Design guidelines and models for PMSMs with non‐overlapping concentrated windings

Purpose -The purpose of this paper is to minimize the torque pulsation in Halbach array permanent magnet synchronous machines (PMSMs). Design/methodology/approach -Because of its specific structure, the cogging torque influences the main part of the torque pulsation in a Halbach array PMSM. In this paper, first it is shown that the conventional magnet skewing method does not have a significant effect on the torque pulsation in this motor, and then an improved skewing method with fewer skewing steps is proposed. In this method permanent magnet segments are placed sinusoidally, with two-step skewing along the rotor. Generalization with different combinations of slots and poles is considered for a Halbach array PMSM. Findings -Using a detailed finite element method (FEM) it was found that with the proposed technique the cogging torque factor is reduced to as low as 8 percent, while the average value of the torque is maintained near the machine nominal average torque. Practical implications -Halbach array PMSMs are very good candidates for high dynamic performance applications such as aerospace applications due to their high acceleration and deceleration features. This technique also resolves the mechanical vibration and acoustic noise issues, which are caused by torque pulsation and significantly affect machine performance. Originality/value -The originality of this paper lies in the FEM results. Since Halbach array PMSMs have a special structure it was shown that the conventional skewing method does not work well for this machine. The new proposed technique has a significant effect on the torque pulsation.

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“…A concentrated double layer winding configuration is considered in this study for the following reasons (Refaie, 2010;Soulard and Meier, 2011):…”

Section: Introductionmentioning

confidence: 99%

Improved technique for minimizing torque pulsation in Halbach array permanent magnet machines

Sadeghi

Parsa²

2012

COMPEL - The International Journal for Computation and Mathematics in Electrical and Electronic Engineering

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“…The usual criteria when assessing the different possible combinations focus on the following aspects [18,19]: † High fundamental winding factor in order to maximise the machine's torque. † Periodicities in the winding layout so as to avoid the presence of unbalanced radial forces.…”

Section: Introductionmentioning

confidence: 99%

“…Although single-layer FSCWs have been mostly adopted in fault-tolerant designs, it is also possible to design double-layer FSCW machines having the same features [16]. Double-layer FSCWs offer some advantages over their single-layer counterparts, such as shorter end-windings, lower MMF harmonic content and therefore lower rotor losses [18]. As a consequence, the present paper considers both types of winding.…”

Section: Introductionmentioning

confidence: 99%

“…There are many possible combinations of phases, poles and slots that lead to a FSCW, both single‐layer and double‐layer. The usual criteria when assessing the different possible combinations focus on the following aspects [18, 19]: High fundamental winding factor in order to maximise the machine's torque. Periodicities in the winding layout so as to avoid the presence of unbalanced radial forces. Low magneto motive force (MMF) harmonic content in order to minimise losses in the rotor. Reduced cogging torque and torque ripple. Low mutual inductance between phases. Modularity. Although single‐layer FSCWs have been mostly adopted in fault‐tolerant designs, it is also possible to design double‐layer FSCW machines having the same features [16]. Double‐layer FSCWs offer some advantages over their single‐layer counterparts, such as shorter end‐windings, lower MMF harmonic content and therefore lower rotor losses [18].…”

Section: Introductionmentioning

confidence: 99%

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Fault‐tolerant permanent magnet synchronous machine – phase, pole and slot number selection criterion based on inductance calculation

Prieto

Martínez-Iturralde

Fontán

et al. 2015

IET Electric Power Applications

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Interest in permanent magnet synchronous machines for safety-critical applications has been increasing over the years. One of the most common methods for providing fault tolerance to a permanent magnet machine is the active control from the drive side. This method requires designing machines with the lowest possible mutual coupling between phases and a selfinductance that is high enough to limit the fault currents. Fractional-slot concentrated windings have been proposed as the most advantageous solution to meet these requirements. When comparing the numerous combinations of phases, poles and slots that give rise to a fractional-slot concentrated winding, the usual criteria only focus on obtaining a single-layer winding and do not actually consider the relationship between the self-inductance and the mutual inductance between phases. Moreover, they give no recommendations regarding the optimal number of phases from a magnetic point of view. The present work aims to cover this gap by obtaining analytical expressions for the calculation of the inductances in a permanent magnet machine. The derived expressions are investigated regardless of the geometry of the machine, and the criteria for selecting the most promising combinations in terms of the machine's fault tolerance are extracted. Nomenclature List of acronymsFEA finite-element analysis FEM finite-element method FSCW fractional-slot concentrated winding GCD greatest common divisor (mathematical function) ISA integrated starter alternator MMF magneto motive force PMSM permanent magnet synchronous machine List of symbols A magnetic vector potential [T·m] B magnetic flux density [T] H magnetic field intensity [A/m] L b base inductance [H] L ii phase self-inductance [H] L ij mutual inductance between phases [H] N s number of turns wound in series per phase Q number of stator slots R r rotor outer radius [m] R s stator inner radius [m] W magnetic energy [J] B slot width [m] b 0 slot opening width [m] g air-gap length [m] h slot height [m] h 0 slot opening height [m] i slot slot current [A] j slot slot current density [A/m 2 ] k w, s1 fundamental winding factor l ef effective length of the machine [m] m number of phases p number of pole pairs q number of slots per pole and phase t electric periodicity of the machine, GCD( p, Q) w magnetic energy density [J/m 3 ] α 0 slot opening angle [rad] α slot slot angle [rad] β slot leakage-related dimensionless parameter γ slot leakage-related dimensionless parameter δ air-gap inductance-related dimensionless parameter l permeance coefficient μ 0 permeability of free space [H/m] j relationship between air-gap inductance coefficients ς relationship between slot inductance coefficients f figure of merit

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“…Moreover, these Fourier-based analytical models do not require any experimental parameters. It is therefore no surprise that the interest in such models is very high [3][4][5][6][7][8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Voltage Sources in 2D Fourier-Based Analytical Models of Electric Machines

Hannon

Sergeant

Dupré

2015

Mathematical Problems in Engineering

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The importance of extensive optimizations during the design of electric machines entails a need for fast and accurate simulation tools. For that reason, Fourier-based analytical models have gained a lot of popularity. The problem, however, is that these models typically require a current density as input. This is in contrast with the fact that the great majority of modern drive trains are powered with the help of a pulse-width modulated voltage-source inverter. To overcome that mismatch, this paper presents a coupling of classical Fourier-based models with the equation for the terminal voltage of an electric machine, a technique that is well known in finite-element modeling but has not yet been translated to Fourier-based analytical models. Both a very general discussion of the technique and a specific example are discussed. The presented work is validated with the help of a finite-element model. A very good accuracy is obtained.

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Design guidelines and models for PMSMs with non‐overlapping concentrated windings

Cited by 7 publications

References 40 publications

Improved technique for minimizing torque pulsation in Halbach array permanent magnet machines

Improved technique for minimizing torque pulsation in Halbach array permanent magnet machines

Fault‐tolerant permanent magnet synchronous machine – phase, pole and slot number selection criterion based on inductance calculation

Voltage Sources in 2D Fourier-Based Analytical Models of Electric Machines

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