Novel Design of Permanent Magnet-Assisted Synchronous Reluctance Motor Using Metal Additive Manufacturing Technology Md Jabed Hossain, Paxton Schroeder and Roy A McCann Department of Electrical Engineering and Computer Science (EECS) University of Arkansas Fayetteville, USA Abstract—This paper presents an advanced design and investigation of a Permanent Magnet Assisted Synchronous Reluctance Motor (PM-Assisted-SynRM). This unique design incorporates a two-level permanent magnet flux barrier to secure the permanent magnet, accompanied by an additional third-level flux barrier, aiming to achieve a sinusoidal air-gap flux density. The main innovation involves introducing a higher number of stator slots to enhance output power density. These stator slots are designed to house rectangular copper windings, thereby increasing the slot fill factor. The consideration of a single turn in each slot is explored to minimize dv/dt interference and enable the utilization of higher frequency power electronics drives. The challenges in manufacturing complex geometry stator and rotor laminations are addressed through the application of metal additive manufacturing technology. The efficacy of the proposed model is evaluated by validating its characteristics, including output torque, torque ripple, radial air-gap flux density, cogging torque, static torque, and back-EMFs, through finite element analysis (FEA). Keywords—Finite element analysis (FEA), analytical design, PM-Assisted-SynRM, flux barrier (FB), torque ripple, back EMFs. I. INTRODUCTION The PM-Assisted-SynRM has attracted considerable attention for combining the advantages of Permanent Magnet Synchronous Motors with Synchronous Reluctance Motors. PM-Assisted-SynRM are widely utilized in industrial drive, electric vehicles, and aerospace, because of their characteristics, including high power density, efficiency, a wide speed range, minimal reliance on permanent magnets (PMs), compact size, and lightweight design [1, 2]. The common rotor configuration for PM-Assisted-SynRM utilizes a multi-layer flux barrier, and a complex rotor structure, contributing to torque ripple that could cause noticeable noise, vibration, and a short lifespan [3]. Numerous studies in the literature address the reduction of torque ripple and the limiting of vibration. A model encompassing electromagnetic, structural, and acoustic aspect has been created to assess the noise and vibration characteristics of electrical machines [4]. The application of the PM shifting technique focuses on reducing torque ripples, and combining this technique with an appropriate flux barrier open angle is designed to improve torque capability [5]. Research findings suggest that adjusting the position of the reluctance axis within an irregular rotor core leads to the magnet-axis-shift effect [6]. Bianchi et al [7] presented various configurations of flux barriers based on their respective polarities. Sanada et al. [8] utilized an asymmetrical arrangement of flux barriers intentionally misaligning their outer edges with the teeth, aiming to reduce torque ripple. It has been shown that the utilization of an arc-shaped flux barrier is advantageous for PM-Assisted-SynRM in achieving higher torque and power density [9, 10]. Jabed et al. demonstrated the integration of higher number of stator slots in both IPM motors [11] and SPM motors [12]. There is limited research in the current literature that addresses both the reduction of torque ripple and the simultaneous increase in output torque density. This study aims to alleviate the torque ripple and enhance output power density by introducing a novel design for PM-Assisted- SynRM. The main goals of this project can be outlined as follows: • Introducing a higher number of stator slots to improve the output power density. • Employing rectangular stator slots to enhance the slot fill factor. Each stator slot features a single-turn coil, reducing parasitic capacitance and facilitating high- frequency power electronics drive. • Proposing a novel rotor design to achieve a sinusoidal air-gap flux density and minimize cogging torque. • Utilizing metal additive technology for the manufacturing of the complex geometry of rotor and stator lamination. Detailed manufacturing information is presented in the concluding section. II. DESIGN OF PM-ASSISTED-SYNRM A. Novel PM-Assisted-SynRMs Fig. 1 depicts a single pole of a PM-Assisted-SynRM, featuring a distributed winding with a total of 90 slots and 6 poles. The rotor lamination is composed of three layers of flux barriers in each pole, and the rotor magnets are positioned between two flux barriers using magnets of two different dimensions, arranged in an asymmetrical manner. The stator and rotor core laminations use the steel sheet M19_26G. The details of the proposed topology specifications can be found in Table I. B. Design Basics of PM-Assisted-SynRMs The expression of the torque equation of PM-Assisted- SynRM in the d-q reference frame is presented as follows:   = 3 2  2   −       + 3 2  2     (1) This work was supported in part by the U.S. National Science Foundation under award no. 2230857 as part of the I-Corps program.