Abstract: 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.

Abstract: 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.

Abstract: 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).