Power supply system with adaptive blown fuse detection using negative sequence component
AssigneeLiebert Corporation
InventorsXian Chen, Brian P. Heber
Life of this patent
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Abstract
Existing measurements of an input component (such as voltage or current) in a three phase power supply system are decomposed into a negative sequence component. The negative sequence component, which is significantly higher when a rectifier fuse is blown, is compared to a threshold and a determination made that a rectifier fuse is blown when the negative component exceeds the threshold. In an aspect, an adaptive algorithm is used to make the detection work better in the range of the nominal frequency of the input voltage. In an aspect, the negative sequence is determined indirectly from the existing measurements.
Claims25
A three-phase power supply system, comprising:
- an AC/DC converter having a three phase power input coupled through three fuses to three legs of three phase AC power (Phase A, Phase B, Phase C), an output coupled to a DC bus, and a control input coupled to an output of a control module;
- the three phase input power having input components including current and voltage, the control module generating three arrays of data for one of the input components, one array for each of the three phases of the three phase input power including a Phase A sample data array for a Phase A component of the input component, a Phase B sample data array for a Phase B component of the input component, and a Phase C sample data array for a Phase C component of the input component;
- the control module generating a negative sequence of the input component for which it generated the data arrays by taking one third of the sum of point Ia, point Ib. and point Ic, where point Ia is a datum in the Phase A data array when the negative sequence is being determined, point Ib. is a datum point in the line cycle that is 240 degrees delayed from the point Ia, and point Ic is a datum point in the line cycle that is 120 degrees delayed from the point Ia, and the control module determining that an input fuse is blown if the value of the negative sequence of the input component exceeds a threshold.
In a three phase power supply system having an AC/DC converter, the AC/DC converter having a power input coupled through input fuses to three phase AC power and an output coupled to the DC bus, the three phase input power having input components including current and voltage, a method of determining if any of the input fuses are blown, comprising:
- generating with a control module of the uninterruptible power supply system three arrays of data for one of the input components for each of the three phases of the three phase input power including a Phase A data array, a Phase B data array and a Phase C data array and storing the three arrays of data in a memory;
- generating with the control module a negative sequence of the input component for which it generates the data arrays by determining the negative sequence at current sample time by taking one third of the sum of point Ia, point Ib and point Ic, where point, Iais a datum in the Phase A data array when the negative sequence is being determined, point Ib is a datum point in the line cycle that is 240 degrees delayed from the point Ia, and point Ic is a datum point in the line cycle that is 120 degrees delayed from the point Ia, and determining with the control module that at least one of the input fuses is blown if the value of the negative sequence exceeds a threshold.
Dependencies are inferred from the claim text.