Abb Inc.

Alpo Vallinmaki

Douglas W Karraker

Dennis Tyczkowski

A voltage measuring device includes an input configured to be coupled to a secondary of an inductive coupling of a DC to DC voltage converter. A switch coupled to the input forms a discharge path parallel to a sampling capacitor dependent on the voltage at the input equaling or exceeding a first voltage threshold and independent of an output voltage at the output of the device. The sampling capacitor is coupled to the output. A rectifier in series with the sampling capacitor is biased to conduct upon the input voltage, minus the output voltage, equaling or exceeding a second voltage.

DC bus voltage measurement circuit

A system for use in ac to ac or dc to ac power conversion equipment to detect faults in an inverter when the inverter is in a high impedance mode. The system detects ground faults or cross wiring conditions by converting the inverter outputs to digital signals and evaluating the frequencies of the resulting signals. The system keeps the inverter in the high impedance mode until after it has been determined that neither of the described abnormal statuses exist. The system tests for both of the abnormal statuses on power up and thereafter tests only for a ground fault whenever the inverter switches are disabled.

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Mukwonago, WI, United States of America

Alpo Vallinmaki