Abstract: A driving control device of a motor includes a phase current control device for controlling a phase current which is fed to a phase coil of each phases of a motor in a predetermined control period of each phase coils so as to become a predetermined target current, respectively, a convergent control device for converging the phase current after the end of the control period of each phase coils and a driving signal generating device for generating a driving signal which controls the end timing of the phase current convergent control by the convergent control device so that the phase current convergent control is ended between a timing at which a reverse torque is generated by the phase current and the end timing of the control period for next phase coil.

Abstract: A driving control device of a motor includes a phase current control device for controlling a phase current which is fed to a phase coil of each phases of a motor in a predetermined control period of each phase coils so as to become a predetermined target current, respectively, a convergent control device for converging the phase current after the end of the control period of each phase coils and a driving signal generating device for generating a driving signal which controls the end timing of the phase current convergent control by the convergent control device so that the phase current convergent control is ended between a timing at which a reverse torque is generated by the phase current and the end timing of the control period for next phase coil.

Abstract: An overheating protection system for a switching module prevents thermal breakdown of switching devices for passing currents through a load, for example an electric motor, while making it possible for the switching module to provide as much required current to the load as possible. The system comprises a temperature detector for detecting the temperature of a switching module, a temperature estimator for calculating a temperature change rate of a switching device inside the switching module corresponding to a current passed through the load and calculating an estimated value of the internal temperature of the switching module on the basis of the calculated temperature change rate and the detected temperature and a current limiter for on the basis of the estimated value correcting a target current value of a current controller controlling a current passed by the switching device.

Abstract: A system which energizes an SR motor with a three phase sequential and time sharing energization. Coil of respective phase is energized in an interval from an energization ON angle to an energization OFF angle. The OFF angle is advanced in reverse proportion to a speed and a target torque of a rotor of the motor in a high speed range exceeding a threshold Rbase which is an upper limit of a speed range in which a high noises is generated by a tangential oscillation of the rotor. The OFF angle is advanced in proportion to the speed of the rotor and in reverse proportion to the target torque in a low speed range under the threshold Rbase. The advance prevents the generation of noises. The system includes a compensator which corrects an energization level for accommodating an actual acceleration to a target acceleration of the rotor.

Abstract: The period Tn needed to count a lowermost bit of a signal of which an absolute value of difference between a last real data .theta.(k) and a present real data .theta.(k+1) is assumed to be quantized in a data block period To is obtained. One digital quantity is successively accumulated on the present real data .theta.(k+1) every period Tn to obtain interpolation data C, D . . . . At the point t1 a final interpolation data G is adapted to be added or subtracted, the total of added or subtracted digital quantity exceeds the absolute value of difference. Accordingly, a final interpolation data G is held until a next real data .theta.(k+2) is output.

Abstract: The generation of oscillations and acoustic noises which result from a rapid change in the magnetic flux upon switching the energization is suppressed, while simultaneously preventing a reduction in the driving efficiency and preventing a resonance from occurring. The current waveform as the current rises or fails is switched in accordance with the rotational speed of the SR motor to minimize a change in the magnetic flux, thus suppressing a reduction in the driving torque. A time interval required for the current to rise or fall is chosen to be greater than one-half the period of the natural frequency of SR motor.

Abstract: Suppression of a peak noise level as may be caused by a resonance when an SR motor is driven is intended. An offset is intentionally provided between a position for a maximum drive efficiency where the energization is to be switched and a position where the energization is actually switched. Such offsets s1, s2, s3, . . . are generated in terms of random numbers, producing a fluctuation in the frequency of the oscillations which result. The fluctuation in the frequency is effective to prevent the occurrence of a resonance. In order to avoid a resulting reduction in the drive efficiency, the magnitude of such offsets are limited to lie within a permissible shift angle, which is in turn determined in terms of the prevailing torque and number of revolutions, by reference to a map.

Abstract: An ultrasonic motor is provided which generates oscillations in only two directions so as to more efficiently provide for the transmission of driving torque from the driving member to the driven rotor member. The motor includes a stator having a driving portion on a side surface of the stator and a vibrating member for generating radial and circumferential oscillations on the stator member. A rotor is urged against the driving portion of the stator and a further member is provided which continually urges the rotor against the stator so as to provide for the transmission of drive between the rotor and stator.

Abstract: An ultrasonic motor comprises an elastic member inserted between a piezoelectric vibrator and a rotor. The elastic member comprises a base portion and plurality of projecting portions. Each of the projecting portions tapers toward its free end and is preferably of trapezoidal shape. The ratio of height to maximum width for each projecting portion is at least 1.0. The elastic member has a natural frequency substantially corresponding to a drive frequency of the vibrator.