INTRODUCTION TO ELECTRICAL MACHINES

Introduction:

This chapter considers the basic working principles of the so-called ‘classical’set of machines. This set of machines represents the asynchronous (induction),synchronous, DC machines, and variable reluctance machines. Thelatter will be discussed in the book ‘Advanced Electrical Drives’ currently underdevelopment by the authors of this book. Of these classical machines, theasynchronous machine is most widely used in a large range of applications.

Note that the term ‘machine’ is used here, which means that the unit is able tooperate as a motor (converting electrical power into mechanical power) or as agenerator (converting mechanical power into electrical power). The machinecan be fed via a power electronic converter or connected directly to an AC orDC supply.

Central to this chapter is the development of an ‘ideal rotating transformer’,which is in fact a logical extension of the two-phase ITF module discussed inchapter 6. We will then look to the conditions required for producing constanttorque in an electrical machine. This in turn will allow us to derive the principleof operation for the three classical machine types.