Primary-Side LED Converter Threshold Control Under Isolation Limits
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Solution Overview
Problem
Existing technologies fail to accurately control the output voltage of primary side switched converters, which are not efficient in providing a specific range within an industry, discipline, or technical classification (typically extracted from the technical field paragraph to capture the core field, appropriately generalized).
Innovation Solution
The solution involves a method for operating an isolated primary side switched converter, which includes a switching network with two or four switches, a current sensing unit, and a control unit to detect LED current and ambient temperature, adjusting the threshold voltage based on LED current and temperature deviations, ensuring efficient compensation and safe operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the output voltage threshold is set below 60V (e.g., at 50V) to ensure safety, then safety is improved, but the maximum output voltage capability deteriorates
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the threshold voltage based on LED current and temperature conditions. Instead of using a fixed threshold below 60V, the system calculates a compensated threshold voltage that varies with operating parameters, allowing the output voltage to approach 60V safely while maintaining safety margins under all operating conditions.
Solution Approach 2:
The patent implements feedback by continuously monitoring LED current and temperature, then using this information to adjust the threshold voltage setting. The control unit receives feedback about actual operating conditions and modifies the shutdown threshold accordingly, enabling the system to operate closer to 60V when conditions permit while maintaining safety.
2Reliability
If magnetic coupling sensing is used to detect output voltage, then galvanic isolation is maintained, but measurement precision deteriorates due to leakage flux and voltage drops
Solution Approach 1:
The patent uses an intermediary approach by introducing compensation parameters that account for the inaccuracies introduced by magnetic coupling sensing. Rather than directly using the imperfect sensed voltage, the system calculates a compensated threshold that incorporates correction factors for leakage flux and voltage drops, effectively mediating between the imperfect measurement and the required accurate control.
Solution Approach 2:
The patent applies parameter changes by modifying the threshold voltage calculation to include compensation for sensing inaccuracies. The threshold is adjusted based on LED current and temperature parameters that correlate with the magnitude of leakage flux and voltage drops, thereby compensating for measurement errors without breaking galvanic isolation.
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
This method allows for a higher output voltage without exceeding safety limits, providing a robust and efficient voltage supply to LED loads by compensating for current and temperature-dependent deviations, thereby ensuring safe operation and reducing voltage fluctuations.
Implementation Method 1
an auxiliary winding (L51c) on a primary side of a galvanic isolation stage which is magnetically coupled to at least one secondary side winding (L51a, L51b)
Data Source
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AI summary
The invention relates to a method (100) for operating an isolated primary side switched converter (300) for providing a voltage supply to an LED load (401), wherein the converter comprises a galvanic isolation stage (301), the method comprising the steps of: • detecting (101) a feedback signal at a primary side of the galvanic isolation stage (301), wherein the feedback signal corresponds to a secondary side voltage, • determining (103) an LED supply voltage based on the feedback signal, • calculating (105) a threshold value based on a constant reference voltage and an adjustment factor, wherein the adjustment factor is a dynamic factor whose absolute value increases with increasing LED current, and • interrupting (107) the voltage supply to the LED load (401) if the determined LED supply voltage exceeds the threshold value.