Rotating Electrical Machines

Chapter 3

Synchronous Machines

3.1. Introduction

The industrial value of synchronous machines is considerable: first, used as generators (called “AC generators”), they provide almost all the production of electric energy.

In addition, associated with static converters (inverters or cycloconverters) functioning on variable frequencies, synchronous motors have become essential during recent decades in a number of industrial areas: rail traction, naval propulsion, manufacturing industry, iron and steel industry, oil exploitation, machine-tools, etc.

In this chapter, we shall mainly consider cylindrical machines, however we will address salient pole machines at the end of the chapter.

3.2. Introduction and equations of the cylindrical synchronous machine

3.2.1. General description

We shall consider a machine with cylindrical field spools, each one having 2p poles at the stator as well as at the rotor. In most cases the field system is at the rotor. It is supplied with DC current or provided with permanent magnets. The field current is usually injected in the rotor via slip rings and brushes. The armature (Figure 3.1), which usually is 3-phase, is at the stator and makes exchanges with a source (network or static converter) or with a voltage and current charge assumed to be sinusoidal a priori. Depending on the kind of power exchanged by the machine with its environment, we shall either talk about an AC generator or about a synchronous motor.

We shall usually assume the machines to ...