Date and City

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2019 Innovation User Conference

22 May 2019, Coventry

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Giulia Malinverno

Research Engineer

Motor Design Ltd.

Advanced Motor-CAD modelling with link to ANSYS Maxwell

Introduction to Motor Design Ltd.

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Software developers: Motor-CAD

• Developers of Motor-CAD – world-leading tool for the design and

analysis of electric motors

• High level of customer support and engineering know-how

• Developed with expert electric machine designers.

Consultancy

• Design, analysis & training

• Led by motor design experts with significant industry and academic

experience.

Research

• Involved in collaborative government/EU-funded research projects

• Collaborate with Universities worldwide to develop electric machine

modelling techniques and create validation data.

Motor-CAD: Motor Design Software

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• Covers all typical types of radial flux rotating electric machines

• Motor Types:‐ Brushless permanent magnet (inner & outer rotor)

‐ Induction

‐ Synchronous reluctance

‐ Switched reluctance

‐ Synchronous wound field

‐ Permanent magnet DC

‐ Single phase induction

• Uses a combination of analytical and numerical modelling techniques

3D visualisation and CAD export

Flux Density shading

Slot temperature

distribution

Transient thermal

analysis

Efficiency map

Motor-CAD

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• The market leading tool dedicated to the design and analysis of electric motors.

• Enables rapid and accurate electromagnetic, thermal and mechanical analysis of an electric machine across the full operating envelope.

• Designed and developed in close collaboration with expert electric machine designers.

• Embedded engineering expertise.• Great customer support and response to user feedback.

Motor-CAD EMag

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Motor-CAD electromagnetic module:

• Extensive range of parametrisedtemplates & geometries

• Calculates torque, power, losses, voltages, currents, inductances, flux linkages and forces.

• Designs can be input and calculated in minutes allowing lots of iteration and full exploration of the design space; ensuring optimal design decisions.

Interior PM machine design Switched reluctance machine

design

Synchronous wound field machine

designInduction machine design

Motor-CAD EMag

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Motor-CAD electromagnetic module:

• Combined 2D finite element and analytical modelling approach

• Calculates electrical & electromagnetic performance

• Coupled solution with the thermal model

• Automatically set-up calculations for different performance tests.

Motor-CAD EMag

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Motor-CAD electromagnetic module:

• Embedded 2D transient FEA solver

• Meshing, boundary conditions automatically set-up

• Advanced calculations such a eddy current in magnets, induction machine rotor bars & AC winding losses.

• DXF and scriptable geometries, custom current waveforms, multi-slice skew.

• Enables engineers to account for complex electromagnetic effects early in the design process

Flux density plot from FEA solver Calculated voltage waveform

FEA geometry and region editor AC loss in a hairpin winding

Motor-CAD Therm

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Motor-CAD thermal module:

• Industry standard tool for thermal analysis of electric machines with over 20 years of inbuilt experience.

• Calculates temperature of the motor components in steady-state and transient operating conditions.

• Enables accurate modelling of thermal behaviour within seconds of calculation.

• Enables understanding of main heat transfer paths and opportunities to significantly improve output.

• Allows iteration and full exploration of the design space, alongside electromagnetic analysis; ensuring optimal design decisions.

Visualisation of oil

spray coolingThermal network

Radial temperature

distribution Thermal transient solution

Motor-CAD Therm

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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 cooing of end windings

• Direct conductor cooling‐ e.g. Slot ducts with oil

Through

ventilation

with radial

ducts

Fan cooled

machine with

cowling

Water jacket

with axial

channels

Motor-CAD Therm

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Thermal Network:

• Thermal and flow network generated automatically

• 3D network includes radial & axial heat transfer

• Detailed visualisation and calculation of the slot cross section

• CFD, FEA and empirical correlations behind all calculations.

Motor-CAD Lab

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Motor-CAD Virtual Testing Laboratory:

• Efficiency & loss maps

• Peak torque/speed curves

• Continuous torque/speed curves

• Duty cycle analysis

• Open & short circuit tests

• Automatically applies maximum torque/amp control strategies to replicate performance of machine with inverter

• Essential calculations for designing and analysing inverter driven machines with range of operating conditions.

Motor-CAD Lab

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Modelling Approach:

• To generate the map and cycle data, thousands of operating points have to be calculated.

• We use the FEA and analytical EMagsolvers to build inductance and loss maps of the machine design.

• Couples with the thermal solver to predict combined EMag and thermal behaviour.

• All calculations efficiency maps, duty cycles etc. can be calculated in minutes, and hence used during an iterative design process.

Motor-CAD Lab

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Peak and continuous operation:

• Machines are often specified on their peak and continuous operating characteristics.

• The peak curve is typically constrained by the inverter current limit and DC link voltage.

• The continuous operating curve is typically limited by the winding and/or the rotor temperature.

