Linear LED Driver Reducing LED Count via Energy Storage
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Solution Overview
Problem
Current LED driver technologies require a high number of LEDs due to the need for the sum of Forward Voltage (VF) values to match the maximum output voltage of the rectifier bridge, leading to inefficiencies and reduced stability as input voltage changes, especially at high voltages.
Innovation Solution
A linear constant current LED drive device comprising a rectifier module, energy storage component, switch module, constant current supply module, measurement module, and control module, which controls the energy storage component to charge and discharge, allowing the rectifier module to supply power to the LEDs only when necessary, thereby reducing the number of LEDs required and maintaining high efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the sum of VF values of LEDs matches the maximum output voltage of the rectifier bridge, then the LED driver can operate at maximum voltage utilization, but the number of LEDs required increases significantly (about 80 LEDs for 220V application)
Solution Approach 1:
The patent divides the LED string into multiple parallel groups, where each group contains a reduced number of LEDs in series. By segmenting the overall LED configuration and using parallel connections, the circuit can operate at lower voltage per group while maintaining total current output, thereby reducing the number of LEDs needed compared to a single long series string.
Solution Approach 2:
The patent employs dynamic voltage detection and adaptive control to adjust the operating voltage based on actual input conditions. The driver dynamically selects appropriate LED groups to activate and adjusts their current distribution, allowing flexible operation across different input voltages without requiring a fixed high LED count designed for maximum voltage.
2Adaptability or versatility
If the input voltage varies (rises or lowers), then the capacitor voltage changes accordingly, but the system efficiency deteriorates and power consumption increases sharply at very high input voltages
Solution Approach 1:
The patent incorporates voltage detection circuits that continuously monitor input voltage levels and provide feedback to the control logic. Based on this feedback, the system automatically adjusts its operating mode, selecting appropriate LED groups and current distribution strategies to maintain optimal efficiency across the full input voltage range.
Solution Approach 2:
The patent changes operating parameters dynamically based on input voltage conditions. When input voltage is high, the system activates fewer LED groups in parallel with reduced current per group; when input voltage is low, it activates more groups with higher current. This parameter adaptation prevents excessive power consumption at high voltages while maintaining adaptability across the voltage range.
3Power
If more LEDs are used to match the maximum rectifier output voltage, then voltage utilization improves, but the system stability and reliability worsen due to increased sensitivity to input voltage changes
Solution Approach 1:
By segmenting LEDs into multiple parallel groups, the patent reduces the voltage stress on each individual LED string. This segmentation isolates failures to specific groups rather than affecting the entire string, improving reliability while maintaining good voltage utilization through selective activation of groups based on input 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
Enables a significant reduction in the number of LEDs needed while maintaining high driving efficiency by controlling the energy storage component to charge and discharge based on voltage thresholds, ensuring the sum of VF values does not exceed the maximum output voltage, thus providing flexibility and stability across varying input voltages.
Implementation Method 1
an energy storage component, a switch module, a constant current supply module... the switch module controls the energy storage component to charge and discharge
Implementation Method 2
the rectifier module rectifies an alternating current (AC) from an external input
Data Source
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Figure 5a~6
AI summary
A linear constant current LED drive device capable of driving reduced number of LEDs, comprises: a rectifier module, an energy storage component, a switch module, a constant current supply module, a measurement module and a control module. When voltage differences between two ends of both switch module and constant current supply module are less than according threshold voltages, control module turns on switch module, enabling rectifier module to charge energy storage component and LED string lights. When voltage difference between two ends of either switch module or constant current supply module exceeds according threshold voltage, control module turns off switch module, enabling energy storage component to charge LED string lights. So rectifier module and energy storage component supply electricity to plurality of LED string lights alternately, number of LEDs can be reduced, while maintaining high drive efficiency.