maxwell v16 12 -...

ANSYS Maxwell 3D Field Simulator v16 User’s Guide

12.4 Prius Motor - Maxwell 2D Transient to FLUENT 3D Steady State

2-Way Coupling with Demagnetization

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Maxwell v16

Maxwell 2D Transient to FLUENT 3D Steady State 2-Way Coupling with Demagnetization

This workshop shows how Maxwell 2D transient is 2-way coupled with FLUENT 3d steady state. Time averaged but spatially distributive Ohmic losses in the magnets and core losses in the stator and rotor are transferred from Maxwell 2D to a 3D mesh in FLUENT for temperature calculation. Then temperature is mapped back to Maxwell to affect electrical conductivity and B-H curves. Demagnetization is also turned on in Maxwell. This workshop shows steps related to transferring losses from Maxwell to FLUENT and does not contain details about Maxwell or FLUENT. Please refer to FLUENT Users’ Guide for information on FLUENT Setup

Prerequisites

Maxwell V16 and FLUENT V14.5 need to be installed in order to carry out this workshop, which are releases under ANSYS Workbench R14.5. ANSYS Workbench needs to be installed for the loss transfer.

Geometry and mesh used inside FLUENT




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Maxwell v16

The Maxwell Project The Maxwell project contains a 2D geometry of a Prius motor The setup of this motor has already been partially done To obtain more details about the setup please refer to Example 11.1 of Maxwell 2D Workshops

Stator

Phase A

Phase B

Phase C

Magnets

Rotor

Shaft




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Maxwell v16

Launch Maxwell To Lunch Maxwell

Double the Maxwell icon Or go to All Programs and look for your Ansoft installation.

Change Material for the Magnets

RMB on NdFe35 and select Properties.. Select Add Material Make the changes according to the panel

Name Nonlinear 625000 Thermal Modifier 1.0-0.0010876*(Temp-20) 1.0-0.00647425*(Temp-20)




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Maxwell v16

Import Intrinsic B-H Curve Click B-H Curve

Select Intrinsic and answer no to the pop-up question. Select Import Dataset and select the provided B-H curve file, intrinsic_BH.tab. This is the intrinsic B-H curve at the reference temperature of 20 C.




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Maxwell v16

Make Copper Conductivity a Function of Temperature RMB on Copper and select Properties.. Select View/Edit Material Make the changes according to the panel

Thermal Modifier 1.0/(1.0+0.0068*(Temp-20))




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Maxwell v16

Set up Temperature Dependency Go to Maxwell 2D>Set Object Temperature Make the changes according to the panel

Set up Demagnitization (Optional)

Go to Setup1

20 C is the reference

temperature




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Maxwell v16

Simulate and Plot Torque Go to Analysis and do the simulation. Plot Torque vs Time

Note that you could redo the calculation with a different temperature. Below is the new torque results with temperature of 100 C. The torque is reduced with elevated temperature. Save and Close Maxwell.

This concludes the Maxwell standalone calculation.




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Maxwell v16

Coupled Simulation with Fluent Will Be Performed Next Launch ANSYS Workbench

To Launch Workbench Select the Microsoft Start button , select All Programs > ANSYS 14.5> Workbench 14.5

Import Maxwell Project File Since we are using an existing Maxwell project, we will import it into Workbench. Users can create a new Maxwell Analysis System to setup a new problem. To Import Maxwell File

Select the menu item File > Import Change the file type to Maxwell Project File (*.mxwl) Browse to the location where workshop input files are located Select the file “Ex_12_4_2Way_Demag.mxwl” and Open it.

Launch Maxwell

A Maxwell analysis system will be created as shown below. To Lunch Maxwell

Double click on the solution tab of Maxwell analysis system.




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Maxwell v16

Set up Feedback Go to Maxwell2D > Set up Object Temperature Enable feedback

Analyze

To start the solution process Select the menu item Maxwell 2D > Analyze All This may take up to 5 min.




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Maxwell v16

Plot Losses Create Parameter for Total Losses

Select the menu item Maxwell 2D > Fields > Calculator 1. Select Input > Quantity >TotalLoss 2. Select Input >Geometry >Surface > Stator 3. Select Scalar > integrate 4. Select Add 5. Specify the name of the expression as Loss_Stator 6. Press Done

Plot Loss Vs Time Select the menu item Maxwell 2D > Results > Create Field Reports > Rectangular Plot In Report window

1. Category: Calculator Expressions 2. Quantity: Loss_Stator 3. Select New Report 4. Press Close 5. Choose the range as shown to plot the results.




