Design and Analysis of Wound Field Three-Phase Flux Switching Machine with Non-overlap Windings and Salient Rotor

Abstract

Topologies for three-phase salient rotor flux-switching machines having non-overlap armature and field windings are presented. Salient rotor is used to modulate and switch the polarity of the flux linkage in the armature winding and this phenomenon represents the basic principle of operation of these types of machines. Non-overlap windings and toothed-rotor are the clear advantages of these topologies as the copper losses gets reduce and rotor becomes more robust. Finite Element Analysis (FEA) is used to examine the three phase topology of proposed Wound-field flux switching motor (WFFSM) with non-overlap windings and salient rotor. Coil test analysis, peak armature flux linkage, cogging torque, induced emf and average torque are examined. On the basis of these analyses, it is confirmed that 24S-10P has high flux linkage, less cogging torque and high average torque as compared to other WFFSMs.Keywords: Wound-field flux switching motor (WFFSM), topology, salient rotor, non-overlap windings IntroductionIn the mid 1950s, the first concept of flux switching machine (FSM) has been founded and printed. 4 stator slots and 4 rotor poles (4S-4P) permanent magnet FSM i.e. permanent magnet single-phase limited angle actuator or more well-known as Laws relay has been developed [1], and then single phase generator with 4 stator slots, and 4or 6 rotor poles (4S-4/6P) has been invented [2].Over the last decade, many FSM topologies have been introduced for various application i.e. automotive, domestic appliances, aerospace etc. FSM can be classified into three groups that are permanent magnet (PM) FSM, Field Excitation (FE) FSM and Hybrid Excitation (HE) FSM. PM and field winding are the main sources of flux in PMFSM and FEFSM while in HEFSM, both field winding and permanent magnet produces the flux [3][4][5][6]. In all these FSMs, the armature winding and field winding or PMare located on the stator. When compare with other FSMs, the FEFSM motor has advantages of low cost, simple construction, magnet-less machine, and variable flux control capabilities suitable for various performances. Furthermore, to manufacture the FEFSM motors, the PM on the stator of conventional PMFSMs is replaced by DC field excitation coil. In other words, the FEFSM motors having salient-rotor structure is a novel topology, merging the principles of the SRMs and inductor generator [7][8].The performance of FSM is enhanced by using segmental rotor configuration in recent research [9]. Segmental rotor is designed in a manner such that to achieve bipolar flux in armature winding, which has neither magnets nor winding. To produce bipolar flux linkages in this way, a toothed-rotor structure may be used but it requires overlap windings on the stator [10]. Non-overlap windings have been used in [11] to increase the efficiency by reducing the copper losses and enhanced the speed torque characteristics of FSM.A three-phase FSM using a segmental rotor has been proposed in [12] to improve fault tolerance to a reduction in torque pulsations and power con...

Non-Conventional, Non-Permanent Magnet Wind Generator Candidates

“…The flux switching mechanism has a fundamental principle of using the salient rotor for field modulation while producing flux-linkage polarity switching in the armature windings. Hence, reluctance is minimized by aligning the stator and rotor poles, with an increased inductance path, and vice versa [98,99]. Once again, the rotor of the FSM has no windings or PMs but just a laminated iron core.…”

Review of Switched Flux Wound-Field Machines Technology

“…Many research works were published in the last decade in this domain, as [48] which introduce analytical models to calculate the flux linkage, [49] which develop models based on magnetic equivalent circuits, or [50] where the analytical model is created using FEM analysis results. Deterministic optimization and genetic algorithm are usually applied for improvement of flux linkage.…”

“…In 3-f SFWFMs, the winding arrangments as well as rotor teeth number and stator slots play vital role in flux linkage. Overlapping windings [30,37,42], non-overlapping stator [31,47,50] and torioidal FEC winding arrangements [40] are normally used for SFWFMs. However, overlapping windings and toroidal FEC have less flux linkage due to long flux path and flux leakage to the outer surface while non-overlapping armature and field windings arrangement of 3-f SFWFMs discussed in [46] and [47] have high flux linkage due to short end windings and all field coils in same direction.…”