ABSTRACT
This chapter presents a brief fundamental to electrical special machines which have special applications. Stepper motors, brushless direct current (DC) motor, and switched reluctance motor are the examples of some special machines that are mostly used. The parameter step angle can determine the number of steps per revolution and the accuracy of the position. If the stepping rate is increased too quickly, the motor loses synchronism and stops. The chapter discusses some technical terms that are used for specifying the characteristics of a stepping motor. A permanent-magnet DC motor is similar to an ordinary DC shunt motor except that its field is provided by permanent magnets instead of a salient-pole wound-field structure. Low-inertia DC motors are so designed as to make their armature mass very low. This permits them to start, stop and change direction, and speed very quickly making them suitable for instrumentation applications. The chapter provides a short description of servomotors, synchro motors, and resolvers.
