초록 ▼

Method and apparatus are disclosed wherein a circuit for detecting the phase angle of a motor is disclosed. This circuit utilizes zero crossing detectors to compare the voltage and current signals such that a digital signal indicating the value of the phase angle by the duration of the signal is gen

Method and apparatus are disclosed wherein a circuit for detecting the phase angle of a motor is disclosed. This circuit utilizes zero crossing detectors to compare the voltage and current signals such that a digital signal indicating the value of the phase angle by the duration of the signal is generated. Additionally, a method and apparatus for comparing the phase angle to the reference phase angle value is disclosed. Means for updating the reference value and for comparing the detected value to the reference value to determine appropriate defrost initiation time are additionally disclosed.

대표청구항 ▼

A method of determining when to initiate a defrost cycle to remove accumulated frost from a heat exchanger forming a portion of a refrigeration circuit including an electric motor driven compressor which comprises the steps of: determining a reference phase angle equal to the phase angle of the elec

A method of determining when to initiate a defrost cycle to remove accumulated frost from a heat exchanger forming a portion of a refrigeration circuit including an electric motor driven compressor which comprises the steps of: determining a reference phase angle equal to the phase angle of the electric motor driving the compressor when the heat exchanger is in a frost free condition; monitoring the operating phase angle of the electric motor; comparing the operating phase angle to the reference phase angle; and initiating a defrost cycle when the step of comparing determines the operating phase angle exceeds the reference phase angle by a predetermined value.