| 摘要 |
PURPOSE:To reduce an inflow current for a three-phase induction motor and to suppress a current in a power line to a current limit value or lower by a method wherein, when the current limit value is exceeded, a slip frequency for the three-phase induction motor is lowered. CONSTITUTION:Currents in power lines 2a to 2c are detected by a current detector, they are read by a control part A 12, and a detected current value IS is output from the current detector. The detected current value IS is compared with a current-limit set value IL in a current comparison part 32. When IS>IL, a slip frequency fs is lowered, a frequency command for a motor inverter 8 is generated, and the motor inverter 8 is driven by the frequency. Thereby, since an inflow current for a three-phase induction motor can be suppressed to be low, the currents for the power lines can be suppressed to a limit value or lower. |
