Three-Phase Induction Machines

Like other electrical machines, induction machines can be operated as either generators or motors. However, they are primarily used as induction motors. We will concentrate on motoring and later consider applications where induction generation is attractive.

Induction machines have traditionally been by far the most common type of motor used in industrial, commercial or residential settings. Depending on location (which affects other electrical energy uses, such as lighting, space heating) some estimates suggest that induction motors may consume up to 70% of all electrical energy generated. There are three underlying reasons why induction motors are the general purpose motor of choice:

• Induction motors are relatively cheap
• Induction motors are robust
• Induction motors will start when connected to an AC supply without the need for any power electronics or controls

Notwithstanding the above statements, the position of induction machines as the standard tool for systems requiring electic machinery is challenged by the use of permanent magnet synchronous machines operated with variable speed drives. The value of speed control to acheive overall system efficiencies or control requirements has changed the overall machines market in the past 2 decades.