Self Excited unduction generator

The stepper motors are simple in concept and construction, and used III a widevariety of applications in industry.But their operation is somewhat complicated and requires sophisticated control andmotor drive electronics to achieve useful and desired operating characteristics. Sothere are two approaches to avoid negative torque (regenerative effect) production,and improvement the performance of the motor. This thesis introduces the firstpossibility is angle control.To obtain the maximum performance from stepper motor, an appropriate switchingON and OFF angle control must be applied. Otherwise, its high torque cannot bemaintained over a wide speed range. The angle control includes, the advancedswitching ON angle with varying the conduction period of each phase to the supply,the early switching OFF angle with varying the conduction period of each phase tothe supply, variation of both advanced switching ON angle and the early switchingOFF angle together with maintain constant conduction period of each phase to thesupply; and finally variation of the advanced switching ON angle with fixing theearly switching OFF angle.While the other possibility, designing the rotor poles wider than the stator poles. Thisresults in a region of constant inductance separating the positive and negative dUd (Jregions, which in turn provides additional time for the phase current to be turned offbefore the region of negative torque production is reached.