Parallel LED String Fault Detection With Bidirectional Conduction
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Solution Overview
Problem
High power LED lighting systems face failure due to open circuits in LED strings, leading to overcurrent in remaining strings, which can damage the entire system, and existing fault detection methods incur efficiency losses and power supply difficulties.
Innovation Solution
A bidirectional conduction arrangement across parallel LED strings senses potential differences to generate a fault signal, triggering a control circuit to decrease output power, using optocouplers for low-cost, low-power loss protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If multiple LED strings are connected in parallel to reduce output voltage, then safety regulation is satisfied, but the risk of system failure increases when one LED fails open circuit
Solution Approach 1:
The patent applies preliminary action by implementing fault detection and protection mechanisms before LED failure occurs. A sensing circuit continuously monitors each LED string's current, and when an open circuit is detected, the control circuit immediately reduces or shuts off power to prevent overcurrent damage to other strings. This proactive approach ensures system reliability while maintaining the parallel configuration for safe voltage levels.
2Reliability
If fault detection methods using sensing resistors and comparators are implemented, then open circuit detection is achieved, but efficiency is affected and power supply difficulties arise
Solution Approach 1:
The patent applies self-service by using the LED string's own current flow as the sensing mechanism. The sensing circuit monitors the current through the LED string itself, utilizing the existing operational current rather than requiring separate power sources or complex detection systems. This approach maintains detection accuracy while minimizing additional power consumption and preserving system efficiency.
3Loss of energy
If bidirectional conduction arrangement is used to sense potential difference, then fault signal generation is achieved with minimal power loss, but device complexity increases
Solution Approach 1:
The patent applies the intermediary principle by introducing a bidirectional conduction arrangement (such as an optocoupler or transistor pair) that acts as a mediator between the LED strings and the control circuit. This intermediary component senses potential differences caused by LED failures and converts them into fault signals without requiring direct electrical connection between the high-power LED strings and the control circuit, thereby minimizing power loss while managing circuit complexity through modular design.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Provides effective fault protection with minimal power loss, ensuring reliable operation of the LED lighting circuit by preventing overcurrent and overheating, scalable to multiple LED strings with a single monitoring circuit.
Implementation Method 1
a bidirectional conduction arrangement connected between the first tap and the second tap and adapted to be triggered to be conductive when a voltage potential difference between the first tap and the second tap exceeds a threshold
Implementation Method 2
using optocouplers for low-cost, low-power loss protection
Data Source
AI summary
A LED lighting circuit comprising: an LED arrangement comprising a first LED string (D1, . . . D72) with a first tap (20) between two LEDs in the first LED string (D1, . . . D72) and a second LED string (D73, . . . D144) with a second tap (22) between two LEDs in the second string (D73, . . . D144), the first and second LED strings connected in parallel,: a power supply arrangement (23) adapted to receive an input power and to provide an output power to the LED arrangement; a bidirectional conduction arrangement (24) connected between the first tap (20) and the second tap (22), said bidirectional conduction arrangement (24) is adapted to be triggered to be conductive when a voltage potential difference between the first tap (20) and the second tap (22) exceeds a threshold, wherein a current conducted by the bidirectional conduction arrangement (24) is adapted to generate a fault signal at a first detection output (240); and a control circuit (27) connected to the first detection output (240) and adapted to control the power supply arrangement (23) to decrease the output power when receiving said fault signal.