This chapter deals with a wide range of electromagnetic devices used for conversion of electrical energy to mechanical energy, or simply a process of transforming electrical energy to a useful form. The electric machine systems for energy processing are:

  • Generators, connected to prime movers (steam-, gas-, or hydro-turbine systems), convert mechanical energy to electrical energy for production of electrical power.
  • Transformers process (transform) electric energy from the most convenient generation voltage to a voltage level suitable for transmission to a load point and into voltage appropriate for distribution.
  • Electric motors are used to convert electrical energy to mechanical energy for drive systems and further energy processing.
  • Electronic converters process electric power from AC to DC or DC to AC with controllable voltage, current, or frequency.
  • Drive-system controls of motors and converters are capable of controlling the speed or position of mechanical loads.


The conversion of power or energy from one machine to another is achieved using magnetic fields that depend on a variety of materials, structures, locations, and intensities. To understand how the magnetic field works or changes as a function of time, we employ Maxwell's equations, and its application to different machine types.

Maxwell's equations may be expressed in differential and integral forms, summarized in the following ...

Get Energy Processing and Smart Grid now with O’Reilly online learning.

O’Reilly members experience live online training, plus books, videos, and digital content from 200+ publishers.