Optimal design and analysis of asymmetrical rotor structure for synchronous reluctance motor

doi:10.3785/j.issn.1008-973X.2025.05.019

Journal of ZheJiang University (Engineering Science)

2025, Vol. 59

Issue (5): 1063-1071 DOI: 10.3785/j.issn.1008-973X.2025.05.019

Optimal design and analysis of asymmetrical rotor structure for synchronous reluctance motor

Xiaoyi CHAI1(

),Yan DONG1,*(

),Rongzhe LIU2

1. School of Electrical Engineering, Hebei University of Technology, Tianjin 300130, China
2. Gree Electric Appliances, Inc. of Zhuhai, Zhuhai 519070, China

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Abstract

An asymmetric Bezier-shaped rotor structure was proposed aiming at the problems such as large torque ripple and low output torque of the synchronous reluctance motor (SynRM). The equivalent quadratic Bezier curve was utilized to determine the flux barrier boundary and establish the initial model. The asymmetric design of the rotor was implemented by changing the flux barrier offset. The sensitivity of thickness, endpoint angles, and offset of the flux barrier to the torque performance was analyzed to screen significant parameters. Then the values of the significant parameters were determined by using the multi-objective snake algorithm (MOSO) with the objectives of increasing the output torque and reducing the torque ripple. The target motor was determined based on the Pareto frontier solution. The torque performance of the SynRM with asymmetric Bezier-shaped, circular-shaped, and hyperbolic-shaped rotor structures was compared and analyzed. Results showed that the torque of the SynRM with asymmetric Bezier-shaped rotor structure was increased by 2.7 N·m and the torque ripple was reduced by 8.53% compared with circular-shaped rotor structure under the rated current. The torque ripple was reduced by 15.49% of the SynRM compared with hyperbolic-shaped rotor structure. The feasibility of the optimized design scheme was verified by the comparison between the prototype experiment and the simulation results.

Key words： synchronous reluctance motor Bezier-shaped rotor structure asymmetric flux barrier average output torque low torque ripple

Received: 21 March 2024 Published: 25 April 2025

CLC:	TM 341
	TM 352

Fund: 国家自然科学基金资助项目（U20A201284）.

Corresponding Authors: Yan DONG E-mail: chaixiaoyi_0107@163.com;dongyan73@hebut.edu.cn

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Cite this article:

Xiaoyi CHAI,Yan DONG,Rongzhe LIU. Optimal design and analysis of asymmetrical rotor structure for synchronous reluctance motor. Journal of ZheJiang University (Engineering Science), 2025, 59(5): 1063-1071.

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https://www.zjujournals.com/eng/10.3785/j.issn.1008-973X.2025.05.019 OR https://www.zjujournals.com/eng/Y2025/V59/I5/1063

同步磁阻电机非对称转子结构优化设计与分析

针对同步磁阻电机（SynRM）转矩脉动大和输出转矩低的问题，提出非对称贝塞尔（Bezier）形转子结构. 利用等价二次Bezier曲线确定磁障边界并建立初始模型，通过改变磁障偏移量进行转子非对称设计. 分析磁障厚度、磁障张角和磁障偏移量对转矩性能的灵敏度，筛选出显著参数. 以提高输出转矩和降低转矩脉动为优化目标，采用多目标蛇算法（MOSO）对显著参数进行优化，根据帕累托（Pareto）前沿解确定目标电机. 对比分析非对称Bezier形、圆弧形、双曲线形转子结构的SynRM转矩性能. 结果表明，在额定电流下，非对称Bezier形较圆弧形转子结构的SynRM转矩提升了2.7 N·m，转矩脉动降低了8.53%，较双曲线形转子结构的SynRM转矩脉动降低了15.49%. 样机实验与仿真结果的对比验证了优化设计方案的可行性.

关键词： 同步磁阻电机, Bezier形转子结构, 非对称磁障, 平均输出转矩, 低转矩脉动

Fig.1 Geometry and parameter of Bezier-shaped rotor structure

Fig.2 Geometry of circular-shaped and hyperbolic-shaped rotor structure

Fig.3 Formation principle of quadratic Bezier curve

Fig.4 Formation principle of flux barrier boundary based on equivalent quadratic Bezier curve

Tab.1 Main parameter of motor

Fig.5 Motor torque curve of Bezier-shaped rotor structure with different number of flux barrier layer

Fig.6 Optimization parameter of Bezier-shaped rotor structure

Fig.7 Optimization flow chart of Bezier-shaped rotor structure

Fig.8 Sensitivity of 25 optimization parameters of rotor structure to torque performance

Fig.9 Mechanism of elite selection and roulette strategy for sorting and parameter optimization in iteration

Fig.10 Flow chart of MOSO algorithm combining elite selection and roulette wheel selection method

Fig.11 Pareto frontier solution of MOSO and other algorithm for torque performance

Fig.12 Motor torque and harmonic analysis of three rotor structures under rated current

Tab.2 Torque performance of motor with three rotor structures under rated current

Fig.13 Inductance and salient pole ratio of motor with three rotor structures under different current

Fig.14 Torque performance of motor with three rotor structures under different current

Fig.15 Power factor of motor with three rotor structures under different current

Fig.16 Torque performance of motor with three rotor structures at different current angle

Fig.17 Stress and strain of circular-shaped rotor structure under steady state

Fig.18 Stress and strain of hyperbolic-shaped rotor structure under steady state

Fig.19 Stress and strain of Bezier-shaped rotor structure under steady state

Fig.20 Experiment platform of SynRM with Bezier-shaped rotor structure based on DSP

Fig.21 Experimental torque curve of SynRM with Bezier-shaped rotor under different current

Tab.3 Torque performance in simulation and experiment of SynRM with Bezier-shaped rotor under different current


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