Method and apparatus for detecting isolation faults in motor/inverter systems

摘要

A method for detecting an isolation fault in a system comprising a source connected an inverter through a circuit interrupter, the inverter connected to windings of an electric motor for driving the electric motor, is presented. The method comprising operating the inverter (1) to yield a zero net current in the windings of the electric motor other than leakage current resulting from an isolation fault or (2) to apply a voltage to at least one of the windings of the electric motor for a period of time given an ohmic level of an isolation fault to be detected; and measuring a voltage in the system, wherein a voltage level measured during this operation of the inverter is indicative of the existence of an isolation fault. Thereafter, the circuit interrupter is actuated in response to the voltage level indicative of the existence of the isolation fault.