Method and apparatus for fault detection of series diodes in rectifiers
AssigneesANDRITZ HYDRO GmbH, Accumetrics Associates, Inc.
InventorsJohn Mark Reschovsky, Staci Jane Elaan, Walter Reisinger
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Abstract
A method and apparatus for fault detection of series diodes in rectifiers is disclosed, wherein the voltages across one or both of the individual diodes, and/or the voltage across the pair of diodes are measured to determine a ratio between two of those voltages. The ratio is then analyzed to determine if a fault (e.g., a short circuit or an open circuit) is present. In some embodiments, circuitry can be included to compensate for the normal variations in diode characteristics (e.g., reverse leakage current, reverse recovery charge) between the pair of series diodes to minimize the potential for erroneous fault detection.
Claims30
A method for fault detection of a first diode and a second diode connected in series in a rectifier of an AC signal, the method comprising the steps of:
- measuring a first voltage across the first diode;
- measuring a second voltage across the first diode and the second diode;
- determining the voltage ratio between the first voltage and the second voltage;
- and
- determining whether the voltage ratio is within a range of values,
- wherein a fault is detected in the first diode or the second diode if the voltage ratio is outside of the range of values.
A method for fault detection of a first diode and a second diode connected in series in a rectifier of an AC signal, the method comprising the steps of:
- measuring a first voltage across the first diode;
- measuring a second voltage across the second diode;
- determining the voltage ratio between the first voltage and the second voltage;
- and
- determining whether the voltage ratio is within a range of values,
- wherein a fault is detected in the first diode or the second diode if the voltage ratio is outside of the range of values.
An apparatus for fault detection of a first diode and a second diode connected in series in a rectifier of an AC signal, the apparatus comprising:
- a first resistor connected in parallel across the first diode, wherein the parallel connection of the first resistor and the first diode results in a first voltage across the first diode during the reverse polarity cycle of the AC signal;
- and
- a second resistor connected in parallel across the second diode, wherein the parallel connection of the second resistor and the second diode results in a second voltage across the second diode during the reverse polarity cycle of the AC signal;
- wherein the ratio of the first voltage to the sum of the first voltage and the second voltage is within a range of values, and the ratio of the second voltage to the sum of the first voltage and the second voltage is within the range of values.
Dependencies are inferred from the claim text.