# Electromagnetics for electrical machines PDF

The contents of this book are based on the syllabi of MTech courses on electrical machines in some of the Indian universities and technical institutes. It is basically designed to serve for a one-semester course at the postgraduate level for electrical engineering students. Its contents are mainly confined to the linear theory of electromagnetics. Since this book lays more emphasis on concepts than on developing problem-solving skills, no numerical methods (viz. an iterative solution using relaxation techniques, finite difference methods, finite-element methods, the method of moment, etc.) are included. The first few introductory chapters of this book may also be used by students of physics, electronics and communication engineering, as well as those research scholars who are concerned with the problems involving electromagnetics. The contents of this book are divided into the following nine chapters.

Chapter 1 is an introductory chapter that highlights the essence of field theory and its correlation with the electrical machines.

Chapter 2 includes a review of Maxwell’s equations and scalar and vector potentials. It briefly describes the special cases leading to the Laplace, Poisson’s, eddy current and wave equations.

## Electromagnetics for electrical machines.

Chapter 3 includes the uniqueness theorems, generalized Poynting theorem and a brief treatment of the Helmholtz theorem. It also deals with the approximation theorems developed to enhance the acceptability of approximate solutions of the field equations obtained under certain specified boundary conditions.

Chapter 4 is devoted to the solution of Laplace equation encountered in the design of electrical machines. It also introduces the Schwarz–Christoffel transformation and its applications and includes the determination of airgap permeance.

Chapter 5 outlines the solutions for eddy current equations. The skin effects in circular conductors, eddy currents in solid and laminated iron cores are also discussed.

Chapter 6 is devoted to the analyses of electromagnetic fields in laminated rotor induction machines. Field theory for anisotropic media and its application in laminated-rotor induction machines is briefly presented. The effects of skewed rotor slots in laminated-rotor induction machines are discussed.

Chapter 7 presents three-dimensional field analyses for three-phase solid rotor induction machines. It also describes the end effects in solid rotor induction machines. Field analysis for harmonic fields, in solid rotor induction machines due to tooth ripples, is also discussed.

Chapter 8 includes the examples relating to the slot leakage inductance of rotating electrical machines, transformer leakage inductance and theory of hysteresis machines. It presents the modelling of fields for a potentially new type of single-phase induction motor with composite poles. It also includes the electromagnetic transients in solid-conducting plates. An extension of this treatment may lead to the study of electromagnetic transients in electrical machines. Chapter 9 briefly describes the common techniques employed in numerical analysis. It also classifies all the cases described in Chapters 4 through 8 in accordance with the equations involved therein. This chapter also indicates the methods through which these equations can be solved to yield the desired results.