LED Driver Circuit Power Regulation via Transformer Feedback
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Solution Overview
Problem
LED light intensity is not maintained constant due to variations in forward voltage over time or between LEDs, caused by aging and temperature changes, leading to inconsistent light output when using conventional dimming systems.
Innovation Solution
A circuit and method that monitors input voltage to adjust current flow through a transformer's primary side, ensuring a constant power delivery to LEDs irrespective of their forward voltage or current, using a PWM signal to control the switch QSW and maintain predetermined power levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional constant current driving is used, then LED forward voltage variations are compensated, but light intensity becomes inconsistent due to aging and temperature changes
Solution Approach 1:
The patent implements a feedback mechanism where the LED forward voltage is continuously monitored and fed back to the control circuit. The control circuit adjusts the driving current dynamically based on the feedback signal, compensating for voltage variations caused by aging and temperature changes to maintain consistent light intensity output.
Solution Approach 2:
The patent changes the driving parameter from constant current to constant power delivery. By controlling the power delivered to the LED rather than maintaining a fixed current, the system adapts to forward voltage changes and maintains optimal LED performance and light intensity consistency over time and temperature variations.
2Measurement precision
If forward current is maintained constant, then light intensity should be predictable, but actual light output varies due to forward voltage changes
Solution Approach 1:
The control circuit uses feedback from the LED forward voltage measurement to dynamically adjust the driving current. This ensures that the light output remains predictable and consistent by continuously compensating for voltage changes through real-time current adjustment based on actual LED conditions.
3Ease of operation
If dimming control is implemented, then light intensity can be adjusted, but forward voltage variations cause inconsistent dimming performance
Solution Approach 1:
The dimming control system incorporates feedback from LED forward voltage measurements to adjust the dimming operation. This ensures consistent dimming performance across different LED units and over time, as the system adapts to voltage variations while maintaining the desired light intensity reduction level.
Solution Approach 2:
The patent changes the dimming control approach by regulating power delivery rather than using fixed current reduction. This allows for more accurate and consistent dimming control that adapts to LED forward voltage changes, maintaining uniform dimming performance across different operating conditions.
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 maintains consistent LED light intensity by regulating power delivery, regardless of changes in forward voltage or current, and adapts to fluctuations in line voltage, ensuring predictable light output.
Implementation Method 1
Circuits and methods for driving an LED from a secondary side of a transformer are disclosed herein
Data Source
AI summary
Circuits and methods for driving an LED from a secondary side of a transformer are disclosed herein. An embodiment of the method includes monitoring an input voltage to determine the power level intended to drive the LED. The current flow through the primary side of the transformer is adjusted to make the power actually driving the LED equal to the power intended to drive the LED.