1 © 2017 ANSYS, Inc. May 1, 2017

Overview of Electronic Transformer

Simulations

Gerd Prillwitz

May 1, 2018

ANSYS, Inc

2 © 2017 ANSYS, Inc. May 1, 2017

Conduction

Convection

Radiation

Phase Change

Mass Transport

More…

Thermal

Compressible

Incompressible

Laminar Flow

Turbulence

Multiphase Flow

Non-Newtonian Fluids

More…

Fluids

Quasi static (Low Freq)

Full Wave

Joule Heating

Eddy currents

Current flow

Circuit Coupling

More…

ElectromagneticsStructural

Large Displacements

Finite Strain

Contact

Multibody Dynamics

Random Vibration

Implicit & Explicit

More…

Simplorer System Simulation Framework

Reduced order Models, Co-Simulation3rd-party Coupling, Scripting Automation

Simulation Coupling Framework

ANSYS Simulation Environment

3 © 2017 ANSYS, Inc. May 1, 2017

What are some of the challenges which will be covered?

• Electric Field effects:• varying dielectric permitivities

• varying dimensions and shape

• 3D field effects

• Magnetic effects: • nonlinear materials

• eddy currents

• proximity effects

• time diffusion of magnetic fields

• transient excitations

• 3D field effects

Technical Issues for Transformer Design

4 © 2017 ANSYS, Inc. May 1, 2017

• ANSYS provides an electromagnetic, multi-physics and system solution for both Power and Electronictransformers:

– Electromagnetic performance (losses, forces, impedances, …)

– Multi-physics capability (thermal, structural, acoustics)

– System Level models (ECE and frequency dependent ROMs)

• For Power Transformer applications (50-60Hz, kW-MW power), the eddy current and electrostatic solvers are used primarily. Cores use laminated steel.

• For Electronic Transformer applications (kHz, mW-W power), where analysis over a wide frequency range is needed (DC-MHz), the Eddy Current solver is used primarily. The transient solver can also be used for non-sinusoidal excitation to study losses. Cores use solid ferrites with linear permeability.

• Fast and accurate solution, easy-to-use with automatic adaptive meshing and high performance computing (HPC)

Electronic Transformer

Power Transformer

Two Categories for Transformers

5 © 2017 ANSYS, Inc. May 1, 2017

• For Power and Electronic transformers, ANSYS provides various electromagnetic, multi-physics and system solutions:

• Electromagnetic performance (losses, forces, impedances, …)

• Multi-physics capability (thermal, structural, acoustics)

• System Level models (ECE and frequency dependent ROMs)

• Fast and accurate solution, easy-to-use with automatic adaptive meshing and high performance computing (HPC)

Electronic Transformer Power Transformer

Transformer Design Methodology

6 © 2017 ANSYS, Inc. May 1, 2017

SimplorerSystem Analysis

Q3DRLCG Parasitics

ANSYS Mechanical

Thermal

Model order Reduction

Co-simulation

Field Solution

Model Generation

Icepak Thermal

with air flow

Maxwell 3D3D FEA

Overall Transformer Solution Flow

PExprtModel Creation

ETKElectronic

Transformer Kit

7 © 2017 ANSYS, Inc. May 1, 2017

• Solves 2-D and 3-D electromagnetic

field problems using FEA

• Five Solution Types: Electrostatic,

Magnetostatic, Eddy Current, Transient

Electric, Transient Magnetic

• Determines R,L,C, forces, torques,

losses, saturation, time-induced effects

• Simulation of: Power Magnetics,

Inductors, Transformers, Motors, Generators, Actuators, Bus bars

• Co-simulation with Simplorer, Simulink

• Direct link from PExprt, RMxprt

• Direct link to ANSYS Mechanical

Maxwell Introduction

8 © 2017 ANSYS, Inc. May 1, 2017

• Three Basic Simulation Types:- Circuits- Block Diagrams- State Machines

• Multi-domain simulator for electrical, magnetic, mechanical, fluid, and thermal systems

