Okuma Corporation

Yuji Uchida

Takeshi Sakai

Tomohiro Shibata

Hisashi Kondou

Ai Kojima

A motor control device includes an abnormality determination unit that determines the presence of any abnormality in a current detector. The abnormality determination unit includes, for example, a U-phase abnormality determination device. The U-phase abnormality determination device calculates, as a voltage command threshold, a value obtained by adding a dead time voltage error, which is a voltage error occurring due to a dead time, to an ideal voltage command threshold, which is a value obtained by multiplying a prescribed reference current value by a motor resistance value, and outputs a signal indicating an abnormality in the current detector when the effective value of a voltage command value is equal to or greater than the voltage command threshold and the effective value of a current detection value is equal to or less than a current detection threshold that is lower than the reference current value.

Motor control device and abnormality detection method for current detector provided in motor control device

A numerical control apparatus of a machine tool that performs tapping, includes a numerical control, an acceleration learning block, an acceleration/deceleration processing unit that applies an acceleration/deceleration process to the command acceleration and the position command value to calculate a post-acceleration/deceleration position command value, a position control unit that calculates a speed command value based on the post-acceleration/deceleration position command value, a speed/torque control unit that calculates a motor torque command value from the speed command value, and a current control unit that calculates a motor current value of a spindle motor from the motor torque command value. The acceleration learning block outputs, as the command acceleration A, an initial command acceleration A[0] which is smaller than the calculated command acceleration, in accordance with a state quantity of the spindle motor, to the acceleration/deceleration processing unit.

Numerical control apparatus

A position control apparatus includes an inversion detector which detects an inversion of a position command and generates an inversion detection signal, a deflection characteristic storage unit which stores a deflection characteristic representing an amount of deflection with respect to a torque command, and an inversion correction calculator which calculates an inversion correction amount. The inversion correction calculator stores a torque command immediately before the inversion, and calculates the inversion correction amount from a difference between an amount of deflection immediately before inversion in which the stored torque command is checked with the deflection characteristic, and an amount of deflection after the inversion in which a value obtained by inverting a sign of the stored torque command is checked with the deflection characteristic. A value obtained by adding the inversion correction amount to the position command value is used for position error calculation.

Growing community of inventors

Niwa-gun Aichi, Japan

Yuji Uchida