Primary-Side LED Converter Feedback for Dynamic Shutdown Thresholds
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Solution Overview
Problem
Primary side switched converters for LED loads face challenges in accurately determining output voltage due to fluctuations, leading to conservative shutdown thresholds, which limit the supply voltage below the recommended 60 volts to prevent exceeding the maximum safe level.
Innovation Solution
A method and converter design that detect feedback signals from the secondary side, calculate a dynamic threshold voltage based on a reference voltage and an adjustment factor that increases with LED current, allowing for efficient compensation of voltage deviations, enabling a higher output voltage without exceeding the 60-volt limit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the shutdown threshold is set below the 60-volt safety limit (e.g., at 50 volts) to account for voltage fluctuations and tolerances, then safety is improved, but the converter cannot provide supply voltage near the optimal 60-volt threshold, reducing efficiency
Solution Approach 1:
The patent changes the parameter of the shutdown threshold from a fixed conservative value to a dynamic value that adapts based on detected voltage deviations. By continuously monitoring actual output voltage and adjusting the threshold accordingly, the system maintains safety while operating closer to the optimal 60-volt limit, thus resolving the contradiction between safety and efficiency
Solution Approach 2:
The patent implements a feedback mechanism where the converter detects the actual output voltage and uses this information to adjust the shutdown threshold. This closed-loop feedback allows the system to compensate for voltage fluctuations and tolerances dynamically, enabling safer operation at higher voltages closer to the 60-volt limit while maintaining reliability
2Use of energy by moving object
If the converter operates near the 60-volt threshold to maximize efficiency, then energy efficiency is improved, but the risk of exceeding the safety threshold due to voltage fluctuations increases
Solution Approach 1:
The patent applies dynamics by making the shutdown threshold adaptive rather than static. The threshold dynamically adjusts based on real-time voltage measurements and detected deviations, allowing the converter to safely operate near the 60-volt limit while automatically responding to fluctuations, thus resolving the contradiction between efficiency and safety
3Reliability
If a fixed conservative shutdown threshold is used to account for voltage tolerances, then safety margin is improved, but voltage determination precision is effectively reduced due to the inability to compensate for current-dependent deviations
Solution Approach 1:
The patent changes the shutdown threshold parameter from fixed to variable, allowing it to adapt to different operating conditions and current-dependent voltage deviations. This dynamic adjustment maintains safety margins while improving voltage determination precision by compensating for actual deviations rather than using a conservative fixed threshold
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 approach effectively compensates for current-dependent deviations, allowing for a higher output voltage, such as 54 volts, while ensuring it remains below the 60-volt safety threshold, thereby improving the efficiency and reliability of the voltage supply to LED loads.
Implementation Method 1
an auxiliary winding on the primary side of the galvanic isolation stage which is magnetically coupled to at least one secondary side winding
Data Source
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, andinterrupting (107) the voltage supply to the LED load (401) if the determined LED supply voltage exceeds the threshold value.