Modeling and Simulation for Power Electronics and Electrical Drives dr. ir. P.J. van Duijsen Simulation Research Haus der Technik, München, 2003

Modeling and Simulation for Power Electronics and

Electrical Drives

dr. ir. P.J. van Duijsen Simulation Research

Haus der Technik, München, 2003

9.12.2003 (c) 2003 Simulation Research 2

Contents

• I - Introduction• II - Components• III - Models• IV - Simulation• V - Special models• VI - Tools• VII - Examples• VIII - Conclusions


I - Introduction

• Identify the components• Models• Parameters


Identify the components

• Different components require different models• First identify these components


Models

• What can we model– Complexity of the model

– Availability of parameter


Parameters

• What is a model– Reflection of the users imagination, how a design

should work


II - Components

• Power Electronics• Electrical machine• Mechanical load• Main• Control

PowerElectronics

MechanicalLoadMain

Control

ElectricalMachine


III - Models

• Multilevel Modeling– Circuit model

– Block Diagram

– Modeling language


IV - Simulation

• What is simulation• Mathematical methods• Programs


What is Simulation

• Simulation is a prediction of what might happen


What can we simulate

• Large simulations take a lot of time• Large simulations increase complexity and clarity


Methods and Programs

• Mathematical methods– State Space

– DAE

– MNA

• Various programs– Spice

– Matlab/Simulink

– Saber

– Caspoc


Mathematical Methods

• ODE (State Space)– Causal time varying

systems

• MNA– Circuit models

• DAE– Equations

• Mathematics


Various programs

• Spice– Electronics (General)

• Matlab/Simulink– Systems described by a Block Diagram (General)

• Saber– Systems described by equations (General)

• Caspoc– Systems and Circuits (PE & ED)


V - Special models

• Power Electronics– Semiconductor models

– Heat sink

– Parasistics

– Analog / digital control

– Embedded control

• Electrical Machines– Machine models

– Mechanical load


Semiconductor models

• Mosfet / IGBT– Gate charge

– Cgd non-linear behavior

– Temperature dependent On-resistance Rds

• Diode– Reverse recovery

Detailed Behavioral/Circuit Model

Component stress isequal in each period

Ideal Model

Circuit design

Ideal Model

Control Design Circuitlayout

Detailed Behavioral/Circuit Model

Single periodcomponent stressanalysis

Number of simulated periods

Mod

el C

ompl

exity

Behavioral Model

Predict losses andtransient behavior

Simulation takesto much time andproduces to muchdata


Mosfet / IGBT Dynamics

• Non linear gate-drain capacitance Cgd


Temperature dependence Mosfet

• At T=125 Celcius, the drain-source resistance is doubled from Ron

to 2*Ron


Spice diode model

• Reverse recovery is modeled by a non-linear capacitor


Reverse recovery modeling

• Model based on measurement


Reverse recovery

• Reverse recovery is dependent on IF and di/dt


Heat sink models

• Parameters from data sheet

• Parameters from known structures

• Parameters from FEM analysis


Parameters from a data sheet

• Thermal resistance and thermal capacitance are from the manufacturers data sheet

• Zth is modeled using parallel RC models• Calculate losses in the mosfet and diode• Calculate temperature and feed back into the

semiconductors


Parameters from know structures

• Calculate Rth & Cth from geometry


Parameters from FEM analysis

• Calculate Zth in FEM analysis and use it in the simulation


Parasitic inductance

• Model parasitic inductance for simulating high turn-off voltages Vds


Analog / Digital control

• Analog control as– Electric circuit using Opamp models

– Block diagram (more efficient)

• Digital control– Logical components

– Modeling language (more efficient)


Block diagram vs Circuit model

• Block diagram model for a PI control• 4 blocks• Calculation effort ~ 4


Block diagram vs Circuit model

• Circuit model for the PI control

• No. of nodes = 17 - 4• Calculation effort ~

(4/3) * (13)^3


Using C/Pascal to create models

• Replace blocks by C/Pascal code

• Model complex control systems

• Use the debugger to debug these models


Embedded Control

• Embedded Control models


Machine models

• Connections– Electrical properties

– Mechanical properties

• Model– State Space equations

– Lumped circuit model

– Reduced Order Model from FEM analysis


VI - Tools

• Integrated Modeling and Simulation– Modeling Electrical machines

• Connection to FEM tools

– Modeling Power Electronics• Connection to Packaging analyzers

– Modeling Control• Creating Embedded C code

– Control design• Small signal modeling

• Connection to design tools


VII - Example

• Synchronous generator• PWM induction machine drive• Switched Reluctance Machine• Variable structure system in Caspoc and

Simulink


Example - Synchronous machine


Example - PWM induction machine drive


Example - Switched Reluctance machine

• Electric connections:– u,I

• Mechanical connect.:– T,angular speed


Example - Variable structure system in Caspoc and Simulink

• Caspoc:– Inverter

– Machine

– Load


Example - Variable structure system in Caspoc and Simulink

• Simulink:– VSS Control

• Comparison switched Caspoc model with averaged model in Simulink


Example Switched Reluctance Machine (SRM)

• Design of the SRM in Tesla

• FEM analysis of the SRM in ANSYS

• Reduced order model from ANSYS in Caspoc

• Design of the power electronics and control in Caspoc

• Export of the control algorithm to Embedded C-code for the microprocessor


Geometric design in Tesla


FEM analysis in ANSYS


Complete model and simulation in Caspoc


Embedded C-code for the control


Conclusions - SRM

• Export of C code from Block diagram• Including the exported code in the simulation• Debugging during simulation


VIII - Conclusions

• A model is a reflection of the users imagination, how a design should work!

• Simulation is a prediction of what might happen!

Documents

Modeling and Simulation for Power Electronics and Electrical Drives dr. ir. P.J. van Duijsen Simulation Research Haus der Technik, München, 2003