Electric Machines and Drives

1

Physics of Electric Machines

1.1 Introduction

Electric machines are devices used for energy conversion, mostly between mechanical and electrical forms. An electric motor is a machine that converts the electrical energy given to it as input to mechanical energy output; a generator does the reverse by producing electrical energy from mechanical energy input. Study of electric machines, therefore, requires knowledge and understanding of the principles of energy conversion.

Electric machines come in a wide variety of forms and sizes and are used in markedly different ways and applications. Consider, on the one hand, a small electric motor that rotates and precisely positions a compact disk in a CD drive and, on the other hand, a massive ...