| 摘要 |
It is possible to control the DC intermediate voltage to be constant without using a device for returning regenerative resistance or regenerative energy to a power source and to safely continue operation of an AC motor even if an instantaneous stop occurs. An AC motor control method includes: a step of detecting a stop of AC power supply by power supply stop detection means arranged in a power converter, a step of outputting a speed reduction start instruction to an inverter unit, a step of calculating a speed reduction rate 1 from a target value and a detection value of the DC intermediate voltage so that the DC intermediate voltage is to be constant during speed reduction of the AC motor, a step of calculating a speed reduction rate 2 from the change ratio of the DC intermediate voltage, a step of calculating a torque instruction so that speed reduction follows the speed reduction time, a step of changing the torque limit value of the motor side and the regenerative side according to the DC intermediate voltage detection value, a step of terminating the speed reduction when voltage returns to the voltage before the power supply stop detection or the DC intermediate voltage increases during speed reduction, and a step of storing the output frequency before the power supply stop detection when returning to the normal control. |
