ABSTRACT
The final chapter of the book is allocated to induction machines and in particular to the widely used induction motors. A short description of induction generators which are useful for use with wind turbines is also included at the end of this chapter. The stator windings of induction machines are essentially the same as those of synchronous machines. However, their rotor windings are different. They are usually of the squirrel-cage type, and have no external connections. Therefore they have many advantages, which are well described in this chapter. However, the differences of the wound rotor type of induction motors are also indicated where necessary. Operational principles of the squirrel cage type of motors are discussed in detail, and equivalent circuit of complete induction motor per phase is obtained to derive the torque expression. Power relationships in induction motors along with numerical examples are included for a more comprehensive understanding of these motors. One of the most important features of the three-phase induction motors is their self-start feature. In Chapter 9, advantages of three-phase induction motors along with starting problems of single-phase induction motor are extensively covered. Various ways of starting single-phase induction motors are discussed in detail. Lastly, a brief description is included for induction generators.
