Power Converter Fuse State Detection Using Voltage and Phase
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Solution Overview
Problem
Existing methods for determining whether a breaking device, such as a fuse, in a power conversion system is open or has melted are prone to erroneous determinations, especially when temporary voltage reductions occur, making it difficult to distinguish between fuse melting and normal voltage fluctuations.
Innovation Solution
A power conversion device equipped with first and second voltage sensors to detect voltages on both sides of the breaking device, and a determination unit that calculates voltage and phase differences to reliably determine if the breaking device is open or has melted by setting threshold values for voltage and phase differences, ensuring accurate detection through a combination of both criteria.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If voltage threshold comparison method is used to detect fuse melting, then detection simplicity is improved, but measurement precision deteriorates due to inability to distinguish fuse melting from temporary voltage reductions
Solution Approach 1:
The patent transitions from single-dimension voltage magnitude comparison to two-dimensional analysis by introducing phase angle detection alongside voltage magnitude. The determination unit now evaluates both the absolute voltage difference and the phase difference between primary and secondary sides, creating a multidimensional detection criterion that resolves the ambiguity of temporary voltage reductions versus actual fuse melting.
2Device complexity
If only voltage difference threshold is used for breaking device status determination, then device complexity is reduced, but reliability deteriorates due to erroneous determination during temporary voltage reductions
Solution Approach 1:
The patent segments the detection criterion into two independent components: voltage difference threshold and phase difference threshold. Instead of using a single composite threshold, the determination unit evaluates voltage difference and phase difference separately, requiring both conditions to be satisfied simultaneously for fuse melting detection. This segmentation prevents erroneous determination during temporary voltage reductions where only voltage difference changes but phase difference remains normal.
3Ease of manufacture
If simple voltage comparison method is used, then manufacturing cost is reduced, but measurement precision deteriorates due to inability to accurately detect breaking device operational state
Solution Approach 1:
The patent uses voltage sensors on both the primary side and secondary side of the fuse to create duplicate voltage measurements. By comparing the copied voltage signals from both sides, the system can detect abnormalities without requiring expensive specialized equipment. The determination unit analyzes the relationship between these copied voltage signals to accurately determine fuse operational state.
Data Source
AI summary
A power conversion device provided between a DC power supply and an AC electric path, including: a breaking device provided to at least one line of an output electric path in the power conversion device; a first voltage sensor provided on a primary side of the breaking device; a second voltage sensor provided on a secondary side of the breaking device; and a determination unit which calculates a primary-side voltage and a secondary-side voltage, and a primary-side phase and a secondary-side phase and determines that the breaking device is opened, by occurrence of an event in which an absolute value of a voltage difference between the primary-side voltage and the secondary-side voltage is greater than a voltage difference threshold value and an absolute value of a phase difference between the primary-side phase and the secondary-side phase is greater than a phase difference threshold value.