• Integrated analysis with EM tools (Maxwell, PExprt, Q3D, RMxprt, HFSS) and thermal tools (ANSYS CFD, ANSYS Icepack)

• Co-simulation with Maxwell and Simulink• Optimization and Statistical analysis • VHDL-AMS capability

SUM2_6

CONST

id_ref

G(s)

GS2

I

I_PART_id

GAIN

idLIMIT

yd

UL := 9

LL := -9

GAIN

P_PART_id

KP := 0.76

IMP = 0

IMP = 1IMP = 0

IMP = 1

IMP = 0 and RLine.I <= ILOW

IMP = 1 and RLine.I >= IUP

IMP = 0 and RLine.I >= IUP

IMP = 1 and RLine.I <= ILOW

SET: CS1:=-1SET: CS2:=-1SET: CS3:=-1SET: CS4:=-1

SET: CS1:=-1SET: CS2:=1SET: CS3:=-1SET: CS4:=-1

SET: CS1:=1SET: CS2:=-1SET: CS3:=-1SET: CS4:=-1

SET: CS1:=-1SET: CS2:=-1SET: CS3:=-1SET: CS4:=-1

Circuits

Block Diagrams

State Machines

12

R1 R2 R3 R450

1k 1k50

C1 C2

3.3u

3.3u

V0 := 5 V0 := 0

N0005

N0003N0004

N0002

Simplorer Introduction

9 © 2017 ANSYS, Inc. May 1, 2017

SIMPLORER

PExprt

Maxwell

• Magnetic Design and Optimization tool for Ferrite and Laminated Transformers and Inductors including: multi-winding transformers, coupled inductors, and flyback components

• Contains seven manufacturer libraries for common components:

• Cores, Bobbins, Wires

• Toroidal, Planar, Wire-wound

• Analytical or FEA based solution includes skin and proximity effects, gap effects, thermal effects

• Winding Losses, Core Losses, R,L,C Parameters and Temperature Rise

• Couples to Simplorer using frequency dependent netlist for device

PExprt Introduction

10 © 2017 ANSYS, Inc. May 1, 2017

• Coupled Thermal and Stress Analysis for electromagnetic devices including: • Static Thermal• Transient Thermal• CFD• Static Stress• Acoustical Analysis

• Steady-state and transient thermal-flow simulations considering all modes of heat transfer

• ANSYS CFD – includes ANSYS FLUENT and ANSYS CFX multi-purpose fluid flow solvers

• Icepak – specifically for electronics thermal management at component, board and system level

• Acoustical Solver

ANSYS Mechanical-Icepak Introduction

11 © 2017 ANSYS, Inc. May 1, 2017

• Q3D is a tool streamlined for quickly characterizing electrical parasitics

• Q3D includes two tools:

• Q3D Extractor: 3-D quasi-static lumped RLC parameter extractor. Linear permeability = 1.

• 2D Extractor: 2-D T-line RLGC parameter extractor. Linear permeability.

DC 1.5 GHz 15 GHz ???

