Apparatus and method for controlling the operating frequency of compressor in air conditioning apparatus

DETAILED DESCRIPTION It is the object of the present invention to provide an apparatus and method for suppressing noise and vibrations of a compressor caused by the lower order harmonic frequency by controlling the operation frequency of the compressor.
In order to achieve the object, the line voltage of any two phases of three phase AC power is detected through a high pass filter.
The line voltage is amplified by an amplifier.
A microprocessor receives the amplified line voltage via an input terminal.
The microprocessor determines whether the line voltage is below the first set value, between the first set value or the second set value or above the second set value.
When the line voltage is below the first set value, the compressor operates in the previous operation state.
When the line voltage is between the first set value and the second set value, the compressor operates in an operation state 1 step lower than the previous speed.
When the line voltage is above the second set value, the compressor operates in the lowest operation state.
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