| 摘要 |
PROBLEM TO BE SOLVED: To improve the control performance of a motor by generating a voltage that is proportional to a current value from an inverter that is subjected to current control based on a current command value and amplifying and ADD- converting a voltage value with a variable amplification rate according to the current command value. SOLUTION: A three-phase current generated by an inverter 1 is supplied to an AC servo motor 3 for drive control. The U phase current is detected by a current detector 2 and is inputted to an operational amplifier 4, and a detection voltage is amplified and is outputted to an A/D converter 5 and is processed as current detection data. When a current command value is large, a switch 6 is tuned on by the output of a comparator 7 for short-circuiting a feedback resistor R3, and the amplification rate of the operational amplifier 4 is reduced by R2/R1, thus detecting a large current. When a current command value is small, the switch 6 is turned off by the output of the comparator 7 and the feedback resistor R3 is inserted and then the amplification rate of the operational amplifier 4 increases by (R2+R3)/R1. Therefore, by suppressing a current detection resolution, vibration can be suppressed when the motor stops. |
