maxwell v15 12 - cadfamily.com maxwell 3d field simulator v15 user’s guide 12.1 multiphysics...

ANSYS Maxwell 3D Field Simulator v15 User’s Guide

12.1

Multiphysics Coupling - IGBT

12.1-‹#›

Maxwell v15

Insulated Gate Bipolar Transistor (IGBT) Insulated Gate Bipolar Transistor is power semiconductor device used for high

efficiency and fast switching in modern appliances such as electric cars, trains,

variable speed refrigerators, air-conditioners, etc.

These devices are designed for carrying high currents and many times lead to

failures in Bondwires due to high thermal stresses.

In this example, we will be modeling an IGBT device using Maxwell to get Heat

losses and Lorentz forces in Bondwires and then transfer this data to ANSYS

Mechanical to calculate Stresses on the wires and determine regions prone to

failure.

In addition, thermal conductivity of all components will be set as function of

temperature. Temperature data from ANSYS Mechanical will be transferred back

to Maxwell to calculate exact heat losses.

Total geometry is a six leg IGBT system. To simplify the tutorial, we will be

modeling only one leg in the example.

Maxwell

Steady State Thermal

Static Structural


12.1


12.1-‹#›

Maxwell v15

ANSYS Maxwell Design Environment The following features of the ANSYS Maxwell Design Environment are used to

create the models covered in this topic

Boundaries/Excitations

Current: Stranded

Analysis

Magnetostatic

Steady State Thermal (ANSYS Mechanical)

Static Structural (ANSYS Mechanical)

Results

Force

Field Overlays:

J Field

Temperature

Equivalent Stress

Deformation


12.1


12.1-‹#›

Maxwell v15

Prerequisites To Run this Tutorial

ANSYS Workbench R13/R14 needs to be installed for performing this

tutorial

ANSYS Mechanical licenses are needed

Maxwell needs to be integrated with ANSYS Workbench while installation

Launching ANSYS Workbench To launch Workbench:

1. Click the Microsoft Start button, select Programs, and select ANSYS 14.0

> Workbench

Open Maxwell Project To Open Maxwell File

In ANSYS Workbench Project window, select the menu item File > Import

Set file type to Maxwell Project File (.mxwl)

Locate the file Ex_5_9_IGBT_One_Leg.mxwl and Open it

Maxwell Analysis System will be automatically created as shown in below

image

Launch Maxwell To Launch Maxwell

Right click on Geometry tab of Maxwell 3D Analysis system and select

Edit


12.1


12.1-‹#›

Maxwell v15

Description of Geometry Six Leg IGBT Device

Below shown is the image of a six leg IGBT device.

The device has three phase supply, Positive and Negative terminals as

shown in image

There are 12 IGBT chips and 12 diodes, six on each side of terminal wires

Diodes and IGBT chips are connected with each other using Aluminum

Bondwires

In this tutorial, we will be considering only one leg of geometry which is

shown in rectangle in below image.

Negative

Terminal

Positive

Terminal

Phase A Phase B Phase C

One Leg

Diodes

12 in Total

IGBTs

12 in Total


12.1


12.1-‹#›

Maxwell v15

Input File Description One Leg IGBT Geometry

Input file contains the geometry of one leg separated out of Six leg IGBT

system. Names and Material definition to all parts is already done. Model

tree should look as shown in the image.

A_Bar, A_Out, A_Upper corresponds to Phase A of Supply. N_Bar

corresponds to Negative terminal while P_Bar corresponds to the positive

terminal.

Diodes A1_B, A2_B and IGBT A2_B are in “OFF” conditions. They have

been assigned with material as “vacuum” as they do not contribute to the

field.

Bondwires G1, G2, G3 and G4 will be the focus of this simulation as these

thin wires carry very high currents and more likely to fail due to thermal

stresses.


12.1


12.1-‹#›

Maxwell v15

Set Solution Type To set the Solution Type:

Select the menu item Maxwell 3D > Solution Type

Solution Type Window:

