LED Driving Circuit with Segmented AC-DC Conversion
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Solution Overview
Problem
Existing driving circuits for LEDs face issues with current ripple and flicker, leading to unstable LED current and decreased lighting quality, and require improvement in power factor to achieve energy-saving, which is not effectively addressed by traditional power factor correctors.
Innovation Solution
A driving circuit comprising a rectifier circuit, an LED driver integrated circuit with a regulator, voltage detector, signal generator, and buck boost LED driver, which converts AC power to DC and then to Constant Current (CC) for stable LED operation, while employing a power factor corrector to minimize power consumption and improve power factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a power factor corrector is employed in the driving circuit, then the power factor is improved and energy-saving is achieved, but current ripple and flicker problems occur, making LED current unstable and declining lighting quality
Solution Approach 1:
The patent segments the power conversion process into two distinct stages: first converting AC to DC, then converting DC to constant current. This segmentation allows each stage to be optimized independently, avoiding the need for a traditional power factor corrector that causes ripple and flicker issues while still achieving improved power factor and stable LED current.
Solution Approach 2:
Instead of using a conventional power factor corrector approach that directly processes AC power and causes ripple, the patent inverts the approach by first rectifying AC to DC and then using a DC-DC converter to generate constant current. This inverted sequence eliminates the harmful effects while maintaining power factor improvement.
2Device complexity
If AC power is directly converted to drive LED load, then the circuit structure is simplified, but power factor deteriorates and energy efficiency decreases
Solution Approach 1:
The patent divides the power conversion into two functional modules: a rectifier circuit for AC-to-DC conversion and a DC-DC converter for constant current generation. This segmentation, while adding components, creates a more efficient energy conversion path that improves power factor and overall energy efficiency compared to direct AC-LED driving.
Solution Approach 2:
The patent introduces DC power as an intermediary between AC power and LED load. This DC intermediate stage acts as a mediator that enables efficient power factor correction and stable current regulation, bridging the gap between AC input and LED requirements while minimizing energy loss.
3Loss of energy
If traditional power factor corrector is used, then power factor is improved, but LED current becomes unstable due to current ripple and flicker
Solution Approach 1:
The patent inverts the conventional power factor correction approach by not using a traditional PFC circuit. Instead, it rectifies AC to DC first, then uses a DC-DC converter to generate constant current, thereby achieving power factor improvement without the current ripple and flicker that plague traditional PFC circuits.
Solution Approach 2:
The patent replaces the mechanical/analogue power factor correction mechanism with a digital control-based DC-DC conversion system. This substitution uses pulse-width modulation and digital signal processing to achieve precise current regulation and power factor correction without the inherent ripple and flicker of traditional analog PFC circuits.
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
The solution stabilizes LED current and voltage, reduces ripples and flicker, enhances lighting quality, and minimizes unnecessary power consumption by effectively converting AC power to stable DC and then CC, thereby improving the power factor and overall energy efficiency.
Implementation Method 1
The rectifier circuit rectifies an ac power supply into a dc power supply
Implementation Method 2
The voltage detector detects whether the regulated voltage meets a voltage requirement
Data Source
AI summary
A driving circuit includes a rectifier circuit and a LED driver integrated circuit. The rectifier circuit rectifies an ac power supply into a de power supply. The LED driver integrated circuit includes a regulator circuit, a voltage detector, a buck boost LED driver, and a common ground terminal. The regulator circuit regulates the dc power supply into a regulated voltage. The voltage detector detects whether the regulated voltage meets a voltage requirement and output the regulated voltage when the voltage requirement is met. The buck boost LED driver converts the regulated voltage detected into an output driving voltage according to a remaining voltage at a negative terminal of the LED load to drive the LED load. Voltage potentials at the common ground terminal and at a load ground terminal of the LED load are the same.