الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
The stepper motors are simple in concept and construction, and used III a wide
variety of applications in industry.
But their operation is somewhat complicated and requires sophisticated control and
motor drive electronics to achieve useful and desired operating characteristics. So
there are two approaches to avoid negative torque (regenerative effect) production,
and improvement the performance of the motor. This thesis introduces the first
possibility is angle control.
To obtain the maximum performance from stepper motor, an appropriate switching
ON and OFF angle control must be applied. Otherwise, its high torque cannot be
maintained over a wide speed range. The angle control includes, the advanced
switching 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 to
the supply, variation of both advanced switching ON angle and the early switching
OFF angle together with maintain constant conduction period of each phase to the
supply; and finally variation of the advanced switching ON angle with fixing the
early switching OFF angle.
While the other possibility, designing the rotor poles wider than the stator poles. This
results in a region of constant inductance separating the positive and negative dUd (J
regions, which in turn provides additional time for the phase current to be turned off
before the region of negative torque production is reached.