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

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 Dr. B. Umamaheswari, Anna University

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? Dr. B. Umamaheswari, Anna University

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 Dr. B. Umamaheswari, Anna University

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 Dr. B. Umamaheswari, Anna University

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 Dr. B. Umamaheswari, Anna University

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. Dr. B. Umamaheswari, Anna University

Topics for Presentation Let us discuss the following topics using software tools Electro-Magnetics Electro-mechanics DC Machines AC Machines Dr. B. Umamaheswari, Anna University

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 Dr. B. Umamaheswari, Anna University

Magnetic circuit The Amphere’s 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 Dr. B. Umamaheswari, Anna University

Electrical equivalent For the purpose of analysis, an equivalent electrical circuit can be drawn. Flux => current MMF => emf Reluctance => Resistance Linear BH- relationship Program1 Non-linear BH relationship program2 Dr. B. Umamaheswari, Anna University

Linear case Linear BH- relationship Air gap reluctance is Rg Core Reluctance is Rl << 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 Dr. B. Umamaheswari, Anna University

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 Dr. B. Umamaheswari, Anna University

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 Dr. B. Umamaheswari, Anna University

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 . Dr. B. Umamaheswari, Anna University

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 Dr. B. Umamaheswari, Anna University

Electro-mechanics A coil (Armature) placed in the airgap subjected to time-varying magnetic field experiences an induced voltage { Faraday’s 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 Fleming’s Left Hand Rule. This is the principle of motoring Dr. B. Umamaheswari, Anna University

Principle of Motoring & Generation Dr. B. Umamaheswari, Anna University

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 Dr. B. Umamaheswari, Anna University

MATLAB CODING DC MOTOR EQUIVALENT CIRCUIT Dr. B. Umamaheswari, Anna University

Separately excited Torque speed characteristics Matlab model Matlab code Dr. B. Umamaheswari, Anna University

Other EXCITATION SCHEMES Dr. B. Umamaheswari, Anna University

Load Profiles Dr. B. Umamaheswari, Anna University

Series excited Torque speed characteristics Matlab model Matlab code Dr. B. Umamaheswari, Anna University

Simulation DC-Chopper performance Program_Chopper Dr. B. Umamaheswari, Anna University

Chopper fed DC Drive MATLAB program Dr. B. Umamaheswari, Anna University

Closed loop PI Control of Chopper fed DC motor Matlab model Dr. B. Umamaheswari, Anna University

Induction Machine Steady state Equivalent circuit Dr. B. Umamaheswari, Anna University

Three Phase Induction machine Circle diagram can be obtained using the following program to predetermine the steady stae characteristics Circle diagram Dr. B. Umamaheswari, Anna University

3ф INDUCTION MOTOR Torque speed characteristics can be obtained using the following program MATLAB CODE MATLAB MODEL Dr. B. Umamaheswari, Anna University

SINGLE PHASE IM Closed Loop Speed control V/F control Dr. B. Umamaheswari, Anna University

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 Dr. B. Umamaheswari, Anna University

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