Book contents
- Frontmatter
- Contents
- Preface
- Chapter 1 Magnetic Circuits, Fields, and Forces
- Chapter 2 Introduction to Linear Electric Actuators and Generators
- CHAPTER 3 Linear Induction Actuators
- CHAPTER 4 Linear Permanent Magnet Synchronous Actuators
- CHAPTER 5 Linear Reluctance Synchronous Actuators
- CHAPTER 6 Linear Switched Reluctance Actuators
- CHAPTER 7 Linear Stepper Actuators
- CHAPTER 8 Linear Electric Generators
- Index
CHAPTER 3 - Linear Induction Actuators
Published online by Cambridge University Press: 19 September 2009
- Frontmatter
- Contents
- Preface
- Chapter 1 Magnetic Circuits, Fields, and Forces
- Chapter 2 Introduction to Linear Electric Actuators and Generators
- CHAPTER 3 Linear Induction Actuators
- CHAPTER 4 Linear Permanent Magnet Synchronous Actuators
- CHAPTER 5 Linear Reluctance Synchronous Actuators
- CHAPTER 6 Linear Switched Reluctance Actuators
- CHAPTER 7 Linear Stepper Actuators
- CHAPTER 8 Linear Electric Generators
- Index
Summary
Having given a general introduction to linear electric actuators in the preceding chapter, we now consider various types of LEAs in some detail. In this chapter, we begin with linear induction actuators (LIAs). These are essentially derived from rotary induction motors and resemble linear induction motors with restricted and controlled linear motion. Before we present an analysis of LIAs, it is worthwhile discussing some of the constraints under which these devices must operate.
PERFORMANCE SPECIFICATIONS
Linear induction actuators are used for short travel (between 2 and 3 m) and thus are characterized by rather small mechanical airgaps of about 1 mm. Also, the operating speed is generally less than 2 m/s. LIAs, as low-speed direct-drive systems, are characterized by the rated thrust Fxm for a given duty cycle and a peak (short-duration) thrust Fxp developed at standstill. LIAs are used only with variable-voltage variable-frequency static power converters or voltage-source inverters to obtain good energy conversion efficiencies and controlled thrust or positioning. The ac source—three-phase, in general—which supplies the static power converter is specified in terms of voltage and frequency: rated values and usual deviations. Few LIAs work continuously; short duty cycles are typical. In either case, the cooling system of the primary should also be specified as it determines the rated (design) current density in the LIA windings.
The performance of the control system of the LIA must also be specified.
- Type
- Chapter
- Information
- Linear Electric Actuators and Generators , pp. 45 - 90Publisher: Cambridge University PressPrint publication year: 1997