Q3D

2D Extractor

HFSSX

10cm1

L

2mm5

W

Q3D Extractor - Introduction

12 © 2017 ANSYS, Inc. May 1, 2017

SimplorerSystem Analysis

ANSYS Mechanical

Thermal

Model order Reduction

Co-simulation

Field Solution

Model Generation

Icepak Thermal

with air flow

Maxwell 3D3D FEA

Electronics Transformer Solution Flow

PExprtModel Creation

1) PEmag/ETK → Maxwell 3D Eddy Current ROM → Simplorer

2) Maxwell ↔ ANSYS Mechanical

3) Maxwell ↔ Icepak

4) Maxwell 3D Transient with HPC/TDM

ETKElectronic

Transformer Kit

13 © 2017 ANSYS, Inc. May 1, 2017

PEmag → Maxwell 3D → Simplorer

• PExprt/PEmag to create Maxwell 3D Eddy Current model

• Maxwell to create ROM for Simplorer

14 © 2017 ANSYS, Inc. May 1, 2017

Electronic Transformer Kit → Maxwell 3D

• ETK script to create Maxwell 3D Eddy Current model

• Maxwell to create ROM for Simplorer

15 © 2017 ANSYS, Inc. May 1, 2017

Temperature Rise

Losses

Maxwell ↔ ANSYS Mechanical 2-way Thermal Coupling

• Maxwell 3D Eddy Current

• Mechanical Pro steady state thermal (without air flow)

16 © 2017 ANSYS, Inc. May 1, 2017

Maxwell ↔ Icepak 2-way Thermal Coupling

• Maxwell 3D Eddy Current

• Icepak with airflow

17 © 2017 ANSYS, Inc. May 1, 2017

Nonlinear Core

Primary Solid Windings

Secondary Solid Windings

Finite Elements: 900kDOFs’: 1.5MilTime Steps: 1,000Input Voltage Rising Time: 20ns

Input Voltage

Maxwell 3D Transient with HPC/TDM

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Maxwell 3D Transient with HPC/TDM

Induced Voltage

Power Loss

Currents375V

17.5W

15A

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0

2

4

6

8

10

12

14

16

18

20

64 128 256

Spe

ed

Up

Fac

or

Number of Cores

HPC Performance

Maxwell 3D Transient with TDM

No-TDM: 5 days simulation

11 h:20m

08h:40m

06h:30m

20 © 2017 ANSYS, Inc. May 1, 2017

Higher losses near core gap

Proximity Losses and temperature rise in foil windings

21 © 2017 ANSYS, Inc. May 1, 2017

• Frequency dependent netlist

including R,L, C

• Current density plot showing

skin and proximity effects

• Flux lines plot

AC Frequency Effects considered

22 © 2017 ANSYS, Inc. May 1, 2017

• Windings are connected

with a schematic

• All turns are individually

modeled

Core

gap

Bobbin

Insulation (green)

Complicated Multi-Winding Designs

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• Temperature rise using ANSYS Mechanical

alpha can be functional

Temperature dependent convection coefficient

Proximity Losses and temperature rise in foil windings

24 © 2017 ANSYS, Inc. May 1, 2017

0.00 25.00 50.00 75.00 100.00 125.00 150.00Amps [A]

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

Y1 [m

H]

3D Incremental and Apparent Inductance ANSOFT

Curve Info

Incremental InductanceSetup1 : LastAdaptive

Apparent InductanceImported

2D

3D

Incremental Inductance

• Incremental inductance for DC biased cores

• Using differential flux linkage and differential current (dλ/di)

25 © 2017 ANSYS, Inc. May 1, 2017

• Determines capacitance between all

defined voltage sources

• Winding-Winding or turn-turn

• Netlist can be exported for circuit

analysis

Winding Capacitance

26 © 2017 ANSYS, Inc. May 1, 2017

Core Loss Computation

• Steinmetz method used

• Coefficients derived from Loss vs B curves

• Reports Eddy, Hysteresis, Excess losses

27 © 2017 ANSYS, Inc. May 1, 2017

Temperature Dependent Conductivty

• As temp increases, conductivity decreases and loss density increases

Initial Loss Density at 22°C

Final Loss Density

Increased Loss Density at operating temp

28 © 2017 ANSYS, Inc. May 1, 2017

• Analyze 6-winding transformer

using FEA at different

frequencies

• Consider all geometry and field

effects (gap, skin, proximity)

Interconnected Multi-Winding Designs

29 © 2017 ANSYS, Inc. May 1, 2017

• Use PEmag or UDP to draw windings

• Determine leakage inductance, resistance, capacitance, and losses

ODID

TH

Toroidal Transformers and Inductors

30 © 2017 ANSYS, Inc. May 1, 2017

Questions?