Estimation of Stray Capacitance and Permittivity between Compressor Motor Windings and Stator in Operation

Abstract

This paper proposes a method to estimate the stray capacitance between compressor motor windings and stator in operation, and the permittivity of refrigerant and lubricant oil mixture in this area. By applying this method, the complex experiment equipments and sensors are unnecessary. The estimation about the stray capacitance between the motor windings and stator in operation becomes possible according to the equivalent circuit of the inverter air conditioner by analyzing the high frequency leakage current of ground line. Further, the permittivity of refrigerant and lubricant oil mixture can be calculated by comparing the stray capacitance of equivalent circuit in operation with the stray capacitance of the compressor without refrigerant and lubricant oil. It is meaningful to discuss and solve the problem of EMI (electromagnetic interference) noise.