Direct AC Drive LED Array with Reconfigurable Controller
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Solution Overview
Problem
Conventional LED light sources powered by AC sources suffer from low efficiency and flicker due to the need for AC-DC converters, and direct AC operation results in inefficient use of LEDs with significant power losses and reduced light output, as they must be connected in series to withstand peak voltages, leading to excessive component and packaging costs.
Innovation Solution
A light source utilizing a reconfigurable two-dimensional LED array and a controller that adjusts the array's configuration based on the AC power potential, ensuring the minimum bias potential is below the power potential when it exceeds a threshold and the maximum bias potential is not exceeded, thereby optimizing LED operation and reducing power losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If AC-DC power converter is used to power LED light sources, then the LED can operate with constant current for high conversion efficiency, but the cost of the power converter increases significantly and power losses reduce overall efficiency
Solution Approach 1:
The patent removes the AC-DC power converter from the LED lighting system, allowing the LED to operate directly from AC power. This extraction of the converter eliminates its cost and power losses while the LED string is designed to tolerate AC voltage variations through careful selection of LED forward voltage characteristics and operating current.
Solution Approach 2:
The LED string is designed to self-regulate its operation under AC power without external conversion. The LEDs' inherent electrical characteristics and the string configuration allow them to automatically adapt to the AC waveform, converting AC power directly to light without requiring an external power converter.
2Reliability
If multiple LEDs are connected in series to withstand peak AC voltage, then the maximum voltage is accommodated, but the number of LEDs required increases significantly compared to DC driving schemes
Solution Approach 1:
The patent operates LEDs at higher current levels than typical DC driving schemes, which changes the electrical parameters to allow fewer LEDs to be used. By accepting higher instantaneous power dissipation and heat generation that can be managed through thermal design, the system reduces the total number of LEDs needed while still accommodating peak AC voltages.
3Device complexity
If LEDs are operated directly from AC power without power conversion, then component costs are reduced, but efficiency is low and flicker occurs
Solution Approach 1:
The patent removes the efficiency-reducing power converter while implementing direct AC operation. By eliminating the converter's power losses and implementing proper LED string configuration and current management, the system achieves both low component cost and high operational efficiency simultaneously.
4Reliability
If direct AC operation is implemented without power conversion, then the system is simpler and more reliable, but significant power losses occur and light output is reduced
Solution Approach 1:
The LED string is designed to self-regulate under AC power, automatically managing power dissipation and heat generation. The system accepts the AC waveform directly and converts it to light through the LEDs' inherent characteristics, achieving high reliability without external conversion while minimizing power losses through optimized operating parameters.
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 enhances the efficiency and reliability of LED light sources by maintaining consistent light output throughout the AC cycle, reducing flicker, and minimizing power losses, while also reducing component and packaging costs by allowing for fewer LEDs to be used.
Implementation Method 1
Light-emitting diodes (LEDs) are an important class of solid-state devices that convert electric energy to light
Implementation Method 2
the current through the LED increases exponentially with voltage above the turn-on voltage until the current is limited by the series resistance of the LED
Data Source
AI summary
A light source and method for operating a light source are disclosed. The present invention includes a light source and method for using the same. The light source includes a power coupler, a reconfigurable two-dimensional LED array and a controller. The power coupler is configured to receive a power potential that varies as a function of time. The LED array has a plurality of configurations of LEDs, each configuration being characterized by a minimum bias potential and a maximum bias potential. The LED array generates light when a potential between first and second power terminals is greater than the minimum bias potential. The controller varies the configuration of the array such that the power potential remains between the minimum and maximum bias potentials as the power potential varies.