| 摘要 |
PURPOSE:To provide an inverter unit producing output for performing variable speed control of a motor in which operation can be sustained without requiring special setting such as stall level through such control as the accelerating time is prolonged as increasing rate of motor current increases. CONSTITUTION:A control section 4 comprises a PWM circuit 5, a drive circuit 6, a current detecting means 7, an effective value operating means 8, an accelerating/decelerating means 9, a frequency setter 10, a comparing means 11, and a frequency index switching means 12. The control section 4 further comprises an increase rate detecting means 13 for converting current values detected through the current detecting means 7 and the effective value operating means 8 into an increase rate K, and a multiplier 14 for obtaining the product of the current increase rate K and a current accelerating time Tacc (now). A limiter 15 for limiting the product above a set acceterating time, and means 16 for switching the accelerating time input of the accelerating/decelerating means 9 to the multiplier 14 side at the time of acceleration otherwise to the set accelerating time Tacc are also provided. |
