Tapped Buck Converter LED Driver for Harmonic Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Single-stage Buck converters used to power LEDs experience interruption periods due to input voltage being lower than the threshold voltage of the load section, leading to elevated harmonic components and compromised circuit performance, making it impractical for high-quality LED lighting systems.
Innovation Solution
An integrated LED lighting system with a Buck converter and a switching circuit that applies DC current to LED strings in sequence based on instantaneous voltage levels, reducing the duration of interruption periods and minimizing total harmonic distortion by dynamically disconnecting strings during low voltage conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-stage Buck converter is used to power LEDs, then circuit simplicity is improved, but interruption periods occur when input voltage is lower than threshold voltage, leading to elevated harmonic components and compromised circuit performance
Solution Approach 1:
The LED load section is divided into multiple strings with different threshold voltages. The switching circuit selectively activates specific strings based on the instantaneous input voltage level, ensuring that at least one string can be powered without interruption across the full AC voltage cycle, thereby eliminating harmonic distortion while maintaining circuit simplicity.
Solution Approach 2:
The switching circuit dynamically selects which LED string to activate based on the real-time instantaneous voltage level. This dynamic adaptation allows the system to operate continuously without interruption periods, resolving the contradiction between simple circuit design and reliable performance across varying voltage conditions.
2Illumination intensity
If DC current is applied to all LED strings simultaneously, then complete illumination is improved, but interruption periods occur during low voltage conditions, causing harmonic distortion
Solution Approach 1:
The LED load section is divided into multiple strings with different threshold voltages. The switching circuit selectively activates specific strings based on the instantaneous input voltage level, ensuring that at least one string can be powered without interruption across the full AC voltage cycle, thereby eliminating harmonic distortion while maintaining circuit simplicity.
Solution Approach 2:
Different LED strings are assigned different threshold voltage characteristics. During low voltage conditions, the switching circuit activates only those strings with lower threshold voltages, providing localized illumination that adapts to available power while preventing the system-wide interruption that would cause harmonic distortion.
3Duration of action of stationary object
If LED strings with different threshold voltages are used, then continuous operation without interruption is improved, but device complexity increases
Solution Approach 1:
The LED load section is divided into multiple strings with different threshold voltages. The switching circuit selectively activates specific strings based on the instantaneous input voltage level, ensuring that at least one string can be powered without interruption across the full AC voltage cycle, thereby eliminating harmonic distortion while maintaining circuit simplicity.
Solution Approach 2:
Multiple LED strings with different threshold voltage characteristics are combined into a single load section. The switching circuit integrates control of these diverse strings, allowing the system to leverage their combined voltage range to achieve continuous operation without requiring complex external voltage regulation circuitry.
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 significantly reduces the duration of interruption periods and total harmonic distortion, making single-stage Buck converter circuits practical for high-quality LED lighting systems by ensuring efficient power delivery and reducing electromagnetic interference.
Implementation Method 1
A buck converter is disposed on the electronics board and is electrically coupled to provide a direct current (DC) current based on an AC current at the AC input
Data Source
AI summary
Systems, devices and methods are described herein. An integrated light emitting diode (LED) lighting system includes an electronics board. An alternating current (AC) input is disposed on the electronics board. Multiple strings of LED devices are disposed on the electronics board, each having an individual voltage threshold. A buck converter is disposed on the electronics board and is electrically coupled to provide a direct current (DC) current based on an AC current at the AC input. A switching circuit is disposed on the electronics board and is electrically coupled to the strings of LED devices to apply the DC current to each of the strings in a sequence beginning at a time when an instantaneous voltage level at the AC input reaches the individual threshold voltage of a first one of the strings of LED devices in the sequence.