A Consequent-Pole Magnetic-Geared Machine With Axially Embedded Permanent Magnets for Hybrid Electric Vehicle

Abstract

This paper reveals the fundamental reason for the asymmetrical issue in magnetic-geared machines (MGMs) based on flux modulation theory. The analysis indicates that the magnetic circuits of three-phase windings in MGMs are inherently asymmetrical. This asymmetrical issue is even more severe in conventional consequent-pole MGMs (CP-MGMs) because of the more distorted magnetic field. Hence, to address the asymmetrical issue, a novel structure featuring enhanced harmonic elimination capability is proposed in this paper. Consequently, torque density can also be improved. In particular, the proposed CP-MGM employs modular structure and axially embedded permanent magnets (PMs) to achieve symmetrical back electromotive force (EMF) waveforms and improved torque capability, respectively. To further improve the electromagnetic performance of the proposed CP-MGM, the PM arc ratio and flux modulator width ratio are analytically designed, which provides a general design guideline for CP-MGMs. To illustrate the merits of the proposed CP-MGM, a few other MGMs are included for a fair comparison based on finite element analysis (FEA). Results show the proposed CP-MGM can achieve more symmetrical back EMF waveforms and lower torque ripple, as well as lower PM consumption and higher torque density, as compared with its MGM counterparts.INDEX TERMS Asymmetrical magnetic circuit, cost-effective, high torque density, magnetic-geared machine.

A New Hybrid Concentrated-Winding Concept With Improved Power Factor for Permanent Magnet Vernier Machine

“…Based on (9), the winding factor of the proposed hybrid-CW PMVM can be obtained as shown in Fig. 6, in comparison with two benchmark PMVMs.…”

“…Numerous researches have been conducted to improve the power factor. Novel rotor topologies with different PM arrangements have been investigated to improve the power factor by enhancing the magnetic loading, such as consequent pole [9], Halbach array [10], spoke-type [11], and U-type PMs [12]. Among these various topologies, the spoke-type PMVMs exhibit the most promising performance by flux focusing effect, while the field modulation is weakened by the flux barrier effect.…”

Performance analysis of dual stator six‐phase embedded‐pole permanent magnet synchronous motor for electric vehicle application

“…In Ref. [28], to resolve the asymmetrical issues in magnetically geared machines, the authors have proposed a novel structure called consequent pole magnetic geared machines (CP‐MGM). The CP‐MGM makes use of the axially embedded PM to obtain an enhanced torque and symmetrical BEMF.…”

“…But in terms of reliability, the embedded pole machines are much better than the surface-mounted ones. For high-speed applications, the embedded pole magnets are preferred, due to their magnet orientation [27,28]. Moreover, it is pointed out that the concept of the embedded pole magnet has been utilised in many permanent magnet synchronous machines to enhance various performance parameters.…”

Novel Differential Evolutionary Optimization Approach for an Integrated Motor-Magnetic Gear Used for Propulsion Systems

“…In addition, the mechanical gear involves several well-known drawbacks: physical contact (friction) between the teeth, need for lubrication, local heat, material fatigue, and consequent mechanical losses [1]. In the case of magnetic gears (MGs), these drawbacks are avoided [2], [3], [4]. In this context, our research proposes a propulsion unit that eliminates mechanical transmission.…”