• The lab model can be used to easily generate these characteristics curves for any electric machine design.

Motor-CAD Lab

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Duty cycle analysis:

• Losses, efficiency and energy usage can be calculated across any duty cycle.

• The behaviour of the machine is solved with the thermal model to give temperature rise against time.

• The variation of losses and magnet flux (torque/amp) with temperature is accounted for.

• This enables engineers to design a machine with minimum size/cost and optimise the design for maximum cycle efficiency.

Motor-CAD Mechanical

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Stress Analysis for High Speed rotors:

• FE solution based

• Very fast – solves within a couple of seconds

• Template or DXF import options available

• Enables engineers to consider Magnetic and Mechanical performance trade-off in design optimisation

Motor-CAD/ANSYS Maxwell link: 3D export

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Topics:

• Set the Motor-CAD model

• How to generate the 2D Ansys model from Motor-CAD

• What the script does step by step

• Results

• Challenges and solutions

Set the Motor-CAD model

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The example will consider the Nissan Leaf motor:

For the 3D export set the model in the Emag module:

• Set the geometry, winding pattern, materials and the calculation where the user has to define speed, peak current, DC bus voltage and phase advance. In the same tab the torque performance test has to be defined.

• Finally the user has to be sure to set a reasonable number of points per cycle in the torque calculation. This data will be exported in order to use the same number of points in ANSYS Maxwell.

Geometry settings Winding pattern

Calculation tab.

How to generate the 2D Ansys model from Motor-CAD

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• Creating the ANSYS electronics desktop VBS file.

• Motor-CAD will automatically create a VBS file which will include all the information needed to recreate the Motor-CAD Emag model.

• Run the script in ANSYS Electronics Desktop to get the 2D model.

• The script takes into account the symmetry factor to generate the model, this is necessary in order to save computational time, especially when the 3D calculation will be carried out.

What the script does step by step

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• The script automatically saves the 2D model in order to start building the 3D model. It does so in order to save time otherwise we should run every time the 2D script and then the one to get the 3D model.

• The script retrieves the design and computational parameters from Motor-CAD by using the function “GetVariable”.

• All these parameters will be stored in ANSYS Maxwell and they will be needed to create the 3D design.

What the script does step by step

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• Once the design properties are stored in ANSYS, the script starts to extrude the 3D model by retrieving the axial length set in Motor-CAD.

What the script does step by step

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Next steps will consist of:

• Delete items that are not needed

• Create a band tool: It’s a UDP used as a subtract tool to derive a partial model.

• Create the end windings for the three phases. For the Nissan Leaf have to be LapCoil.

• Create bands: It’s a UDP and has to include all the moving parts (rotor and permanent magnets). The band object must be somewhat larger then the rotating parts. In our model three different bands have been used in order to have a finer mesh in the air gap.

• Create region: It’s a UDP and is a band which includes all the moving and static parts.

What the script does step by step

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• Set the transient solution and symmetry multiplier: At this step the script will use Maxwell’s symmetry option to significantly reduce the model’s size and therefore its simulation time without affecting the results. ANSYS Maxwell has the powerful option to carry out simulations by taking into account the smallest symmetry section of a model.

• Apply master/slave boundaries: To utiliseMaxwell’s symmetry options fully, we will need to set the planes where symmetry occurs.

• Set half of the axial length.

What the script does step by step

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• Assign the phase terminals: At this step we need to create winding excitations and associate them with the phase A,B and C coils. To set the excitation, we must first create another entity called “terminal”, which essentially defines a cross-section of the coil. It’s part of the UDP LapCoil.

• Assign excitations.

• Assign coil terminals: it’s needed to define the winding pattern.

What the script does step by step

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• Assign motion setup: The script assigns the motion type which in this case will be the rotation around the z axis. The assignment must include all the rotating parts (bands, rotor and magnets).

• Set the analysis set up where the time step and the stop time are defined.

Results

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▪ 3D torque:

With an average value of 89.36 Nm.

• 2D torque:

With an average value of 90.23 Nm

Results

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▪ 3D flux linkage: • 2D flux linkage:

Results

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▪ 3D induced voltage: • 2D induced voltage:

Challenge Solution

Results

• Get the 3D model in a short time.

• Set up the model as in Motor-CAD in order to make possible the comparison of the results.

• Save computational time, which in the 3D case could be longer than usual.

• Start from the already existing link from Motor-CAD and ANSYS in order to get the 2D model.

• Develop the script and divided it in steps in order to make more clear each step.

• Use the symmetry factor to use the model’s symmetry and save simulation’s time.

• We achieve a good design for the 3D model.

• Good results comparison between ANSYS 3D/2D.

• The user can get the 3D model in less than a minute just by clicking a button.

Presentation Title (required) [28pt, bold]

Thank You and Questions

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