LED Segment Bypass for Flicker Reduction
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Solution Overview
Problem
Existing LED systems face issues with power factor correction, harmonics, and flicker when operating high-power LED modules, particularly due to the direct connection of series-connected LEDs to the AC voltage grid, leading to inefficient energy use and non-compliance with normative standards.
Innovation Solution
A circuit design that includes multiple series-connected segments with different semiconductor light-emitting elements, each with its own driver, allowing for dynamic bypassing based on instantaneous mains voltage values and switching states, optimizing the operation of LEDs without explicit measurement of the rectified mains voltage, and utilizing a current regulator to manage voltage changes and ensure efficient power distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If series-connected LEDs are operated directly on the AC voltage grid, then the circuit complexity is reduced, but severe light modulation (flicker) and energy-inefficient utilization occur
Solution Approach 1:
The LED string is divided into multiple segments with different forward voltages, allowing selective bypassing of segments to match the instantaneous mains voltage. This segmentation enables efficient energy utilization while maintaining relatively simple circuitry through the use of basic switching components.
Solution Approach 2:
The circuit dynamically adjusts the number of active LEDs in series by bypassing segments based on the instantaneous mains voltage level. This dynamic adaptation eliminates flicker and optimizes energy efficiency without requiring complex control systems, as the switching is triggered by simple voltage threshold detection.
2Device complexity
If series-connected LEDs are operated directly on the AC voltage grid, then the circuit complexity is reduced, but severe light modulation (flicker) occurs
Solution Approach 1:
The LED string is divided into multiple segments with different forward voltages, allowing selective bypassing of segments to match the instantaneous mains voltage. This segmentation enables efficient energy utilization while maintaining relatively simple circuitry through the use of basic switching components.
Solution Approach 2:
The circuit dynamically adjusts the number of active LEDs in series by bypassing segments based on the instantaneous mains voltage level. This dynamic adaptation eliminates flicker and optimizes energy efficiency without requiring complex control systems, as the switching is triggered by simple voltage threshold detection.
3Adaptability or versatility
If a rectifier is connected upstream of the series circuit including LEDs, then the circuit can operate from AC voltage, but power factor correction problems and harmonics occur
Solution Approach 1:
The circuit uses the periodic nature of the rectified mains voltage to trigger segment bypassing at appropriate moments in the voltage cycle. By synchronizing the bypassing action with the voltage waveform, the circuit achieves good power factor correction and minimizes harmonics without requiring active power factor correction circuits.
Solution Approach 2:
The circuit converts the potentially harmful voltage variations and ripple from the rectifier into useful control signals for segment bypassing. The rectified voltage's periodic peaks naturally trigger the bypassing of LED segments, transforming what could be a source of harmonics into an effective timing mechanism for power optimization.
4Productivity
If different semiconductor light-emitting elements with different forward voltages are used in segments, then optimized actuation is achieved, but the manufacturing complexity increases
Solution Approach 1:
The invention utilizes LED segments with different forward voltage parameters to enable voltage-matched operation at different points in the mains voltage cycle. While this requires selecting LEDs with specific voltage characteristics, it allows the circuit to operate efficiently across a wide voltage range without complex control electronics, balancing manufacturing feasibility with operational efficiency.
Data Source
AI summary
A circuit for actuating semiconductor light-emitting elements, wherein the circuit is supplied by a rectified mains voltage, may include at least two series-connected segments, which each have one or more series-connected semiconductor light-emitting elements, wherein the semiconductor light-emitting elements in at least two of the segments are different, which results in different forward voltages of the segments, and in each case one driver for actuating a segment, wherein the driver has at least one electronic switch, by means of which the segment may be bypassed, wherein the circuit arrangement is designed to decide to bypass the segment assigned to the circuit arrangement, on the basis of an instantaneous value of the rectified mains voltage and on the basis of the bypass state of the adjacent segments.