Design and analysis of a new outer‐rotor permanent‐magnet flux‐switching machine for electric vehicle propulsion

Abstract

Purpose − The purpose of this paper is to propose a new outer-rotor permanent-magnet flux-switching machine for in-wheel electric vehicle propulsion. The paper documents both the design procedure and performance investigation of this novel machine. Design/methodology/approach − The topology and preliminary sizing equations of the outer-rotor permanent-magnet flux-switching machine are introduced. Both the number and width of rotor poles are then optimized using comprehensive two-dimensional FEA. The machine losses are particularly investigated by transient FEA for the optimal design. Findings − A outer-rotor permanent-magnet flux-switching machine, with 12 stator poles and 22 rotor poles, is most suitable for the proposed application. The analytical sizing equations are quite efficient with a suitable level of accuracy for preliminary design. The optimal rotor pole width from the FEA results is nearly 1.3 times of the original one. The efficiency of the proposed machine under rated load is relatively low, nearly 85%, as a result of significant eddy current losses in the permanent magnets, which can be effectively suppressed by implementing segmentation. The predicted outstanding performance implies that by adopting magnet segmentation the proposed machine is a leading contender for direct electric vehicle drives. Research limitations/implications − The end effects, which could be considerable in the machine with relatively short axial length, are neglected during the study. In addition, due to the high current density and deep slot, proximity losses in the winding which is not issued in this research could be significant. All the limitations mentioned above could bring corresponding errors to the results. Although the research is concentrated on the application of electric vehicle drive, the techniques can be potentially employed for other applications. Practical implications − The practical implementation of such a machine is confronted with several mechanical hurdles, especially the thermal issues which can be addressed by implementing innovative cooling system. Originality/value − The outer-rotor permanent-magnet flux-switching machines so far have not been addressed yet. This research provides designers with the technical background and another alternative for electric vehicle propulsion.

Investigation of a Co-Axial Dual-Mechanical Ports Flux-Switching Permanent Magnet Machine for Hybrid Electric Vehicles

“…However, for the outer machine, since it is directly coupled with the powertrain system of the vehicle and is controlled by the speed of the wheels, the electromagnetic pole pair number of the rotor should be larger than that of the inner machine. According to the recommended equation derived for an outer rotor structure, the outer rotor pole number can be determined as [14]:…”

High Torque Flux Switching Permanent Magnet Machine in Segmented Outer Rotor using Appropriate Split Ratio for Electric Scooter Propulsion

“…1643 associated with PMSM, this paper presents a permanent magnet flux switching motor (FSM) employing segmented outer rotor in which all active parts of armature winding and permanent magnet flux source are located on the stationary stator leaving the rotating rotor passive to contain with rotation for optimum performance [6]. This machine uses less materials for its construction, making its construction cost low.…”

“…The FSPM motor for pure electric scooter propulsion should build a torque on the rotor which is expressed in Equation (2). Meanwhile, the acceptable range of cogging torque for machine safe operation must not exceed 10% of the average torque [21].…”

“…Permanent magnet motors (PMMs) have been popular for traction vehicle drive because; it ensures loss-free excitation and eliminates the complications of external electric circuit connections. Moreover, permanent magnet motors have high torque and high efficiency [2]- [4]. Typically, permanent magnet synchronous motor utilizes so much mass of 2 kg permanent magnet (PM) making its construction fragile and market price very expensive.…”

Design investigation of three phase HEFSM with outer-rotor configuration

“…Nevertheless, previous research and development of HEFSMs have focused on inner-rotor configuration, and hard to find researches on outer-rotor HEFSM. According to the developed machine of PMFSM with outer-rotor configuration, the machine can provide higher torque and power density and increase it efficiency [12]- [13]. Therefore, this paper presents a design investigation of three phase outer-rotor HEFSM to meet the target performances.…”