1. Choose Magnetostatic

2. Click the OK button

Assign Excitations To Assign Phase Current

Select the menu item Edit > Select > Faces or press F from the keyboard to

change selection to faces

Select the face of A_Out as shown in image

Select the menu item Maxwell 3D > Excitations > Assign >Current

In Current Excitation window,

1. Name: PhaseA

2. Value: 40 A

3. Type: Solid

4. Direction: Positive Z

5. Press OK


12.1


12.1-‹#›

Maxwell v15

To Assign Terminal Current to P_Bar

Select the face of P_Bar as shown in image



1. Name: PTerm

2. Value: 20 A

3. Type: Solid

4. Direction: Negative X

5. Press OK

To Assign Terminal Current to A_Upper

Select the face of A_Upper as shown in image



1. Name: PTerm2

2. Value: 20 A

3. Type: Solid

4. Direction: Negative X

5. Press OK


12.1


12.1-‹#›

Maxwell v15

Set Temperature Dependent Material Properties Note: In this step, thermal conductivity of Copper and Aluminum will be set as

function of temperature. At the start, temperature of all objects is considered to

be at 22 ̊C. After Solving for Temperature in ANSYS Mechanical, temperature

data will be transferred back to Maxwell and solution will recalculated with new

temperatures applied through ANSYS Mechanical.

To Set Thermal Modifier for Copper

Right click on copper material tab from the history tree and select

properties

In Select Definition window,

1. Select option View/Edit Material

2. In View/Edit Material window

1. Thermal Modifier: Checked

2. Bulk Conductivity:

Thermal Modifier: Select Edit

In Edit Thermal Modifier window,

Modifier: Set to

if(Temp > 1000, 0.2, if(Temp < 0, 1, 1/(1+0.004*Temp)))

Press OK

3. Press OK

3. Press OK


12.1


12.1-‹#›

Maxwell v15

To Set Thermal Modifier for Aluminum

Right click on aluminum material tab from the history tree and select

properties

In Select Definition window,

1. Select option View/Edit Material

2. In View/Edit Material window

1. Thermal Modifier: Checked

2. Bulk Conductivity:

Thermal Modifier: Select Edit

In Edit Thermal Modifier window,

Modifier: Set to

if(Temp > 1000, 0.2, if(Temp < 0, 1, 1/(1+0.004*Temp)))

Press OK

3. Press OK

3. Press OK

Set Object Temperature To Set Object Temperature

Select the menu item Maxwell 3D > Set Object Temperature

In Temperature of Objects window,

1. Include Temperature Dependence: Checked

2. Enable Feedback: Checked

3. Ensure all objects are set to 22 cel

4. Press OK


12.1


12.1-‹#›

Maxwell v15

Define Region Create Simulation Region

Select the menu item Draw > Region

In Region window,

1. Pad individual directions: Checked

2. +X = 0

3. -X = 100

4. +Y = 100

5. -Y = 100

6. +Z = 0

7. -Z = 100

8. Press OK


12.1


12.1-‹#›

Maxwell v15

Analysis Setup To create an analysis setup:

Select the menu item Maxwell 3D > Analysis Setup > Add Solution Setup

Solution Setup Window:

1. General Tab

Percentage Error: 0.2

2. ConvergenceTab

Refinement Per Pass: 50

3. Click the OK button

Model Validation To validate the model:

Select the menu item Maxwell 3D > Validation Check

Click the Close button

Note: To view any errors or warning messages, use the Message Manager.

Analyze To start the solution process:

1. Select the menu item Maxwell 3D > Analyze All


12.1


12.1-‹#›

Maxwell v15

Solution Data To view the Solution Data:

Select the menu item Maxwell 3D > Results > Solution Data

To view the Profile:

1. Click the Profile Tab.

To view the Convergence:

1. Click the Convergence Tab

Note: The default view is for convergence is Table. Select

the Plot radio button to view a graphical representations of

the convergence data.


12.1


12.1-‹#›

Maxwell v15

Mag_J Plot Hide Region

Select the menu item Edit > Select > Objects or press O from the keyboard

to change selection to Objects

Select Region from the history tree

Select the menu item View > Visibility> Hide Selection > Active View

Create Field Plot

Select the menu item Edit > Select All Visible

Select menu item Maxwell 3D > Fields > Fields > J > Mag_J

In Create Field Plot window

1. Plot on surface only: Checked

2. Select Done

Modify Plot Attributes

Double click on the legend to change plot properties

In the window

1. Scale tab

Num. Division: 50

User Limits: Checked

1. Min: 1000

2. Max: 5e+7

Log: Checked

2. Press Apply and Close


12.1


12.1-‹#›

Maxwell v15

The plot of the Mag_J will be as below:

Volume current density is high in thin sections of Bondwire_G1 and

Bondwire_G2

Exit Maxwell To Close Maxwell

Select the menu item File > Close Desktop

Save Project Save Workbench Project

To save the project, goto the Workbench project window and select menu

item File > Save As

Save the file with the name Ex_12_1_IGBT_One_Leg


12.1


12.1-‹#›

Maxwell v15

Create Steady State Thermal System To Create a Steady State Thermal Analysis System

