ABSTRACT
This chapter presents the starting and speed control methods of line-start (constant stator frequency) cage and wound-rotor induction machines (IMs). It unfolds and compliments two main categories of close loop speed control: V/f control (with stabilising loops recently) and field-oriented control, illustrated by exemplary mechanical characteristics and block (structural) control diagrams, by self-explanatory numerical examples. Starting refers to speed, current, and torque variations in an induction motor when fed directly or indirectly from a rather constant voltage and frequency local power grid. The chapter introduces the main methods for speed control and their corresponding steady-state characteristics. For cage-rotor induction motors, all speed control methods have to act on the stator windings as only they are available. When the IMs are provided with a wound rotor, speed control is performed by adding a variable resistor to the rotor circuit and connecting a power converter to the rotor to introduce or extract power from the rotor.
