Simulation of Electrical Machines, drives and Control using software tools

1
Simulation of Electrical Machines, drives and
Control using software tools

• Dr. B. Umamaheswari
• Professor
• Dept of Electrical Electronics Engineering,
• College of Engineering Guindy
• Anna University Chennai
• Programs linked in the enclosed slides can be
  run in MATLAB-SIMULINK platform

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The Teaching and Learning Process

• An Effective Teaching-Learning Process may
  require the following 5-step sequence
• OPTRA
• O Organising
• P Preparation
• T Transmission
• R Reception
• A Assimilation
• Let us present this lecture in these 5-steps

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Organizing

• The theory of electrical machines is best
  explained with analytical models and
  equivalent circuits. Hence with the help of
  software tools these concepts can be best
  explained.
• Let us start with the following questions
• Why do we need tools like MATLAB?
• How, where and when do we these tools?
• To what level do we use these tools?

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Use of software tools like MATLAB SIMULINK

• Best used when the theory requires support of
  analytical expressions i.e. in the form of
  mathematical equations
• The equations could be
• static or dynamic
• Linear or non-linear
• Descriptive or symbolic
• Deterministic or stochastic

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Benefits of using software tools

• To have better understanding of the operating
  principles
• To visualise the characteristics under various
  operating conditions
• To experiment on favourable and non-favourable
  conditions
• To design and test the machines for achieving
  improved performance
• To create a working platform for pre-determining
  the characteristics

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Level of Usage

• Digital simulation for complete functional
  testing -MATLAB/SIMULINK
• Hardware in Loop (HIL) simulation for real time
  testing of the controller RTW and DAQ
• Power Hardware in Loop Simulation (PHIL) for real
  time testing of the Power Electronics and
  Controller - RTW and DAQ
• Embedding the control algorithm on a real time
  embedded target platform RT Target link module

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Suitability of the tool for Electrical Drives and
Control

• Fields involved
• Electrical Machines
• Power Electronics
• Control Theory and
• embedded platforms
• Study involves understanding of analytical
  expressions .
• Simulation of experimental conditions and
  research developments is possible.

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Topics for Presentation

• Let us discuss the following topics using
  software tools
• Electro-Magnetics
• Electro-mechanics
• DC Machines
• AC Machines

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1. Electro-Magnetics

• Under Electro-magnetics the following topics
  are to be discussed.
• Magnetic circuit the linear relationship
• Electrical Equivalent
• Inductance
• Rotating magnetic field
• Use software tools for teaching and research

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Magnetic circuit

• The Ampheres Law
• A current carrying coil produces magnetic field
  whose intensity is decided by the permeability of
  the medium through which the flux passes through.
• BH-curve describes the permeability of a medium
• For linear assumption Permeability is constant

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Electrical equivalent

• For the purpose of analysis, an equivalent
  electrical circuit can be drawn.
• Flux gt current
• MMF gt emf
• Reluctance gt Resistance

• Linear BH- relationship Program1
• Non-linear BH relationship
• program2

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Linear case

• Linear BH- relationship
• Air gap reluctance is Rg
• Core Reluctance is Rl ltlt Rg
• Using voltage division rule, the greater
  Reluctance part gets the greater MMF sahre
• Hence upon the supplied MMF Ni most of the
  MMF is dropped or available across the air-gap
• Program1 describes the flux variation (equation
  1) as a function of airgap length.
• Program1

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Non-Linear case

• Non-linear BH relationship
• Core reluctance is a function of flux
• Use equation (3) to get Hl for various values of
  Bg.
• Superimpose the obtained Hl vs Bg characteristics
  on the BH curve to get Hl and Bg of the given
  circuit.
• Use Program2 to see the results.
• program2

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Inductance

• Self Inductance of a coil describes how much of
  the flux links the coil produced by its own
  current
• Mutual inductance of a coil describes how much of
  the flux links the coil produced by current in
  the other coils.
• Inductance in a salient pole machine is simulated
  using the following program
• MATLAB Program

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Generation of Sinusoidal MMF

• With two sets of coils of carrying currents in
  the opposite directions Square -MMF waveshape
  can be produced.
• Using appropriate Fourier relationship the
  square wave can be resolved into fundamental and
  its harmonic components .

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Rotating magnetic field

• Rotating magnetic field can be produced by Two,
  Three or more phases equally placed along the
  periphery of a circular path
• Rotating MMF of Two phase and Two pole machine
  is illustrated in the following program

• MATLAB Program

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Electro-mechanics

• A coil (Armature) placed in the airgap subjected
  to time-varying magnetic field experiences an
  induced voltage Faradays Law
• It circulates current to oppose its cause (Lenz
  aw)
• Interaction of magnetic flux with armature
  current produces mechanical force
• Direction of force is given by Flemings Left
  Hand Rule.
• This is the principle of motoring

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Principle of Motoring Generation
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Simulation of DC Machine characteristics

• Equivalent circuit of DC machine with separate
  excitation is illustrated in the figure
• Using software simulation the characteristics can
  be studied

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MATLAB CODING

• DC MOTOR
• EQUIVALENT CIRCUIT

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Separately excited

• Torque speed characteristics
• Matlab model
• Matlab code

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Other EXCITATION SCHEMES
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Load Profiles
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Series excited

• Torque speed characteristics
• Matlab model
• Matlab code

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Simulation DC-Chopper performance

• Program_Chopper

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Chopper fed DC Drive

• MATLAB program

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Closed loop PI Control of Chopper fed DC motor

• Matlab model

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Induction Machine

• Steady state Equivalent circuit

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Three Phase Induction machine

• Circle diagram can be obtained using the
  following program to predetermine the steady stae
  characteristics
• Circle diagram

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3? INDUCTION MOTOR

• Torque speed characteristics can be obtained
  using the following program
• MATLAB CODE
• MATLAB MODEL

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SINGLE PHASE IM

• Closed Loop Speed control
• V/F control

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References

• Electric Drives by Ion Boldea and S.A. Nasar
• Electrical Machines by Nagrath and Kothari
• Electrical Machines by Fitzerald and Kingsley
• Power Electronics by B. K. Bose
• Control Systems Engineering by I. J. Nagrath and
  M. Gopal

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Thank You

• B. Umamaheswari
• Professor
• Department of Electrical and Electronics
  Engineering
• Anna University Chennai
• umamahesb_at_annauniv.edu
• This lecture material serves as s a supplement
  for learning electrical machines , drives and
  control for an advanced learner