| 摘要 |
PURPOSE:To eliminate the insufficient output voltage and the insufficient torque due to the variation in the input voltage by switching a voltage/frequency ratio in response to the AC power source voltage. CONSTITUTION:After the frequency of a motor 5 is set in a frequency setter 6, a voltage/frequency setter 10 decides the voltage to be outputted of a power inverter 4 and the frequency, but before this operation, the output of a voltage detector 9 discriminated whether the voltage of a capacitor 3 is higher or lower than the prescribed value is inputted, and if the output is H in case that the capacitor voltage is higher than the prescribed level, the voltage/frequency ratio of the operation this time is selected to the ratio such as I in the graph. On the contrary, if the capacitor voltage is less than the prescribed level and the output of the voltage detector 9 is L, the ratio of II of the graph is selected. Thus, the insufficient output voltage and insufficient torque in the variation of the input voltage can be eliminated. |
