The electrical machines technology is in enduring evolution even though their basic principles were invented more than two centuries ago. For any amount of power rate, all moving electromechanical devices need design, manufacturing, testing, condition monitoring, and control techniques. This way, industrial electronics is without any doubt a key partner of electrical machines in their real environments with applications of sensors, power converters, digital control circuits, and more. Electrical drives efficiently convert electrical power into mechanical power. The increased use of information technology and communication systems not only has created new markets for drives (eg: disc drives) but also enforces more electrical drives to be used in systems as actuators and mechatronic systems. Theory of Machines covers state of the art information on recent trends in the machine tool technologies are surveyed from the view points of high speed and high performance machine tools, combined multifunctional machine tools, ultra precision machine tools and advanced and intelligent control technologies. It illustrates the induced enormous energy saving potential, permitted by using high-efficiency motors. Additionally, the most important barriers to larger high-efficiency motors utilization are identified, and some incentives recommendations are given. Various types of electric machines, including three-phase and single-phase induction machines or doubly fed machines, are addressed. It also gives an insight into the problem of minimizing losses in electric machines and increasing the overall energy efficiency of electric drives.