Influence of Stator MMF Harmonics on the Utilization of Reluctance Torque in Six-Phase PMA-SynRM with FSCW

Abstract

Abstract:Although fractional-slot concentrated winding (FSCW) offers many significant advantages, such as short end-turn windings, high slot filling factor, and low cogging torque, it is frequently limited by excessive stator magnetomotive force (MMF) harmonics which will induce high eddy losses in the permanent magnets (PMs). What is more, in the literature, it can be observed that the reluctance torque of the salient-pole machine with FSCW is usually much lower than that obtained with integral slot winding. To explore the underlying reason why the reluctance torque in a salient machine with FSCW significantly decreases, a new six-phase FSCW with 24 slots and 10 poles, which can significantly reduce the undesirable stator MMF harmonics, is obtained by using the concept of stator shifting. Then, two permanent-magnet-assisted synchronous reluctance machines (PMA-SynRMs) with the proposed winding layout and conventional asymmetric 12-slot/10-pole six-phase winding layout are designed and simulated by the finite-element method (FEM). The reluctance torque, total torque, and d/q-axis inductances with different current phase angles are also compared under different loaded conditions. The results show that a reduction in stator MMF harmonics can indeed lead to a significant enhancement in reluctance torque under heavy loaded conditions, while the dominance will diminish under light loaded conditions.

Analytical Modelling of a Six-Phase Surface Mounted Permanent Magnet Synchronous Motor

“…This model was subsequently utilized to deduce the precise interrelationships among different unitized machine parameters, aiming to achieve optimal performance in both inverter control (IC) and traction scenarios. Cheng et al (9) analyzed a modeling of a sixphase surface mounted PMSM (SPMSM) based on the equivalent magnetic circuit with the magnetic behavior and electrical characteristics.…”

Novel Design of Six-Phase Spoke-Type Ferrite Permanent Magnet Motor for Electric Truck Application

“…Among the reported electric motors used for HDTs, multi-phase rare-earth permanent magnet (RE-PM)-based synchronous machines are widely utilized due to their high torque and power density, maximum speed, and efficiency [1]. For multi-phase machines, fractional-slot concentrated winding (FSCW) is generally utilized because the FSCW provides the inherent fault-tolerant capability, higher winding factor, and lower cogging torque than distributed winding [4][5][6]. However, the FSCW produces unwanted space harmonics in the stator magnetomotive force (MMF), resulting in high eddy current losses in permanent magnet (PM), localized core saturation, and difficulty to produce high reluctance torque from interior-mounted rotor topology [7,8].…”

“…To suppress the stator MMF harmonics, various methods, including PM segmentation [4,5], multilayer winding design [9], coils with a different number of turns per coil side [10], and stator-shifting [11], have been reported. Among these MMF harmonic suppression methods, the stator-shifting concept reduces both sub-and high-order stator MMF harmonics effectively without increasing manufacturing costs and material usage [4][5][6]11]. This concept has been validated with various rotor topologies, including surface-mounted and interior-mounted single-and multi-layer V-type rotor topologies [4][5][6].…”

“…Among these MMF harmonic suppression methods, the stator-shifting concept reduces both sub-and high-order stator MMF harmonics effectively without increasing manufacturing costs and material usage [4][5][6]11]. This concept has been validated with various rotor topologies, including surface-mounted and interior-mounted single-and multi-layer V-type rotor topologies [4][5][6]. However, this concept has not been validated for interior-mounted spoke-type rotor topology yet.…”

Enhanced Flexible Algorithm for the Optimization of Slot Filling Factors in Electrical Machines

“…In particular, high efficiency, high power density and cost-effective manufacturing are required in the automotive industry [1][2][3]. One possible solution to meet these requirements is to optimize the copper filling factor of stator winding [4][5][6][7][8][9][10][11]. In particular, a high copper filling factor involves a more rational and efficient use of copper with economic benefits and improved energy savings.…”