Modeling and Simulation for Power Electronics and Electrical Drives

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Modeling and Simulation for Power Electronics and
Electrical Drives
Haus der Technik, München, 2003

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

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Contents

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

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I - Introduction

• Identify the components
• Models
• Parameters

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Identify the components

• Different components require different models
• First identify these components

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Models

• What can we model
• Complexity of the model
• Availability of parameter

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Parameters

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

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II - Components

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

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III - Models

• Multilevel Modeling
• Circuit model
• Block Diagram
• Modeling language

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IV - Simulation

• What is simulation
• Mathematical methods
• Programs

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What is Simulation

• Simulation is a prediction of what might happen

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What can we simulate

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

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Methods and Programs

• Mathematical methods
• State Space
• DAE
• MNA
• Various programs
• Spice
• Matlab/Simulink
• Saber
• Caspoc

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Mathematical Methods

• ODE (State Space)
• Causal time varying systems
• MNA
• Circuit models
• DAE
• Equations
• Mathematics

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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)

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V - Special models

• Power Electronics
• Semiconductor models
• Heat sink
• Parasistics
• Analog / digital control
• Embedded control
• Electrical Machines
• Machine models
• Mechanical load

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Semiconductor models

• Mosfet / IGBT
• Gate charge
• Cgd non-linear behavior
• Temperature dependent On-resistance Rds
• Diode
• Reverse recovery

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Mosfet / IGBT Dynamics

• Non linear gate-drain capacitance Cgd

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Temperature dependence Mosfet

• At T125 Celcius, the drain-source resistance is
  doubled from Ron to 2Ron

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Spice diode model

• Reverse recovery is modeled by a non-linear
  capacitor

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Reverse recovery modeling

• Model based on measurement

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Reverse recovery

• Reverse recovery is dependent on IF and di/dt

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Heat sink models

• Parameters from data sheet
• Parameters from known structures
• Parameters from FEM analysis

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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

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Parameters from know structures

• Calculate Rth Cth from geometry

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Parameters from FEM analysis

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

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Parasitic inductance

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

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Analog / Digital control

• Analog control as
• Electric circuit using Opamp models
• Block diagram (more efficient)
• Digital control
• Logical components
• Modeling language (more efficient)

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Block diagram vs Circuit model

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

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Block diagram vs Circuit model

• Circuit model for the PI control
• No. of nodes 17 - 4
• Calculation effort (4/3) (13)3

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Using C/Pascal to create models

• Replace blocks by C/Pascal code
• Model complex control systems
• Use the debugger to debug these models

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Embedded Control

• Embedded Control models

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Machine models

• Connections
• Electrical properties
• Mechanical properties
• Model
• State Space equations
• Lumped circuit model
• Reduced Order Model from FEM analysis

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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

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VII - Example

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

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Example - Synchronous machine
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Example - PWM induction machine drive
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Example - Switched Reluctance machine

• Electric connections
• u,I
• Mechanical connect.
• T,angular speed

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Example - Variable structure system in Caspoc
and Simulink

• Caspoc
• Inverter
• Machine
• Load

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Example - Variable structure system in Caspoc
and Simulink

• Simulink
• VSS Control
• Comparison switched Caspoc model with averaged
  model in Simulink

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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

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Geometric design in Tesla
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FEM analysis in ANSYS
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Complete model and simulation in Caspoc
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Embedded C-code for the control
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Conclusions - SRM

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

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VIII - Conclusions

• A model is a reflection of the users imagination,
  how a design should work!
• Simulation is a prediction of what might happen!