Tamagawa Seiki Kabushiki Kaisha

Takaji Yasui

A method for driving a servo-motor detects a power voltage of a servo-motor determine a detected value. Through numeric calculation, the detected value is used to control a voltage command to a power converter, where the power converter supplies the proper currents to the servo-motor. The method does not require the use of a feedback loop, and thus, requires fewer components than the traditional method that also requires the use of a current sensor and an A/D converter.

Servo-motor driving method

A conventional method for driving a servo-motor is carried out by means of a current feedback loop, using a current sensor and an A/D converter. In this conventional set-up, the number of parts was great, cost reduction was difficult and it was difficult to avoid control errors caused by errors in the precision of the current sensor. A method for driving a servo-motor of the present invention comprises freely setting the current control response of a servo-motor (4) by changing the time-constant .tau. using a calculation system Ra+Las, which is opposite with respect to the calculation system of the servo-motor (4), and a primary delay element 1/1+.tau.s.

A conventional method for driving a servo-motor carried out control by means of a current feedback loop, using a current sensor and an A/D converter; therefore, the number of parts was great, cost reduction was difficult and it was difficult to avoid control errors caused by errors in the precision of the current sensor. A method for driving a servo-motor of the present invention comprises detecting a power voltage (V) of a servo-motor (4), controlling a voltage command (Vcmd) to a power converter (3) by numeric calculation using a detected value (Vcc) of this power voltage (V), and controlling power of a drive current (Iu, Iv, Iw).

Growing community of inventors

Nagano, Japan

Takaji Yasui