Induction motors, which hire fundamental rules of electromagnetism in order to produce rotational or translational mechanical movement when supplied by an input electric power, are energy conversion apparatus. These electromechanical devices are very well known for their smoothly run capability if a balanced input power supply, along with a symmetric motor structure, is used simultaneously. This is the reason why a balanced and symmetric three-phase motor supply system is usually preferred in industry due to its gentle and low noise. However, a higher number of phases, despite its rather higher topological complexity, are also possible. Notably, the underlying idea of the operation of this kind of motor is basically not related to different possible structures used in various applications. It quite depends on the nature of the induction phenomenon which couples the stator and rotor magnetic fields. Regardless of the stator geometry, there are generally two types of induction motors as the following: wound rotor, squirrel cage rotor. Generally speaking, the healthy motor behavior in the “line-start”supply mode is targeted. Therefore, readers could potentially follow up future details in terms of more complex operations such as inverter-fed applications. Otherwise, the advanced topics might be of a little bit vague if one does not have the proper background knowledge. All the motor-drive principles required for a better realization of motor behavior are investigated as well. As the starting point, the physical structure of the motor is first illustrated and analyzed in the following section.

Chapter Contents:

• 2.1 Introduction
• 2.2 Induction motor structure
• 2.3 Line-start induction motor: linear and single harmonic model of a healthy motor
• 2.3.1 Flux equation
• 2.3.2 Electromagnetic torque equation
• 2.4 Inverter-fed induction motors
• 2.4.1 Constant voltage per frequency strategy (CV/F)
• 2.4.2 Space vector modulation
• 2.4.3 Analysis of motor behavior in open-loop CV/F mode
• 2.4.4 Reference frame theory of induction motors
• 2.4.5 Field-oriented control of induction motors
• 2.4.6 Direct torque control of induction motors
• References

Inspec keywords: stators; rotors; motor drives; invertors; squirrel cage motors; machine theory

Other keywords: wound rotor; line-start induction motor theory; electromechanical devices; input electric power; motor-drive principles; topological complexity; rotor magnetic fields; balanced input power supply; energy conversion apparatus; translational mechanical movement; symmetric three-phase motor supply system; symmetric motor structure; stator magnetic fields; squirrel cage rotor; rotational mechanical movement; balanced three-phase motor supply system; line-start supply mode; electromagnetism; inverter-fed induction motor theory

Subjects: Asynchronous machines; Drives; DC-AC power convertors (invertors)