Select Steady State Thermal system from the Analysis Systems list

Drag and drop it on the Solution tab of Maxwell 3D Analysis System

Drag and drop the geometry tab of Maxwell analysis system on the

Geometry tab of the Steady State Thermal system

Note: By Dropping Steady State Thermal Analysis System onto Solution

tab of Maxwell System we are establishing a link between Solution tab of

Maxwell and Setup tab of Steady State thermal Analysis System. This will

enable the data transfer from Maxwell to ANSYS Mechanical

Update Maxwell Cell To Update Maxwell Solution

Right click on Solution tab of Maxwell 3D Analysis System and select

update

A tick mark will appear adjacent to Solution tab of Maxwell

Right click on Geometry tab of Steady-State Thermal system and select

Refresh


12.1


12.1-‹#›

Maxwell v15

Define Material Database To Specify Material Data

Right click on Engineering Data tab and select Edit

In Engineering Data window,

1. Select the icon Engineering Data Sources

2. From Engineering Data Sources, select the tab General Materials

3. Press Ctrl and select materials Aluminum Alloy, Copper Alloy and

Silicon Anisotropic, right click and select Add

4. Select Return to Project to exit Engineering Data

Launch ANSYS Mechanical To Launch ANSYS Mechanical

Right click on Model tab of Steady State Thermal Analysis System and

select Edit

In ANSYS Mechanical window, a tab corresponding to Maxwell link will be

automatically added


12.1


12.1-‹#›

Maxwell v15

Set Units To Set Unit System

Select the menu item Units > Metric (mm, kg, N, s, mV, mA)

Rest of the tutorial will be done in this unit system

Define Materials To Define Copper Material

Expand the Geometry tab from the History tree

Press Ctrl and select the objects A_Bar, P_Bar, AA_Plate, AP_Plate,

AN_Plate, N_Bar, A_Out and A_Upper

In Details View Window:

1. Material:

Assignment: Set to Copper Alloy

To Define Aluminum Material

Press Ctrl and select the objects Bonwire_G1, Bondwire_G2, Bondwire_3

and Bondwire_G4


1. Definition:

Assignment: Set to Aluminum Alloy

To Define Silicon Material

Press Ctrl and select the objects Diode_A1_T, Diode_A1_B, Diode_A2_T,

Diode_A2_B, IGBT_A1_T, IGBT_A1_B, IGBT_A2_T and IGBT_A2_B


1. Material:

Assignment: Set to Silicon Anisotropic

Non-linear Effects: No


12.1


12.1-‹#›

Maxwell v15

Assign Mesh Parameters Note: Mesh size variation from bondwires to the bodies attached with it can not

be too large. In order to avoid this, we need to specify smaller mesh sizes to

these bodies.

To Assign Mesh Parameters for Bondwires

Right click on Mesh tab from the tree and select Insert > Sizing

In Details of Sizing window,

1. Geometry:

Change the selection filter to “Bodies”

Press Ctrl and select all Bondwires from Graphic window

Press Apply

2. Element Size: 0.1mm

To Assign Mesh Parameters for Bondwires

Right click on Mesh tab from the tree and select Insert > Sizing

In Details of Sizing window,

1. Geometry:

Press Ctrl and select the bodies AA_Plate, Diode_A1_T,

Diode_A2_T, IGBT_A1_T and IGBT_A2_T from Graphic

window

Press Apply

2. Element Size: 0.25mm


12.1


12.1-‹#›

Maxwell v15

Generate Mesh To Launch Meshing

Right click on Mesh tab and select Generate Mesh

Mesh will be generated and displayed on the Graphic Window


12.1


12.1-‹#›

Maxwell v15

Import Data from Maxwell To Import Heat Generation from Maxwell

Right click on the tab Imported Load (Maxwell3DSolution) and select Insert > Heat Generation

In Details of Imported Heat Generation window,

1. Geometry

Right click in graphic window and select “Select All”

Press Apply

Right click on the tab Imported Load (Maxwell3DSolution) and select Import

Load

Note: An Import Load transfer summery will be created below “Imported

Heat Generation”. This lists error in data transfer due to variation of mesh

in Maxwell and ANSYS Mechanical. The value of scale should be close to

1 in important regions.


