STUDY OF THE DETERMINATION OF PARASIT CAPACITANCE IN INDUCTION MOTORS FED FROM PWM INVERTER

• Main Author: Sutra, Auliya
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/87133
• Institution: Institut Teknologi Bandung

Failures in electric motors can cause highly detrimental impacts. These failures are exacerbated by the presence of parasitic capacitance in the motor. Parasitic capacitance arises due to capacitive coupling between metal components that act as electrical pathways at high frequencies. The implementation of a PWM inverter power supply enables frequency switching adjustments at the inverter output, and in this study, it is used to observe the influence of frequency on parasitic capacitance. The determination of parasitic capacitance in this thesis was conducted experimentally following these procedures: a) configuring the connection between the PWM inverter and the test motor, b) measuring voltage and current, including common-mode voltage, shaft voltage, leakage current, and shaft current, and c) calculating the parasitic capacitance values between the stator-frame, stator-rotor, and rotor-frame of the motor using capacitance characteristic equations. The findings revealed that switching frequency and motor speed influence the magnitude of parasitic capacitance. Within the switching frequency range of 4 kHz to 14 kHz, the highest parasitic capacitance was observed in the stator-frame connection, with the highest average capacitance value occurring at 4 kHz, measured at 349.88 pF. These results are consistent with previous studies. For future research, this study provides recommendations to serve as a reference in efforts to mitigate induction motor failures, particularly electrical failures. One potential area for further study is identifying optimal lamination materials for the stator-frame connection. This would aim to reduce the parasitic capacitance in the stator-frame relationship, which was found to have the highest capacitance value in this study.