It is well known that the step motor can be controlled precisely without using the feedback controller. There are, however, some limitations such as the relatively low operating speed, the small output torque at high speed, and the possibilities of resonance at a certain speed. Therefore, large output torque at high speed, one of the most important design purposes, is desired in the design of the step motor controller.
In this thesis, a method of obtaining the reasonably large and constant torque at high speed is given in order to improve the performances of the open-loop controlled step motor system using the power MOSFET chopper driver, thus resulting in high efficiency compared to the conventional current limiting technique using the resistor. Overall system is controlled using the MC 68000 microprocessor, and the simulated and experimental results are given to show the usefulness of the presented control method.
