| 摘要 |
PURPOSE:To prevent fine frequency and rotational speed variations due to detected room temperature variations and to increase the durability and life of a compressor and its motor by dividing the range of variation in the difference between the room temperature and the preset value into a plurality of zones with respect to the case of upward gradient of the room temperature and downward gradient thereof, and setting the output frequency corresponding to these zones to control the rotational speed of the compressor. CONSTITUTION:Zones are computed based on an output from temperature detection means 21 and data of temperature difference memory means 22, that is, the previous temperature difference detected values, separately for the upward gradient value and the downward gradient value of the room temperature that is, for the rise and fall of the temperature difference and stored in zone memory means 24. Output frequency calculating means 25 computes output frequencies (f) corresponding to zones based on the output of zone computing means 23 and data of zone memory means 24. Frequency instruction means 28 receiving signal of output frequency calculating means 25 outputs an instruction adapted to a frequency converter 3. Thus, the output of the frequency converter and the rotational speed of a compressor does not frequently vary and hence a smooth operation becomes possible.
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