Abstract: As a method for energizing a three-phase stepping motor of Y-connection, driving current values are set to be values resembling sine wave input approximation, thus making it possible to effect driving at small vibration. Energizing of the three-phase stepping motor is performed by a two-three phase driving scheme which calls for alternately effecting a two-phase excitation of the coils in the motor and a three-phase excitation of the coils in the motor. The driving current flowing through each of the coils approximates a sine wave having normalized values defined by .+-. 1, .+-. 0.87, .+-. 0.5 and 0.

Abstract: According to this invention, there is provided a drive circuit for a multi-phase brushless DC motor comprising a rotational position detector for detecting a rotational position of a rotor of the motor, a commutation control device for selecting a drive coil to be conducted from the plurality of drive coils, a drive output circuit for supplying a drive current to the drive coil selected by the commutation control devices, a DC servo control loop for detecting a motor speed on the basis of a counter electromotive voltage by rotating the motor and by supplying the drive current from the drive output circuit to the motor, and generating a comparison output in accordance with a difference between the motor speed detection output level and the reference voltage to output the comparison output to the drive output circuit through the commutation control device, and a control device for detecting whether the drive current of the drive output circuit is a predetermined value or more and for weakening a control force o

Abstract: A motor control device carries cut feedback control of a motor such that the rotational speed of the motor is equal to the command speed. A control voltage is first calculated as the sum of a first constant times the difference between the command speed and the actual rotational speed, a second constant times the actual rotational speed and a predetermined offset value. The calculated control voltage is corrected on the basis of the phase difference between the command speed and the actual rotational speed and a voltage after the correction is outputted as a motor control voltage. The rotational speed of the motor can be caused to rapidly follow the target speed by adjusting the first and second constants and the offset value whether the command speed is relatively low or high, thereby to make it possible to control the motor at a constant speed.

Abstract: A shunt element and a voltage detection circuit are connected in parallel across the armature of a universal series motor. At relatively light loads on the motor, the armature speed increases, thereby increasing the back e.m.f. of the armature. The voltage detection circuit causes the shunt element to conduct, and a shunt current flows through the field of the motor, thereby increasing the field and limiting the speed of the motor. Various embodiments are disclosed.

Abstract: An apparatus for detecting an over-velocity error condition of a head actuator driven by a voice coil motor in a hard disk drive system includes an integrator for providing an integrated value of the current flowing through the voice coil motor and a detector for detecting when the integrated value exceeds a threshold value. In response to this detection, the supply of current through the voice coil motor is interrupted. To prevent false detections, the integrator is inhibited until the motor current reaches a level indicative of a track access operation.

Abstract: There is disclosed a direct current motor drive system comprising a direct current motor operable in a forward motoring mode receiving current from a power source and in a reverse inversion mode providing inversion current to the power source. The drive system includes a converter for controlling motor operation. The converter converts alternating current, received from the power source, to direct current. The converter supplies direct current across terminals of the motor when operating in the forward motoring mode. The system includes an inversion fault current limiter for limiting inversion fault currents associated with motor operation in the reverse inversion mode without effecting the supply of current to the motor in the forward motoring mode. The inversion fault current limiter is electrically connected in series between the converter and one armature terminal of the motor. The inversion fault limiter includes a diode switch connected in parallel with a resistor.