Electrical Engineering

, Volume 79, Issue 1, pp 31–38 | Cite as

The “Torus-Flux” motor — a novel permanent magnet synchronous machine

  • A. Binder


An ironless permanent magnet synchronous machine with a toruslike armature is presented and its inverter-fed motor performance is discussed. The calculation of the three-dimensional flux density distribution is accomplished by analytical and numerical methods. Test motor experimental results are used to check these calculations. A comparison with permanent magnet motors with cylindrical rotor and surface mounted magnets shows that for the same rated data the “Torus-flux” motor needs a higher amount of magnetic material and armature copper.


Copper Density Distribution Magnetic Material Flux Density Permanent Magnet 
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List of symbols


number of parallel paths per phase

A A/m

electric loading

ACu m2

cross-section of the armature copper wire

Br T

radial component of magnetic flux density


remanence of permanent magnets

Ce W·s/m3

(Esson) output coefficient

dse m

outer diameter of the stator

E V/m

electric field strength

f Hz

electric frequency



ha m

height of armature coil

kd m

distribution factor

i A

current per turn


current per phase (rms-value)

Idc A

d.c.-link current

la m

average conductor length of half a turn (without winding overhangs)

lb m

average conductor length of the winding overhangs

lFe m

iron length

L m

axial motor length including winding overhangs

mFe,s+r kg

mass of laminated stator and rotor iron

mCu kg

mass of armature copper

M A/m


Me Nm

electromagnetic torque


shaft torque

n 1/s

rotational speed

Nph 1/s

number of turns in series per phase (subscript z: per zone)

p 1/s

number of pole pairs

Pad W

additional losses (subscript 0: no-load, 1: load)

Pfr W

friction and windage losses


iron losses

Pin W

input power

Pinv W

inverter losses

Pout W

output power

Pδ W

air-gap power

r m

radial coordinate

rav m

average turn radius

Rph Ω

armature resistance per phase

S A/mm2

current density

t s


ui V

induced voltage

Ui V

rms-value of induced voltage

Udc V

d.c.-link voltage

v m/s

circumferential speed of rotor disk

VM m3

volume of magnets

z m

circumferential coordinate

δ m

air-gap length

θ rad

angle of rotation

κ S/m

electrical conductivity

λ S/m

ordinal number of current harmonic

μ0 Vs/(Am)

magnetic permeability of vacuum

ν Vs/(Am)

ordinal number of a spatial harmonic

τp m

pole pitch

ϕ rad

circumferential angle of an armature turn

Φ Wb

magnetic flux

Der “Torus-Fluß” — Motor — eine neuartige permanentmagneterregte Synchronmaschine


Eine eisenlose permanentmagneterregte Synchronmaschine mit einer torusähnlich geformten Ständerwicklung wird vorgestellt; ihre Eigenschaften als umrichtergespeister Motor werden erläutert. Die Berechnung der dreidimensionalen Feldverteilung wird sowohl analytisch als auch numerisch durchgeführt. Die Berechnungsergebnisse werden mit Meßdaten eines Versuchsmotors überprüft. Ein Vergleich mit permanentmagneterregten Synchronmotoren mit herkömmlichem Zylinderläufer und Luftspaltmagneten zeigt, daß der “Torus-Fluß”-Motor für dieselben Bemessungsdaten mehr Magnetmaterial und Wicklungskupfer benötigt.


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  1. 1.
    The T-Flux Motor, Australian Patent Ref.-Pct/AU94/0405. Lillington Manufacturing Pty. Ltd.: Midomac AustraliaGoogle Scholar
  2. 2.
    Hofmann, H.: Das elektromagnetische Feld. Wien, New York: Springer 1974Google Scholar
  3. 3.
    Vogt, K.: Berechnung rotierender elektrischer Maschinen. Berlin: VEB Technik, 1992Google Scholar
  4. 4.
    Prechtl, A.: Felder und Kräfte in Zylinderspulen. Arch. f. Elektrotechnik 66 (1983) 351–364Google Scholar
  5. 5.
    Yaksh, M.: ANSYS Magnetics User's Guide for revision 5.0. Houston: Swanson Analysis Systems, Inc. 1993Google Scholar
  6. 6.
    Huth, G.: Grenzkennlinien von Drehstrom-Servoantrieben in Blockstromtechnik. etz-Archiv 11 (1989) 401–408Google Scholar

Copyright information

© Springer-Verlag 1996

Authors and Affiliations

  • A. Binder
    • 1
  1. 1.HohenrothGermany

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