| 摘要 |
PURPOSE:To cause no breakdown of a compressor motor by reducing the change rate of an inverter output frequency, when the output frequency of an inverter is lower than a low pass reference value. CONSTITUTION:A change rate decreasing signal output means 11 outputs a change rate decreasing signal to an inverter control means 8, when a detected signal from an output frequency detection means 10 has a frequency lower than f Hz (e.g. 25Hz) and a rise and drop judging means 9 judges the signal to be a drop control. When this change rate decreasing signal is inputted to the inverter control means 8, the control means makes a frequency change rate at the time of performing the frequency control of an inverter 3 slower than that used therefore. Accordingly, the change rate of voltage changing in the manner corresponding to the frequency change becomes slower than the rate used therefore so that there is no possibility of occurrence of the breakdown of a compressor motor 4. |
