Most non-oriented (NO) electrical steel is used in rotating machine cores. Depending on the core design, the steel may be magnetised from d.c. to several hundred Hz over a wide range of flux densities. This book chapter introduces the fundamental principles of motors and generators, particularly focusing on the role of soft magnetic material. The general design and performance characteristics of common families of rotating machines are briefly reviewed. Examples of localised flux and loss distributions are given in order to appreciate the complex magnetisation patterns to which core materials can be subjected.

Chapter Contents:

• 6.1 Basic principles of motors and generators
• 6.2 The d.c. rotating machine
• 6.2.1 Commutator action
• 6.2.2 The magnetic field of a d.c. machine
• 6.3 Practical layout of the d.c. machine
• 6.4 D.C. generators
• 6.5 D.C. motors
• 6.6 Efficiency and building factor of a d.c. machine
• 6.7 A.C. machines
• 6.7.1 The induction motor
• 6.7.1.1 Principle of operation
• 6.7.1.2 Efficiency and building factor of the induction motor
• 6.7.2 The synchronous machine
• 6.7.2.1 The synchronous generator
• 6.7.2.2 The synchronous motor
• 6.7.2.3 Application of GO steel in stator cores of a.c. machines
• 6.8 Soft magnetic materials used in small rotating machines
• 6.9 Categorisation of small motors
• 6.9.1 Stepper motor
• 6.9.2 Universal motor
• 6.9.3 Hysteresis motor
• 6.9.4 Brushless d.c. motor
• 6.9.5 Reluctance motor
• 6.9.6 Switched reluctance motor
• 6.9.7 Shaded pole motor
• 6.9.8 Linear motor
• 6.10 SMC powder cores
• 6.11 Flux and loss distributions in rotating machine cores
• 6.12 Flux density and losses in motors under PWM voltage excitation
• 6.13 Use of electrical machines in variable speed drives
• 6.14 Generators in wind power systems
• 6.15 Laminated cores in rotating machines
• 6.15.1 Traditional lamination route
• 6.15.2 Slinky-laminated cores
• 6.16 Rotating electrical machines in automotive applications
• 6.17 Machine testing
• 6.17.1 No-load test
• 6.17.2 Locked-rotor test
• 6.17.3 Temperature rise
• References

Inspec keywords: iron alloys; machine theory; ferromagnetic materials; soft magnetic materials; electric motors; magnetic cores; electric generators; magnetisation; magnetic leakage; silicon alloys

Other keywords: soft magnetic material; nonoriented electrical steel; flux densities; rotating machine cores; motors; FeSi; complex magnetisation patterns; electrical steel; generators; core design; rotating electrical machines; localised flux; loss distributions

Subjects: d.c. machines; Ferromagnetic materials; Magnetic cores; a.c. machines