A novel five-phase fault-tolerant modular in-wheel permanent-magnet synchronous machine for electric vehicles

Abstract

This paper describes a five-phase fault-tolerant modular in-wheel permanent-magnet synchronous machine (PMSM) for electric vehicles. By adopting both the analytical and finite-element methods, the magnetic isolation abilities of some typical slot/pole combinations are analyzed, and a new fractional-slot concentrated winding topology that features hybrid single/double-layer concentrated windings and modular stator structure is developed. For the proposed hybrid single/double-layer concentrated windings, feasible slot/pole combinations are studied for three-, four-, and five-phase PMSMs. A five-phase in-wheel PMSM that adopts the proposed winding topology is designed and compared with the conventional PMSM, and the proposed machine shows advantages of large output torque, zero mutual inductances, low short-circuit current, and high magnetic isolation ability. Some of the analysis results are verified by experiments. V C 2015 AIP Publishing LLC. With the increasing aggravation of energy crisis and air pollution, electric vehicles (EVs) have drawn wide interests in recent years. Owing to the elimination of mechanical gearboxes, in-wheel direct-drive system enables higher system efficiency and better control of EVs. 1,2 Since the in-wheel electric drive system is the only power source for pure EVs, so continuous operation after faults is very important. Multiphase permanent-magnet (PM) machine that features advantages of high power density and high reliability is promising for in-wheel direct-drive systems. [3][4][5][6] Fractional-slot concentrated windings (FSCWs) are widely adopted for fault-tolerant PM synchronous machines (PMSMs). However, FSCW introduces many space harmonics in the air gap, which takes negative effects on machine performance. The impacts of slot/pole combinations on eddycurrent losses of PMs are analyzed, and single-layer FSCW leads to more rotor losses than double-layer FSCW. 7,8 For the double-layer FSCW, its magnetic isolation ability is poorer than that of the single-layer FSCW.Recently, modular-structure machines are increasingly investigated due to their characteristics of increased faulttolerant ability and simplified manufacturing process. 9,10 For multiphase fault-tolerant PM machines, if the phase failure involves only a part of the machine, the fault part can be replaced by a healthy module, which leads to easy maintenance. Three-phase modular PM machine that features single-layer FSCW is reported. 11 Herein, we report a novel five-phase fault-tolerant PMSM, characterized as hybrid single/double-layer windings, modular stator structure, and high magnetic isolation.Five-phase PMSMs with FSCWs have been developed. 12 The investigated machines include a 20-slot/18-pole PMSM with single-layer FSCW, a 20-slot/18-pole PMSM with double-layer FSCW, and a 30-slot/28-pole PMSM with double-layer FSCW, as shown in Fig. 1. The magnetic isolation ability is investigated by finite-element method (FEM). With PMs removed and only one phase winding activated, the flux distributions are calculated by FE...

Transfer learning‐based surrogate‐assisted design optimisation of a five‐phase magnet‐shaping PMSM

“…The influence degree of different parameters on the same optimisation objective can be compared by the variation range of their S/N ratios. Define the impact factor IF of parameter i on objective j as Equation (34), where range i,j indicates the S/N ratio variable range of parameter i on objective j. The total impact factor of parameters is also given, which is close to the GSA result.…”

“…Offset teeth with 36°crossed electrical angle are introduced so that the stator coils can be full-pitched, which means that the winding factors for all harmonics are equal to 1 and the torque density enhancement from injected harmonic currents is benefited [9,14]. Besides, this tooth-isolated structure has little mutual inductance between phases, which is conducive to the faulttolerant operation [34]. The PMs with shaped profiles are used to improve torque characteristics, which consists of first, third, and fifth harmonic components.…”

Review of High-Power-Density and Fault-Tolerant Design of Propulsion Motors for Electric Aircraft

“…In addition to the winding form, the stator slot structure is also an important factor affecting the self-inductance of the motor. The study in [89] analyzes the main components of motor self-inductance and points out that slot leakage inductance accounts for the largest proportion of motor self-inductance. Further, the study calculates the analytical equation of the slot leakage inductance of the motor based on the slot diagram shown in Figure 37 and points out that in order to enhance the slot leakage inductance, the slot width can be appropriately narrowed and the slot depth can be increased; on the other hand, the enhancement of the slot leakage inductance leads to the increase of the harmonic components of the space magnetomotive force, which results in the increase of the antipotential harmonic content, torque fluctuation, and iron core losses.…”

Coupled Magnetic Field and Thermal Analysis Model for an IPMSM With Modular Three-Phase Winding Topologies for Fault-Tolerant Applications

“…The multisector machine has a multi three-phase winding arrangement in which each three-phase winding set is located in separate sectors of the stator. Similarly, the thermal behaviour of multi-sector machines has been discussed, and a detailed thermal study is presented in literature considering the sector design approach of multi three-phase machines [17][18][19][20][21][22][23].…”