Thermal and Mechanical

System Simulation

ANSYS CONFERENCE & 27. CADFEM USERS’ MEETING

18 – 20 November 2009, Congress Center Leipzig

Evgenii Rudnyi, CADFEM GmbH

erudnyi@cadfem.de

Outline

System level simulation

Simplorer

Coupling Workbench and

Simplorer

Model Order Reduction

Thermal simulation

Electrothermal

Mechanical simulation

Control

Other papers at ACUM

1

Mechatronics: mechanical + electrical + computer sciences

2

3

Simplorer: http://www.ansoft.com/

Circuits

Block Diagrams

State Machines

Equation Blocks

VHDL-AMS

Example of VHDL-AMS

4

Compact Modeling: Transistor Compact Model

Figure from J. Lienemann, E. B. Rudnyi and J. G. Korvink. MST MEMS model

order reduction: Requirements and Benchmarks. Linear Algebra and its

Applications, v. 415, N 2-3, p. 469-498, 2006.

From Finite Elements to System Simulation

6

Electrothermal Simulation with power MOSFET:

From ANSYS Workbench to Simplorer

7

Model Order Reduction

Relatively new technology

Solid mathematical background:

Approximation of large scale

dynamic systems

Dynamic simulation:

Harmonic or transient simulation

Industry application level:

Linear dynamic systems

8

Model Reduction as Projection

Projection onto low-

dimensional subspace

How to find subspace?

Mode superposition is not the best way to do it.

zx V

x V

z

=

uxx BKE

uzz BVKVVEVV TTT

E

Er

9

Implicit Moment Matching

Padé approximation

Matching first moments for the

transfer function

Implicit Moment Matching:

via Krylov Subspace

0

0 )( i

i ssmH

mi mi,red, i 0, ,r

BKsEsH1

)(

0

0, )( i

redired ssmH

s0 0

V span{(K1E,K1b)}

uxx BKE

10

MOR for ANSYS: http://ModelReduction.com

FULL files

Linear Dynamic

System, ODEsCxy

BuKxxExM

MOR Algorithm

Small dimensional

matrices

Current version 2.5

ANSYS Model

Simulink,

Simplorer, VerilogA,

…

MOR for ANSYS Timing: MOR as Fast Solver

Reduced model of dimension 30

11

Dimension,

DoFs

nnz MOR Time

/ANSYS

static

4 267 20 861 1.4

11 445 93 781 1.8

20 360 265 113 1.7

79 171 2 215 638 1.5

152 943 5 887 290 2.2

180 597 7 004 750 1.9

375 801 15 039 875 1.7

System Thermal Simulation in Simplorer

Current : Heat Flow

Voltage : Temperature

Resistor : Thermal

resistance

Capacitor : Thermal

capacitor

Voltage source :

Temperature source

Current source :

Heat Flow source

12

Compact Thermal Models

Looks understandable – but how to do it in practice?

Figure from the book “Fast Simulation of Electro-Thermal MEMS: Efficient Dynamic

Compact Models.” Springer, 2006.13

Electrical vs. Thermal

Thermal phenomena are much more distributed, it is hard to lump

them.

Figure from the book “Fast Simulation of Electro-Thermal MEMS: Efficient Dynamic

Compact Models.” Springer, 2006.14

Electrical flow

cond /ins 108

Heat flow

cond /ins 102

Conductor

Insulator

Freescale Multi-channel Power Devices

15

PCBLeadframe

heavy gauge

wires

control

chippower

chipMOR for ANSYS at

Therminic 2009

More information: Thursday 09:20 - 09:40 Thermoelectric System

simulation: Compact Model Simulation with ANSYS Workbench, Freescale

Chip and its Model in Workbench

Two power MOSFET transistors

16

Interface to call MOR for ANSYS in Workbench

17

Import Reduced Model in Simplorer

Simplorer supports state space model

18

Test Thermal Circuit in Simplorer

Conservative thermal subsystem in Simplorer

Voltage – Temperature

Current – Heat flow

19

Thermal Impedance and Comparison with ANSYS

ANSYS: about 300 000 DoFs, Reduced model: 30 DoFs

The difference is less than 1%

Timing: 60 timesteps is about 30 min in ANSYS

20

Thermal Runaway

Transistor is considered as temperature dependent RDSon

The VHDL-AMS model

21

Thermal Runaway Model

Conservative coupling between electrical and thermal part

22

Transient Turn-on of an Automotive Light-Bulb

23

Transient Turn-on of an Automotive Light-Bulb

24

0.00 10.00 20.00 30.00 40.00 50.00Time [ms]

0.00

5.00

10.00

15.00

20.00

25.00

30.00

35.00

E2

.I [A

]