12.1


12.1-‹#›

Maxwell v15

Specify Convective Boundary To Assign Convective Boundary

Right click on Steady State Thermal tab from the tree and select Insert > Convection

In Details of Convection window,

1. Geometry:

Change the selection filter to “Faces”

Right click in graphic window and select “Select All”

Press Ctrl and select bottom faces as shown in below image

to remove them from selection

Press Apply

2. Film Coefficient: 1e-4 W/mm2 .° C

Create Temperature Field Plot To Create Temperature Contours

Right click on Solution tab from the tree and select Insert > Thermal > Temperature


12.1


12.1-‹#›

Maxwell v15

Solve Thermal Setup To Run the Solution

Right click on Solution tab and select Solve

Solution progress will be shown as below

Temperature Contours Maximum Temperature is in Bondwires which is around 81 ̊C


12.1


12.1-‹#›

Maxwell v15

Transfer Object Temperatures to Maxwell To Transfer Temperature Data to Maxwell

Right click on the tab Imported Load (Maxwell3DSolution) and select

Export Results

Temperatures calculated by Steady State Thermal will be transferred back

to Maxwell

Exit Steady State Thermal To Close ANSYS Mechanical

Select the menu item File > Close Mechanical

Solve Maxwell with Imported Temperatures To Launch Maxwell

Right click on Solution tab of Maxwell 3D analysis system and select Edit

To start the solution process:

Select the menu item Maxwell 3D > Analyze All

Maxwell will read imported temperatures from ANSYS Mechanical and

solve using imported temperature data

Note: Maxwell will now calculate heat losses based on imported

temperatures which can be again applied back to Steady State Thermal

Solver to get refined temperature distribution. These temperatures in turn

can be applied to Maxwell. The process can be repeated until there is no

significant change in Temperature results obtained


12.1


12.1-‹#›

Maxwell v15

Temperature Distribution in Maxwell

Temperature Filed plot can be can be created in Maxwell which will show

imported temperatures

Select the menu item Edit > Select All Visible

Select menu item Maxwell 3D > Fields > Fields > Other > Temperature

In Create Field Plot window

1. Plot on surface only: Checked

2. Select Done

Note: As we applied temperature based properties only for Copper and

Aluminum, plot is for the objects having those materials.

Close Maxwell

Select the menu item File > Close Desktop


12.1


12.1-‹#›

Maxwell v15

Create Static Structural System To Create Static Structural Analysis System

Select Static Structural system from the Analysis Systems list

Drag and drop it on the Solution tab of Steady State Thermal Analysis

System

Select Solution tab of Maxwell 3D Analysis system, drag and drop it on

Setup tab of Static Structural Analysis System

Note: By dropping Solution tab of Maxwell onto Setup tab of Static

Structural System, a link will be created between them. This will ensure

transfer of Lorentz Forces from Maxwell to ANSYS Mechanical

Update Steady State Thermal Cell To Update Thermal Cell

Right click on Results tab of Steady State Analysis System and select

update

New temperature plot can be seem by opening Steady State Thermal

window


12.1


12.1-‹#›

Maxwell v15

Launch ANSYS Mechanical To Launch ANSYS Mechanical

Right click on Setup tab of Static Structural Analysis System and select

Edit

Import Forces from Maxwell To Import Lorentz Forces from Maxwell

Right click on the tab Imported Load (Maxwell3DSolution) and select Insert > Body Force Density

In Details of Body Force Density window,

1. Geometry:


Press Ctrl and select all bondwires from the graphic window

Press Apply

Right click on the tab Imported Load (Maxwell3DSolution) and select Import

Load

Specify Support To Specify Supports

Right click on Static Structural tab of tree and select Insert > Frictionless Support

In Details of Frictionless Support window

1. Geometry:

Select bottom faces of geometry as shown in image

Press Apply


12.1


12.1-‹#›

Maxwell v15

Create Field Plots To Stress Field Plots for Bondwires

Right click on Solution tab and select Insert > Stress > Equivalent (von-Mise

In Details of Equivalent Stress window

1. Geometry:


Select all bondwires

Press Apply

To Deformation Field Plots for Bondwires

Right click on Solution tab and select Insert > Deformation > Total

In Details of Total Deformation window

1. Geometry:

Select all bondwires

Press Apply

Solve Structural Setup To Run the Solution

Right click on Solution tab and select Solve

Solution progress will be shown as below


12.1


12.1-‹#›

Maxwell v15

Field Plots Equivalent Stress

Maximum stress resulting in wires can be compared with the material

properties to predict the failure region.

Deformation

Note: Deformation images are magnified. To view results to the scale

Change the Result to True Scale


12.1


12.1-‹#›

Maxwell v15

Close ANSYS Mechanical To Close ANSYS Mechanical

Select the menu item File > Close Mechanical

Save Workbench project To Save Project

Select the menu item File > Save

maxwell v15 12 - cadfamily.com maxwell 3d field simulator v15 user’s guide 12.1 multiphysics...

Documents