To uniformalize abrasion of a bearing due to difference of the loads of each compressor, by reading the operating current of each compressor with a sensor, and by inputting a longer load-up signal output width into a compressor with the low operating current to eliminate the difference of operating current when the difference between any two current values exceeds a fixed value.
During the operation and control of a refrigerator having a plurality of compressors, the difference between a current i1 of a No.1 compressor and a current i2 of a No.2 compressor becomes larger with the operation time since starting of the operation, and the operation is continued in this condition. When the current difference exceeds a fixed value, the load-up cycle T of the No.2 compressor whose operating current is low is not changed, and the load-up output widths t1, t2 of the No.1 and No.2 compressors are changed to meet the following equation: t2=t1×{1;(i1-i2)/i2}. Thus, the difference between the operating current of the No.2 compressor and that of the No.1 compressor is eliminated, and both of operating currents i1, i2 are equalized each other.
AOYAMA MITSUGI
KANEKO MASARU
YABE KAZUYOSHI
HITACHI SHIMIZU ENG KK
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