LED Lamp Safety Module for EM Ballast Overheating Protection
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Solution Overview
Problem
Mains compatible LED tubes are not fully safe on electromagnetic (EM) ballasts, as a failed diode in the input rectifier can cause direct current to flow through the EM ballast, risking overheating if the lamp input fuse does not blow.
Innovation Solution
Incorporating a safety module with two protection modules in the LED lamp: a first module to interrupt current when the driver fails, and a second module to interrupt current when a diode in the input rectifier fails, with the second module having a lower rated current to ensure safe operation on EM ballasts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single fuse is used for mains compatible LED tubes, then the device complexity is reduced, but the reliability on EM ballasts deteriorates due to inability to protect against DC current from failed diodes
Solution Approach 1:
The protection system is segmented into two distinct modules: a first protection module (fuse F1) for mains failure protection and a second protection module (fuse F2) for EM ballast protection. This segmentation allows each module to be optimized for its specific function, with the second module having a lower rated current (200-500 mA) to detect diode failures that would cause DC current flow through the EM ballast.
Solution Approach 2:
The second protection module acts as an intermediary between the input rectifier and the EM ballast, detecting failed diodes before they can cause harmful DC current to flow through the ballast. This intermediary protection layer prevents the harmful effect from reaching the EM ballast.
2Reliability
If the rated current of the second protection module is set too low, then the protection sensitivity against diode failure improves, but the ease of operation deteriorates due to premature fuse blowing under normal conditions
Solution Approach 1:
The rated current of the second protection module is precisely parameterized to be between 200-500 mA, which is lower than the first module's rated current but carefully selected to distinguish between normal operating conditions and diode failure conditions. This parameter optimization enables the system to be sensitive to harmful DC current while tolerating normal AC operation.
Solution Approach 2:
The second protection module is designed with locally optimized characteristics - a lower rated current specifically tailored for EM ballast protection - while the first module maintains a higher rated current for general mains protection. This local quality differentiation allows each module to perform its specific function effectively.
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
The safety module effectively prevents overheating of the EM ballast by ensuring current interruption in fault conditions, ensuring safe operation of LED lamps on various ballasts while maintaining reliability on mains voltage.
Implementation Method 1
at least one input rectifier with a plurality of diodes for converting an AC current from mains into a DC current
Implementation Method 2
electromagnetic (EM) ballasts
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
The current invention relates to a LED lamp (10) comprising at least one LED light source (103), at least one driver (101) for powering the LED light source (103), at least one input rectifier with a plurality of diodes for converting an AC current from mains into a DC current, providing electrical power to the driver (101), the LED lamp (10) further comprising a safety module comprising one first and one second modules (F1, F2) for protection against overcurrent and overheating of the EM ballast, the first module (F1) being put in series with the driver (101) and designed to interrupt current in case the driver fails when the LED lamp (10) is directly connected to the mains, and the second module (F2) being designed to interrupt current when at least one of the diodes of the input rectifier fails when the lamp is connected to the mains via an EM ballast.