Design and Analysis of a New Fault-Tolerant Permanent-Magnet Vernier Machine for Electric Vehicles

This paper presents the influences of winding magneto-motive force (MMF) harmonics on the torque characteristics in surface-mounted permanent magnet vernier (SPMV) machines. Based on the magnetic gearing effects, the armature magnetic field of the SPMV machines is modulated by flux modulation poles (FMPs). In the modulated magnetic field, a working harmonic which corresponds to the number of the rotor pole pairs generates torque. Unlike regular PM machines, the winding MMF harmonics in the SPMV machines can produce the working harmonic by adjusting the FMP shapes. In order to investigate the effects of the winding MMF harmonics, the operating principle of the SPMV machines is elaborated by an analytical method using the winding MMF distribution and air-gap permeance function. After that, the design method of the FMP shapes that can improve the output torque by using the winding MMF harmonics is proposed. For the SPMV machine having 6 slots and 24 FMPs, the effects of the winding MMF harmonics and the validity of the proposed design method are confirmed by the finite element analysis method. It is shown that the proposed design method can improve the performances of the SPMV machine in terms of the torque density, induced electromagnetic force, and efficiency.

Section: Magnetic Gearsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Influences of Winding MMF Harmonics on Torque Characteristics in Surface-Mounted Permanent Magnet Vernier Machines

Jang

Chang

2017

“…Then, its FEA-based short-circuit current is shown in Figure 3. It can be seen that the short-circuit current is limited because fault-tolerant design is adopted [17]. The main design data are given in Table 1.…”

Section: Topology and Featurementioning

confidence: 99%

“…In [17], a five-phase fault-tolerant PM vernier (FT-PMV) machine with improved torque capability was proposed. Also, though many works seek optimal fault-tolerant control strategies, most of them focus on open-circuit fault, rather than short-circuit fault.…”

Section: Introductionmentioning

confidence: 99%

Simplified Minimum Copper Loss Remedial Control of a Five-Phase Fault-Tolerant Permanent-Magnet Vernier Machine under Short-Circuit Fault

Gu¹,

Zhao²,

Zhang³

2016

Self Cite

Abstract:A fault-tolerant permanent-magnet vernier (FT-PMV) machine incorporates the merits of high fault-tolerant capability and high torque density. In this paper, a new remedial control is proposed for a five-phase FT-PMV machine with short-circuit fault of stator windings. Based on the principle of copper loss minimization, the aims of the proposed control strategy are to keep magnetic motive force (MMF) unchanged and minimize torque ripple. The proposed remedial control strategy contains two parts. Firstly, the remedial currents of the healthy phases are used to compensate for the ripple of MMF caused by the short-circuit current. Secondly, an open-circuit fault-tolerant control strategy is used to compensate for the lack of normal torque in the fault phase. Finally, the vector sum of two parts is adopted to derive the remedial currents. The final expression of the proposed remedial current is simpler than that than these previous methods. In addition, the proposed remedial currents are sinusoidal, which can reduce the reactive component in instantaneous power produced by pulsating torque and iron loss of a sine back-EMF machine. A FT-PMV prototype is built. The simulations and the experiments verify the effectiveness of the proposed strategy.

“…Permanent magnet vernier (PMV) machines have received increasing attention in energy conversion systems such as wind power [1,2], electric propulsion [3][4][5], and robotic servo systems [6], because of their high torque density and high efficiency. The PMV machine has different numbers of stator and rotor poles, but the magnetic fields excited by the armature windings and rotor PMs are coupled by the magnetic gearing effects [7].…”

Section: Introductionmentioning

confidence: 99%

A Novel Design Method for the Geometric Shapes of Flux Modulation Poles in the Surface-Mounted Permanent Magnet Vernier Machines

Jang

Chang

2017

This paper presents a novel approach to determine geometric shapes of flux modulation poles (FMPs) by using the analytical equations for flux density distribution due to armature windings. The magnetic field by the windings is modulated by the FMPs. Then, the resulting magnetic field produces the torque by interacting with the rotor permanent magnets (PMs). Thus, to improve the output power of the machine, the FMP shape should be optimized in terms of the magnetic flux modulation. To do so, the permeance function which can consider the changes of the geometric parameters for the FMPs is defined using the Fourier series analysis method. Consequently, the working harmonic, which is the spatial harmonic of the air-gap magnetic field due to the windings and creates the torque, is given as the function of the geometric variables. The optimal set of design variables to maximize the working harmonic in the analytical equation is obtained by employing the genetic algorithm. The finite element analysis results show that the proposed method improves the output torque of the surface-mounted permanent magnet vernier (SPMV) machines up to 31%. In addition, the torque ripple can be minimized by regulating the harmonic components of the permeance in the analytical equations.