Curve Info

SL1='1' SL2='0' SL3='0'

SL1='1' SL2='1' SL3='0'

SL1='1' SL2='1' SL3='1'

Ansoft LLC FET_Light_Bulb_P21W_2Lamp Currents at turn-on

1 lamp

2 lamps

3 lamps

0.00 10.00 20.00 30.00 40.00 50.00Time [ms]

250.00

300.00

350.00

400.00

450.00

500.00

550.00

TH

M1

.T [ke

l]

Curve Info

THM1.TSL1='1' SL2='0' SL3='0'

THM1.TSL1='1' SL2='1' SL3='0'

THM1.TSL1='1' SL2='1' SL3='1'

Ansoft LLC FET_Light_Bulb_P21W_2Junction Temperature at turn-on

3 lamps

2 lamps

1 lamp

Example of Mechanical System

25

System Level Simulation

26

Hard Disk Drive Actuator/Suspension System

Michael R Hatch, Vibration Simulation Using MATLAB and ANSYS

27

Model Reduction

3352 elements

7344 nodes

21227 equation

400 frequencies takes about 12

min

MOR takes only 3 s

Comparison for head

ANSYS

MOR 30

MOR 80

28

Comparison

29

Comparison

30

Velocity Control: Device as a Black Box

31

Velocity Control: Multiphysics Modeling

32

Model Reduction for the FEM Model

13 347 elements

11 765 nodes

55 481 equations to

solve

200 frequencies

takes about 20 min

Model reduction

takes 8 second

33

Comparison

34

Efficient Simulation of Acoustic FSI

Wednesday 17:00 - 17:20, CADFEM + Simetris

35

System Level Battery Thermal Behavior Study

Thursday, 12:20 - 12:40, CADFEM

36

Battery thermal model

Electrical cell model(cell1)

0 0

EQU

FML1

CONST

Heating

RLoad

RT_LRT_S

CT_LCT_S

IBatt

Ccapacity

Rseries

VOC

CONST

TempRptc

1

2

REF

H

HeatConfig10

H

HeatConfig01

TCell2

TCell1

Q

Tref

Elektrothermische Simulation eines IGBT Wechselrichters

Thursday 11:40 – 12:20, CADFEM + ANSOFT

37

Thermal Domain

Electrical Domain MechanicalDomain

0

R1 R2 R3

MASS_ROT1

DR1

SINE2

SINE1

A

A

A

IN_A

IN_B

IN_C

OUT_A

OUT_B

OUT_C

I_motSimplorer4

A

B

C

N

ROT1

ROT2

Induction_Motor_20kW

Q

Ambient

P1

P2

P3

P4

P5

P6

P7

P8 P

9

P1

0

P1

1

P1

2

P_

RE

F

z_um z_vm z_wm

z_wpz_vpz_up

+

V

VM311 R6 R5 R4

E1

RZM

DR1

RZM

0.00 2.50 5.00 7.50 10.00 12.50 15.00 17.50 20.00Time [ms]

-500.00

-250.00

0.00

250.00

500.00

Y1 [

V]

Curve Info rms

R1.VTR 230.9405

R4.VTR 313.3812

0.00 2.50 5.00 7.50 10.00 12.50 15.00 17.50 20.00Time [ms]

1475.00

1485.00

1495.00

1500.00

MA

SS

_R

OT

1.O

ME

GA

[rp

m]

0.00

50.00

100.00

150.00

180.00

MA

SS

_R

OT

1.P

HI

[deg]

Curve Info

MASS_ROT1.OMEGATR

MASS_ROT1.PHITR

Extraction of Thermal Properties of Thin Films

Thursday, 12:20 - 12:40, T. Bechtold, NXP

Parametric Model Reduction

38

Also on Thursday

16:20 - 16:40, Export von modal reduzierten Körpern aus ANSYS

und deren Echtzeitberechnung, P. Sekler, A. Dadalau

17:00 - 17:20 Application of MOR for ANSYS to Hydro Turbine

Runner Dynamics, F. Lippold (Voith Hydro Holding GmbH & Co. KG,

Heidenheim)

17:00 - 17:20 Zustandsraumbeschreibung von piezo-mechanischen

Systemen auf Grundlage einer Finite-Elemente-Diskretisierung, B.

Kranz (Fraunhofer-Institut IWU, Dresden)

17:20 - 17:40 Parametric Reduction of Multiphysics Models, J.

Mohring (Fraunhofer-Institut ITWM, Kaiserslautern)

17:40 - 18:00 Novel Model Reduction Techniques for Control of

Machine Tools, P. Benner (Technische Universität Chemnitz)39

Conclusion

ANSYS – device level model

Simplorer – system level simulation

MOR for ANSYS – model reduction for ANSYS models

40