LED Luminaire Circuit Segmentation for Overload Protection
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Solution Overview
Problem
In LED luminaires, the failure of an LED string can lead to overloading of remaining strings due to uneven current distribution, posing safety risks such as overheating and electrical shock, especially when constant-current drivers are used.
Innovation Solution
A circuit arrangement with switching elements connected in series to the anode and cathode terminal lines, which isolate and disconnect line sections if the current through an LED string falls below a predetermined value, preventing overloading of other strings upon failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If constant-current drivers are used to supply current to parallel LED strings, then the LEDs can operate with stable current, but if one LED string fails, the total current is redistributed to remaining strings causing overloading and safety hazards
Solution Approach 1:
The patent divides the common anode terminal line into multiple isolated line sections by inserting switching elements at different connection points of LED strings. When an LED string fails, only the specific line section associated with that string is disconnected, while other line sections remain active. This segmentation prevents the redistribution of total current to remaining strings, eliminating overloading risks while maintaining stable operation of functional LEDs.
2Illumination intensity
If LED strings are connected in parallel to increase total light output, then the luminaire can provide sufficient illumination, but upon failure of one string, the current distribution becomes uneven leading to potential safety issues
Solution Approach 1:
The patent introduces switching elements as intermediary components between the anode terminal line and individual LED strings. These switching elements act as mediators that can selectively disconnect specific line sections when LED strings fail. This intermediary mechanism allows the system to maintain parallel connection architecture for sufficient light output while adding a safety layer that prevents harmful current redistribution upon failure.
3Object-affected harmful factors
If dedicated current limiting mechanisms are added to each LED string to prevent overloading, then safety can be improved, but the device complexity and cost increase significantly
Solution Approach 1:
The patent makes the anode terminal line itself multi-functional by dividing it into multiple line sections that can be independently controlled. Each line section serves both as a current path for normal operation and as a controllable disconnect point for safety protection. This universal design eliminates the need for separate dedicated current limiting mechanisms in each LED string, reducing device complexity while maintaining overloading protection.
Data Source
AI summary
A circuit arrangement for an LED luminaire comprises a plurality of LED strings, an anode terminal line, a cathode terminal line, a plurality of first switching elements, connected in series into the anode terminal line and subdivided into individual line sections, and a plurality of second switching elements, connected in series into the cathode terminal line and subdivided into individual line sections. Each of the LED strings may be connected to the anode terminal line via a first switching element and/or the second switching elements. Each of the first switching elements may be configured to feed an operating current to an LED string, to electrically connect line sections if the current flowing through the LED string exceeds a predetermined value, and to electrically isolate line sections if the current flowing through the LED string falls below a predetermined value.