Power Line Current Determination for Inrush vs Short-Circuit Events
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Solution Overview
Problem
Existing DC power feeding systems face challenges in distinguishing between inrush currents and short-circuit currents, leading to increased costs and potential damage due to unnecessary disconnection of load devices.
Innovation Solution
A determination apparatus that includes a cutoff unit, measurement unit, and determination unit to intermittently connect and disconnect the power line, determining the type of current based on changes in current values during multiple operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an inrush current inhibition circuit is provided to inhibit inrush current, then inrush current is suppressed, but the number of components increases and cost becomes large
Solution Approach 1:
The patent extracts the inrush current inhibition function from a separate physical circuit component and integrates it into the control unit's software logic. The control unit determines whether detected overcurrent is an inrush current or short-circuit current based on timing characteristics, eliminating the need for additional inhibition circuits and reducing component count while maintaining reliability.
2Reliability
If an inrush current inhibition circuit is provided to inhibit inrush current, then inrush current is suppressed, but current flows continuously causing loss
Solution Approach 1:
The patent implements periodic action by using intermittent current interruption through timed control. The control unit interrupts current flow only when inrush current is detected, for a specific duration, rather than maintaining continuous current flow through an inhibition circuit. This periodic interruption suppresses inrush current while minimizing energy loss by keeping the circuit open only when necessary.
3Reliability
If circuit breaker operation is disabled for a certain period to prevent inrush current tripping, then inrush current does not cause disconnection, but short circuit cannot be immediately disconnected causing wire or device burnout
Solution Approach 1:
The patent implements feedback by continuously monitoring current characteristics and using this information to control circuit breaker operation. The control unit detects whether overcurrent is an inrush current or short-circuit current based on timing and magnitude feedback, then selectively disables circuit breaker operation only for inrush currents while maintaining immediate tripping capability for short circuits, preventing wire burnout while avoiding unnecessary disconnections.
Solution Approach 2:
The patent applies dynamics by making the circuit breaker's tripping characteristics variable rather than fixed. The control unit dynamically adjusts the circuit breaker's operation property based on real-time current detection, creating a delay curve that prevents tripping for inrush currents while ensuring immediate tripping for short circuits. This dynamic control resolves the contradiction between preventing unnecessary disconnection and ensuring safety.
4Reliability
If circuit breaker operation is disabled for a certain period, then inrush current does not cause disconnection, but determination of inrush current versus short circuit is required
Solution Approach 1:
The patent applies preliminary action by establishing predetermined determination criteria for distinguishing inrush currents from short-circuit currents before actual current events occur. The control unit is pre-programmed with timing thresholds and current magnitude criteria that automatically classify detected overcurrent events. This preliminary setup simplifies real-time detection by providing clear decision rules, reducing the difficulty of current type determination while enabling reliable prevention of unnecessary disconnections.
Data Source
AI summary
A determination apparatus includes: a cutoff unit configured to cut off and connect a power line connecting a DC power supply and a load device; a measurement unit configured to measure a current value flowing through the power line; and a determination unit configured to perform an operation of connecting and cutting off the power line a plurality of times using the cutoff unit and determine whether a predetermined event has occurred based on a change in the current value measured by the measurement unit in the plurality of times of operations.