LED Lighting Device Line Regulation via Current Feedback
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Solution Overview
Problem
LED lighting devices directly driven by rectified AC voltage face challenges in line regulation due to fluctuations in brightness and increased power consumption, leading to inaccurate current levels and overheating.
Innovation Solution
The implementation of a current detecting circuit, a duty cycle detecting circuit, and a current regulating circuit that monitor and adjust the current flowing through a luminescent device to maintain consistent brightness by regulating the current based on feedback and control signals, ensuring it does not exceed a set value, thereby stabilizing the output across varying AC voltage conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the LED lighting device is directly driven by rectified AC voltage, then the device structure is simple, but the line regulation is poor and brightness fluctuates with voltage changes
Solution Approach 1:
The patent employs a current detecting circuit that continuously monitors the LED current and feeds back a voltage signal proportional to the current. This feedback mechanism enables the control circuit to detect current variations and adjust the driving current accordingly, thereby maintaining stable LED brightness despite fluctuations in rectified AC voltage input.
Solution Approach 2:
The patent introduces a current regulating circuit as an intermediary between the rectified AC voltage source and the LED luminescent device. This intermediary circuit includes a switching element and control circuitry that decouples the LED current from direct dependence on input voltage variations, providing stable current regulation while isolating the LED from voltage fluctuations.
2Power
If the rectified AC voltage increases, then the available power increases, but the LED current increases accordingly causing over heat and inaccurate current levels
Solution Approach 1:
The current detecting circuit provides continuous feedback on the actual LED current, enabling the control circuit to maintain the current within a precise target range regardless of input voltage increases. This prevents excessive current that would lead to overheating, while still allowing the device to utilize available power efficiently within safe operating limits.
Solution Approach 2:
The control circuit dynamically adjusts the duty cycle of the switching element based on the detected current level and input voltage conditions. By changing the temporal parameters of current delivery rather than allowing direct proportional increase with voltage, the system maintains accurate current levels and prevents overheating even when higher power is available from the voltage source.
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 solution effectively improves line regulation by maintaining consistent current levels and reducing power consumption, thereby stabilizing the LED lighting device's output and preventing overheating across fluctuating AC voltage conditions.
Implementation Method 1
The current detecting circuit is configured to monitor a first current and provide a feedback voltage associated with the first current
Implementation Method 2
A light emitting diode (LED) lighting device
Implementation Method 3
the second current flows through a luminescent device driven by a rectified AC voltage
Data Source
AI summary
An LED lighting device includes a luminescent device driven by a rectified AC voltage, a current detecting circuit, a current regulating circuit, and a duty cycle detecting circuit. The current regulating circuit is configured to provide a regulating current so that the current flowing through the luminescent device does not exceed the regulating current. The current detecting circuit is configured to monitor the value of the regulating current, and the duty cycle detecting circuit is configured to monitor the duty cycle of the regulating current. The present invention can improve the overall line regulation of the LED lighting device when the rectified AC voltage somehow fluctuates between its upper bound and lower bound.