Matsushita Electric Industrial Co., Ltd.

Matsushita Electrical Industrial Co., Ltd.

Nin Kake

Hisashi Kinoshita

Yoshihiro Ino

Masahiro Ohto

Hideki Yoshitake

An automatic offset adjusting apparatus for current detectors in a digital controller for a servo motor is constructed so that, when errors occur in offset correction values due to a temperature change and the like while the servo motor is in operation, an electrical angle detecting unit detects a ripple of the torque of the servo motor, on the basis of a ripple of a torque command value, and detects a first electrical angle, where the torque command value becomes maximum, and a second electrical angle, where the torque command value becomes minimum, based on an electrical angle signal of the servo motor, a judgement unit judges whether or not offset correction errors have occurred on the basis of a difference between the first and second electrical angles, and, if the judgement unit judges that the offset correction errors have occurred, a correction unit adds adjustment values for the offset correction values corresponding to the first electrical angle to the respective offset correction values to update the offset correction values, whereby the correction of the offset correction values is automatically carried out even while the servo motor is in operation, thereby preventing generation of the ripple of the torque of the servo motor.

Apparatus for automatically adjusting offset correction values for

In a DC motor control system, switching element driving circuits are connected to respective base circuits of four switching elements arranged to form a bridge circuit which has a DC motor connected thereto as an electric load thereon, and an output signal interlocking circuit is provided in each paired driving circuits associated with the corresponding paired switching elements which are connected in series across a DC power source, respectively, thereby preventing simultaneous conduction of each paired switching elements. By virtue of the provision of the output signal interlocking circuits, it is possible to realize a PWM control system for DC motors with a simplified circuit construction and yet to thereby prevent power source short-circuiting trouble with elevated safety and reliability.

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Ikoma, Japan

Nin Kake