| 摘要 |
PURPOSE: To suppress increase in the input side voltage of an inverter during deceleration control smoothly by lowering the output frequency with a new deceleration gradient gentler than that prevailing immediately before the capacitor voltage jumps to overvoltage level immediately after resetting to a level lower than the normal level. CONSTITUTION: A deceleration gradient generator is actuated in response to the operation of stop switch or speed exchange switch for a motor 4 and generates a deceleration gradient of negative polarity without interrupting the driving of an inverter even in the occurrence of an overvoltage state during deceleration control. Consequently, the voltage of a capacitor C can be lowered before an overvoltage relay OVR or an overcurrent relay OCR is tripped thus realizing a smooth deceleration control. |
