MDL Software for Design and
Analysis of Electric Motors
Motor-Design Ltd (MDL)
www.motor-design.com
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Motor-CAD Therm
 network analysis dedicated to thermal
analysis of electric motors & generators
 input geometry using dedicated editors
 select cooling type, materials, etc.
and calculate steady state or
transient temperatures
 network set up automatically using
proven mathematics for heat
transfer and air/fluid flow
 easy to use by non heat
transfer specialists
 15 year of practical experience
built into the heat transfer and
flow algorithms
 provides detailed understanding of
cooling & facilitates optimisation
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Motor-CAD Motor Types
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BPM
Outer Rotor BPM
PMDC
Induction
Synchronous
Switched Reluctance
Claw Pole
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Cooling Types Investigated
Motor-CAD includes proven models for an extensive range of
cooling types:
 TENV: Totally enclosed non-ventilated
 natural convection from housing
 TEFC: Totally enclosed fan cooled
 forced convection from housing
 Through Ventilation
 TE with Internal Circulating Air
 Internal air circulating path
 water jacket as heat exchanger
 Open end-shield cooling
 Water Jackets
 axial or circumferential
 Submersible cooling
 Wet Rotor & Wet Stator cooling
 Spray Cooling
 e.g. oil spray cooling of end windings
 Direct conductor cooling
 e.g. Slot ducts with oil
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Many Geometry Options
 Many geometry options such as housings, rotors, slot types etc.
 Some have more influence on electromagnetic design, others on thermal design
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Steady-State & Transient Analysis
 Some application are steady state
and some operate with complex
transient duty cycle loads
 Even complex transients that are
for several hours of use take a
few seconds to calculate
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Analytical Lumped Circuit Analysis
 Lumps together motor parts with similar
temperatures into discrete network nodes
 Thermal resistance, heat transfer and
temperature difference are analogous to
electrical resistance, current and voltage
 Heat flow between nodes modelled using
thermal resistances for conduction,
convection and radiation
 Proven formulations developed for difficult
heat transfer mechanisms such as
conduction through bundles of wire in slot,
complex surfaces convection (empirical
correlations), interface gaps, etc.
 Power losses are placed at nodes where
heat is generated
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Thermal Lumped Circuit Models
 thermal resistances placed in the circuit to model heat transfer paths in
the machine
 conduction (R = L/kA)
 path area (A) and length (L) from geometry
 thermal conductivity (k) of material
 convection (R = 1/hA)
 heat transfer coefficient (h – W/m2.C) from empirical dimensionless analysis
formulations (correlations)
 many well proven correlations for all kinds of geometry in heat transfer
technical literature
 radiation (R = 1/hA)
 h =  1 F1-2 (T14 – T24)/ (T1 – T2)
 emissivity (1) & view factor (F1-2) from surface finish & geometry
 power input at nodes where losses occur
 thermal capacitances for transient analysis
 Capacitance = Weight  Specific Heat Capacity
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Flow Network Analysis
 Fluid flow modelling of cooling system (through
ventilation, circulating flow, water jackets, etc.)
using flow network analysis
 Proven empirical correlations to calculate
pressure drop due to flow separation and duct
wall friction
 Once flow distribution of the cooling system is
known, the resulting convection heat transfer
can be calculated using convection correlations
fan
characteristic
system resistance
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Motor-CAD Therm Model for Winding
 3d cuboidal elements used to model the winding conductive heat
transfer with proven formulation for effective thermal conductivity
for mix of copper, enamel, impregnation and air
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Motor-CAD Integrated Thermal FEA Solver
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Motor-CAD fully integrated FEA thermal solver allows fast
calibration of winding thermal resistance network and
improved understanding of winding hotspot location
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Continuous Software Development
 Software has been under continual development over the past 17
years with feedback from its hundreds of users worldwide
 New features driven by user requirements
 Many famous users in various sectors
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Automotive (AVL, Bosch, Valeo, Renault, BMW, Daimler, JLR, Porsche, GM, …)
Aerospace (Ametek, BAE, Eaton, Thales, Safran, UTC aerospace …….)
Industrial (ABB, Emerson, Regal Beloit, SEW, Siemens ……)
Heavy Traction (ABB, Bombardier, Caterpillar, Cummings, GE, Komatsu..…)
Renewable (Alstom, Gamesa, GE, Siemens, Vestas ……)
Universities (Nottingham, Sheffield, Manchester, Newcastle, Bristol……)
 Also EU and UK funded projects drive developments
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Evoque_e (development of 3 types of hybrid and electric vehicles)
VENUS (electric traction using axial reluctance motors)
ADEPT (electric traction)
ELETAD/HERRB (more electric helicopter)
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MOTOR DESIGN LIMITED
Thank you for your attention!
Questions are welcomed
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