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Maxwell v16

Calculate Time Average Losses Right click on the plot and select the option Trace Characteristics > Add In Add Trace Characteristics window,

1. Category: Math 2. Function: avg 3. Range: Specified 4. Select Add and Done

The value displayed is around 1206.9 watts It shows time averaged Total Losses for the stator Since this is a 2D case, these losses are in watts per meter We need to multiply this value with length of stator in order to calculate true losses. Since the length is 0.08382 m, the actual total loss for the stator is : 101.2 watts (The correct answer should be 50.6 watts. The bug has been fixed in V17.)




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Maxwell v16

Close Maxwell To Close Maxwell window

Select the menu item File > Close Desktop

Turn on Beta Option

Go to Tools > Options > Appearances to turn on beta option. Beta option is needed for two-way transient Maxwell steady state Fluent coupling.

Save

To Save Workbench Project Return to Workbench Project window Select the menu item File > Save Save the file with the name “Ex_12_4_2Way_Demag.wbpj




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Maxwell v16

Create a FLUENT Component System To Create a FLUENT Component System

Expand the Toolbox for Component Systems and select a Fluent component system from it. Drag and drop the FLUENT System on Project page

Load FLUENT Case File A CFD case file has been provided with the workshop. The case file has all proper setup. This workshop will demonstrate the loss mapping process. To Load Case File

Right click on Setup tab of FLUENT Analysis system and select Import FLUENT Case > Browse Browse to the correct location and select the FLUENT case file “Ex_12_4_2Way_Demag.cas.gz” and select Open A FLUENT Launcher window will pop up as shown in below image. Select Double Precision and press OK to it. A FLUENT window will launch and case file will be imported into FLUENT




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Maxwell v16

Build Links To Create Links

Without closing FLUENT window, return to Workbench project page Drag and drop Solution tab of Maxwell Analysis system onto the Setup tab of FLUENT system Right click on Solution tab of Maxwell Analysis system and select Update Press OK to the pop up window.

Initialize Solution To Initialize the Solution

Go to Solution > Solution Initialization Change the Initialization type to Standard Initialization Press Initialize Note: It is not necessary to initialize the solution before mapping the losses from Maxwell. If you initialize the solution after mapping losses, mapping will be redone automatically




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Maxwell v16

Map Losses from Maxwell To Maps Losses from Maxwell

Select the menu item File > EM Mapping > Volumetric Energy Source In Maxwell Mapping window,

FLUENT Cell Zones: Press Ctrl and select the four zones solid-magnet, solid-rotor, solid-teeth, and solid-yoke. Start: 2.083e-4 Stop: 1.667e-3 Press OK

Mapped Losses After data mapping, FLUENT will display the loss values mapped to selected zones The losses reported for the stator (zone 31 and 37) is 50.1watts Remember that total losses for the stator calculated from Maxwell was 50.6 watts. It can be verified that losses for other regions are also correct.




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Maxwell v16

Perform the Simulation Simulate for 20 iterations using all setting in the case file

Plot Temperature Distribution

To Plot Temperature Go to Display > Graphics and Animations… and double click Contours In Contours window,

Filled: Checked Contour of: Temperature > Static Temperature Surfaces: select all periodic and solid (Tip: using the Match) Press Display and Close

Note: The windings have the highest temperature as expected. There is a temperature gradient across the air gap. The thermal conductivity for the air gap is increased to model the enhanced heat transfer at the gap due to motion.




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Perform Temperature Feedback and 2-Way Coupling Go back to Workbench schematic RMB Solution of Maxwell2D and Enable Update Double click Solution to launch Maxwell Reset time to zero and redo the analysis

RMB Setup1 to reset time to zero. The torque is much less due to magnet being function of temperature. Display temperature to show temperature distribution on the magnets.




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Perform Fluent Analysis again Following the Same Procedure The new mapped loss is the following.

After Some Coupling Iterations, Temperature Converges to a Level Acceptable. Below is a Plot of Temperature Convergence History.

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