-rotor Magnetic-Concentrating PMVM for Power Supply System on Offshore Islands and Reefs[J]. Acta Armamentarii, 2025, 46(S1): 250691-.

Figures/Tables 16

Fig.1 Schematic diagram of magnetic field modulation process

Fig.2 Aggregation-based PMVM topology structure

Fig.3 Motor air gap structure

Fig.4 Magnetic circuit model

Table 1 Prototype parameters

参数	数值	参数	数值
定子内径/mm	150	永磁体极对数	23
定子外径/mm	300	永磁体宽度/mm	12
转子内径/mm	304	永磁体长度/mm	32.5
转子外径/mm	370	绕组串联匝数	290
铁芯轴向长度/mm	323	额定转速/(r·min^-1)	65
定子槽数	30	额定频率/Hz	25

Fig.5 Comparative analysis diagram of no-load magnetic field in motor air gap

Fig.6 Comparison and analysis diagram of no-load reverse electromotive force

Fig.7 Finite element analysis of torque

Fig.8 PMVM potential phase diagram

Table 2 Calculated results of motor inductance obtained by static solution method /mH

绕组	绕组
绕组	A	B	C
A	25.59	0.064	0.061
B	0.064	25.23	0.065
C	0.061	0.065	25.58

Fig.9 Calculation results of motor inductance obtained by transient solution method

Fig.10 Motor experimental platform

Fig.11 Measured output voltage of motor

Fig.12 Experimental circuit diagram of DC attenuation method

Fig.13 Current attenuation waveform

Fig.14 Current attenuation fitting curve

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