Method of and apparatus for damping of stepper motor using non-active windings

摘要

In a disk drive system which uses as stepper motor, overshooting of the desired final position is reduced by short-circuiting the windings of the stepper motor which normally remain open-circuit or are switched off. This short-circuiting provides a current path for any EMF induced in the unused windings. This effect is achieved by connecting a pair of transistors in parallel with each other and with each respective winding. The transistors are connected in opposite polarity to provide a short-circuit regardless of the polarity of the EMF across the windings. The transistors are connected to a microprocessor which is programmed such that the windings are selectively short circuited and the short circuits are applied at a predetermined time with regard to the step so that 'damping' is optimized. The microprocessor may be programmed to switch the transistors on and off as desired giving flexible timing to suit different conditions. One or more stepper motor steps may be treated in this manner.