A Tutorial on General Air-Gap Field Modulation Theory for Electrical Machines

Cheng, Ming; Han, Peng; Du, Yi; Wen, Honghui; Li, Xianglin

doi:10.1109/jestpe.2021.3055224

Cited by 35 publications

(23 citation statements)

References 62 publications

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“…1b. The operating principle of the investigated BDFIM can be well explained by the airgap field modulation theory [30][31] . Once SW2 is energized by AC or DC current, a 2p 2 -pole magneto-motive force (MMF) is created in the airgap.…”

Section: Fundamentals Of Bdfimsmentioning

confidence: 98%

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Spiral vector modeling of brushless doubly-fed induction machines with short-circuited rotor windings

Han

Cheng

Zhang

et al. 2021

Chin. J. Electr. Eng.

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A unified spiral vector model is presented that can be used to assist the finite element method-based performance analysis of brushless doubly-fed induction machines with various short-circuited rotor windings. Specifically, magnet-free brushless doubly-fed induction machines working in doubly-fed or singly-fed synchronous mode are investigated. A dynamic model in spiral vector notation is developed, based on which the torque-angle and power-angle characteristics are derived. It is shown that the investigated brushless machines are equivalent to a traditional non-salient-pole synchronous machine with brushes. By introducing a conversion factor, they can also be analyzed with methods similar to the conventional phasor theory. A comparison is made between the brushless doubly-fed induction machine and non-salient-pole wound-field synchronous machine with brushes, revealing that the performance of the brushless machine degrades faster when the laminated core is saturated. A scaled-down prototype is tested to validate the effectiveness of the theoretical analysis.

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Section: Fundamentals Of Bdfimsmentioning

confidence: 98%

“…Eq. (31) indicates that a BDFIM with shortcircuited rotor windings operated in singly-fed synchronous mode is equivalent to a wound-field non-salient-pole synchronous machine. Its no-load terminal voltage is proportional to the frequency of stator currents and the flux linkage produced by the SW2.…”

Section: Singly-fed Synchronous Operationmentioning

confidence: 99%

Spiral vector modeling of brushless doubly-fed induction machines with short-circuited rotor windings

Han

Cheng

Zhang

et al. 2021

Chin. J. Electr. Eng.

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“…In doubly fed synchronous operation (motoring or generating), the rotor speed is determined by the frequency and pole pairs of SW1 and SW2. There are two scenarios to maintain synchronous operation, that is, sum modulation and difference modulation [7,12,[23][24] . (1) Sum modulation: When the rotor speed satisfies ω r =(ω 1 +ω 2 )/(p 1 +p 2 ), where ω 2 is the electrical angular frequency of SW2 and p 2 is the number of pole pairs of SW2, the number of antinodes of the resultant stator MMF wave in the air gap equals the summation of the two winding pole pairs, as shown in Fig.…”

Section: Stator Mmfmentioning

confidence: 99%

“…The air-gap magnetic field modulation phenomenon in BDFIMs with a simplified loop rotor winding has been briefly analyzed in Refs. [21][22][23] based on the developed theory. This study extends the work published in conference papers [21][22] with a detailed theoretical analysis and enhanced experimental validation.…”

Section: Introductionmentioning

confidence: 99%

Analytical analysis and performance characterization of brushless doubly fed induction machines based on general air-gap field modulation theory

Han

Cheng

Zhu

et al. 2021

Chin. J. Electr. Eng.

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Air-gap magnetic field modulation has been widely observed in electric machines. In this study, we present an analytical analysis and performance characterization of brushless doubly fed induction machines (BDFIMs) fed by two independent converters from the perspective of air-gap field modulation. The spiral-loop winding is studied in detail as an example to show the generalized workflow that can also be used to analyze other short-circuited rotor winding types, such as nested-loop and multiphase double-layer windings. Magnetic field conversion factors are introduced to characterize the modulation behavior of special rotor windings and facilitate their comparison in terms of cross-coupling capability, average torque, and harmonic content of the air-gap flux density waveforms. The stator magnetomotive force (MMF), rotor MMF, and resultant air-gap MMF are considered, based on which the closed-form inductance formulas are derived, and the torque equation is obtained along with the optimal current angle for maximum torque operation by using the virtual work principle. The design equations are then developed for the initial sizing and geometry scaling of the BDFIMs. Transient finite element analysis and experimental measurements are performed to validate the analysis.

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“…The DR figures in many proposed BDFRM designs [7,[25][26][27]. The ducted segmental rotor (DSR), which is receiving growing attention [18,22,[28][29][30][31][32], is closely related to the DR and is a combination of the SR and the DR. Both DR and DSR are preferred over the SPR and the ALR with a better coupling between the stator windings and no excessive iron losses [15,27,33].…”

Section: Radially Laminatedmentioning

confidence: 99%

On Analytical Modeling of the Air Gap Field Modulation in the Brushless Doubly Fed Reluctance Machine

et al. 2021

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The brushless doubly fed reluctance machine (BDFRM) is receiving an increased amount of attention from the research community thanks to its potential as an alternative drive for variable speed applications, both as motor and generator. Currently, the sizing of the BDFRM in the literature is based on the model of an ideal axially laminated rotor (ALR) and discrepancies are hidden in compensation factors which are in turn tuned with a finite element analysis (FEA). This paper proposes an analytical framework to accurately model the air gap field modulation, and by extension the torque density, of the BDFRM with ducted segmental rotor (DSR) and salient pole rotor (SPR). The results are verified with FEA and validated on a BDFRM prototype.

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A Tutorial on General Air-Gap Field Modulation Theory for Electrical Machines

Cited by 35 publications

References 62 publications

Spiral vector modeling of brushless doubly-fed induction machines with short-circuited rotor windings

Spiral vector modeling of brushless doubly-fed induction machines with short-circuited rotor windings

Analytical analysis and performance characterization of brushless doubly fed induction machines based on general air-gap field modulation theory

On Analytical Modeling of the Air Gap Field Modulation in the Brushless Doubly Fed Reluctance Machine

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